Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety: ICCATS 2022 3031211197, 9783031211195

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Lecture Notes in Civil Engineering

Andrey A. Radionov · Dmitrii V. Ulrikh · Svetlana S. Timofeeva · Vladimir N. Alekhin · Vadim R. Gasiyarov   Editors

Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety ICCATS 2022

Lecture Notes in Civil Engineering Volume 308

Series Editors Marco di Prisco, Politecnico di Milano, Milano, Italy Sheng-Hong Chen, School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan, China Ioannis Vayas, Institute of Steel Structures, National Technical University of Athens, Athens, Greece Sanjay Kumar Shukla, School of Engineering, Edith Cowan University, Joondalup, WA, Australia Anuj Sharma, Iowa State University, Ames, IA, USA Nagesh Kumar, Department of Civil Engineering, Indian Institute of Science Bangalore, Bengaluru, Karnataka, India Chien Ming Wang, School of Civil Engineering, The University of Queensland, Brisbane, QLD, Australia

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Andrey A. Radionov · Dmitrii V. Ulrikh · Svetlana S. Timofeeva · Vladimir N. Alekhin · Vadim R. Gasiyarov Editors

Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety ICCATS 2022

Editors Andrey A. Radionov Moscow Polytechnic University Moscow, Russia Svetlana S. Timofeeva Irkutsk National Research State Technical University Irkutsk, Russia

Dmitrii V. Ulrikh South Ural State University Chelyabinsk, Russia Vladimir N. Alekhin Ural Federal University Ekaterinburg, Russia

Vadim R. Gasiyarov Moscow Polytechnic University Moscow, Russia

ISSN 2366-2557 ISSN 2366-2565 (electronic) Lecture Notes in Civil Engineering ISBN 978-3-031-21119-5 ISBN 978-3-031-21120-1 (eBook) https://doi.org/10.1007/978-3-031-21120-1 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Preface

The International Conference on Construction, Architecture and Technosphere Safety (ICCATS-2022) was organized by Moscow Polytechnic University, Moscow, Irkutsk National Research Technical University, Irkutsk and Ural Federal University named after the first President of Russia B. N. Yeltsin, Yekaterinburg on 4–10 of September 2022. The conference program encompassed a wide range of topics and was divided into 4 sections: Industrial and Civil Engineering; Special and Unique Structures Construction; Urban Engineering and Planning; Engineering Structure Safety, Environmental Engineering and Environmental Protection. Participants could take part in the conference in a traditional face-to-face format and as the format of video conference remotely. The international program committee has selected a total of 58 papers for publishing in Lecture Notes in Civil Engineering (Springer International Publishing AG). On behalf of the Organizing Committee, we express appreciation to our colleagues who participated in the review procedure of the papers and especially thank members of the International Program Committee, who helped us to organize this conference. We express our gratitude to the participants for their active work at the conference sections and look forward to meeting at ICCATS-2023 next September in Sochi, Russia. Moscow, Russia Chelyabinsk, Russia Irkutsk, Russia Ekaterinburg, Russia Moscow, Russia

Prof. Andrey A. Radionov Prof. Dmitrii V. Ulrikh Prof. Svetlana S. Timofeeva Prof. Vladimir N. Alekhin Prof. Vadim R. Gasiyarov

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Contents

Industrial and Sivil Engineering Blast-Induced Seismicity Impact on the Stability of Hydraulic Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . U. A. Yatimov, A. J. Yatimov, N. S. Safaraliev, I. A. Yatimov, and L. D. Safarov Modeling of Connection Nodes of Elements Rod Structures . . . . . . . . . . . I. Alaverdov, N. Buzalo, N. Tsaritova, A. Kurbanova, and I. Platonova The Actuality of Geotechnical Monitoring on the Example of Construction Objects in Tyumen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. A. Stepanov Prospects for the Use of Painted Ceramic Facing Materials Using Man-Made Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. S. Romanyuk, L. V. Klimova, V. M. Kurdashov, A. I. Izvarin, and V. S. Yatsenko Parametric Studies of Intra-Modular Connections Stiffness . . . . . . . . . . . V. Shirokov and T. Belash Responsive Architecture as a Synthetic Field in Architecture and Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. Zolotareva and A. Ponomarev Use of Soft Wood Waste in the Production of Wood Particle Boards . . . . A. Titunin, T. Vakhnina, I. Susoeva, and A. Titunin Junior Assessing the Applicability of Sand Hydraulic Conductivity Calculation Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. V. Nikitin and O. M. Zaborskaya Lining Application by Means of Guniting (Using Machine TOR-1) . . . . . M. B. Permyakov, E. I. Pashkov, and T. V. Krasnova

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24

35

45

58 70

80 89

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Impact of the Coolant Flow Velocity on the Thermal Condition of Flat-Plate Solar Collectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T. V. Shchukina, A. S. Efanova, and I. S. Kurasov

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Polymer-Cement Concrete Based on Polyvinyl Acetate Dispersion for Construction 3D Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 A. Puzatova, S. Sokolnikova, and M. Dmitrieva General Formula of Beams Strengthening . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 A. A. Sobakin and V. K. Fedorov Determining the Water Demand of Fine Aggregates . . . . . . . . . . . . . . . . . . 128 I. L. Kostiunina, A. L. Rozovskii, and S. N. Pogorelov Increasing the Energy Efficiency of Buildings . . . . . . . . . . . . . . . . . . . . . . . . 137 L. M. Vesova and A. A. Churakov The Use of PVC Waste in Concrete with the Addition of PVAc . . . . . . . . . 147 S. Sokolnikova, A. Puzatova, and M. Dmitrieva Bearing Capacity and Deformability of Connections of Wooden Structures on TGC Dowel Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 S. A. Isupov Increasing the Resistance of Chloromagnesian Composites to Cracking Under Prolonged Water Saturation . . . . . . . . . . . . . . . . . . . . . . 168 G. Averina, V. Koshelev, and L. Kramar Steady-State Nonlinear Heat and Mass Transfer in Multilayer Enclosing Structures of Buildings and Constructions . . . . . . . . . . . . . . . . . 178 R. A. Sadykov and A. K. Mukhametzianova Modeling of Construction Objects When Considering Repair Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 Ya. Lvovich, I. Lvovich, A. Preobrazhenskiy, and Yu. Preobrazhenskiy Static Three-Point Bending Tests on 3D Printed Multilayer Composite Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206 I. A. Solovev, M. V. Shitikova, and A. V. Mazaev Stress–Strain Properties of Concrete at Early Freezing . . . . . . . . . . . . . . . . 217 R. T. Brzhanov, M. K. Suimenova, G. I. Esbolay, K. M. Shaikhieyva, and B. S. Akmurzaeva A Modified Implicit Scheme for the Numerical Dynamic Analysis of Beam Elements Considering Nonlocal in Time Internal Damping . . . . 226 V. N. Sidorov, E. S. Badina, and E. P. Detina Optimizing the Structure of Construction Mixes for 3D Printing . . . . . . . 235 V. A. Solonina, I. A. Surovtsev, and M. D. Butakova

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Evaluation of Deformation Properties of Portland Cement Mortars Modified with Microfiber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 V. A. Dmitrienko, S. A. Maslenikov, O. V. Pashkova, and N. A. Dmitrienko Energy-Saving Technologies for the Construction and Operation of Buildings in the Arctic Zone of the Russian Federation . . . . . . . . . . . . . 258 E. P. Sharovarova and V. N. Alekhin Influence of Surface Tension Forces of Modifiers on Some Properties of Composite Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 A. Pichugin, A. Pchelnikov, O. Smirnova, and S. Tkachenko Methodology of Determination of the Platform Joint of Reinforced Concrete Large-Panel Buildings Stiffnesses . . . . . . . . . . . . . . . . . . . . . . . . . . 277 Z. Abaev, A. Valiev, and M. Kodzaev Special and Unique Structures Construction Damping of Structures of Earthquake-Resistant Suspended Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 T. Belash and I. Svitlik The Design of Architectural Forms Based on Irregular Curves . . . . . . . . . 298 V. A. Korotkiy, E. A. Usmanova, and L. I. Khmarova “Healthy” Architecture: Synthesis of Humanistic Approaches . . . . . . . . . 309 T. Yu. Bystrova, A. M. Postnikova, and A. V. Garas Features of Designing Unique Architectural Objects in Extreme Natural Environments: The Precedents of Application . . . . . . . . . . . . . . . . 320 N. A. Saprykina Optimization of Microclimate Parameters in Tent-Frame Buildings . . . . 330 I. Yu. Shelekhov and M. I. Shelekhov Method of Hydraulic Calculation of Gas Distribution Networks . . . . . . . . 340 O. N. Medvedeva and S. D. Perevalov Urban Engineering and Planning Industrial Renovation in Context Sustainable Urban Development . . . . . 353 N. M. Shabalina The Compositional Regulation of the Historic Environment and Urban Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363 E. Prutskova and O. Finaeva Integrating Standard Residential Buildings with Architecture and Space of Historically Sensitive Environment . . . . . . . . . . . . . . . . . . . . . 374 N. V. Kuznetsova and P. V. Monastyrev

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Relationship Between the Formation of Post-Covid Residential Complexes and the Architecture of Soviet Commune Houses . . . . . . . . . . 384 I. N. Maltseva and E. S. Zhilyakova Improving the Efficiency of Urban Wastewater Treatment Plants Based on Information Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396 A. Antonets, N. Buzalo, M. Trubchaninov, and S. Scherbakov Comprehensive Analysis of Pedestrian and Walking Spaces of Cities (Including Coastal Areas) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406 N. Burilo, A. Kruglikova, A. Tsyba, I. Makarikhina, and A. Volikova The Influence of the Building Configuration on the Occurrence of Increased Wind Speeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415 V. D. Olenkov, A. V. Alemanov, A. O. Kolmogorova, A. E. Sarayeva, and E. S. Sozikina Engineering Structure Safety, Environmental Engineering and Environmental Protection Irregular Process Type Effect on Fatigue Crack Propagation Rate . . . . . 427 I. Gadolina, N. Dinyaeva, and M. Bubnov Ensuring the Safety of a Quarry Distribution Network with a Voltage of 6–35 kV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436 Kh. D. Boboev, R. T. Abdullozoda, O. S. Sayfiddinzoda, I. T. Abdullozoda, and K. V. Ivshina Analysis of Recreational Zones Negative Impact on Water Area of Lake Baikal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446 O. Grebneva, O. Lavygina, and O. Vanteeva Basic Procedure to Estimate the Accumulated Environmental Damage Caused by Mining Facilities as Exemplified by the Kachkanar Tailing Dump in the Middle Urals . . . . . . . . . . . . . . . . . 456 V. A. Pochechun, V. E. Konovalov, and A. I. Semyachkov Technosphere Safety in Russia by Ensuring Carbon Neutrality in the Face of Climate Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467 N. Umnyakova and I. Shubin Drilling Waste as a Promising Man-Made Material for the Synthesis of Aluminosilicate Proppant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478 A. A. Tretyak, A. A. Chumakov, V. A. Smoliy, D. A. Golovko, and N. S. Goltsman Application of Kaniadakis κ-Statistics to Load and Impact Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 489 A. Bushinskaya and S. Timashev

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Specifics of Applying the Fragility Theory to Technical Systems and Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 S. Timashev and A. Bushinskaya Suspended Ceiling Safety for Firefighters in Case of Fire in the Attic . . . 513 S. V. Fedosov, A. A. Lazarev, V. G. Kotlov, V. G. Malichenko, and D. E. Tsvetkov Biocidal Corrosion-Resistant Composite Coatings from Industrial Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523 Yu. E. Tokach, A. A. Balakhonov, V. Yu. Zhilenko, V. A. Doroganov, and M. M. Flores Arias Influence of Modifying Additives on the Structure and Properties of Porous Geopolymer Building Materials Based on Solid Fuel Combustion Waste of Arctic Thermal Power Plants . . . . . . . . . . . . . . . . . . . 534 E. A. Yatsenko, B. M. Goltsman, S. V. Trofimov, Yu.V. Novikov, and T. A. Bondareva Structural Ceramics Low-Temperature Phases Colouring Theoretical Basics and Its Colour Management . . . . . . . . . . . . . . . . . . . . . . 544 N. D. Yatsenko, A. I. Yatsenko, N. A. Vilbitskaya, O. I. Sazonova, and R. V. Savanchuk Bayesian Network Modeling for Analysis and Prediction of Accidents in Railway Transportation of Dangerous Goods . . . . . . . . . . 554 M. V. Chikir and L. V. Poluyan Waste from Extraction, Enrichment and Combustion of Solid Fuels is a Promising Raw Material for the Synthesis of Geopolymer Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564 A. V. Ryabova, V. D. Tkachenko, I. V. Rusakevich, I. D. Morozov, and A. N. Ivanov The Possibility of Using Lithium-Containing Waste in the Russian Federation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 574 K. A. Vorobyev, I. V. Shadrunova, and T. V. Chekushina Artificial Intelligence for Water Supply Systems . . . . . . . . . . . . . . . . . . . . . . 583 M. Novosjolov, D. Ulrikh, and M. Bryukhov Using Wheat Straw for Treatment of Urban Surface Water Run-Offs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596 O. A. Samodolova, A. P. Samodolov, D. V. Ulrikh, and S. S. Timofeeva Sorption Properties of Composite Materials Based on Hemp Hulls and the Byproducts of Silicon Production Used to Remove Antibiotics from Wastewater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604 S. S. Timofeeva, M. S. Tepina, and O. V. Tukalova

Industrial and Sivil Engineering

Blast-Induced Seismicity Impact on the Stability of Hydraulic Structures U. A. Yatimov1,2(B) , A. J. Yatimov3 , N. S. Safaraliev4 , I. A. Yatimov1 , and L. D. Safarov4 1 South Ural State University, 76, Lenin Ave., Chelyabinsk 454080, Russia

[email protected]

2 South Ural Federal Research Center of MiG of the Ural Branch of the Russian Academy of

Science, Ter. Ilmeny Res., Miass 456317, Russia 3 Tajik Technical University, 10 Ak. Radzhabovs St., Dushanbe 734042, Tajikistan 4 Tajik National University, 17, Rudaki Ave., Dushanbe 734025, Tajikistan

Abstract. In this article we analyze the influence of the blast-induced seismicity on the stability of hydraulic structures. It is known that when hydraulic tunnels are constructed during blasting works, both on the surface and in the underground space, one should take into account the influence of seismic effects on their stability. The task of forecasting and ensuring the stability of mine workings during earthquakes is very challenging because residual deformations appear in the rocks within shot points. Notably, during construction, blasting operations are often performed in the immediate vicinity of underground mines. This is the reason for limiting the number of massive blasts when the action of seismic waves should be taken into account. The analysis of this problem allowed us to conclude that under the influence of a seismic force, underground blasts can be used near existing dams and hydraulic structures and it does not have a dangerous influence on them. Keywords: Hydraulic structures · Impacts · Earthquakes · Explosions · Blast waves · Geological factors · Deformations

1 Introduction Many underground mines of various profiles are built during the construction of different hydroelectric power plants. Occupying large areas, underground structures have various shapes in cross-sections. So, for example, the tunnels of the Nurek and Rogun HPPs, which are built on the Vakhsh river in Tajikistan have the cross-sectional areas of 125–150 m2 [1–5]. Such mines are generally designed for a long service life; therefore, they are laid in hard rocks, which can be broken only by the blast energy, and the simultaneous blast of a significant amount of explosives (E) is widely used [6–8]. When performing blasting operations during the construction of hydraulic tunnels both on the surface and in underground conditions, one should take into account their © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_1

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U. A. Yatimov et al.

seismic effect on the stability of underground mines and a hydraulic structure on the surface since the latter is functionally dependent on several mining engineering factors [9, 10]. Domes of mines are the place where fractured rocks are in the least stable state because all blocks cut by the blast are almost not redistributed to the power of the mines and completely interact with the cohesion forces between rock blocks. If the weight of the cut block is larger than the adhesion force between the blocks, the blocks collapse; if the adhesion force is less, the block may move during the blasting concussion. In the conditions of dynamic effects of rock pressure, the task of forecasting and ensuring the stability of mine workings becomes much more complicated.

2 Blast Impact on Hydraulic Structures Within the focal point, the rock is subjected to loads causing residual deformations. Near the crushing zone, these are cracks and stabs, while closer to the boundaries of the focal point deformations are represented by microcracks and hidden plastic deformations without a visible change in the rock volume. However, there are certain irreversible residual deformations within the entire focal point, wherefore this rock volume can be called a zone of inelastic deformation. The dimensions of this zone are determined by the reduced distance, which is 2.5–10 m/kg for various rocks. The amplitude of the vibration train propagating from the crushing zone is dominated by volumetric longitudinal and transverse waves intensely damping with distance. The size of this near seismic zone is 10 m/kg1/3 for all types of rocks, and the vibrations damp first proportionally to the cube, and then—to the square of the distance. The vibration speed in this zone decreases from 10 to 3 cm/s (Table 1). Table 1. Equivalent reduced distance and damping factor. Zones

Nature of rock deformation

Equivalent reduced distance

Equivalent damping factor

Zones of inelastic behavior

Intensive development of open cracks

0.1–0.6

3

Appearance of closed cracks radial and parallel to the open surface

0.6–3

2

Residual microdeformations

3–6

2

Near seismic zone

Nonlinear elastic

6–10

2

Far seismic zone

same

10–170

1.5

Zone of weak seismic vibrations

Elastic

More than 170

1.0

Blast-Induced Seismicity Impact

5

As the waves propagate, starting from a distance corresponding to the equivalent reduced distance of 10 m/kg1/3 in terms of the amplitude of the vibration speed, surface waves begin to dominate. The surface waves damp in proportion to the distance raised to the power of 1.5. This zone extends from the exploded charges to the distances corresponding to the equivalent reduced distance from 10 to 170 m/kg/3 , and the maximum vibration speed in it decreases from 3 cm/s to 0.5 cm/m. This is a far seismic zone, outside of which the massif experiences weak seismic vibrations that attenuate proportional to the distance. The permissible vibration speed is taken as the permissible seismic effect of blasts. Then, to determine the equivalent reduced distance, we can use the following simplified equations: • for the zone of inelastic behavior of the rock and the near seismic zone,  Re = rgr · rc1 /ϑpr • for the far seismic zone, Re = 0.45 ·

 2 3  rgr · rc1 /ϑpr

(1)

(2)

• for the zone of weak seismic vibrations, Re = 0.025 · rgr · rc1 /ϑpr

(3)

√ where: Re = r/ 3 Q [3]Q; rgr is the coefficient taking into account the seismicity of the water cut in rocks at the base of buildings and structures; rc1 is the coefficient of seismicity of the blasted rocks. rgr = kv ·

rc1 rc2

(4)

rc1 and rc2 are accepted for category I of rocks by their seismicity—10; kv is the correction for the water cut in soils and rocks in the protected area. The values of kv for the ground water laying below 15 mare 10; flooded rock massifs—1.2; soils at a groundwater level of 5–15 m—1.3; at a groundwater level up to 5 m—2; very watered—3. Blasting operations during the construction of a hydroelectric power plant are often performed in the immediate vicinity of underground mines and chambers, block pillars and dams. This imposes certain restrictions on large-scale blasts, which should be designed and conducted accounting for the effect of seismic waves. During large-scale blasts, zones of dangerous stresses in the massif may appear. The magnitude of this stress is determined by the physical, mechanical, and structural features of the massif and can be determined experimentally. One of the main indicators characterizing the negative influence of seismic loads is, in turn, determined mainly by the value of the simultaneously exploded charge of the explosive. Therefore, the main way of reducing the dangerous influence of the seismic effect is to calculate the permissible value of the explosive charge blasted in a quarry and mines.

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To reduce the intensity of seismic vibrations, we propose to switch to a seismicsafe technology in the application of such blasting schemes. This technology would prevent the maximum mass of the simultaneously blasted explosive from exceeding the calculated value, and would allow for the deceleration time to fluctuate within the optimal range of 25–50 ms. When expanding vertical workings during the construction of underground hydroelectric power plants (placing of a gate gallery, tension shafts, machine rooms, etc.), delineation wells are drilled by vertical wells with diameters of 85–100 mm parallel to the bore rising to the entire depth (up to 30 m) (Fig. 1). Wells with entry ways of up to 30 m are used if the bore has a large depth. The distance between the delineation wells, depending on the strength of the rocks, is 15-20dz . Blast firing is delayed. This method is most effective as it provides a high performance rate with low labor intensity. The disadvantage of this method is the inaccuracy of delineating the bore cross-section at increased distances between the delineation wells, except for the cases of using smoothwall blasting by the method of preliminary presplitting. Besides, if this work method is used, there are increasing harmful seismic effects of the blast on closely located mine workings and structures (Fig. 1) [11–13].

Fig. 1. Bore expansion scheme: 1—pilot shothole, 2—wells, 3—blasted rock.

The choice of the method for expanding the bore in a particular case is made based on the available tunneling equipment and the mining conditions of the work. To reduce overshoot cracking in the rock mass, smoothwall blasting is used, the peculiarity of which is to reduce the blast energy and the rational arrangement of the delineation boreholes. A decrease in the concentration of the blast per 1 m of the borehole is achieved by using explosives with high (360–450 cm3 ) performance in small-diameter cartridges (21–24 mm) or by using explosives with low (260–300 cm3 ) performance in cartridges of normal diameter (24–32 mm) [14]. The use of smoothwall blasting reduces the depth of cracks in the rock mass by 4–7 times, reduces overbreak by about 3 times and the cost of fixing 1 m of an underground structure by 1.5 times. Smoothwall blasting can be performed by preliminary delineation. In this case, the boreholes are placed around the perimeter, every second one is charged. The distance

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between the boreholes is taken equal to 4–6 diameters of the borehole. The delineating holes are blasted first. When the charges of the delineating holes explode, a gap between the holes is formed. This gap serves as a screen and prevents the passage of the blast wave and stresses into the aquifer rock mass during the explosion of the charges of the main boreholes. When installing deepwater intakes for taking water from existing reservoirs or lakes, it is necessary to blast the pillar left between the reservoir and the tunnel face, which is a very crucial moment; the process sometimes becomes complicated by the fact that hydrotechnical structures can be located nearby, which can be affected by both seismic vibrations during the explosion and increased water pressure (above the hydrostatic). Such a situation arose during the construction of a water intake for the Chute de Piel underground hydroelectric power plant in Canada [15, 16]. The Chute de Piel hydroelectric power plant with a capacity of 736 MW was commissioned in 1960. The reservoir was created as a result of building a concrete dam with a height of 48 m in 1943. Therefore, the tunneling excavation was stopped at a distance of 21 m from the slope surface, leaving a rock pillar with a diameter of 18 m and a volume of 10 thousand m3 , which was blasted with a charge weighing 27 tons [15, 17, 18]. The dam is located 200 m from the water intake. The same granite-gneisses and paragneisses as in the area of the water intake, with numerous cracks parallel to the river, are confined to the dam’s base. The dam was designed on the expectation of earthquakes with an acceleration of 0.055 d. The horseshoe-shaped tunnel has a gate length from the reservoir to the shaft equal to 200 m and a height of 16 m at the entrance and 25 m at the shaft (Fig. 2) [15].

Fig. 2. Longitudinal section of the water intake of the Chute de Piel hydroelectric power plants in Canada hydroelectric power plant tunnel: 1—rock pillar (plug); 2—the water level in the reservoir during the explosion; 3—pocket; 4—faced section of the tunnel; 5—the highest water level in the reservoir; 6—supply tunnel; 7—temporary concrete plug.

A well with a volume of 17 thousand m3 was made below the pillar in the tunnel to intercept the blasted rock during the water breakthrough after the blast. The relative position of the pillar and the well was determined by experiments on models. In order to be able to assess the impact of the blast on the dam (due to the proximity of the dam and the large size of the charge), 24 experimental explosions of charges weighing 2.3–11.3 kg and 1 with a weight of 520 kg were first performed at a depth of 20 m and 90–200 m distance from the dam when constructing a water intake shaft. Seismographs

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and accelerometers were placed on the dam and gates to measure the magnitudes of deformations and pressures. It is known that the blast energy propagates from the source with the speed of sound and decays at a distance determined by the physical properties of the medium. At any point on the surface around the explosion, the vibration amplitudes A, vibration frequency f , vibration speed V and acceleration α are connected by dependencies arising from the sinusoidal displacement law, and the amplitude is a blasting function W, the distance from the explosion point and the nature of ground at a given point. ϑ = 2π · f · A; α = 4π 2 f 2 A

(5)

On the basis of numerous experiments, the United States Bureau of Mines proposed the following formula: A = W 2/3 · (0.00302e−0.00469d + 0.00004)

(6)

where, A is amplitude, cm; W is the charge weight, kg; d is distance, m; e is the basis of natural logarithms. Bulkheads protecting construction sites from water, as a rule, are made of soil or of soil and stone. In some cases, rock pillars are left for the fence. Depending on the type of structure to be protected and the hydrotechnical characteristics of the river, the design and size of the bulkhead can vary widely. The destruction of bulkheads is carried out during the completion of construction work in the protected pit and the commissioning of the structure. Bulkhead demolition work is carried out in two or three stages. The first stage is, in all cases, chipping away the bulkheads to the minimum permissible size. This part of work is usually very significant and can be up to 70% or more of the total volume of work connected with the bulkheads. This is explained by the fact that the structural dimensions of the bulkhead are determined by the conditions of its operation at the maximum water level. Chipping away the bulkhead to the extent required makes it possible to reduce the scale of the blast carried out to destroy it, as well as the volume of subsequent rework. Minimizing the total weight of the charges reduces the risk of damage to nearby hydraulic structures. When blasting bulkheads, various combinations of the location of borehole charges are often used. As an example, Fig. 3 shows a diagram of the location of borehole charges when blasting the pit bulkhead of the entrance portal of the first construction tunnel of the Nurek hydroelectric power plant [19, 20]. Here, charges were used in vertical wells with a diameter of 200 mm drilled from the ridge of the bulkhead, and in slightly inclined wells with a diameter of 105 mm drilled from a foundation pit protected by the bulkhead (Fig. 3). As a result of the blast, the dirt pile was located approximately at the level of the water’s edge, and the water overflow over the blasted area was insignificant. Barring of the rocks blasted for the water passage was carried out with the help of an excavator. If a blast occurs in water or near a reservoir, then it is necessary to take into account the increase in pressure above the hydrostatic one. The maximum pressure P from the

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Fig. 3. A diagram showing the location of borehole charges when blasting the pit bulkhead of the entrance portal of the first construction tunnel of the Nurek hydroelectric power plant: 1—vertical borehole charges; 2—slightly inclined borehole charges; 3—sandstone; 4—filled soil.

blast in water is determined by the formula.  1/3  W P=k· R

(7)

where: R is the distance from the blasting site to a given point; W is the charge weight, kg; k is a constant coefficient determined empirically. The first series of tests (24 small underwater explosions) was carried out with the aim of determining the increased water pressure on the dam’s gates during blasts. In some experiments from this series, an air curtain was created in front of the gates; frames made of perforated pipes were lowered into the water, into which compressed air was supplied under a pressure of 3.5 at. As a result of the experiments, the following dependence was obtained:   1/3 W · 103 (8) P=F· R 1/3

It can be extrapolated to the value WR , corresponding to the expected Big Bang. To determine the effect of such explosions on the increase in water pressure, prior to the main blasts, several trial blasts of charges in boreholes drilled in the base of the reservoir were carried out. It turned out that the increase in the water pressure as the result of blasting the charge in the borehole is 20% of that blasted in the water. Therefore, to calculate the formula (6), the value of a charge weighing 27,000 × 0.2 = 5400 kg must be substituted in it (the pillar was supposed to be blasted with a charge of 27 tons). At the same time, it turned out that the increase in pressure on the gates was 50 kg/sec and, accordingly, the gates could not withstand such a load [15]. Measurements of the gate deformations during small blasts showed that with the help of an air curtain placed in front of the gates it is possible to reduce the pressure transmitted to the gates by 6–7 times, however, out of caution, we considered it impossible to make such a decision, and therefore, by the time of the blast, the water horizon in the reservoir was lowered to the crest of an overfall dam. When blasting a charge weighing 520 kg, the change showed that the vibration amplitude at the dam is 0.11 mm, and the accelerations were increased by calculation, at which such results as 1.6 mm and 8.4 g, respectively, were obtained.

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Based on the analysis of literature sources and regulatory documents, the values of the amplitude of 1 mm and the acceleration of 3 g were considered dangerous, and the conditions for the planned blasting operations appeared to be very arduous [15, 20]. Two blasting methods were considered. The first method was the “Kayot” method, when the charge was located in two concentric galleries, passed through the pillar, and exploded instantly. In addition, deep boreholes were drilled every 46 cm along the contour of the future hole in the pillar. The second method was drilling deep frontal boreholes, as in the development of tunnels with short-delayed blasting of charges using electric detonators with millisecond retarders [15]. The results of the blast turned out to be quite satisfactory from all points of view. The hole was good, the well was only partially filled, as part of the cliff was thrown into the reservoir. The water pouring into the tunnel carried only a small amount of finely broken stones in the water intake, which were easily removed. The blast did not cause any damage to the dam, although the relative displacement of the sections was 0.4 1 mm. The bond between the concrete and the cliff was not violated, which was verified using pre-drilled boreholes. The increase in pressure from the blast wave in the water turned out to be less than that calculated from the pre-splits of a charge weighing 10 kg (Table 2). Table 2. Indicators of the seismic effects of blasts. Indicators Amplitude (cm)

As per calculation 0.05–0.16

Actual On the crest

At the base

0.20

0.06

Speed (cm/s)

5.0–15.0

10.0–15.0

4.5

Acceleration, shares, g

3.5–8.4

1.2

0.7

Frequency (number/s)

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10.0–15.0

10.0–20.0

3 Conclusion To sum up what has been said above, it is important to add that under certain conditions, even in the case of large tunnels, it is possible to carry out excavation works using underground blasts. However, in this case seismic impact on existing dams and other hydraulic structures should be taken into account. It is clear from our observations that experiments with small charges and existing empirical formulas can give incorrect ideas about the nature and numerical parameters of the phenomenon. It was revealed that the existing “Hazard Criteria” of seismic effects are unacceptable for high dams, and the increase in pressure from a wave arising from an underground blast in a reservoir is small and may not be taken into account. It can be reduced by creating air curtains. Minimizing the total weight of the charges reduces the risk of damage to nearby hydraulic structures and tunnels. Taking into account the fact that the destruction of

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bulkheads by an explosion is performed in built-up areas, one should very carefully assess the danger of harmful effects of blasts concerning seismicity, air shock waves, water hammer and flyrocks ejected from the blast site.

References 1. Mining and blasting operations in hydraulic engineering (1973). Tula, p 175 2. Rechitskii VI (2015) The results of comprehensive studies at the site of underground structures of the Rogun HPP. Hydrotech Constr 12:29–40 3. Davlatshoev SK, Yatimov TA, Yatimov UA (2019) Research methods for seismoacoustic monitoring of large underground structures. In: ICCATS-2021: International Conference on Construction, Architecture and Technosphere Safety, Chelyabinsk, September 2019. IOP Conf Ser Mater Sci Eng, vol 687. Chelyabinsk, 044042 4. Stepanov VYa (1979) The stressed state of the rock mass in the area of construction of the Rogun hydroelectric complex. In: Stressed—the deformed state and stability of rocky slopes and quarry sides. Ilim, Frunze, pp 345−350 5. Yatimov AJ, Hasanov NM (2014) Ensuring the stability of mine workings in deep rock massifs. In: Proceedings of the 7th international science-to-practice conference, Tajik Technical University, Dushanbe 2014, pp 72−74 6. Ananin GP, AI Zuikov (1972) Mining works in hydraulic engineering. Tula, p 157 7. Yatimov AJ, Siyamardov Z, Khochaev P (2016) Consolidation of rocks in the construction of underground hydroelectric power plants. Bull Tajik Natl Univ 192:199–202 8. Khasanov NM, Yatimov AJ (2018) Analysis of seismic impact on the mine working support with a circular cross-section. J Kyrgyz State Tech Univ 45:302–312 9. Yatimov UA, Yatimov AJ, Yatimov EA (2020) The nature of the dynamic stress field formation around the underground hydraulic mine workings. In: ICCATS-2021: International conference on construction, architecture and technosphere safety, Sochi, September 2020. IOP Conf Ser Mater Sci Eng 962:032023 10. Yatimov AD, Suleimanova MA (2016) Factors influencing the process and parameters of displacement of rocks and the earth’s surface. Sci Innov 9:100–104 11. Nasonov ID (1992) Construction technology for underground structures. Construction of horizontal and inclined workings. Nedra, Moscow, p 300 12. Eristov VS, Mazur MM (1996) Design and construction of large dams. In: Underground works and improvement of rock foundations of dams. Leningrad, Energia Publishing House, p 202 13. Yatimov AJ, Yatimov TA, Yatimov UA (2019) Statistical analysis of field measurements during the excavation of mine workings and their assessment. In: ICCATS-2021: International conference on construction, architecture and technosphere safety, South Ural State University, September 2019. IOP Conf Ser Mater Sci Eng 687:044043 14. Khasanov NM, Yatimov UA (2018) Geological factors affecting the destruction of the stability of hydraulic tunnels. Bull Kyrgyz State Univ Constr Transp Architect 60:94–98 15. Yatimov UA, Yatimov AJ, Yatimov TA (2020) Consolidation of rocks in chamber workings and tunnels during the construction of underground hydroelectric power plants. In: ICCATS2021: International conference on construction, architecture and technosphere safety, Sochi, September 2020. IOP Conf Ser Mater Sci Eng 962:032024 16. Zuikov AI, Mnatsakanov LN, Gerasimov VA (1972) Basics of blasting technology in industrial construction. Tula, p 205 17. Bulychev NS (1982) Mechanics of underground structures. Nedra, Moscow, p 271

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18. Bashkuev EB, Beisebaev AM (1983) Design of blasting operations in industry. Nedra, Moscow, p 359 19. Khasanov NM, Yatimov UA, Yakubov AO (2018) Theoretical and experimental studies of seismic resistance of underground passages. In: ICCATS-2021: International conference on construction, architecture and technosphere safety, South Ural State University, September 2018. IOP Conf Ser Mater Sci Eng 451:012113 20. Khasanov NM, Yakubov AO, Yatimov UA (2018) Impact of ground transport on pedestrian undercrossings and shallow Subways. In: ICCATS-2021: International conference on construction, architecture and technosphere safety, South Ural State University, September 2018. IOP Conf Ser Mater Sci Eng 451:012112

Modeling of Connection Nodes of Elements Rod Structures I. Alaverdov, N. Buzalo, N. Tsaritova(B) , A. Kurbanova, and I. Platonova Platov South-Russian State Polytechnic University (NPI), 132, Prosveshcheniya, Novocherkassk 346428, Russia [email protected]

Abstract. The article deals with the design of spatial rod coverings and their nodal connections. The main goal is to find new solutions for nodal joints and methods for their manufacture. Current developments of nodal joints have many disadvantages that lead to high labor costs and high consumption of steel. It turns out that original and effective solutions for nodes exist in nature. For an unconventional solution of technical problems, architectural bionics productively uses the nodes and details of natural systems. Natural tubular structures, such as bones, trunks, branches, have excellent mechanical properties due to their minimal weight and maximum moment of inertia. Bionics allows you to simulate the connections elements of coating based on natural analogs. The creation of new nodes for spatial rod coverings can be done by 3D printing using metal powder. This makes it possible to switch to industrial fabrication of nodal elements. 3D printed parts are highly accurate and reliable. Based on this research, bionics and 3D printing with powdered metal will help to succeed in the development of new spatial systems. Keywords: Architectural bionics · Rod coverings · Natural analogs · Nodal connections · 3D printing

1 Introduction Rolled steel profiles began to be widely used for buildings, tower and bridge structures relatively recently—only 100–150 years ago. The use of metal allowed to reduce the mass of the constructions, make the constructions of coatings transparent to light. In the beginning of twentieth century the Russian engineer Vladimir Shukhov (1853–1939) created the first net shells [1]. The basic principle of Shukhov’s steel mesh structures is that they consist of individual rods that form a spatial grid. This was a great advantage of Shukhov’s structures, since the curved surfaces of the towers and roofs were formed from straight rods. The most important advantage of these structures was that they were, on average, two times lighter than the corresponding structures of other systems. Shukhov’s hyperboloid towers gained the greatest popularity (Fig. 1). At the beginning of the XX century. water towers of the Shukhov system were built in many cities of Russia, and their height ranged from 9 to 40 m and the number of rods from 25 to 80. According to Shukhov’s design, in 1897–1898, workshops with roofs of double © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_2

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curvature were built at the Vyksa plant. For the first time in world construction practice, the possibility of creating a spatial rectangular coating with double curvature has been clearly demonstrated. Shukhov’s mesh structures at the end of the nineteenth century. had no analogues in world practice and were a genuine engineering discovery.

Fig. 1. Shukhov TV Tower, Moscow.

Currently, spatial metal structures of a tubular section are widely used in construction practice. This is due to the even distribution of stress in the elements and the elegance of the forms. An example is a tower built in 2011 in Cincinnati, USA, at the top of which there is a steel structure consisting of 15 arches and hundreds of other steel elements, which looks like a tiara (Fig. 2). The main arches are made of pipes with a diameter of 16 inches, the other arches are made of pipes with a diameter of 4–8.625 inches.

Fig. 2. The Great American Tower, Cincinnati, USA.

Closed cross-sections of tubular metal profiles have large multidirectional axial radius of gyration [2], which makes them very effective in tension, compression, and

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bending with a minimum mass [3]. In addition, steel tubular rods with proper protection are more resistant to corrosion and fire. However, the manufacture of tubular rod assemblies is quite laborious and expensive, because it includes a large amount of cutting, drilling and welding, which increases the cost of the project [4].

2 Methods and Materials Reducing the complexity of manufacturing and installation, the maximum degree of prefabrication of metal structures of the coating, reducing the consumption of steel— these trends in the development of the construction industry are fully consistent with the use of spatial rod structures of the coating. All parts of light metal structures are unified, have a minimum number of standard sizes. Serial factory production of the same type of elements on production lines does not require the use and readjustment of expensive equipment, is carried out in a short time, structural parts are transported to the installation site in a compact form, assembled using standard nodal parts without the use of welding, which improves the quality of assembly. Nodal connections for tubular elements are difficult and expensive to manufacture as they involve a significant amount of cutting, drilling and welding, resulting in a large amount of waste, workplace safety issues and a large carbon footprint in the environment [5]. Manufacturing of nodal parts of spatial rod structures has a great impact on the overall project budget [4]. There are mainly three methods of connect tubular elements: a. direct welding of profiles to each other, welding of stiffeners to ensure local stability of parts [6, 7]. This method requires careful quality control to prevent brittle fracture of the welded joints (hot and cold cracking, lack of penetration, etc.). b. steel casting [8, 9]: parts of complex shape can be made using molds. They are rational in the sequential manufacture of a large number of similar parts using the same mold. It is possible to use only standard molds—a completely “arbitrary shape” is impossible. c. connectors of spatial rod constructions (for example, “bolt-ball” or “Mero” connection) [10, 11]: a large number of details of such systems make it difficult to transfer stresses in the node. Popular in recent decades architectural the concepts of futurism and avant-garde require the use of asymmetric structures, complex connections of elements in knots (for example, the designs of the great architect Zaha Mohammad Hadid), which leads to a very complex and expensive production process. The intricate shapes of the coating require the use of tubular elements intersecting at different angles. As a result, joints of complex geometry with a high density of welded joints are obtained. In addition, nodal joints are subjected to extreme loads, especially during construction in seismic areas: residual stresses are possible in welds, and stress concentration in places of holes and complex lines of cuts. Related problems that led to emergency situations are described in special literature [12–15].

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A distinctive feature of bionics in architecture is the imitation of natural forms, taking into account scientific knowledge about them. Creating an environmentally friendly environment that is friendly to humans with the help of new energy-efficient technologies can be an ideal direction for the development of the architecture of the future. There has been a tendency for the direct use of living systems and biological mechanisms in technical schemes. The architect looks for opportunities and conditions for adapting natural systems to solve engineering problems, models a technical device or architectural element based on biological objects or processes. Bionic models brought to life new, unusual architectural forms, functionally optimal and original in their artistic qualities. An important moment that played a role in the appeal of architects and designers to wildlife was the introduction into practice of spatial structures that are economically justified, but more complex in design. Such forms are successfully used in various typological areas of architecture, in the construction of large-span and high-rise structures, and in the creation of rapidly transforming structures. The need for the use of mobile structures, prefabricated buildings increases in the conditions of the development of hardto-reach territories, the construction of seasonal structures. The principles of dynamic adaptation of buildings and structures are widely used in various fields—exhibition and concert venues, advertising, design of the architectural environment in recreational areas. In architectural practice, the principle of constructing natural spatial lattice systems is used—radiolarians, diatoms, some fungi, shells. In these models, the principle of distribution of material is especially clearly manifested, with the expectation of the most random and multidirectional action of loads. To solve technical problems, architectural bionics effectively uses the nodes and details of natural systems [16]. Natural tubular structures, such as bones, trunks, branches, have sufficient strength and stiffness characteristics due to the minimum mass and maximum moment of inertia, since the material of the element is as far as possible from the center of gravity of the cross section [17]. Over the billions of years of the life of the planet Earth, nature has created ideal forms of elements and nodal connections with a minimum stress concentration and maximum rigidity and strength. Many living beings (humans, animals, insects, trees) have outstanding examples of the use of tubular systems [18]. For example, a bamboo branch is a tubular element with stiffeners in places where the load from branches and leaves is applied (Fig. 3).

Fig. 3. The bamboo branch with stiffeners.

The authors used the methodology of architectural bionics [19] to develop mesh structures for building coverings. The spatial model of covering is constructed by analogy with the transformation scheme of the musculoskeletal system of mammals and arachnids. The common kinematic features of these natural analogues are the presence

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of rigid "rod" elements of constant length and flexible elements of variable length (muscles). The connection of the links of the rigid elements to each other is articulated. The transformation of these systems is associated with physical forces that change the length of the flexible elements, and with the possibility of rotation in the node due to the presence of certain types of hinges between the rigid "rods". Various combinations of elements of variable and constant length are used in the design of natural analogs -elements of variable length (muscles) and the links of skeletal rods. An example is the metasomas of a tropical scorpion (Fig. 4).

Fig. 4. Kinematic scheme of a tropical scorpion.

3 Results On the basis of the hinge joint of the bones of the human skeleton, it is possible to create variants of the technical solution for the joint of elements in the rod systems of spatial coverings. If the principle of the device of the human knee joint, in which the femur and the tibia are connected according to the principle of a “cylindrical” hinge (one degree of freedom), is used in rod spatial structures, it is possible to obtain spatial structures of variable spans and heights, as well as to simplify the process of their assembly and installation (Fig. 5). In the natural analogue of the rod system, the bones are connected by external flexible ligaments, and are set in motion by muscles (“flexors” and “extensors”). In the technical model of the node, the connection is carried out both by an external rigid cage, and an elastic bond, as well as by an internal flexible system of cables, which, when stretched, creates a spatial rigid fixed structure of the coating. The work of the muscles can be carried out by a telescopic hydraulic device installed in certain rods of the structural system [20–22]. As a rule, elements of light steel structures are interconnected by welding or bolts. To install a stiffener inside a tubular element by welding, it must be cut and welded several times (Fig. 6a).

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Fig. 5. Swivel joint of rigid rods: a scheme of the knee joint; b hinge connection of the rods in a rigid cage; c hinge connection using rubber tubes; d hinge connection with a flexible cord inside the rods.

When bolted (Fig. 6b), prestressed threaded bolts and parts with milled surfaces welded to tubular rods are used. In this case, the bolt holes reduce the bearing capacity of the elements and provoke local stress concentration. According to research of Inzhutov I.S., Dmitriev P.A., Deordiev S.V., Zakharyuta V.V. [23], in addition to the general classification of joints (welded and bolted), 6 types can be distinguished: 1. Direct welding of elements with (Fig. 5a) or without a connector. This kind of joints allows you to combine a different number of elements in space at any angle. But it has a number of disadvantages: a large amount of installation welding work, the complexity of the alignment of angles and, in this regard, possible misalignment, of joints, heterogeneity of the weld and residual welding stresses, strict requirements for the lengths of the rods. 2. Bolted connection without additional connector (Fig. 6b). It has a low material consumption. This kind require careful alignment therefore they do not allow errors in the deviation of the lengths of the rods.

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Fig. 6. Joints of tubular rods of the spatial system: a welded; b welded and bolted, without additional connector; c cylinder-shaped core; d, e axle-bolted connection; f connection on spatial gussets.

3. Connection with a cylinder-shaped core (Fig. 6c). These systems are not for heavy loads. They are difficult to manufacture and have backlash. 4. Axle-bolted connection with bolts from the rods to the connector (Fig. 6d) and from the connector to the rods (Fig. 6e). They are good in the following: versatility of use, compactness of connectors, low labor intensity of installation, dismountable and aesthetics. But they have a strict requirement for the tolerances of the lengths of the rods. 5. Connection on spatial gussets (Fig. 6f). The disadvantage is the flexibility of the joints due to the difference in the diameter of the hole and the diameter of the bolt.

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Because of this, there is a redistribution of stresses. But the difference in diameters is also an advantage of bolted systems since it compensates for errors in the length of the rods and such systems are easier to assemble. The article [24] proposes an alternative to the traditional methods of manufacturing parts of bar structures using welding or bolts. The authors propose to adapt the design of the connecting element to the geometry of a spatial coating of any shape to provide the required rigidity, strength and local stability. The result is an optimal connecting element that can be printed on a 3D printer and then welded (or bolted) to the tubular rod elements of a spatial structure of even the most complex geometry (Figs. 7 and 8).

Fig. 7. Nodal geometry adaptation.

Fig. 8. Unstiffened and benchmark models.

Today 3D printing using metal powder is the fastest growing segment of 3D printing. The growth of additive manufacturing is related to business opportunities and, directly,

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with the available materials and their cost. Of course, inexpensive metal powders are key factors for 3D printing. As a result, they realize its potential and transform industrial production. The advantages of using metal powder include: • • • •

Details are obtained of high robustness. Printing can be carried out with high resolution. The metal is characterized by heat resistance. There is a possibility of secondary processing of the material.

Thanks to these points, 3D printing will be able to produce complex nodal elements designed according to the principle of hinge joints in living organisms. The nodal elements made in this way will facilitate the design, avoiding most of the disadvantages of traditional nodal connections.

4 Conclusion The dynamics of modern socio-functional processes and transformations in society finds a direct manifestation in the means of their organization, that is, in the architectural environment that responds to organizational and spatial transformations. Optimal solutions to emerging architectural problems can be sought in natural biological systems. The study of engineering solutions of nature, the patterns of formation and structure formation of living tissues, structural systems of living organisms on the principles of saving material, energy and ensuring reliability helps to solve engineering problems, create original architectural forms, new structural systems. The development of construction equipment and technologies based on 3D printing makes it possible to implement even the most daring ideas of an architect. In the twenty-first century, the use of spatial structures, many of which have bionic counterparts, has become a hallmark of the innovative thinking of practicing architects. The most famous of them, the Pritzker Prize winners, are committed to pure geometric forms, created from glass and steel based on natural prototypes. Modern nodal joint designs based on powder metal 3D printing have many disadvantages today, lead to high labor costs and high material consumption, but with the development of technology, they will help to achieve success in the development of spatial systems. Architectural and construction practice know many schemes of two-layer structures, the rigidity and geometric invariance of which is ensured both by the space structuring system itself, i.e. by geometry, and by the type of connection of the rods. The rapidly transforming structures in the presence of hinged joints are able to transform from a plane, that is, bend in one or all three directions of triangulation, only when the length of the rods of the upper or lower layers’ changes in the directions corresponding. Algorithmic architecture, based on digital models that turn into architectural forms, allows you to look for rational options for space-planning solutions, diversify architectural forms and compositional means, and create large open spaces. But for the highest quality result, it is necessary to study and work out every detail of such systems in detail.

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The use of bionic principles of constructive transformation in architecture, based on the achievements of building technology and the use of visual programming languages, creates significant advantages in the development of unique architectural concepts for future buildings and opens up prospects for the implementation of functional processes in almost all areas of human activity.

References 1. Shukhov VG (1977) Selected works, vol 1. Structural mechanics, Academy of Sciences of the USSR, Moscow, p 192 2. Zhuravlev AA, Zhuravlev DA (2014) Sterzhnevye konstrukcii cilindricheskih obolochek (Rod constructions of cylindrical shells). Rostov-na-Donu 3. Duarte HPCSG, Lima Luciano, da PCG, Vellasco Pedro, Silva André (2017) Structural behaviour of stainless steel tubular columns. In: Tubular Structures XVI: Proceedings of the 16th international symposium for tubular structures (ISTS 2017, 4–6 December 2017). https://doi.org/10.1201/9781351210843-66 4. Kanyilmaz A (2019) The problematic nature of steel hollow section joint fabrication, and a remedy using laser cutting technology: a review of research, applications, opportunities. Eng Struct 183:1027–1048 5. Clean Air Task Force (2009) “About EOR” Archived March 13, 2012, at the Wayback Machine 6. Xiao-Ling Z, Tong L (2011) New development in steel tubular joints. Adv Struct Eng 14:699– 716. https://doi.org/10.1260/1369-4332.14.4.699 7. Wardenier J (1982) Hollow section joints, Doctoral thesis. Delft University Press 8. De Oliveira C (2015) Steel castings in structural design—case studies. SEAOC convention proceedings. Bellevue, Washington, DC, pp 427–439 9. Wang L, Dong H, Li J (2013) Balance fatigue design of cast steel nodes in tubular steel structures. The Scientific World Journal, p 10 10. Stephan S, Sánchez-Alvarez J, Knebel K (2004) Reticulated structures on free-form surfaces. In: Proceedings of IASS 2004 symposium in Montpellier-France 11. Ghasemi M, Davoodi M, Mostafavian S (2010) Tensile stiffness of MERO-type connector regarding bolt tightness. J Appl Sci 10(9):724–730. https://doi.org/10.3923/jas.2010.724.730 12. Imam B, Chryssanthopoulos MK (2010) A review of metallic bridge failure statistics. In: IABMAS conference 2010-07-11—2010-07-15, Philadelphia, USA. https://doi.org/10.1201/ b10430-502 13. Moan T (1985) The progressive structural failure of the Alexander L. Kielland platform. In: Maier G (ed) Case histories in offshore Engineering. International Centre for Mechanical Sciences (Courses and Lectures), vol 283. Springer, Vienna. https://doi.org/10.1007/978-37091-2742-1_1 14. Vayas I, Ermopoulos J, Thanopoulos P (2006) Collapse of the roof over the archaeological site in Santorin, Greece. Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin Stahlbau, issue 75 15. Gulf F, Mehr AC (2016) Sultan Mizan Zainal Abidin Stadium roof collapse, Kuala Terengganu, Malaysia (Lack of Safety Issues). EPH—Int J Math Stat 2–10:14–23 16. Lebedev YuS et al (1990) Architectural bionics. Stroyizdat, Moscow 17. Taylor D (2015) Fatigue-resistant components: what can we learn from nature? Proc IMechE Part C: J Mech Eng Sci 229(7):1186–1193 18. Tsaritova N, Buzalo NA, Tumasov A, Platonova I, Kurbanov A, Kalinina AA (2019) Transformable Systems of spatial structures based on bionic analogues. In: Proceedings of the International Symposium “Engineering and Earth Sciences: Applied and Fundamental Research” dedicated to the 85th anniversary of H.I. Ibragimov (ISEES 2019)

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19. Lebedev YS (ed) (1990) Architectural bionics. Stroyizdat, Moscow, p 269 20. Tumasov AA, Tsaritova NG (2016) Transformable spatial core structures of coatings. Int Res J 12–3(54):190–194 21. Tumasov A, Tsaritova N, Kurbanov A, Kalinina A (2017) Geometric parameters of rod transformable arch systems. Constr Architect 5:135–140 22. Buzalo NA, Alekseev S, Tsaritova N (2016) Numerical analysis of spatial structural node bearing capacity in the view of the geometrical and physical nonlinearity. Proc Eng 150:1748– 1753 23. Inzhutov IS, Dmitriev PA, Deordiev SV, Zakharyuta VV (2013) Analysis of available space structure joints and design of demountable modular joints. Vestnik MGSU 3:61–71 24. Kanyilmaz A, Berto F, Paoletti I et al (2021) Nature-inspired optimization of tubular joints for metal 3D printing. Struct Multidisc Optim 63:767–787. https://doi.org/10.1007/s00158020-02729-7

The Actuality of Geotechnical Monitoring on the Example of Construction Objects in Tyumen M. A. Stepanov(B) Industrial University of Tyumen, Volodarskogo Street, 38, Tyumen 625001, Russia [email protected]

Abstract. The article discusses about the actuality of timely geotechnical monitoring of the buildings and surrounding structures. Analysis of the regulatory standards, regarding the geotechnical monitoring requirements, was done. As part of the implementation of geotechnical monitoring complex research of 16 objects in one of the microdistricts of Tyumen were carried out. The order of that research was the control of the mechanical safety of buildings and structures. The article presents the results and analysis of its implementation. So, for one of the objects in Tyumen, geotechnical monitoring revealed the need the stabilization of continuous uneven settlements. To investigate the current situation was made of the stress-strain state analysis of the soil base at the moment and after the completion of filtration consolidation under the conditions of the initial state of the building, constructed according to the project, and taking into account different types of soil reinforcement. Authors presents the results of choosing the method of the differential settlements stabilization as part of construction scientific-technical support. Conducting timely geotechnical monitoring allows to detect the possibility of an emergency at an early stage and take the necessary measures to solve the problem of soil base and foundation strengthening. Analysis of the regulatory standards, regarding the geotechnical monitoring requirements, was done. Authors presents the results of buildings geotechnical monitoring in one of Tyumen districts for mechanical safety control purposing and choosing the method of the differential settlements stabilization as part of construction scientific-technical support. Keywords: Geotechnical monitoring · Building safety · Building code · Foundation · Soil base · Differential settlements · Settlements stabilization · Technology · Reinforcement · Pile

1 Introduction To date, construction in Russia has been developing at a high pace. The urban infrastructure provides for the construction of medium- and high-rise buildings—up to 25 floors and more, various large administrative, sports and social institutions, often in unfavourable engineering-geological and hydrogeological conditions. And, due to a © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_3

The Actuality of Geotechnical Monitoring on the Example

25

number of reasons: significant uneven soil deformations, accidents, collapses of buildings and structures are increasingly occurring, both related to the existing building under the influence of new construction, and new building after commissioning [1–11]. One of the ways to solve the problem of ensuring the building safety and structures reliability is to conduct geotechnical monitoring. To date, there are various methods for conducting observations of buildings based on modern technologies [12–22]. The concept of geotechnical monitoring was introduced into construction practice by V.M. Ulitsky at the end of the last century. Together with A.G. Shashkin, he developed the concept of geotechnical support for construction and reconstruction of different buildings and structures. On the basis of this concept the territorial construction standards of St. Petersburg were developed and approved by the Gosstroy of Russia [23]. According to this concept, the geotechnical category of the object complexity depended on the building responsibility level, the technical condition of the surrounding objects and structures and the risk caused by reconstruction or new construction. The concept also established the need to monitor the quality of work and the safety of buildings and structures for the 2-nd and 3-d geotechnical categories. For the first time, the basic requirements for geotechnical monitoring (purpose, composition, scope, methods and list of works) at the federal level are briefly given in set of rules “SP-50-101-2004”, and its necessity is indicated in the Federal Law No. 384-FZ. In recent years, in new and updated editions of building codes, the development and expansion of the requirements for geotechnical monitoring has taken place. Today we have set of rules “SP 305.132580”, which release is completely devoted to monitoring process (Table 1). Table 1. Geotechnical monitoring in the regulatory documentation system of Russian Federation. Document

Date of introduction

Status

Federal law no. 384-FZ

July 1, 2010

Set of rules “50-101-2004”

March 9, 2004

State standard GOST “31,937-2011”

January 1, 2014 Valid, mandatory

Main points of geotechnical monitoring Monitoring the state of the foundation, building structures as a way to ensure the safety of buildings and structures during operation

Valid

Basic requirements for geotechnical monitoring (purpose, composition, scope, methods and list of works) Rules and recommendations for general monitoring of the technical condition of buildings and structures (continued)

26

M. A. Stepanov Table 1. (continued)

Document

Date of introduction

Status

Main points of geotechnical monitoring

Set of rules “22.13330.2011”

May 20, 2011

Cancelled in part; The main criteria for mandatory clauses in determining the need for force geotechnical monitoring, which depending on the height of the building, the depth of the pit, the building responsibility level and the category of complexity of the engineering-geological conditions (EGC)

Set of rules “22.13330.2016”

June 17, 2017

Valid, voluntary

The concept of geotechnical category, the need for geotechnical monitoring for objects of the2-d and 3-d geotechnical category

Set of rules “248.1325800.2016”

September 1, 2016

Valid, voluntary

Repeats the main paragraphs of “SP22.13330.2016”

Set of rules “305.1325800.2017”

April 18, 2018

Valid

Document details the paragraphs of “SP22.13330.2016” in terms of the observation methods, monitoring results analysis and the algorithm of actions in case of the dangerous situation; supplements in terms of monitoring in special conditions

The new standards prescribe geotechnical monitoring for the buildings of 2-d and 3-d geotechnical categories, i.e. for all objects of normal and high level of responsibility. This changes in national standards and codes will require developers to carry out geotechnical monitoring for almost all modern new buildings. Geotechnical monitoring is an important tool for ensuring the reliability and safe operation of buildings and structures at all stages of the construction process. So, the determination of its main parameters based on the requirements of modern standards is an urgent task.

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27

2 Geotechnical Monitoring Program Geotechnical monitoring is carried out in accordance with the program developed as part of the main project documentation. The geotechnical monitoring program determines the composition, volumes, frequency and methods of work, taking into account the necessary features of the construction site. Algorithm for creating a geotechnical monitoring program: (1) Determination of the main parameters of the construction object. (2) The assignment of geotechnical category depending on the building level of responsibility and the category of complexity of the engineering and geological conditions of the construction site. (3) The selection of controlled parameters depending on the parameters of the object and its geotechnical category. (4) Determining the duration of geotechnical monitoring and the frequency of fixing changes in controlled parameters. (5) Requirements determination for reporting documentation and analysis of the results.

3 Approbation of the Algorithm for Creating a Geotechnical Monitoring Program As part of the implementation of geotechnical monitoring complex research of 16 objects in one of the microdistricts of Tyumen were carried out. The order of that research was the control of the mechanical safety of buildings and structures. The geotechnical monitoring program compiled on the basis of the developed algorithm, provided for surveying the technical condition of buildings, analyzing the engineering and geological conditions of the construction site and for fixing changes in the main controlled parameters, such as: (1) (2) (3) (4)

Settlements; Relative differential settlements; Additional settlements of foundations and their relative difference; Width and depth of the cracks in building constructions.

To evaluate the results of geotechnical monitoring, the developed program proposes three levels of geotechnical risk (according to the highest of the obtained values for the structures) (Table 2). The obtained data make it possible to assess the different displacements of points and can serve as the first signal of the possibility of dangerous situations, which becomes the reason for increased control over the state of buildings. Evaluation of the results of geodetic survey is presented in Table 3. The analysis of the obtained data showed that out of 16 objects of geotechnical monitoring, only for two the ratio of the maximum relative differential settlements to the maximum allowable is less than 75%. For the other 14 objects, this ratio ranges from 104 to 288% (Fig. 1).

28

M. A. Stepanov Table 2. Geotechnical risk level.

The ratio of the actual value of the indicator to the limit

Geotechnical risk level

Recommendations

From 0 to 75%

Green (normal)

No additional action required at this time

From 75 to 100%

Yellow (increased level of attention)

It is necessary to additionally fix the displacements of the structure twice with a frequency of once every 6 months to assess the dynamics of the increasing of deformations

More than 100%

Red (high level of attention) It’s required an instrumental examination of the technical condition of the building structures. It is necessary to additionally fix the displacements of the structure four times with a frequency of once every 3 months

After analyzing the results of the survey, the building owner was given recommendations to make the measurements every 3 months during the year. It was need to fix the dynamics of the development of differential settlements over time and issue an opinion on further work, as part of an instrumental survey of the building structures.

4 Elimination of Differential Settlements of the Building For one of the objects in Tyumen, geotechnical monitoring revealed the need the stabilization of continuous uneven settlements. According to monitoring data, the building had a 19 cm deviation from the vertical at the level of the parapet. After the problem was discovered, the contractor reinforced the foundation and soil base in areas of maximum stresses under the foundation slab with soil-cement piles (SCP) with a diameter of 600 mm and a length of 4.5 m. Ongoing geotechnical monitoring showed further development of differential settlements and their continuous nature. It was led to the scientific and technical support for construction in order to select a method of strengthening soil base that can reduce relative differential settlements and stabilize them. The investigated object is a 12-story section of a brick residential building with an underground floor, rectangular in plan with overall dimensions in the axes of 13.69 × 26.3 m. Upper Quaternary and Modern deposits took part in the geological structure of the studied section of the construction site. The base is composed of loams of various composition and condition, bulk soils, consisting of loam, sand and construction debris. The lower layer was of dense fine sand with a thickness of 5.8 to 6 m.

The Actuality of Geotechnical Monitoring on the Example

29

Table 3. Data analysis results. No.

Wall material

Year of construction

Maximum relative differential settlements

Maximum allowable (ultimate) differential settlements

The ratio of the relative differential settlements to the maximum allowable (%)

Level of risk

1

Brick

2010

0,0038

0,0024

158

Red

2

Brick

2007

0,0053

0,0024

221

Red

3

Panel house

2007

0,0046

0,0016

288

Red

4

Brick

2007

0,0048

0,0024

200

Red

5

Panel house

2007

0,0038

0,0016

238

Red

6

Panel house

2008

0,0026

0,0016

163

Red

7

Brick

2008

0,0033

0,0024

138

Red

8

Brick

2010

0,0010

0,0024

42

9

Brick

2007

0,0026

0,0024

108

10

Panel house

2007

0,0006

0,0016

38

11

Brick

2009

0,0034

0,0024

142

Red

12

Panel house

2009

0,0024

0,0016

150

Red

13

Panel house

2009

0,0029

0,0016

181

Red

14

Brick

2009

0,0025

0,0024

104

Red

15

Panel house

2009

0,0023

0,0016

144

Red

16

Panel house

2008

0,0039

0,0016

244

Red

Green Red Green

The Hardening Soil model was chosen for numerical simulation in the Plaxis software package. The calculation was carried out taking into account the stage-by-stage technology of work performance and consolidation. To investigate the current situation was made of the stress-strain state analysis of the soil base at the moment and after the completion of filtration consolidation under the conditions of the initial state of the building, constructed according to the project (Fig. 2), and taking into account the first reinforcement with soil-cement piles 4.5 m long (Fig. 3). The constructed model correlates with geotechnical monitoring data (error up to 8%). Further, it was considered the option of additional strengthening of the foundation with soil–cement piles 10.2 m long, proposed by the contractor (Fig. 4). As an alternative, it was proposed to use Atlant type piles 24 m long with their support in the bottom layer of strong dense sand (Fig. 5). In this case, this piles used as

30

M. A. Stepanov

Fig. 1. Scheme of geotechnical risk levels in the investigation area. Website: https://yandex.ru/ maps/55/tyumen.

Fig. 2. a Deformed scheme and b vertical displacements of soils after completion of filtration consolidation without reinforcement.

The Actuality of Geotechnical Monitoring on the Example

31

Fig. 3. a Deformed scheme and b vertical displacements of soils after completion of filtration consolidation, taking into account the first strengthening of the SCP 4.5 m long.

Fig. 4. a Deformed scheme and b vertical displacements of soils after reinforcement with soilcement piles 10.2 m long.

a support that will fix the position of the building section, will stabilize and eventually minimize the relative difference in the settlements of a residential building. Based on the obtained data, it was created a graph of the values of the building relative differential settlements for various options of strengthening the soil base (Fig. 6). An analysis of the results of scientific and technical support for construction showed that the reinforcement with soil-cement piles 4.5 m long does not eliminate the differential settlements of the building, and after the completion of filtration consolidation, the relative differential settlements will only increase by 7.7%. The option proposed by the contractor for the additional reinforcement with soil-cement piles 10.2 m long will reduce the uneven settlement by 5%.

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M. A. Stepanov

Fig. 5. a Deformed scheme and b vertical displacements of soils after reinforcement with Atlant type piles.

Fig. 6. Relative differential settlements at various stages of soil base strengthening.

The use of Atlant technology piles, which was adopted as a result of the work, allows to reduce the uneven settlement by 35.5% and achieve values that do not exceed the normative ones. At present, the work to strengthen the soil base has been completed, geotechnical monitoring continues and confirms the correctness of the decisions, as well as the importance of its timely implementation to ensure the safety of buildings and structures.

5 Conclusion Conducting timely geotechnical monitoring allows to detect the possibility of an emergency at an early stage and take the necessary measures to solve the problem of soil base and foundation strengthening. New building regulations establish the necessity of geotechnical monitoring for majority part of modern buildings at all stages of the construction process. In the event that these measures become mandatory, the introduction of geotechnical monitoring into general practice will make it possible to avoid serious problems caused by over limit settlements by constantly control of the reliability and mechanical safety of buildings and structures.

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References 1. Bogov SG, Bochkarev NP (2015) Geotekhnicheskij monitoring pri nulevom cikle stroitel’stva zdanij s podzemnym prostranstvom (Geotechnical monitoring during the zero cycle of construction of buildings with underground space). Zhilishchnoe stroitel’stvo 1:36–41 2. Gryaznova EA (2017) Obespechenie bezopasnosti i ehkspluatacionnoj nadezhnosti zdanij, pri stroitel’stve i rekonstrukcii (Ensuring the safety and operational reliability of buildings during construction and reconstruction). Nauchnoe obozrenie 20:15–17 3. Il’ichev VA, Nikiforova NS, Gotman YuA, (2017) Structural safety security of objects with an underground part by transformation of soil properties: Alabyano-Baltic Tunnel in Moscow. S Mech & F Eng 2:35–39 4. Novikov YuA, Shchukina VN, Golyakova YuE (2017) O neobkhodimosti geotekhnicheskogo monitoringa ob"ektov istoriko-kul’turnogo naslediya na primere g. Tyumeni (On the need for geotechnical monitoring of objects of historical and cultural heritage on the example of the city of Tyumen). Interekspo Geo Sibir’ 1:66–70 5. Osokin AI, Tatarinov SV, Denisova OO, Makarova EV (2014) Sistema geotekhnicheskogo monitoringa kak sredstvo obespecheniya bezopasnosti stroitel’stva (Geotechnical monitoring system as a means of ensuring construction safety). Zhilishchnoe stroitel’stvo 9:10–18 6. Petrukhin VP (2010) Geotekhnicheskie problemy stroitel’stva v Moskve – krupnejshem megapolise Rossii (Geotechnical problems of construction in Moscow, Russia’s largest metropolis). Geotekhnicheskie problemy megapolisov 1:259 7. Ponomarev AB, Zakharov AV, Sazonova SA et al (2015) Geotekhnicheskij monitoring zhilogo doma (Geotechnical monitoring of a residential building). Zhilishchnoe stroitel’stvo 9:41–45 8. Stepanov MA, Mal’ceva TV, Kraev AN et al (2017) Ustranenie progressiruyushchego razvitiya neravnomernosti osadok mnogoehtazhnogo zhilogo doma na lentochnykh svajnykh fundamentakh (Elimination of the progressive development of uneven soil settlements of a multistorey residential building on strip pile foundations). Internet-zhurnal “NAUKOVEDENIE” 4. http://naukovedenie.ru/PDF/62TVN417.pdf 9. Castagnetti C, Cosentini RM, Lancellotta R et al (2017) Geodetic monitoring and geotechnical analyses of subsidence induced settlements of historic structures. Struct Control Health Monit 24(12):e2030 10. Gudehus G, Touplikiotis A (2018) On the stability of geotechnical systems and its fractal progressive loss. Acta Geotech 13(2):317–328 11. Zekhniev FF, Vnukov DA, Astaf’ev SV et al (2014) Instrumental’nye nablyudeniya za gruntovym massivom sklona na ob"ekte stroitel’stva khrama Arkhangela Mikhaila v d. Putilkovo Moskovskoj oblasti (Instrumental observations of the slope soil at the construction site of the Church of the Archangel Michael in the village of Putilkovo, Moscow Region). Vestnik PNIPU 4:286–297 12. Lanis AL, Razuvaev DA (2017) Povyshenie kachestva usileniya gruntovykh massivov po rezul’tatam geotekhnicheskogo monitoring (Improving the quality of soil strengthening based on the results of geotechnical monitoring). Vestnik Sibirskogo gosudarstvennogo universiteta putej soobshcheniya 4(43):5–11 13. Mangushev RA, Oshurkov NV, VEh, Gutovskij (2010) Vliyanie stroitel’stva trekhurovnevogo podzemnogo prostranstva na zhilye zdaniya okruzhayushchej zastrojki (The impact of the construction of a three-level underground space on residential buildings in the surrounding area). Zhilishchnoe stroitel’stvo 5:23 14. Mirsayapov IT, Khasanov RR, Safin DR (2016) Geotekhnicheskij monitoring zdaniya pri rekonstrukcii pamyatnika istorii i arkhitektury (Geotechnical monitoring of a building during the reconstruction of a monument of history and architecture.). Izvestiya Kazanskogo gosudarstvennogo arkhitekturno-stroitel’nogo universiteta 4(38):270–276

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15. Mirsayapov IT, Koroleva IV (2013) Osobennosti geotekhnicheskogo monitoringa unikal’nykh zdanij i sooruzhenij (Features of geotechnical monitoring of unique buildings and structures). Izvestiya KGASU 4(26):167–172 16. YaA P, Epifanceva LR, Stepanov MA et al (2017) Geotekhnicheskij monitoring stroitel’stva zhilogo doma na lentochno-obolochechnykh fundamentakh v gorode Tyumeni (Geotechnical monitoring of the construction of a residential building on strip-shell foundations in the city of Tyumen). Promyshlennoe i grazhdanskoe stroitel’stvo 10:59–66 17. Ulickij VM, Shashkin AG, Shashkin KG (2003) Prichiny obrusheniya zhilogo doma na Dvinskoj ulice v Peterburge (Causes of the collapse of a residential building on Dvinskaya Street in St. Petersburg). Rekonstrukciya gorodov i geotekhnicheskoe stroitel’stvo 5:153–159 18. Yugov AM, Novikov NS, Gavrilyuk AS (2015) Geotekhnicheskij monitoring pri ustrojstve “steny v grunte” v stesnennykh usloviyakh (Geotechnical monitoring during the construction of a “wall in the ground” in cramped conditions). Vestnik MGSU 7:57–68 19. Matsiy V (2017) Geotechnical monitoring of the automobile Road. IOP Conf S Earth and Env Sci 95(2):022029 20. De Souza CN, Filho MJGS, De Paiva Valadares OC et al (2018) Georeferenced monitoring of displacements of gabion walls. Proc Inst C Eng Geotech Eng 171:64–77 21. Romanova G, Pleshko M, Rossinskaya M et al (2018) Management and monitoring of urban environment in the integrated development of underground space. Adv Int S Comp 692:1111– 1124 22. Stepanov MA et al (2021) Geotechnical monitoring results of 22-storey buildings on combined strip pile foundations with prestressed soil bases. J Phys Conf Ser 1928:012027 23. Ulickij VM, Shashkin AG (2002) Koncepciya geotekhnicheskogo soprovozhdeniya stroitel’stva i rekonstrukcii dlya novoj redakcii peterburgskikh geotekhnicheskikh norm (The concept of geotechnical support of construction and reconstruction for the new edition of the St. Petersburg geotechnical codes). Rekonstrukciya gorodov i geotekhnicheskoe stroitel’stvo 5:29–43

Prospects for the Use of Painted Ceramic Facing Materials Using Man-Made Waste V. S. Romanyuk(B) , L. V. Klimova, V. M. Kurdashov, A. I. Izvarin, and V. S. Yatsenko Platov South-Russian State Polytechnic University (NPI), 132, Prosveshcheniya St., Novocherkassk 346428, Russia [email protected]

Abstract. The production of ceramic products is one of the most materialintensive industries. The relevance of research is based on the need to develop new modern technologies and methods for the production of facing ceramic bricks, expanding the range of produced building ceramics, by introducing man-made waste into the composition of the ceramic charge. This is due to the annual increase in the volume of various non-recyclable industrial wastes, which can serve as cheap raw materials and modifiers that improve the properties of ceramics in some cases, and the depletion of natural clay raw materials used in the ceramics industry, which is an acute economic problem, as it affects the quality and cost. manufactured products. The study is aimed at the recycling and reuse of man-made waste, which will create a reserve of competitive raw materials for the production of facing bricks. The methods of utilization and processing of production wastes were studied, the advantages and disadvantages of each were identified, and the most optimal method was chosen, which was introduced into the technology of manufacturing ceramic facing bricks. Keywords: Ceramic materials · Facing bricks · Man-made waste · Clay raw materials · Construction industry · Recycling

1 Introduction The ceramic industry is developing, creating and filling new niches in a changing environment. Ceramic products have an almost unlimited service life. Products such as wall bricks, ceramic tiles, facade and facing tiles, artistic and pottery ceramics, etc., are architecturally more expressive and durable in color, texture, shape. Ceramic brick remains the main material of wall ceramics. Structures made of ceramic materials are perceived as prestigious, their aesthetic appeal is preserved over time. The ceramic industry, like other areas of the building materials industry, is experiencing a shortage of mineral raw materials due to the depletion of natural resources. In addition, the quality of natural raw materials is often reduced. Raw materials have to be adjusted with additives or other types of raw materials, for example, man-made. The development of modern innovative technologies for the production of building materials in the XXI century. predetermines the use of industrial waste as additional © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_4

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V. S. Romanyuk et al.

sources of raw materials. This is due, on the one hand, to the depletion of natural raw materials, on the other hand, to the intensive accumulation of industrial waste. In the modern world, the disposal of man-made waste is one of the main problems. It is customary to call waste from various industrial enterprises as man-made, it is also customary to attribute waste from thermal power plants and construction waste. Since the volume of industrial waste significantly exceeds the volume of waste from housing and communal services, the development of new methods for their disposal is more relevant than ever [1]. There are various ways to dispose of man-made waste. Depending on the chemical composition and physical state, each type of waste has its own optimal method of processing. For example, waste from galvanic, metallurgical and mining industries, which are mainly slags and sludge, is most rationally used as a filler for various building materials (ceramics, cement and asphalt concrete mixtures), as well as for backfilling when laying roads and leveling the terrain. Glass waste is usually processed into glass wool, but foam glass, interior tiles and water glass can also be produced. Waste rubber and plastics are used for the production of polymer sand tiles, thermal insulation materials, as well as for the production of fuel and energy resources by pyrolysis [2]. The use of recycled materials reduces the amount of waste sent to landfills and reduces the extraction of clay and other minerals needed to produce ceramic materials. Recycling also reduces energy consumption, as it usually takes less energy to make a product from waste than to make it from virgin raw materials. This, in turn, helps to reduce the use of fuel in production and helps reduce environmental pollution.

2 Experimental Part The increase in growth and investment in capital construction and housing stock, set the task of increasing the production of environmentally friendly and durable materials, in which the leading role is given to various types of ceramic building materials: wall, roofing, heat-insulating, finishing. An analysis of changes in the growth rates of consumption of the main types of small-piece wall material, which include ceramic and silicate bricks, as well as a wide sector of blocks made of various materials, made it possible to establish that the share of ceramic wall materials in the Russian Federation as a whole accounts for more than 50% of the entire list of wall materials (Fig. 1). Projects related to such new types of building materials for the Russian consumer as clinker bricks and porous ceramic blocks are actively developing [3].

Fig. 1. The structure of the production of ceramic wall materials in Russia for 2021–2022.

Prospects for the Use of Painted Ceramic Facing Materials

37

The range of output of the Russian industry of ceramic products in the total volume includes the following types of products: bricks, blocks, tiles, roofing tiles. Manufactured products differ in shape and a wide range of color palettes, which makes it possible to translate into reality multiple technical and architectural projects that guarantee the creation of a comfortable environment for the life and living of citizens. As can be seen from the diagram, facing bricks account for a significant proportion of all ceramic wall materials produced. It occupies the second position in terms of output after ordinary bricks. Facing ceramic materials are used for exterior and interior decoration of buildings for various purposes. In modern low-rise construction, facing bricks of a wide range of colors are actively used. Most often it is produced from white-burning clays with the addition of various kinds of dyes, pigments, or by combining two types of clays. Due to the decrease in the nature of the reserves of used clay, it becomes necessary to introduce man-made waste into production, thereby reducing the consumption of natural raw materials and preserving its reserves. Technogenic waste is industrial production, which includes solid, liquid and gaseous waste generated at enterprises in the process of obtaining the final product from raw materials. First of all, technogenic wastes are the remains of raw materials, materials and semi-finished products formed during the production of products or the performance of work and have lost their original consumer properties in whole or in part [4, 5]. Currently, in the Russian Federation, industrial enterprises annually generate about 36 million tons of dusty and gaseous wastes, 45 km3 of sewage and up to 10 billion tons of solid wastes, of which the main part is ash and slag from thermal power plants (TPPs), waste from mining and mineral processing, waste from metallurgical industries, construction waste, as well as waste from the chemical and forestry industries. At the same time, according to the data of Rosprirodnadzor, only 10–20% of the resulting waste materials are reused or neutralized, and the rest is sent to storage, gradually accumulating. Processing of industrial waste can become a source of a large amount of raw materials for the chemical, construction and metallurgical industries. At present, the use of man-made waste in construction is the main direction in the processing of man-made waste, which allows processing various types of waste in large quantities to obtain products of a sufficiently high quality. 2.1 Utilization of Ash and Slag Waste The most important for the construction industry and the first place in terms of volume among ferrous metallurgy wastes are blast-furnace slags. Their composition can include up to 30 different chemical elements, mainly in the form of oxides, among which SiO2 , Al2 O3 , CaO, MgO are contained in the greatest amount. The first method of processing blast-furnace slag is granulation. Blast furnace and electrothermophosphorus slags in case of granulation can be used in the production of cements. An alternative use of ferrous slags is to use them for the manufacture of mineral wool. Slag pumice can be used to fill concrete. Blast-furnace slags from dumps formed when waste is dumped into a dump are also in demand. Basically, coarse aggregate is used when laying roads, and also as a primer under the lower layer of concrete coatings.

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V. S. Romanyuk et al.

Ash and slag waste from thermal power plants is most widely used in the cement industry as a slow-hardening independent binder for road construction as an active hydraulic additive in combination with inorganic, bitumen or polymer-bitumen binders, as a filler or a low-active additive instead of part of the cement. The active use of ash and slag waste in the manufacture of silicate bricks can significantly reduce the use of lime (savings can range from 10 to 50% depending on the composition) and sand (savings of about 30%). The largest amount of ash and slag waste is used in road construction, where they are used for backfilling uneven terrain, as well as a filler for asphalt concrete pavements. As a filler, ash is also used in the production of mastic for rolled roofing materials [6, 7]. 2.2 Utilization of Mining Waste Dumps formed after the development of minerals contain a large amount of raw materials valuable for the construction industry, such as chalk, clay, sand and others. The dumps of ore beneficiation enterprises contain even more valuable components, non-ferrous metal ores, for example, are used in the production of composite binders, refractories, facing materials, mineral fibers and other types of products. At the moment, the dumps of the enrichment enterprises are practically not used. However, recent studies have discovered the possibility of using tailings and mining waste in the production of porous aggregates for ceramic products, sand-lime bricks, plaster and masonry mortars, which are actively used in construction [8]. 2.3 Utilization of Waste Rubber and Plastics Compared to mineral waste, it is more difficult to recycle plastic and rubber waste. The most large-tonnage and widespread rubber waste are tires. The most common methods for their disposal are burning for heat, pyrolysis to produce liquid fuels similar in properties to gasoline, and solid fuels that can serve as a substitute for charcoal. It is also very popular to manufacture rubber crumb to replace synthetic and natural rubber in the production of various rubber products. Shredded rubber products are used for the production of insulating materials, flooring, soundproofing materials, drainage mats. In construction, plastic waste is primarily used as a binder for the production of composite materials and products, in which the most promising direction is the use of crushed waste as fillers. Waste plastics are also used in compositions with traditional building materials to modify their properties, to obtain soundproof boards and panels, in the production of sealants used in the construction of buildings, hydraulic structures, etc. [9]. 2.4 Utilization of Glass Waste Waste glass (cullet) can have a variety of origins. There are many options for their use. Glass wool is an excellent heat and sound insulator. In its manufacture, cullet is melted down into a special fiber, which is the basis of the product. Thermal insulation, which primarily includes foam glass, which is a vitreous material penetrated by numerous uniform pores. It is characterized by low volumetric weight,

Prospects for the Use of Painted Ceramic Facing Materials

39

low thermal conductivity and low water absorption. Also, on the basis of cullet, silica foam, foam concrete, foam glass-crystalline materials, etc. can be obtained. Liquid glass (silicate glue), which is a universal material and is widely used in various industrial and domestic areas. In construction, liquid glass is used for waterproofing, as an additive in concrete, etc. Broken glass replaces sand in the production of liquid glass, which reduces the cost of production. Along with the above directions, glass waste can be used as a filler in the production of facing products and as an additive, which is a source of the vitreous phase in the production of self-glazing building ceramics and other types of ceramic products [10, 11]. 2.5 Utilization of Chemical Industry Waste Chemical industry waste containing calcium sulfate in one form or another is a source for the production of gypsum and anhydrite binders and products (phosphogypsum, fluorogypsum, titanogypsum, borogypsum, sulfogypsum). After appropriate processing, including washing off acid residues, cleaning from mechanical impurities, roasting and crushing to the required size, all of the above waste is converted into a high-quality gypsum binder used for the production of mortars, drywall and gypsum figurines for decorating interiors. Washed and cleaned, but unfired, gypsum can be used as a filler in the production of various composite materials to increase density [12]. 2.6 Utilization of Wood Waste Wood waste is one of the most widely used in various fields. In the construction industry, wood waste can be used in the following areas: sawdust can be used to make bricks and gypsum sheets; wood chips and cement chipboards, which are used in the construction of houses, can be made from shavings. Chips, mainly coniferous, are used to produce arbolite, a building material that is unique in its characteristics. One of the main methods of processing wood waste into building materials is the production of board materials. Small sawdust is used for the manufacture of fiberboard and chipboard [13–15]. 2.7 Disposal of Sludge Waste Sludge waste includes sediments of suspensions obtained in metallurgical and chemical industries as a result of processes carried out by the hydrochemical method. This type of man-made waste is a source of large reserves of secondary raw materials for the production of building materials. The main type of sludge waste is drill cuttings, which is understood as an aqueous suspension, in which solid particles are substances formed during the destruction of the surface of broken rock and during abrasion of the tool lowered into the wells. The solid component of drill cuttings can also be represented by clay minerals. An effective technology for the disposal of drilling workings is their solidification, carried out by mixing the cleaned drill cuttings with special sorbents and cement. The neutralized product produced in this way is used in the manufacture of building materials.

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Sludge waste also includes galvanic sludge (galvanic waste) obtained during the treatment of wastewater from industrial enterprises involved in the application of galvanic coatings [16]. At the moment, technologies have been developed for the disposal of galvanic waste with the production of filler for various building materials and products, for example: ceramic tiles, expanded clay, silicate and ceramic bricks, synthetic rubber, concrete, expanded clay, etc. Galvanic sludges are also actively used as additives in cement mortar for laying bricks and in asphalt concrete mix. Utilization of galvanic waste by adding it to the asphalt concrete mix allows saving crushed stone filler by about 30%. The use of galvanic sludge generated as a result of chemical treatment of wastewater from galvanizing shops in the production of building ceramics leads to an increase in porosity and water absorption with a decrease in strength, frost resistance and thermal conductivity. The use of galvanic sludge together with fluxes and additives that form the vitreous phase makes it possible to impart strength, chemical and thermal resistance to the vitreous phase. There are developments on the use of galvanic sludge as a filler in the production of polymer composite protective coatings. A wide range of production of ceramic products from highly porous heat-insulating building materials to clinker bricks opens up the possibility of using a wide variety of man-made waste. However, each separately formed type of waste, due to its unique composition and distinctive properties, requires an individual approach to the development of a technology for its recycling. As a result of an analytical review [6–16] of types of technogenic waste for the development of technology for the production of facing bricks using them in the raw material composition, drill cuttings were chosen, since during the studies it was found that its composition contains a high percentage of the clay component. The production technology of facing bricks has a number of features. It includes the following stages [17]: 1. extraction, homogenization and transportation of raw materials to the manufacturer’s plant; 2. preparation of additives; 3. processing of the main raw material and preparation of the plastic mass; 4. pressing. The plastic mass is pressed into the shape of a bar. Then cut off; 5. drying raw. Drying removes moisture; 6. roasting raw. Constant dosing is done using box feeders. Component components are delivered to the feeder through a metal grate with 15 × 15 cm cells, designed to retain foreign large objects and protect against accidents. Transportation of raw materials to various operations of the technological process can be performed using belt conveyors. Next, clay and drill cuttings are subjected to primary coarse grinding on disintegrator rollers. Stones, falling on the small portage, can be thrown by it through the large portage into the estrus, from where they are removed. After grinding, the raw material is fed to a drying drum for drying, the heat carrier of which is flue gases from special furnaces. In the discharge section of the drum, hinged

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41

metal chains are used to speed up the process of loosening and grinding clay and drill cuttings during the drying process, which makes it possible to obtain raw materials with more uniform moisture and increase the productivity of the drum. A hammer mill is used to grind cullet. After primary processing, clay, drill cuttings and cullet undergo control screening, carried out with the help of vibrating screens. After the screening process, the raw materials are stored in intermediate bins. With the help of poppet feeders, clay, drill cuttings and cullet from intermediate storage bins are fed for joint grinding in a continuous ball mill, to exclude the possibility of contamination of raw materials with iron, uralite cylinders with a diameter of 16– 25 mm, flint pebbles or porcelain balls are used as grinding bodies. The amount of raw material loaded into the mill must completely fill the cavity between the balls and cover them with a thin layer from above. After joint grinding, the mixture is fed into a twin-shaft paddle mixer with water supplied to it. In the clay mixer, the charge is evenly moistened and mixed until a homogeneous mass. Further, the clay mixer works as a feeder for the forming unit. During operation, the agitator shafts are covered with the mixture being processed no higher than 1/3 of the height of the shaft blades in the upper position. Pressing samples in one-sided and one-stage way on a hydraulic press. At the same time, the pressing pressure, the dimensions and shapes of the products (2–3 times per shift) and the strength of the raw material (every shift) are constantly monitored. The resulting raw material is transported to the drying place by trolleys. Drying is carried out in a tunnel dryer with mechanized loading and unloading, with automated temperature control and regulation. At the initial stage of drying, when the raw material comes into contact with an already cooled and moistened heat carrier, which provides a mild regime, while eliminating cracking. In the process of finishing drying, when the raw material is at the stage of drying and shrinkage processes, it perceives the coolant at elevated temperatures, which contributes to the implementation of the drying process. The trolleys are installed in the tunnel close to each other and are periodically fed forward by a special pusher. The heat carrier through the inlet channel and the opening with an open gate is fed into the tunnel from the side where the dried raw material is unloaded and is discharged from the opposite end with the second gate open to the outlet channel leading to the suction fan. A mixture of air and flue gases is used as a drying agent (heat carrier). It is also possible to use a cyclic supply of coolant. The method consists in cyclic heating and cooling of the surface of the raw material, as a result of which there is a forced acceleration of the external and internal diffusion of moisture in the raw material. In this case, the drying process can be reduced by 1.5–3 times. After the drying process is completed, the samples are fed to the muffle tunnel furnace for firing. The firing temperature is 1000 ºC. The principle of operation of the tunnel kiln is that the raw material moves while the individual thermal zones of the kiln are stationary, while the temperature zones and the firing temperature curve remain constant. The advantages of tunnel kilns include the fact that they are amenable to mechanization and automation, they are easy and relatively cheap to maintain, and the disadvantages are a relatively large temperature difference in various zones of the kiln and, especially,

42

V. S. Romanyuk et al.

in the preparation zone, the possibility of cold air suction from below, rapid wear of the trolleys from the high temperature in the firing zone. Fired products undergo quality control and go to the warehouse of finished products [17, 18]. Studies have been carried out on the behavior of the ceramic mass for the production of facing bricks during firing, with the addition of drill cuttings to it. The test samples (tiles) were molded in accordance with the specified composition, dried to a residual moisture content of about 3–5%, and fired at temperatures of 900 °C, 1000 °C, 1100 °C. During firing, the temperature was raised at a rate of 2°/min and the final temperature was held for 1 h. Cooling is natural, lasting at least 10 h. After firing, each specimen was carefully inspected, noting the location of the specimens in the kiln; color and uniformity of its distribution over the shard; cracks; change in shape due to different shrinkage, which may occur due to uneven temperature distribution in the furnace; deformation or melting of samples associated with overburning. The studied compositions of the samples are presented in Table 1. Table 1. Compositions of the studied samples. Material

Content, mass % 1

2

3

4

5

Drilling waste

90

85

80

75

70

Clay

10

15

20

25

30

For each temperature regime of firing, 10 samples were molded, of which each two subsequent ones were of a given raw material composition indicated in Table 1. As can be seen from Fig. 2, in the course of the post-firing visual examination of the samples, bricks of different raw composition, but of the same firing temperature regime, at first glance, do not differ much from each other, but if we consider each composition separately, we can notice changes in the visual characteristics of the fired samples. at different temperatures: • the color becomes darker with increasing temperature; • a small number of cracks; there is no deformation and melting of the samples; • in samples with a high content of sludge in the composition (No. 1–3) at a temperature of 1100 °C, efflorescence is observed on the surface, and shiny and yellow blotches are present on these samples, which indicates the content of various impurities in the sludge [18]. The first ten samples have a light brown-orange color, which is determined by the firing temperature of 900 °C. The next ten samples were fired at a temperature of 1000 °C and have a clay brown color. The last ten samples, with a firing temperature of 1100 °C, are distinguished by a walnut brown color. All samples have a dense, well-sintered shard.

Prospects for the Use of Painted Ceramic Facing Materials

43

Fig. 2. Studied samples after firing.

Thus, based on the results of the experiment, it can be argued that the color of the finished product after firing largely depends on the percentage of drill cuttings in its raw material composition. The higher the content of sludge in the mass, the darker the color of the brick, and vice versa, the lower the percentage of sludge, the lighter and dimmer the color.

3 Conclusion The construction industry can be the main consumer of man-made waste. In this direction of production activity, mankind uses natural resources that are maximally ready for use, since they require minimal labor costs. The extraction of natural raw materials from interconnected natural states, where its presence ensures the balance and stability of the environment, introduces an imbalance in the system of self-organizing processes of the geosystem. This imbalance can be reduced by changing the natural resource base of the construction industry by replenishing it with a new type of raw material—man-made. The value of technogenic raw materials in the manufacture of building materials can be significant. The technogenic raw material, which is closest in composition and properties to the clay raw material used in the technology of ceramic facing bricks, is drill cuttings. In this regard, there is a technical and economic interest that causes this type of man-made raw materials. This is due, firstly, to the existing huge reserves of sludge waste, secondly, to the aggravated environmental situation, and thirdly, to the search for new mineral raw materials, equivalent in quality and properties to traditional ones, but more accessible and cheaper. However, there has not yet been a wide involvement in the production of stocks of raw materials from drilling oil sludge. The considered technogenic wastes as modifiers of the ceramic industry allow not only to expand the raw material base for the production of facing ceramics, but also to preserve the ecological state in the country. Acknowledgements. The work was performed in SRSPU (NPI) with the financial support of the Russian Science Foundation under agreement No. 20-79-10142 «Development of an effective

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technology for the synthesis of aluminosilicate proppants using oil and gas drilling waste from the Southern Federal District» (supervisor—A.A. Tretyak).

References 1. Kuvykin NA, Bubnov AG and Grinevich VI (2004) Hazardous industrial waste. Ivan. state chemical-technological un-t, Ivanovo, p 148 2. Pichugin EA (2013) Assessment of the impact of drilling waste on the environment. Young Scient 9:122–124 3. Tretyak AA, Yatsenko EA, Onofrienko SA, Karelskaya EV (2021) Identification of drilling wastes and their use. Bulletin of the Tomsk Polytechnic University, Georesource Engineering 4. Yatsenko EA, Tretyak AA, Chumakov AA, Golovko DA (2021) Prospects for the use of drilling fluids for the synthesis of aluminosilicate proppants. Mater Today Mater 38:1886– 1888 5. Yatsenko EA, Goltsman BM, Chumakov AA, Vilbitskaya NA, Li W (2021) Research on the synthesis of proppants used for oil production by hydraulic lining. Mater Sci Forum 1037:181–188 6. Goltsman BM, Yatsenko EA, NYu, Komunzhieva, Yatsenko LA, Gerashchenko VS, Smoliy VA (2020) Influence of fluxes on the synthesis of porous materials based on native silicate raw materials. Glass Ceram (English translation of Glass and Ceramics) 77(5–6):240–244 7. Federal Agency for Technical Regulation and Metrology. Production of ceramic products (2015) BAT Bureau, Moscow, pp 66–78 8. Al’myashev VI and Gusarov VV (1999) Thermal methods of analysis: textbook. allowance, SPbGTU (LETI), St. Petersburg, p 40. 9. Wendlandt W (1978) Thermal methods of analysis. Per. from English. In: Stepanov VA, Bershtein VA (eds). Mir, Moscow, p 527 10. Ya S (1987) Theory of thermal analysis: physical and chemical properties of solid inorganic substances. Mir, Moscow, p 456 11. Savelyeva VN (ed) (1996) Landfill for the disposal and processing of drilling waste and oil production: Fundamental technological solutions. Book. 3. Development of fundamental solutions for the neutralization and disposal of drilling waste and oil-contaminated sands. NGDU, Surgut, p 101 12. Deneko Y (2014) About the problem of drilling waste processing. Oil Gas Siberia 1(14):29–30 13. Maksimovich VG and Bukov NN (2013) Neutralization of oil sludge and cleaning oil pipelines of oil deposits in the Krasnodar Territory. Materials of the XI International Seminar on Magnetic Resonance (spectroscopy, tomography and ecology). Rostov-on-Don, p 120 14. Aminova AS, Gaibullaev SA, Juraev KA (2015) Tech. The use of oil sludge is a rational way of their disposal. Young Scient 2:124–126 15. Pashchenko AA (1986) Physical chemistry of silicates: a textbook for universities. Higher school, Moscow, p 367 16. Budnikova PP, Poluboyarinova DN (eds) (1972) Chemical technology of ceramics and refractories: textbook. Stroyizdat, Moscow, p 552 17. Gorshkov BS, Saveliev VG, Fedorov NF (1988) Physical chemistry of silicates and other refractory compounds: textbook. Higher School, Moscow, p 400 18. Strelov KK (1985) Theoretical foundations of refractory technology: a tutorial. Metallurgy, Moscow, p 480

Parametric Studies of Intra-Modular Connections Stiffness V. Shirokov(B) and T. Belash JSC Research Center of Construction, 2-nd Institutskaya Str., 6, Moscow 109428, Russia [email protected]

Abstract. The article is focused on the study of the stiffness of intra-module connections of stacked modules buildings with corner columns. A review of literary sources devoted to this issue has been carried out. It was revealed that the vast majority of the compounds considered by the researchers are semi-rigid according to the classification of Eurocode. Therefore, within the article, data is provided on parametric numerical studies of the rotational stiffness of the used types of nodes with different parameters to establish the boundaries of rigid joints of a crossbar with a column of modular buildings. Within the study, five types of intra-module connections were considered: without stiffeners, with vertical stiffener, with horizontal stiffeners. The main variable parameter for nodes with a vertical stiffener was the height of the stiffener. For nodes with horizontal stiffeners, the variable parameters were the width and thickness of the stiffener, as well as the material of the main elements and welding. Based on the results of numerical studies of the parameters of rotational stiffness of intra-module connections, it was found that the high strength materials could slightly increase the rotational stiffness of joints; rigid nodes with vertical ribs have a lower material consumption compared to nodes with horizontal ribs; nodes with horizontal ribs have more increased load carrying ability. Keywords: Modular buildings · Initial stiffness · Semi-rigid joints · Rigid joints · Intra-module connections · Stiffener

1 Introduction Modular buildings are a modern and actively developing construction technology. The main feature of modular construction is the erection of a structure from volume modular blocks manufactured at the factory, each of which is also a separate building element. The main structural material for the modules is steel. 1.1 Modular Buildings Classification Modular buildings are classified according to the following criteria: structural system of the building, constructive solution of modules, nodal connections [1–9]. According to the constructive system: © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_5

46

V. Shirokov and T. Belash

• stacked modules system • system with core • external frame system According to the constructive solutions of the modules: • corner supported modules • load-bearing walls modules • non-bearing walls modules According to the location of connection nodes in the building: • • • •

intra-module connections inter-module connections module to foundation connection module to core connection (if necessary)

This article is devoted to the study of the stiffness of intra-modular connections of buildings from composed corner supported modules. Stiffness of intra-module connections affects the strain-stress behavior of the framework, the stability of the vertical members and the compliance of the building as a whole under the action of transverse loads. 1.2 Intra-Module Connection Rotational Stiffness Researches Annan [10] writes that the connection between the column and the beam is usually considered rigid, but does not provide studies or specific data. Liew [7] notes that beamto-column connections in a module must be rigid, and also states in [5, 6] that a beamto-column connection can usually be considered as a rigid connection if full-strength welds are used. At the same time, Liew [7] marks that at the moment there are no recommendations for the design of rigid intra-module nodes, so it is necessary to carry out numerical analysis and experimental studies of these compounds. The stiffness classification of the joints differs according to Eurocode 3. kb · E · Ib − rigid joint; Lb

(1)

Sj,R > Sj,ini > Sj,P − semi rigid joint;

(2)

0, 5 · E · Ib − pin joint; Lb

(3)

Sj,ini > Sj,R =

Sj,ini < Sj,P =

where S j,R , S j,P are limiting values of rotational stiffness for rigid and pin joints respectively; E is the modulus of elasticity of steel; L b —moment of inertia of the crossbar (fastening element); L b —crossbar span; k b is a coefficient that takes into account vertical

Parametric Studies of Intra-Modular Connections Stiffness

47

ties: k b = 8—for frame of framework in which the bracing system surrounds horizontal movements by 80 per cent upon location detection; k b = 25—for other frames. In the literature, there are few studies of the rotational stiffness of intra-module joints [11–19]. These studies were carried out for a limited set of nodes with a small set of variable parameters; a brief summary is given in Table 1. According to Table 1, it can be seen that almost all the nodes considered in the studies are semi-rigid for the dimensions of the elements of typical modular buildings. Therefore, when calculating the framework, it is necessary to take into account the flexibility of the joints. It is also worth noting that the given data [11–19] are valid only for the considered specific nodes. So, it is necessary to carry out more extensive research of the rotational stiffness of the used types of nodes with different parameters to set the limits of the rigid connections of the crossbar with the column in modular buildings.

2 Parametric Numerical Researches of Intra-module Connection Rotational Stiffness Within the study, five types of intra-module connections were considered: • vertical member made of square hollow section, beam made of square hollow section without stiffeners (SHS-SHS) • vertical member made of square hollow section, beam made of channel profile without stiffeners (SHS-C) • vertical member made of square hollow section, beam made of square hollow section with vertical stiffener (SHS-SHS-VS) • vertical member made of square hollow section, beam made of channel profile with vertical stiffener (SHS-C-VS) • vertical member made of square hollow section, beam made of channel profile with horizontal stiffeners (SHS-C-HS) Parametric numerical studies were carried out using the IDEA StatiCa software package, which was specially created for calculating nodal connections. Within this study, the mode for calculating the stiffness of the element attachment according to Eurocode was used. The software package plots the “M-ϕ” dependence graph and calculates the rotational stiffness independently according to the actual deformations and forces determined during the calculation process. Connection diagrams are shown in Fig. 1. Cross section of square hollow sections is accepted according to Russian National Standard 30,245-2003, cross sections of channel profiles with parallel flange edges according to Russian National Standard 8240-97. For joints without stiffeners and with vertical stiffeners, steel S245 was adopted for all elements, weld legs k f = 4 mm, welding material—E42. The steel grade, legs and materials of the joints do not have a significant effect on the rotational stiffness of the joints under consideration, therefore, in this study, these parameters are unchanged. For connections with horizontal stiffeners, the strength characteristics of elements and welds can have a significant effect. Therefore, for this type of nodes, two options were considered: steel S245, welding material—E42, weld legs k f = 4 mm; S345, welding material—E50, weld legs k f = 4 mm.

Beam

C 250 × 100 × 4

–

RHS 250 × 150 × 8 RHS 150 × 150 × 8

C 250 × 140 × 10 C 200 × 140 × 10 C 225 × 140 × 10 C 250 × 140 × 10

Column

HSS 200 × 100 × 6

Cold formed angle 150 × 210 × 30 × 25

HSS 150 × 150 × 8

HSS 150 × 150 × 8

References

[11]

[12]

[13]

[14]

6015,82 4425,77 4564,23 4780,73 4862,68

CT4.0 BD10 BD14 BL32 BL36

20,868,31

20,522,58 20,559,69 23,886,37 22,014,79 19,466,81

Model-2

Model-3 Model-4 Model-5 Model-6 Model-9

2749

5161,89

–

5120,12

CT3.5

1090,3

With stiffener VL40

515,4

S j,ini (kNm/rad)

Without stiffener

Specimen

166,097,8

185,482,4

207,977,6

166,097,8

166,097,8

166,097,8

129,734,68

16,675,7

16,675,7

16,675,7

16,675,7

16,675,7

16,675,7

16,675,7

34,649,2

34,649,2

S j,R (kNm/rad)

Table 1. Investigations of the rotational stiffness of intra-module joints.

3321,956

3709,648

4159,552

3321,956

3321,956

3321,956

2594,694

333,514

333,514

333,514

333,514

333,514

333,514

333,514

692,984

692,984

S j,P (kNm/rad)

(continued)

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Pin

Classification

48 V. Shirokov and T. Belash

Beam

C 200 × 75 × 6

HSS 150 × 150 × 8

HSS 200 × 200 × 8 HSS 200 × 200 × 6

C 350 × 100 × 6

Column

HSS 125 × 125 × 6

HSS 150 × 150 × 8

HSS 200 × 200 × 10

RHS 150 × 100 × 6

References

[15]

[16]

[17]

[18, 19] 7935,57 6692,6 7234,92 5935,53 6733,85

C150-4.5-2 C150-6.0-2 C200-4.5-1 C200-6.0-1

15,800

QS2 C200-4.5-2

16,700

MS3 6905,09

18,300

MS2

Ref-W

16,100

11,150

Stiffener 170 mm MS1

9390

Stiffener 100 mm

7780

21,132

Model-12 Case 2

22,239,96

Model-11 2235

20,622,74

Model-10

Case 1

S j,ini (kNm/rad)

Specimen

Table 1. (continued)

112,908,6

112,908,6

112,908,6

112,908,6

112,908,6

112,908,6

131,819,4

131,819,4

131,819,4

131,819,4

29,083,08

29,083,08

24,293,58

24,293,58

166,097,8

166,097,8

166,097,8

S j,R (kNm/rad)

2258,172

2258,172

2258,172

2258,172

2258,172

2258,172

2636,388

2636,388

2636,388

2636,388

581,6616

581,6616

485,8716

485,8716

3321,956

3321,956

3321,956

S j,P (kNm/rad)

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Semi-rigid

Classification

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Fig. 1. a SHS-SHS; b SHS-C; c SHS-SHS-VS; d SHS-C-VS; e SHS-C-HS.

2.1 Joints Without Stiffeners SHS-SHS and SHS-C In the course of study he rotational stiffness of SHS-SHS nodes, a number of schemes with different parameters of the connected elements were calculated. The vertical members of one cross section were alternately attached to crossbars of different dimensions, not exceeding the dimensions of the vertical member. When connecting with a beam with a smaller cross section than the column’s cross section, alignment is performed

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along the outer edge of the elements. For parametric research, the following set of cross sections is accepted: • vertical member of square hollow sections: 70 × 4, 70 × 5, 70 × 6, 80 × 4, 80 × 5, 80 × 6, 90 × 4, 90 × 5, 90 × 6, 100 × 4, 100 × 5, 100 × 6, 120 × 4, 120 × 5, 120 ×6 • crossbars of square hollow sections: 60 × 4, 60 × 5, 60 × 6, 70 × 4, 70 × 5, 70 × 6, 80 × 4, 80 × 5, 80 × 6, 90 × 4, 90 × 5, 90 × 6, 100 × 4, 100 × 5, 100 × 6, 120 × 4, 120 × 5, 120 × 6 A total of 178 numerical experiments were performed to determine the rotational stiffness of joints of the SHS-SHS type. As part of the study of the rotational stiffness of SHS-C type joints, a number of schemes with different parameters of the connected elements were calculated. To the vertical members of the same cross section, crossbars of various cross sections were alternately fastened, at the same time, for design reasons, connection options are excluded in which the width of the channel flange is greater than the width of the cross section of the vertical member. Beams and columns are aligned along the outer edge of the channel wall. For parametric research, the following set of cross sections is accepted: • vertical member of square hollow sections: 80 × 4, 80 × 5, 80 × 6, 90 × 4, 90 × 5, 90 × 6, 100 × 4, 100 × 5, 100 × 6, 120 × 4, 120 × 5, 120 × 6 crossbars of channel profile: 12UP, 14UP, 16UP, 18UP, 20UP, 22UP, 24UP, 27UP, 30UP • A total of 87 numerical experiments were performed to determine the rotational stiffness of SHS-C joints. 2.2 Joints with Vertical Stiffeners SHS-SHS-VS and SHS-C-VS As part of the research of the rotational stiffness of joints with vertical stiffeners, the nodes of the connection a vertical member made of square hollow section with beams made of square hollow sections and channel profiles are considered. According to studies of connections without stiffeners, nodes with vertical members with the smallest wall thickness have the minimum stiffness. Therefore, within the considering joints with stiffeners, nodes of attachment to vertical members with a wall thickness of 4 mm are considered. Vertical stiffeners are assumed to be one-sided along the outer faces of beams and vertical members. The height (hp ) and width of the rib are taken equal, trimming at 45z with an indent of 20 mm from the facets of the bearing elements. The thickness of the ribs is taken equal to 4 mm, since their dimensions have the greatest influence on the rotational stiffness of the joint. At the same time, for structural reasons, the minimum size of the rib is hp = 40 mm. The task of the research is to determine the dimensions of the vertical stiffeners, in which the connection is rigid for any span of the crossbar. Studies of the rotational stiffness of SHS-SHS-VS nodes were carried out by calculating a number of schemes with different parameters of the connected elements. The variable parameter was the height of the stiffener, which was changed with a 10 mm difference. For this research, the following set of cross sections of the main elements was adopted:

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• vertical member of square hollow sections: 80 × 4, 90 × 4, 100 × 4, 120 × 4 • crossbars of square hollow sections: 80 × 4, 90 × 4, 100 × 4, 120 × 4 In the course of studying the rotational stiffness of SHS-C-VS nodes, a number of schemes with different parameters of the connected elements were calculated. The main variable parameter was the height of the stiffener, which was changed with 10 mm step. For this research, the following set of cross sections of the main elements was adopted: • vertical member of square hollow sections: 80 × 4, 90 × 4, 100 × 4, 120 × 4 • crossbars of channel profile: 12UP, 14UP, 16UP, 18UP, 20UP, 22UP, 24UP, 27UP, 30UP. 2.3 Joints with Horizontal Stiffeners SHS-C-HS As part of the study of the rotational stiffness of joints with horizontal stiffeners, the nodes of the connection of a vertical member of a square hollow section with beams made of channel profiles are considered. Just as for joints of the SHS-C-VS type, the joints with horizontal stiffeners, nodes of attachment to vertical members with a wall thickness of 4 mm were considered in this study. Horizontal plates are located on both sides of the cross section of the crossbars (top and bottom) and have the same thickness. The upper stiffener has a cutout for the column and is attached to it by welding. The lower stiffener is welded to the beam flanges and the end of the vertical member, also performing the functions of a plug and a splice plate. Cutting of plates is at 45º with an initial size of sloped edge 30 mm. The minimum size of the rib is taken to be 40 mm larger than the size of the cross section of the column. Connections with horizontal stiffeners are more complex than those with vertical ribs. Therefore, for SHS-C-HS connections, the width (bp ) and thickness (t p ) of the stiffener are taken as variable parameters, since both of these parameters affect the rotational stiffness of the joint. The dimensions of the plates (bp ) were changed in 10 mm, while the size of the sloped edge (be ) increased with the same parameter. The thickness of the stiffener varied in the range from 4 to 10 mm with step of 1 mm. For this study, the following set of cross sections of the main elements was adopted: • vertical member of square hollow sections: 80 × 4, 90 × 4, 100 × 4, 120 × 4 • crossbars of channel profile: 12UP, 14UP, 16UP, 18UP, 20UP, 22UP, 24UP, 27UP, 30UP Also, to assess the influence of the strength characteristics of the joint elements on the stiffness of the joint, two options were considered: steel S245, welding material—E42, weld legs k f = 4 mm; S345, welding material—E50, weld legs k f = 4 mm. The task of the research is to establish the dimensions of the horizontal stiffeners, in which the connection is rigid for any span of the crossbar.

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3 Results and Analysis The papers [20–23] present the main results of studies of rigid intra-module connections of the SHS-SHS, SHS-C, SHS-SHS-VS, SHS-C-VS, SHS-C-HS types. This article provides an analysis of the comparison of these nodes. To assess the effectiveness of the appliance of one or another constructive solution of an intra-module connection, construction coefficients for each type of node were calculated: khs = 1 +

2 · Vp  , Ab · lb

(4)

kvs = 1 +

4 · Vp  , Ab · lb

(5)

where k hs and k vs are construction coefficients for nodes with horizontal and vertical stiffeners, respectively. Further, the designations k vs1 are used for SHS-SHS-VS nodes, k vs2 —for SHS-C-VS nodes, k hs3 —for SHS-C-HS nodes (S245 steel, E42 welding), SHS-C-HS nodes (steel S345, welding E50); Ab —cross-sectional area of the k hs4 —for  crossbar; l b —total length of longitudinal and transverse crossbars. According to formulas (4) and (5), the construction coefficient depends on the dimensions of the module and the cross  section of the crossbars. To analyze the change in the coefficients k, the total length lb = 9 m was taken as corresponding to the most common module sizes. To compare different types of cross sections of crossbars (square hollow section and channel profile) on the graphs, the change in the construction coefficient is given relative to the limiting moment M j,rd , which the node can withstand (Figs. 2, 3, 4 and 5).

Fig. 2. Changing of “k” coefficient for connections with a vertical member of square hollow section 120 × 4.

Figures 2, 3, 4 and 5 show that the building coefficients of nodes with vertical ribs practically do not change and are equal to k vs1 = 1.02–1.03; k vs2 = 1.01 –1.02. For connections with horizontal ribs, the construction coefficients vary over a wider range

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Fig. 3. Changing of “k” coefficient for connections with a vertical member of square hollow section 100 × 4.

Fig. 4. Changing of “k” coefficient for connections with a vertical member of square hollow section 90 × 4.

Fig. 5. Changing of “k” coefficient for connections with a vertical member of square hollow section 80 × 4.

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and depend on the cross section of the vertical member, which is explained by the design of the node. In this case, the changes of intervals do not depend on the materials of the elements and welding and are k hs3 = k hs4 = 1.01–1.11. An analysis of graphs 2 and 3 shows that when using steel S345 and welding E50, construction coefficients decrease compared to the option of steel S245 and welding E42 within the following limits: for nodes connecting with vertical members made of pipe 120 × 4, weight decreases by 0.48–0.77%; for nodes connecting with vertical members made of pipe 100 × 4  = 0.0045 ÷ 0.0060, the weight is reduced by 0.45–0.6%. Thus, the appliance of high-strength materials to increase the rotational stiffness of the nodes is not effective. When studying the influence of the parameters of joints similar to the considered types on their stiffness, materials with minimal strength characteristics should be taken. Figures 2, 3, 4 and 5 clearly show that nodes with vertical rids have the smallest building coefficients. The exception is connections with a vertical member from a pipe 120 × 4, where for the limiting moments M j.rd = 15 – 18 kNm, the values of k vs2 and k hs3 are equal to each other. Thus, from the point of view of rotational stiffness, it is more efficient to apply nodes with vertical ribs. However, these connections have a lower bearing capacity compared to nodes with horizontal ribs and are less aesthetic, because it is problematic to arrange them in the thickness of the floor. In cases where it is necessary to ensure a high bearing capacity of the connection of the crossbar with the column or to arrange a flat ceiling without protrusions, nodes with horizontal ribs should be applied.

4 Conclusion Based on the performed numerical parametric studies of the rotational stiffness of intramodule connections, the following conclusions can be drawn: • the appliance of high strength materials to increase the rotational stiffness of the nodes is not effective. When studying the influence of the parameters of joints similar to the considered types on their stiffness, it is advisable to take materials with minimal strength characteristics • from the point of view of rotational stiffness, it is more efficient to apply nodes with vertical ribs • nodes with horizontal ribs should be applied in cases where it is necessary to ensure a high bearing capacity of the connection between the crossbar and the column or arrange a flat ceiling without protrusions.

References 1. Lacey AW, Chen W, Hao H et al (2018) Structural response of modular buildings—an overview. J Build Eng 23:45–56. https://doi.org/10.1016/j.jobe.2017.12.008 2. Deng E-F, Zong L, Ding Y et al (2020) Seismic performance of mid-to-high rise modular steel construction—a critical review. Thin-Walled Struct 155:106924. https://doi.org/10.1016/ j.tws.2020.106924

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3. Lawson RM, Ogden R, Pedreschi R et al (2005) Developments in pre-fabricated systems in light steel and modular construction. Struct Eng 83:28–35 4. Lawson RM, Richards J (2010) Modular design for high-rise buildings. Proc Inst Civil Eng Struct Build 163:151–164. https://doi.org/10.1680/stbu.2010.163.3.151 5. Liew JR (2018) Innovation in modular building construction. In: Proceedings of the 9th International conference on advances in steel structures-(ICASS 2018), pp 1–14. https://doi. org/10.18057/ICASS2018.K.05 6. Liew JYR, Dai Z, Chua YS (2018) Steel concrete composite systems for modular construction of high-rise buildings. In: 12th International Conference on Advances in Steel-Concrete Composite Structures (ASCCS 2018). Universitat Politècnica de València, València, Spain, June 27–29, 2018, pp 59–65. https://doi.org/10.4995/ASCCS2018.2018.7220 7. Liew JYR, Dai Z, Chua YS (2019) Steel concrete composite systems for modular construction of high-rise buildings. Structures 21:135–149. https://doi.org/10.1016/j.istruc.2019.02.010 8. Thai H-T, Ngo T, Uy B (2020) A review on modular construction for high-rise buildings. Structures 28:1265–1290. https://doi.org/10.1016/j.istruc.2020.09.070 9. Chen Z, Khan K, Khan A et al (2021) Exploration of the multidirectional stability and response of prefabricated volumetric modular steel structures. J Constr Steel Res 184:106826. https:// doi.org/10.1016/j.jcsr.2021.106826 10. Annan CD, Youssef MA, El-Naggar MH (2009) Experimental evaluation of the seismic performance of modular steel-braced frames. Eng Struct 31:1435–1446. https://doi.org/10. 1016/j.engstruct.2009.02.024 11. Cho B-H, Lee J-S, Kim H et al (2019) Structural performance of a new blind-bolted frame modular beam-column connection under lateral loading. Appl Sci 9:1929. https://doi.org/10. 3390/app9091929 12. Zhang J-F, Zhao J-J, Deng E-F et al (2021) Component method based rotation performance and design method for the connection in ATLS modular house. Thin-Walled Struct 164:107803. https://doi.org/10.1016/j.tws.2021.107803 13. Khan K, Yan J-B (2021) Numerical studies on the seismic behaviour of a prefabricated multistorey modular steel building with new-type bolted joints. Adv Steel Constr 17:1–9. https:// doi.org/10.18057/IJASC.2021.17.1.1 14. Ma R, Xia J, Chang H et al (2021) Experimental and numerical investigation of mechanical properties on novel modular connections with superimposed beams. Eng Struct 232:111858. https://doi.org/10.1016/j.engstruct.2021.111858 15. Choi K-S, Kim H-J (2015) An analytical study on rotational capacity of beam-column joints in unit modular frames. Int J Civil Struct Constr Archit Eng 9:83–86. https://doi.org/10.5281/ zenodo.1098106 16. Wang Y, Xia J, Ma R et al (2019) Experimental study on the flexural behavior of an innovative modular steel building connection with installed bolts in the columns. Appl Sci 9:3468. https:// doi.org/10.3390/app9173468 17. Deng E-F, Zong L, Ding Y et al (2018) Monotonic and cyclic response of bolted connections with welded cover plate for modular steel construction. Eng Struct 167:407–419. https://doi. org/10.1016/j.engstruct.2018.04.028 18. Lee S, Park J, Kwak E et al (2017) Verification of the seismic performance of a rigidly connected modular system depending on the shape and size of the ceiling bracket. Materials 10:263. https://doi.org/10.3390/ma10030263 19. Lee S, Park J, Shon S et al (2018) Seismic performance evaluation of the ceiling-bracket-type modular joint with various bracket parameters. J Constr Steel Res 150:298–325. https://doi. org/10.1016/j.jcsr.2018.08.008 20. Shirokov VS, VYu, Alpatov, Gordeyev EA (2021) Research into the stiffness of beam-column joints of modular prefabricated buildings. Vestnik MGSU 16(1):20–29. https://doi.org/10. 22227/1997-0935.2021.1.20-29

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21. Shirokov VS, Gordeeva TE (2020) Research of joint connection rigidness of crossbar and column in a modular building. Bull Civil Eng 6(83):90–96. https://doi.org/10.23968/19995571-2020-17-6-90-96 22. Shirokov VS, Veremeenko OYu, Alpatov VYu (2021). Investigation of the modular building metal frame nodal connection rotational stiffness. In: E3S Web of conferences 281:01045. EDP sciences. https://doi.org/10.1051/e3sconf/202128101045 23. Shirokov VS, Belash TA (2022) Research of intra-module joints rigidness with horizontal stiffeners. Ind Civil Eng 4:57–63. https://doi.org/10.33622/0869-7019.2022.04.57-63

Responsive Architecture as a Synthetic Field in Architecture and Construction M. Zolotareva(B) and A. Ponomarev Saint Petersburg State University of Architecture and Civil Engineering (SPbGASU), 4 Vtoraya Krasnoarmeiskaya, Saint Petersburg 190005, Russia [email protected]

Abstract. This paper reviews responsive architecture, a dynamically developing aspect of design and construction, encompassing fundamental engineering and technological principles, architectural and design content, and green architecture elements to meet the needs of society and the individual. The key thesis of responsive architecture is “nothing in nature is motionless”. As part of nature’s context, the individual has the right to exist in a sustainable environment, the development of which is shaped through environmental, economic, and social aspects. Our research characterizes the key directions of responsive architecture’s development and development prospects in the context of the current technological processes and social needs. Since responsive architecture is based on synthesis, we rely on materials from various design fields (including engineering and technical solutions, mobile form-making, green architecture, etc.). When elaborating on the concept of responsive architecture, we looked at the potential responsiveness of different urban environment items: element, object, and city fragment. We examined the following aspects: technologies for working with natural systems and landscaped environments; modeling sustainable systems; defining approaches to the use of form-making and designer tools to ensure the responsiveness of environmental elements. Keywords: Mobile architecture · Architecture · Design · Green engineering · Technical solutions · Sustainable living

1 Introduction What makes our research topic particularly relevant is the close relationship between the development of modern architectural, construction, and engineering industries and the needs and guiding values of society, where dynamics, mobility, and environmental comfort take the spotlight. While a fairly new phenomenon, responsive architectural spaces as an aspect of architectural praxis are currently seeing active development and are capable of resolving spatial arrangement issues with the help of dynamic form-making principles. Notably, the solutions presented can be relevant not just to the spatial transformation of buildings and structures but even to neighborhoods and separate elements of the urban environment. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_6

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Currently, architecture is not just a form of construction art; it also demonstrates openness to a variety of disciplines that allow for adopting responsive solutions that will help arrange architectural sites and reshape the urban space. Responsive architecture finds itself at the crossroads of three-dimensional art, design, and engineering technology, serving as a catalyst for the integration of architectural and engineering processes. The concept of responsive architecture is evidently multifaceted, prompting researchers and practitioners to investigate the matter in several directions: • engineering and technological solutions (Rolf Disch, William McDonough, Glenn Murcutt, Norman Foster et al.); • mobile form-making methods (Jean Nouvel, Dominique Perrault, Santiago Calatrava, David Fisher, Robert Konieczny et al.); • architectural theory and practice in the environmental aspect (Werner Sobek, Emilio Ambasz, Wang Shu, Renzo Piano, Vincent Callebaut et al.); • promoting the sustainable development of the urban environment (Jacque Fresco, Ken Yeang, Sunand Prasad et al.). We must point out that the aforementioned “distribution” of research and design practices among representatives of global architecture is more or less arbitrary. Right now, the main aim of architectural thought is the sustainable development of the environment that human beings exist in. This becomes a vital factor in project execution. The goal of this study was to analyze the features of responsive architectural environments and determine development trends in this field. As we list the objectives of our study, we focus on the following: • • • •

Classifying the historical development of responsive architecture as a field. Clarifying the concept of responsive architecture. Characterizing the main development directions within responsive architecture. Singling out the development prospects of responsive architecture in the context of modern technological processes and social needs.

2 Methods The research methods are based on a comprehensive overview of the components that make up responsive architecture as a concept. A delve into the history of this architectural phenomenon will aid us with drawing conclusions on the prerequisites for its emergence. Due to the multifaceted nature of our research target, we are going to apply comparative and descriptive analysis to the individual features of completed and in-progress sites that fall under the responsive architecture category. We, therefore, carry out an analysis of materials coming from sources in fundamentally distinct fields and aspects of design (engineering and technical solutions, mobile form-making, green architecture, and so on).

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3 Results 3.1 Development of Responsive Space Concepts: A Historical Overview Mobility, interchangeability, transformation: these terms have been part of architectural praxis for a long time. However, an active search for solutions in this field did not start until the 1920s. Here, we can single out several specializations. The transformation of a static object’s internal structure became the basis for residential building design in the 1920s. It included movable partitions, built-in furniture, sleeping space modifications that increase the zone accessible during the day, and more. The “manifesto” of this design school was the development of the Weissenhof Estate, where many of the residential buildings allowed for spatial mobility. Projects by Le Corbusier, Ludwig Mies van der Rohe, and Mart Stam relied on making architectural spaces more responsive to the residents’ changing needs. Theo van Doesburg, an architect, painter, and new art theorist, who blended time and space together to create an effect of “plasticism”, proposed a theory of plasticity in architecture. Motion and organic matter were seen as an alternative to a lifeless, static state. In the 1910s, art began to seek ways of depicting a moving object. The roots of this search lie in easel painting and sculpture, which were considered the most mobile forms of art, especially when compared to architecture. Italian futurists, including Umberto Boccioni, Luigi Russolo, and Giacomo Balla, renounced static form and attempted to capture motion. The next step toward embodying form dynamics in architecture was the work of Russian constructivists: V. Tatlin, El Lissitzky, N. Ladovsky, and K. Melnikov [1]. Melnikov’s lighthouse-like design of a monument to the great seafarer Columbus set the development course for dynamic architecture and its adoption of kinetic elements for many decades ahead. That monument was rotated by a winged structure made out of two cones embedded into each other. Both the visual perception and the color scheme of the composition changed in the process. Another future-oriented movement involved working with the urban space and adapting it to new social values. In the early twentieth century, the teachings of Ebenezer Howard spearheaded the efforts to design and create garden cities next to major urban communities like London, Brussels, Hamburg, Essen, etc. This was followed by the linear city concept. One could say that a linear city is an “expanded” centric model of Howard’s garden city. With its length greater than its width, its cross-section provides access to natural landscapes adjacent to the urban area. The first such city was designed by Arturo Soria y Mata for Madrid in the late nineteenth century. Le Corbusier also proposed a similar concept for the urban development of Algiers. In that particular case, the axis of the linear city was supposed to run along the road formed by the buildings’ roofs. The concept found its supporters in Soviet Russia as well. Projects with vertical urban zoning really stand out here in terms of working with urban space. The most fantastical out of them is G. Krutikov’s flying city [2]. An alumnus of N. Ladovsky’s design workshop at the Higher Institute of Arts and Technology, he presented his vision of a city of the future. Krutikov’s core idea was that in a new society, humankind would leave the ground and build its homes within the air space. He set out the general principles of his theory in 1929, writing that architecture is striving to become

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more and more mobile… the modern city layout, stationary, dead, and inconvenient, should be replaced with a mobile layout based on new spatial arrangement principles. Vertically zoned city projects were also proposed by other futurist architects: A. Lavinsky (city on springs), El Lissitzky (horizontal skyscrapers) [3], and K. Melnikov (multi-story parking garages above bridges over the Seine in Paris). In the 1920–1930s, futurists worked on whimsical projects of linear and hovering cities with moving kinetic objects, displaying the kind of architectural creativity that was enthusiastically picked up again in the 1960s. For instance, the development of responsive architecture trends continued in the dynamic spatial urbanism concepts by Japanese metabolists: Kiyonori Kikutake, Fumihiko Maki, and others. The main concept, based on the “unfinished yet complete” aesthetic formula, was the cyclical sequence of changes in the urban organism. To solve the acute problem of accommodating the growing population of Japan, the metabolists proposed three-dimensional territorial zoning; the territories were to include the rigid, unchanging frame, and the “fabric”, which was a dynamic, variable space responsive to adaptation and growth. For projects like Tokyo 1960 (Kenz¯o Tange), The City in the Air (Arata Isozaki), or The Floating City (Kisho Kurokawa), the main subject was the three-dimensional environment as a whole. One of the projects (Kurokawa’s Nakagin Capsule Tower) was brought to completion, demonstrating, first and foremost, the financial infeasibility of interchanging obsolete elements. Here, we would like to share our personal opinion that the 1960s were not the right time for adopting these ideas. The Japanese Shimizu Corporation resurrected the concept of an eco-city in the ocean almost 50 years later. British architects went even further in enhancing the dynamic city concept. In the Living Pod project (Archigram Group, 1966), architect David Greene compared the residential structure’s external form with clothing. The Living Pod moves on little legs and can be parked anywhere, in the city or in nature. Another project by the same group is Walking City by Ron Herron (1964). This object of considerable size (400 m in length and 200 m in height) makes for quite a decent apartment building. Amid environmental concerns in the second half of the twentieth century, spurred on by climate change, the depletion of the ozone layer, ocean pollution, and the rise of the water level, along with energy problems, architects began to actively fantasize about making spatial structures more environmentally friendly; some of those fantasies would later on become a reality. Let us look at the most noteworthy projects in this field. Rael San Fratello Architects envisioned flying gardens, aimed at improving the ecology in major metropolises. The gardens were, in fact, controlled airships with plants, which were supposed to hover over areas with the worst environmental conditions. Belgian architect Vincent Callebaut proposed multiple solutions for climate improvement. One of his projects, which he called Hydrogenase, was a hovering, airship-like structure that was shaped like a lotus flower. The architect designed a device for the biotechnological extraction of hydrogen from a certain species of algae. Another one of his ideas is the design of giant island-like ships that can be turned into residential communities. Due to the islands’ shape, the project became known as Lilypad. Considering the limitations of the paper size, we cannot properly cover all of the futuristic projects that were based on adapting responsive spaces to human needs.

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3.2 Clarifying the Notion of Responsive Architecture Our historical overview demonstrates that many of the architectural and technical fields containing a responsive component developed separately, each following its own direction, and it was not until the beginning of the twenty-first century that they were blended together into a single multidisciplinary field under a shared trend, “responsive spaces”. This makes it possible to clarify our definition of “responsive architectural spaces”. The term “responsive architecture” was first used in the late 1960s by American IT designer Nicholas Negroponte. At that time, cybernetics began seeing use as a tool to solve spatial design problems; thus, Negroponte proposed applying computer technologies to organizing spaces and structures in order to use said spaces and structures in a more efficient and rational way. The structure, meaning, and semantics of the term “responsive architecture” have changed substantially since then [4]. Let us consider the different levels of adapting a responsive space: an object element, a building, and a city fragment. On the element level, the following qualities get evaluated: interactivity and the presence of properties that initiate a response to environmental changes. Some of the objects studied in this context may include “smart” facades or roofs. American architect Doris Kim Sung uses composite materials called thermo bimetals to create a room enclosure that reacts to air temperature and illumination, protecting people from the sun and providing ventilation as required. Another example is the “smart” facade of the Media-Tic building in Barcelona. This structure is built out of a special material that lets through light but not heat. As a result, the interior stays pleasantly cool even on the hottest summer days. In addition, the film is charged by natural sunlight even on a cloudy day, allowing the structure to glow at night for eight hours. Besides, thanks to the use of environmentally friendly energy sources, carbon dioxide emissions are reduced by 90%. To assess a building’s responsiveness, we must look at it from the standpoint of various aspects and features, including the following: • technical and compositional capacity for transforming the layout or volume regularly or periodically [5], • integration of adjacent disciplines (eco-friendliness, energy efficiency, etc.), • interactivity and the ability to respond to changes in the environment or human needs [6]. This assessment may be based on a single parameter or an aggregate set of parameters. For example, the aspect of “technical and compositional capacity for transforming the layout or volume regularly or periodically” can be applied to historical buildings that have lost their original function but can be re-purposed. There are several examples to be considered here, mostly concerning the renovation of industrial sites. Among them, are the following: the culture and entertainment center inside an old train carriage repair depot (Atelier Brückner, 2005–2019, Stuttgart); the Kings Cross Gas Holder Triplet (Wilkinson Eyre, 2015, London); the transformation of Longhua Airport Fuel Tanks into the Tank Shanghai Art Center and Park (OPEN Architecture, 2019, Shanghai), or the exhibition space at the GES-2 power station (Renzo Piano, 2021, Moscow).

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As an environmental element, responsiveness is seen in the light of the following thesis: “Nothing in nature is motionless”. Space is seen as a living organism that considers and responds to people’s needs, which, in turn, are shaped by the laws of social development. Notably, this applies both to historical environments and newly created environments. In this case, the presence of an environmental component is the most significant factor [7]. A striking example is a competition for the design of the central district in Sofia, the capital of Bulgaria, which was held in 2009. The participants included Dominique Perrault, Norman Foster, Zaha Hadid, Massimiliano Fuksas, and other architects. Each of them determined the role of the green space within the district that was to be renovated. The first place ultimately went to Perrault, who considered maintaining a link with the natural surroundings one of the primary goals for his design: the park stretching across the entire new district, Sofia City, became the development axis. The more refined concept of responsive architecture looks as follows: Responsive architecture is a synthetic field in architecture and construction, aimed at the formation of a sustainable environment for human activity. It is founded on completing project tasks, which, in turn, are dictated by human nature, the structure of society and culture, and the requirements for optimal living conditions. Responsive architecture practices cover a range of theoretical research disciplines and unorthodox aspects of project design.

4 Discussion The bold “dreams” of the 20th-century innovators were concurrent with the continued development of static traditional architecture, based on the unbacked theories of social well-being and ambitions of architects that thought they “knew best”. At one point, these theories and ambitions got shattered, in the most literal sense of the word. The demolition of the Pruitt–Igoe residential complex in St. Louis in 1972 demonstrated a crisis of architecture that refused to change in response to the current demands of society (what Ch. Jenks called the humane environment). This is exactly where we can see the fundamental difference between traditional architecture and responsive architecture, which relies on information received from the surrounding context and from human beings. Interestingly enough, responsive architecture can work on different levels, from microsystems to megastructures [8], and has the potential for flexible development that will account for the essential parameters relevant to bridging systems like humankind, the city, and nature [9]. As we clarified the definition of responsive architecture, we considered the properties of responsive environments (object element, building, city fragment). A review of responsive architecture’s development requires a list of competencies that ensure potential responsiveness in this context. 1. Technologies for working with natural systems and landscaped environments. Here, we must account for several aspects [10] of the aforementioned competence:

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1.1. Introduction of green areas into building and zone designs. When reconstructing sites and territories, it is essential to prioritize landscape reconstruction [11]. Making old cities more eco-friendly is a major issue today. A positive example in this field is set by the city of Barcelona, where authorities initiated the integration of green areas into the existing urban environment. In essence, the project involves creating “green corridors” within the city, linking Barcelona proper with natural landscapes along its periphery. The plans also include creating green pedestrian zones in the Eixample neighborhood, and a park infrastructure in the Poblenou area. Poblenou has been under reconstruction since the early twenty-first century. The key trend is the adaptation of an abandoned industrial area for museum and exhibition spaces; offices and residential buildings are being built here as well, with some land plots reserved for landscaping. 1.2. The use of green technologies, including horizontal [12] and vertical landscaping [13]. Notable architects in this field include Patrick Blanc, who creates “living walls” inside and outside buildings that perform various functions; Édouard François with his green facade projects (for instance, the M6B2 residential complex, also known as the Tower of Biodiversity, built in Paris in 2016); and Renzo Piano, who created a green roof for the reconstructed building of the California Academy of Sciences in San Francisco (2008). The project designed by MVRDV from the Netherlands for the Stein development company is compelling in both its simplicity and originality. The project, known as Green Villa, features an open-air shelf structure with potted plants instead of a facade. 1.3. The use of energy and resource [14] conservation technologies includes improving the energy efficiency of buildings [15], the use of “clean energy” (sun, heat), and the use of “gray” water (rainwater) for technical needs [16]. With the introduction of green international certificates in the 1990s, it became possible to assess and rate the quality of efficient energy and resources consumption. The first green international certification system was BREEAM, an environmental efficiency assessment method that was developed in 1990 in the United Kingdom. This assessment involves awarding points for various environmental safety aspects. It was this standard that guided the design of the Olympic Village in London in 2012, as well as the Arrowhead office complex in the same city, which is a completely passive site and does not require any external energy. The LEED (Leadership in Energy and Environmental Design) global standard provides an assessment after the site gets used for one year. For example, the 2010 reconstruction of a high-rise building in Frankfurt am Main, where Deutsche Bank has its headquarters, received high marks under the LEED standard. 2. System modeling. System modeling ensures high result effectiveness at a low cost due to the ability to analyze the interactions between the site’s systems early on [17]. This competence of responsive architecture relies on comprehensive effort on the part of a team of experts, working together to achieve the desired result [18]. For example, to design a site with a set of specified energy conservation features, it is

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necessary to use energy-focused operation models in order to calculate the potential energy efficiency. During the design of the aforementioned California Academy of Sciences building in San Francisco (architect: Renzo Piano), each stage was accompanied by modeling for debugging engineering systems. This part of the project was overseen by engineer Matt Rossi. The experts analyzed the space by applying the computational fluid dynamics method. Notably, their tests were aimed not just at ensuring the thermal comfort of visitors but also at supplying unpolluted air. The adoption of such a comprehensive approach made it possible to design one of the world’s greenest buildings. The end result received platinum certification under the LEED standard. 3. New approaches to form-making. This applies to designing kinetic [19], interactive systems [20], capable of responding to changes in the environment [21] or human needs. A notable example is the Ballet Mécanique transformable house, built by Manuel Herz Architects in Zurich in 2017. Filled with countless semantic meanings (references to the movie by Fernand Leger, the nearby Center Le Corbusier, the movement of foliage to mimic the tree that once stood here), the house changes to adjust to the mood and lifestyle of its inhabitants. The steel supports of the facade wall and the built-in hydraulic system allow for setting up balconies and sunshades, and for opening or closing the windows. Another trend that we can see in this field is the desire to “breathe life” into the structures surrounding objects that are pretty much utilitarian. In Denmark, a site called SDU Campus Kolding was built by Henning Larsen Architects in 2014, with a facade that, thanks to special sensors, reacts to the level of incoming light and maintains indoor heat. If required, a mechanical system moves the elements of the facade. The LIGO research center, in turn, might have looked like an ordinary white cube, so common in traditional architecture, if it were not for the magnetic pendulum mounted on its facade. This kinetic system, developed by the Exploratorium artists Sean Laney, Charles Sowers, and Peter Richards in collaboration with scientists from the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2006, helps illustrate what the center is doing: studying the propagation of waves, gravity, and light. Kinematics reacting to the movement of the sun is one of the most promising branches of responsive architecture [22]. The most famous example of an architectural form that shifts when lit up by the sun, is the Quadracci Pavilion at the Milwaukee Art Museum in the USA. It was created in 2001 by architect Santiago Calatrava, whose works are clearly impacted by his special reverence for light. The pavilion features a unique movable structure on its roof. It is shaped like wings with a 66-m span, unfurling on a sunny day and folding up at night or when the sky is overcast. The first rotating object was Villa Sunflower (Villa Girasole) built by Italian engineer Angelo Invernizzi near Verona in 1929–1935 [23]. The name of the building is due to the fact that it rotates to follow the sun as it moves, like a sunflower. The turning mechanism was located in an eight-story tower resembling a lighthouse. The energy was provided by diesel motors. Another heliotropic building was a house designed by Rolf Disch in 1994. It was followed by countless similar structures,

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culminating in the dynamically changing skyscraper concept suggested by architect David Fisher in Dubai in 2008. 4. The use of designer tools to ensure the responsiveness of environmental elements. In this context, design has evolved from kinetic art objects to a highly interactive environment with links to augmented reality. The designer’s toolset is fairly diverse [24] and finds active use in responsive spaces as a fairly mobile environmental element. Here, we would like to look into combining design with technology [25]. One of the examples of using the capabilities of design components to make the environment more responsive is set by the works of Dutch designer Daan Roosegaarde, an innovator who creates landscapes of the future and explores the issues of relationships between people, technology, and space. One of his completed projects is a 600 m cycling path made from shimmering stones, which he created in 2014. It was inspired by Van Gogh’s legendary painting, Starry Night, because the cycling path’s location, Nuenen, was where the artist began his creative career. In the same year, the designer collaborated with the Heijmans construction company to build the Smart Highway. This project combines light, energy, and road markings that respond to moving cars. Fluorescent paint absorbs solar energy throughout the day and then emits light at night for up to eight hours. Creating immersive environments is another field that is seeing active development. In studies on the concept of immersiveness, it is usually defined as becoming “part of” a certain artificially formed environment. The phenomenon of immersion has seen fairly extensive coverage in a variety of sources. In the context that we are interested in, the main focus is usually on the technological specifics of affecting human consciousness through the visualization of an artificial environment. Immersion is used extensively in movies, theater, visual art, and the entertainment industry. We believe it possible to consider this among the possible aspects of making spaces more responsive. 5. Creative forecasting. Exploring the capacity of digital technologies and innovative materials for creating a new urban environment. Information technology studies demonstrate a certain breakthrough in expanding the capacity of responsive architecture through combining digital form-making methods and new digital architecture capabilities. Researchers believe that the future of digital architecture lies in the use of nanotechnology for creating complex systems at the level of neurons and atomic particles [8]. Marcos Novak refers to the result of this process as “neural architecture”. In this type of architecture, the functions of architectural forms are going to closely resemble the behavior of living organisms.

5 Conclusions In conclusion, we would like to highlight the results we obtained while working on our research objectives. 1. Through classifying the historical periods in the development of architecture with responsive capabilities, we were able to determine the main directions that research in this field followed in the twentieth century, namely: mobility, interchangeability, transformation, kinetics, green architecture, vertical zoning, etc. Our historical

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overview shows that many of the architectural and technical ideas containing a responsive component developed separately, each going down its own path, and it was not until the beginning of the twenty-first century that all of these insights were brought together under the responsive space trend. 2. We considered responsive architectural practices across different levels of making an architectural space more responsive (object element, building, city fragment). This helped us with clarifying the notion of responsive architecture. Responsive architecture is a synthetic field in architecture and construction, aimed at the formation of a sustainable environment for human activity. It is founded on completing project tasks, which, in turn, are dictated by human nature, the structure of society and culture, and the requirements for optimal living conditions. Responsive architecture practices cover a range of theoretical research disciplines and unorthodox aspects of project design. 3. When dealing with the main development directions in responsive architecture, we singled out a set of competencies that, when applied, open the way for potential responsiveness: • Technologies for working with natural systems and landscaped environments, including the following: the integration of landscaping into building and area designs; the use of green technologies such as horizontal and vertical green zones; the use of energy and resource conservation technologies. • New approaches to form-making, such as the design of kinetic, interactive systems capable of responding to changes in the environment or human needs. • Expert system modeling for helping complete the tasks at hand and ensuring the high effectiveness of the end result at a low cost through the preemptive analysis of interactions between the site’s systems. • The use of designer tools to ensure the responsiveness of environmental elements. Designer tools are vast and diverse, including both transformable modular structures and augmented reality. • Creative forecasting helps designers make unexpected decisions, backing them up with theoretical insights in the field of research, technology, and engineering. 4. Prospects for the development of responsive architecture in the context of modern technological processes and social needs currently demonstrate a highly diverse set of tools and methods for arranging responsive spaces. Despite the achievements of immersive environment design, as well as the potential creation of neural architecture, which will mimic the behavior of biological organisms, each specific environment is going to need an appropriate approach to make it more responsive.

References 1. Bliznakov M (1990) The realization of utopia: Western technology and Soviet avant-garde architecture. In: Brumfield WC (ed) Reshaping Russian architecture: Western technology, utopian dreams. Cambridge University Press, Cambridge, New York, pp 124–128 2. Fitzpatrick S (1974) Cultural revolution in Russia 1928–32. J Contemp Hist 9(1):33–52

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3. Stites R (1989) Revolutionary dreams: utopian vision and experimental life in the Russian revolution. Oxford University Press, New York, NY 4. Bier H, Knight T (2010). Digitally-driven architecture. Footprint: Delft School Des J 6:1–4. https://doi.org/10.7480/footprint.4.1.715 5. Jaskiewicz T (2007). Process-driven architecture: design techniques and methods. In: Proceedings of the 3rd International Conference of the Arab Society for Computer Aided Architectural Design “Em‘body’ing Virtual Architecture” (ASCAAD 2007), Bibliotheca Alexandrina, Alexandria, Egypt, 28–30 November 2007 6. Rabanus C (2010) Virtual reality. In: Sepp HR, Embree L (eds) Handbook of phenomenological aesthetics. Springer, Dordrecht, pp 343–349. https://doi.org/10.1007/978-90-481-24718_68 7. Flake GW (1998). The computational beauty of nature. Computer explorations of fractals, chaos, complex systems, and adaptation. MIT Press, Cambridge, MA 8. Novak M (2006) Transvergence: finite and infinite minds. In: Oosterhuis K, Feireiss L (eds) Game set and match II: the architecture co-laboratory on computer games, advanced geometries, and digital technologies. Episode Publishers, Rotterdam, pp 396–405 9. Podborschi V, Vaculenco M (2004). Natural shapes — a source of inspiration for eco-design. In: Talab˘a D, Roche T (eds) Product engineering. Springer, Dordrecht, p 111–120. doi:https:// doi.org/10.1007/1-4020-2933-0_8 10. Chattopadhyay R (2014) Green tribology, green surface engineering, and global warming. ASM International, Materials Park, OH 11. Bauer M, Mösle P, Schwarz M (2010) Green building. Guidebook for sustainable architecture. Springer, Berlin, Heidelberg.https://doi.org/10.1007/978-3-642-00635-7 12. Stoikov V, Gassiy V (2018) Energy efficiency of housing as a tool for sustainable development. MATEC Web Conf 251:03061. https://doi.org/10.1051/matecconf/201825103061 13. Dorozhkina E (2020) Architectural structures for the formation of vertical landscaping of buildings. IOP Conf Ser Mater Sci Eng 962:042005. https://doi.org/10.1088/1757-899X/962/ 4/042005 14. Strumillo K (2021) Sustainable city- green walls and roofs as ecological solution. IOP Conf Ser Mater Sci Eng 1203:022110. https://doi.org/10.1088/1757-899X/1203/2/022110 15. Elmokadem A, Ekram M, Waseef A, Nashaat B (2018) Kinetic architecture: concepts, history and applications. Int J Sci Res 7(4):750–758. https://doi.org/10.21275/ART20181560 16. Gladden ME (2018) A phenomenological framework of architectural paradigms for the usercentered design of virtual environments. Multimodal Technol Interact 2(4):80. https://doi. org/10.3390/mti2040080 17. Flachbart G, Weibel P (eds) (2005) Disappearing architecture: from real to virtual to quantum. Birkhäuser Publishers for Architecture, Basel. https://doi.org/10.1007/3-7643-7674-0 18. Wiberg M (2011) Interactive textures for architecture and landscaping: digital elements and technologies. IGI Global, New York 19. Jewell N (2014). The Atlanta Falcons’ new rose-shaped stadium opens and closes like a camera aperture. In: Inhabitat. www.inhabitat.com/atlanta-falcons-new-stadium-uses-kinetic-archit ecture-to-retract-rose-petal-roof. Accessed 4 Jan 2021 20. Oosterhuis K, Xia X, Sam EJ (2008) Interactive architecture. Episode Publishers, Rotterdam 21. Jaskiewicz T (2008) Dynamic design matter. Practical considerations for interactive architecture. Archit Mod Inf Technol 3(4):4 22. Pan CA, Jeng T (2008) Exploring sensing-based kinetic design for responsive architecture. In: Proceedings of the 13th International conference on computer aided architectural design research in Asia (CAADRIA), Chiang Mai University, Chiang Mai, Thailand, 9–12 April 2008

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23. Alter L (2018) Villa Girasole: rotating house follows the Sun. http://www.treehugger.com/ corporate-responsibility/1935-villa-girasole-rotating-house-follows-the-sun.html. Accessed 4 Jan 2021 24. Trubiano F (ed) (2013) Design and construction of high-performance homes: building envelopes, renewable energies and integrated practice. Routledge, New York 25. Asefi M (2012) Transformation and movement in architecture: the marriage among art, engineering and technology. Proc Soc Behav Sci 51:1005–1010. https://doi.org/10.1016/j.sbspro. 2012.08.278

Use of Soft Wood Waste in the Production of Wood Particle Boards A. Titunin, T. Vakhnina, I. Susoeva(B) , and A. Titunin Junior Kostroma State University, 17, Dzerzhinsky, Kostroma 156005, Russia [email protected]

Abstract. The article is devoted to the actual problem of using industrial waste in order to obtain composite materials based on special chips with the addition of shavings-waste. The involvement in the processing of unused woodworking waste in full contributes to both expanding the raw material base for the production of composite materials and improving the environmental situation by reducing the negative impact on the environment. An analysis of domestic and foreign experience indicates the effectiveness of the use of cellulose-containing waste in the production of various composite materials. The article presents the results of studies aimed at testing the hypothesis about the possibility of using soft wood waste in the outer layers of board materials obtained using particle board technology. The experimental studies were based on a complete factorial plan, the results of which revealed the main regularities of the process of composite structure formation and obtained mathematical models of its strength properties in the form of regression equations. It has been established that with a specific pressing time of 0.25 min/mm, a temperature of 190 °C and the addition of waste shavings to the outer layers of board materials from 3 to 7% by weight, a material with a tensile strength perpendicular to the board of at least 0.35 MPa will be obtained and strength in static bending not less than 18.2 MPa. The results obtained can be recommended for use in the production of board materials with the required strength properties. Keywords: Machine shavings · Particle boards · Strength · Static bending · Stretching · Regression models

1 Introduction One of the most important areas of resource-saving technologies is the use of renewable plant waste in the production of products. Utilization of plant waste by storing it in landfills causes damage to the environment due to possible decomposition products [1– 5]. The article by D. L. Faria et al. notes that the use of wood waste for the production of particle boards can become an alternative in an attempt to mitigate the negative impact of waste on the environment [6]. Waste valorization is the process of turning waste into more useful products, including materials. The concept of waste management has become even more in demand at the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_7

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present time due to the rapid depletion of natural and primary resources, the increase in waste generation and disposal around the world and the need to develop more sustainable and cost-effective waste management methods [7]. Cellulose is the main renewable biopolymer on Earth. The unique structure of cellulose, a large number of active OH groups on the surface of macromolecules are the reason why researchers around the world are developing composites, including particle board, from cellulose-containing waste. Thus, in a study by P. Rachtanapun and colleagues, particle boards were developed from coffee waste on a urea-formaldehyde binder with the addition of methylene diphenyl diisocyanates [8]. Thermal insulation boards made of a combined filler—soft wood waste and flax and cotton spinning waste—have a good balance of performance [9]. Wood waste is one of the largest volumes. Most of the wood processing industries after the product manufacturing cycle have 25–40% of unused waste. So, for example, despite the continuous development of wood processing technologies, at present, 5 million tons of wood waste are brought from the territory of Moscow enterprises to suburban landfills [1]. Soft wood waste is a traditional raw material in particle board production all over the world. However, it is known that their unregulated addition to special shavings negatively affects the physical and mechanical properties of the boards [10, 11]. Therefore, both in Russia and abroad, work is underway to substantiate rational regimes for the production of boards with the addition of soft wood waste [12–16]. As a binder for the production of boards, both urea-formaldehyde and other types of synthetic binders can be used. The most large-tonnage thermosetting polymer in domestic and world practice is urea-formaldehyde resin (UF). The reasons for the widest use of FSC is that its cost is lower than that of the phenol-formaldehyde binder (PF), and the curing time is much shorter. According to G. Mantanis and colleagues [17], in the European industry for the production of board materials, urea-formaldehyde binder (UF), melamine-urea-formaldehyde (MUF), phenol-formaldehyde (PF) and PMDI polyisocyanates (for the production of oriented strand OSB boards). The share of use of binders in the production of board materials (according to the European federation of the particle board): UF—90–92%, MUF—6–7% and PMDI—1–2% [17]. UF is cheaper than other synthetic binders [18] and has a short curing time, which makes it possible to reduce the board pressing time; therefore, UF was used for the production of boards in this work. It is difficult to ensure the performance of particle boards on a synthetic binder when using waste shavings from wood processing industries, especially with a large proportion of the dust fraction. This is due to the increased absorption of the binder into damaged plant fibers. As a result, the number of adhesive contacts between the filler particles decreases, and a depleted adhesive layer is formed. In combination with a large specific surface area of particles from plant waste, a decrease in the number of adhesive contacts leads to the impossibility of complete gumming of the filler surface and to the formation of a composite with a less durable structure [19].

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The technological process of forming the structure of particle board, as well as other wood-polymer composites, according to A. N. Oblivin and M. V. Lopatnikov [20], determines the patterns of heat transfer, mass, chemical processes of polymerization of the binder, as well as surface phenomena at the interface filler-binder, forming the adhesive and cohesive component of the strength of the material. Therefore, when developing the material, technological factors were taken into account: the features of the curing of a thermosetting polymer matrix—UF, the relationship between the parameters of the pressing process and the indicators of the boards.

2 Methods In the laboratory of the Department of Logging and Wood Processing (KSU, Kostroma), particle boards are being developed with the addition of soft wood waste from coniferous species (spruce, pine). As a research method, regression analysis was chosen, in particular, a complete factorial design. The use of this experimental method made it possible to develop the dependences of the particle board indicators on the pressing temperature and other structure-forming factors. The slabs were made under constant factors: specific pressure during pressing P = 2.6 MPa; the proportion of outer/inner layers—0.4 / 0.6; density of outer layers 900 kg/m3 ; density of inner layers 700 kg/m3 ; addition of machine shavings to the inner layer D2 = 10%. The appearance of boards with the addition of 30% machine shavings to the outer layers is shown in Fig. 1.

Fig. 1. Board with the addition of machine shavings.

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3 Results A full factorial design was used to develop models of the dependencies of composite indicators. Variable factors in the experiment and their levels are presented in Table 1. Output values: Y1 —static bending strength b , MPa; Y2 —tensile strength perpendicular to the face, s , MPa. The plan and statistical processing of the test results of the boards are presented in Table 2. Table 1. Ranges of variation of factors. Factor name

Variation interval, i

Factor notation

Levels of variation

Natural

Coded

−1

0

+1

1. Specific pressing time (min/mm)

τ’

X1

0.18

0.25

0.32

0.7

2. Addition of machine shavings to the outer layers, the amount of the weight of the outer layers (%)

D1

X2

0

15

30

15

3. Board pressing temperature (°C)

T

X3

170

185

200

15

Table 2. Experiment design matrix in coded designations of factors. Y2

S2 2

4.158

0.300

0.006

0.725

0.130

0.003

17.72

1.143

0.386

0.016

20.67

7.125

0.408

0.026

−

22.50

9.998

0.288

0.018

+

−

14.53

15.601

0.127

0.005

−

−

20.02

6.773

0.151

0.001

−

−

15.23

3.323

0.257

0.001

Number of experiments, N

X1

X2

X3

Y1

1

+

+

+

16.69

2

−

+

+

15.75

3

+

−

+

4

−

−

+

5

+

+

6

−

7

+

8

−

S1 2

Based on the results of processing the experimental data, mathematical models (1–2) of the indicators of composites with the addition of soft wood waste were obtained (in coded designations of factors): Y1 = 17.89 + 1.34X1 − 0.52X2 − 0.18X3 + 0.88X1 X2 − 0.97X2 X3 − 1.85X1 X3 (1) Y2 = 0.316 + 0.03X1 − 0.04X2 + 0.05X3 + 0.06X1 X2 − 0.05X2 X3 + 0.01X1 X3 (2)

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On Figs. 2, 3 and 4 are graphs of the dependence of the strength of the board in static bending (Y1 ) and the strength of the boards in tension perpendicular to the board (Y2 ) on the specific pressing time (X1 ), on the proportion of machine shavings added to the outer layers (X2 ), in Figs. 5, 6, 7—from the pressing temperature of the boards (X3 ).

Fig. 2. Graph of the dependence of the strength of boards on static bending from the specific duration of pressing.

4 Conclusions At the maximum proportion of additives in the outer layers of waste shavings and the maximum pressing temperature, with an increase in the specific duration of pressing, the strength of the boards in static bending increases slightly, practically within the limits of dispersion in the experiment. This is due to the large number of adhesive contacts in the outer layers due to their high density and a significant amount of lighter waste shavings. The bending strength of the boards is at a minimum level (at a given specific pressing time), this is influenced by the processes of thermal destruction of the wood component at a temperature of 200 °C. At the maximum specific duration of pressing, an increase in the pressing temperature leads to a decrease in static bending strength, and this is typical for boards on special shavings. So it is for boards containing 30% of machine shaving-waste in the outer layers. The strength of the boards in static bending increases with a minimum specific pressing time with an increase in the pressing temperature.

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Fig. 3. Graph of the dependence of the strength of boards for static bending on the proportion of the addition of machine shavings to the outer layers.

Fig. 4. Graph of the dependence of the strength of boards in static bending on the pressing temperature.

The influence of the pressing temperature on the tensile strength of the boards perpendicular to the board does not differ so sharply with a change in the specific duration

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Fig. 5. Graph of the dependence of the strength of the boards in tension perpendicular to the board from the specific duration of pressing.

Fig. 6. Graph of the dependence of the strength of the boards in tension perpendicular to the face on the proportion of the addition of machine shavings to the outer layers.

of pressing. The effect of the interaction of the factors of the production process is affected, and the fact that the proportion of the addition of machine shavings to the inner

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Fig. 7. Graph of the dependence of the strength of the boards in tension perpendicular to the board on the pressing temperature.

layer is a constant value. The effects of the interaction of the proportion of the addition of machine shavings to the outer layers with the specific duration of pressing and the pressing temperature have the opposite direction, and in total they affect the indicator insignificantly. Pressing at 170 °C with the same combination of manufacturing factors results in higher flexural strength. However, in this case, the tensile strength of the boards perpendicular to the face is less than 0.3 MPa, which does not meet the requirements of Russian Standard 10,632–2014. Analysis of regression models and graphs of dependences of output values on factors of the production process allows us to recommend the following combination of factors: X1 = 0 (specific pressing time 0.25 min/mm); X2 = –0.2…–0.47 (addition of shavings -waste into the outer layers 3…7% of the weight of the shavings of the outer layers); X3 = +0.3 (190 °C). In this case, the strength of the boards in tension perpendicular to the face will be at least 0.35 MPa, and the strength in static bending will be at least 18.2 MPa. An article by D. L. Faria et al. reports the results of tests on slabs produced with different proportions of Hevea brazilian. Boards with a density of 600 kg/m3 were produced on a urea-formaldehyde binder at a temperature of 160 °C and a specific pressure of 4.0 MPa, pressing time 8 min. The ratio of high values of specific pressure and pressing time made it possible to produce boards with the required physical and mechanical parameters [21].

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In a study by a team of authors, an increase in density and pressing temperature made it possible to halve the pressing time and provide the necessary physical and mechanical properties of boards with the addition of softwood machine shavings. Based on the results of the analysis of the models, a rational combination of technological factors was chosen, which will allow the production of material with the required values of the production process indicators. Thus, the problem of developing rational regimes for the production of particle board on a urea-formaldehyde binder with the addition of soft waste from coniferous wood processing has been solved.

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16. Gaff M, Trgala K, Adamová T (2018) Environmental benefits of using recycled wood in the production of wood-based panels. Prag, Czech Republic, CZU 17. Mantanis GI, ETh, Athanassiadou, Barbu MC et al (2017) Adhesive systems used in the European particleboard, MDF and OSB industries. Wood Mat Sci Eng 9:1–13 18. Dunky M (1998) Urea-formaldehyde (UF) adhesive resins for wood. Int J Adhesion Adhesives 18:95–107 19. Titunin AA, Susoeva IV, Vahnina TN (2018) Influence of cyclic temperature and humidity on properties of composites from vegetable raw materials. Structure, properties and quality of wood–2018: materials of the VI International Symposium named after B. N. Ugolev, p 196–200 20. Oblivin AN, Lopatnikov MV (2014) Theoretical foundations of molding composite materials on wood fillers. For Bull 2:103–108 21. Faria DL, Eugênio TMC, Lopes DE et al (2021) Particleboards produced with different proportions of Hevea brasiliensis: residual wood valorization in higher value added products. Agric Sci 45(120). https://doi.org/10.1590/1413-7054202145021420

Assessing the Applicability of Sand Hydraulic Conductivity Calculation Techniques A. V. Nikitin(B) and O. M. Zaborskaya Northern (Arctic) Federal University Named After M.V. Lomonosov, 17, Severnaya Dvina Emb., Arkhangelsk 163002, Russia [email protected]

Abstract. Accurate evaluation of hydraulic conductivity is an important part of estimating water permeability of soils. The article describes the results of hydraulic conductivity evaluation for alluvial sands by field and laboratory methods, as well as by empirical equations. In field conditions, hydraulic conductivity was determined by pouring water in test pits, and in laboratory conditions—by filtration tube surveys. It was established that the discrepancy between the results obtained by laboratory methods and those obtained by field tests reaches 10–16%. Empirical formulas of Hazen, Kozeny-Carman, Slichter, Krüger, and Sauerbrey were used to calculate the hydraulic conductivity of sand. The deviation of the hydraulic conductivity value obtained by field survey from that obtained through calculation is 6–71%. The closest match was produced by the Krüger equation, which accounts for the specific surface area of particles. The article demonstrates that empirical equations based on effective diameter calculations give considerable errors in most cases. The error in determining hydraulic conductivity is also associated with the application of a standard set of sieves (to establish the grain size distribution of sand) featuring a large gap between opening sizes. Keywords: Hydraulic conductivity · Sand · Permeability · Grain-size composition · Calculation methods

1 Introduction Evaluation of water permeability properties is crucial for hydraulic conductivity calculation of waterworks and foundation beds. Hydraulic conductivity, which characterizes water permeability of soils, greatly depends on the evaluation method. Its value can be determined in laboratory conditions, field conditions, and by calculation. Among the laboratory test methods, pit filling with water and pumping-out tests are widely used at present [1–3]. The most common method is water filling into pits proposed by A.K. Boldyrev. In laboratory conditions, sand soils are usually tested for permeability in filtration tubes, and clay soils—in compression and filtration test units. The hydraulic conductivity of soil depends on a variety of factors: test apparatus design, head, test specimen conditioning method, chemical composition of water and its temperature [4–10]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_8

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Regulatory documents governing the design of various waterworks allow calculating the hydraulic conductivity based on stress-strain properties of soils. In some cases, hydraulic conductivity analysis that uses characteristics obtained by calculation produces significant errors [11]. To assess the reliability of hydraulic conductivity calculations, field and laboratory tests were conducted on sand soil.

2 Field and Laboratory Methods to Evaluate Hydraulic Conductivity of Sand Water permeability was studied in field and laboratory conditions for fine and mediumgrained sand. Water permeability of sand in field conditions was found by water filling into test pits. The method of water filling into pits is used for unsaturated soils with the aeration zone thickness more than 1.5 m. The physical properties of sand were determined on samples of undisturbed structure taken from pits. The density of medium-grained test sand is 1.71 g/cm3 , moisture content—6.2%, porosity coefficient—0.65. The density of fine test sand is 1.67 g/cm3 , moisture content—5.4%, porosity coefficient—0.67. The grain size composition of sand was determined by sieve method using a standard set of sieves with opening sizes 10; 5; 2; 1; 0.5; 0.25, and 0.1 mm (Table 1 and Fig. 1). Table 1. Grain-size composition of sand. Grain size composition parameters

Particle size (mm) 5–2 2–1

1–0.5 0.5–0.25 0.25–0.1 a we have M = 0; Q = 0; (Fig. 1b).

(5)

We get the following general equations for the bending moments and shear strengths in section k combining both load cases, taking into account the suggested combinations of function sign   M = −P(a − x)sign 1 + sign(a − x) . (6)   Q = −Psign 1 + sign(a − x) .

(7)

We obtain the following combined formulas for the task conditions in the case of the concentrated moment at an arbitrary point of the beam span (Fig. 2) using the proposed combinations of the sign function,   M = −Msign 1 + sign(a − x) ; (Fig. 2a); (8) Q = 0; (Fig. 2b).

(9)

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Fig. 1. Scheme of a concentrated strength P.

Fig. 2. Loading scheme with a concentrated moment M.

Three loading patterns are encountered depending on the load at equally distributed load q. The following equations are used to determine the moments and transverse strengths at cross-section k with coordinate x for the loading scheme corresponding to Fig. 3 at x ≤ a we have M = −0.5q(a − x)2 ; Q = q(a − x); (Fig.3a);

(10)

at x > a we have M = 0; Q = 0; (Fig.3b).

(11)

The general equations for the moment and transverse strength after combining are   (12) M = −0.5q(a − x)2 sign 1 + sign(a − x) .   Q = q(a − x)sign 1 + sign(a − x) .

(13)

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Fig. 3. Loading scheme with a distributed load q on the left section.

The following equations are used to determine the moments and transverse strengths in section k with coordinate x at loading according to the scheme shown in Fig. 4 at x ≤ a we have M = −0.5qb(2a + b − 2x); Q = qb; (Fig. 4a);

(14)

at a < x < a + b we have M = −0.5q(b − x)2 ; Q = qb; (Fig. 4b);

(15)

at x > a + b we have M = 0; Q = 0; (Fig. 4c).

(16)

General formula for calculating the torque and shear strength can be represented for this loading type        M = 0.5q (a + b − x)2 − b(2a + b − 2x) sign 1 + sign(a − x) − (a + b − x)2 sign 1 + sign(a + b − x) .

(17)

       Q = q bsign 1 + sign(a − x) + (a + b − x)sign 1 + sign(x − a) sign 1 + sign(a + b − x) .

(18) The presented formulas format is not limited to the given equations variants. Additional variants of the general equations are in table (Table 2). They have a number of advantages in comparison with the traditional notation in the form of separate expressions for each section of the bending element in spite of some massive of the general equations obtained. The discrete equations writing makes it difficult to use the mathematical apparatus for the analysis of the stress–strain state of beams and makes difficulties for further transformations of the obtained formulas. The strength equation note unified form allows to simplify an algorithm in compiling programs for the calculation of structures with the use of computer-aided calculation methods. The strength calculation is done in a single cycle using a single equation instead of several equations, which are characteristic of usual calculations. There is no need to

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Fig. 4. Loading scheme with a distributed load q in the middle section.

multiple calculate the strengths for individual sections. The graphical presentation of calculation results in the graphs form and strength diagrams in a graphical or software is greatly simplified. It is possible to make expressions for simultaneous beams loading with various loads for any possible combinations and the place combinations of loads application using the proposed approach for the derivation of general force equations. For example, in case of combined action of concentrated strength, moment and uniformly distributed load located according to the scheme shown in Fig. 5, general formulas for the calculation of forces in any area will look as follows     2M − b(2a + b − 2x) + (a + b − x)2 sign 1 + sign(a − x) M = 0.5q q (19)   − (a + b − x)2 sign 1 + sign(a + b − x) − P(l − x);    Q = q b + (a − x)sign 1 + sign(x − a) + P.

(20)

I

4

I

6

3

3

I

III

2

2

I

5

1

1

3

II

2

1

Option

4

Loading Scheme (Figs. 1–5)

No. n/a

 M = 0.5q{ (a + b − x)2 − b(2a + b − 2x)   sign 1 + sign(a − x) − (a + b − x)2 }∗   sign 1 + sign(a + b − x)

M = {[b(2a + b − 2x)]sign   0.5q 1 + sign(a − x) − (l − x)2 sign   1 + sign(x − a) sign(a − x)}



M = 0.5q{ b(2a + b − 2x) − (l − x)2   sign 1 + sign(a − x) sign(a − x) + (l − x)2 }

 M = 0.5q{ (a + b − x)2 − b(2a + b − 2x)   sign 1 + sign(a − x) − (a + b − x)2 }   ∗sign 1 + sign(a + b − x)

  M = −P(a − x)sign 1 + sign(a − x) .   M = −Msign 1 + sign(a − x)

4

Torque, M

Calculation formulas

Table 2. Calculation formulas.

Q = q{[(b + l − x)]sign  1 + sign(x − a) + l − x}

  sign 1 + sign(a + b − x)

sign(x − a)}

(continued)

  Q = q{bsign 1 + sign(a − x) +   (l − x)sign 1 + sign(x − a)

Q = q{b − [b − (l − x)]   sign 1 + sign(x − a)



0

  Q = −Psign 1 + sign(a − x)

5

Transverse strength, Q

124 A. A. Sobakin and V. K. Fedorov

II

III

10

11

I

9

5

III

8

Option

II

Loading Scheme (Figs. 1–5)

7

No. n/a Transverse strength, Q

  M = q2 { 2M q − b(2a + b − 2x)∗sign 1 + sign(a − x) − (a + b − x)2 ∗     sign 1 + sign(a + b − x) ∗sign 1 + sign(x − a) } − P(l − x)

  sign 1 + sign(a + b − x) − P(l − x)

  Q = q{bsign 1 + sign(a − x) +   (a + b − x)sign 1 + sign(x − a) }∗   sign 1 + sign(a + b − x) + P   sign 1 + sign(x − a) }∗   sign 1 + sign(a + b − x) + P

Q = q{b + (a − x)sign   1 + sign(x − a) + P

2M − b(2a + b − 2x)+ q   (a + b − x)2 }sign 1 + sign(a + b − x) − P(l − x)

M = 0.5q{[

Q = q{[b(a + b − x)]sign   1 + sign(a − x) + (a + b − x)}∗   sign 1 + sign(a + b − x)

M = 0.5q{b(2a + b − 2x)+ 

(a + b − x)2 − b(2a + b − 2x)   sign 1 + sign(x − a) }∗   sign 1 + sign(a + b − x)

M =

Q = q{b − [b − (a + b − x)]     sign 1 + sign(x − a) }∗ 0.5q{b(2a + b − 2x)sign 1 + sign(a − x) + (a + b − x)2 ∗       sign 1 + sign(a + b − x) sign 1 + sign(x − a) ∗sign 1 + sign(a + b − x) }

Torque, M

Calculation formulas

Table 2. (continued)

General Formula of Beams Strengthening 125

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Fig. 5. Loading scheme of by concentrated strength, moment and distributed load q.

4 Results 1. The presented formula in general form describing the strengths allows a wide application of mathematical apparatus for the analysis of the stress–strain state of the element. 2. The resulting equations are continuous, differentiable and, due to the constant function value which is a constant, allow mathematical transformations. 3. 3.Multiple calculation of strengths in individual sections, depending on the position of the cross-section in question is excluded. 4. The automated calculation has certain difficulties in beams with a large number of sections, without discrete methods for determining strengths in matrix form. 5. The common notation in the form of a single formula instead of several ones referring to different sections of an element greatly helps the widespread adoption of automated calculation methods using simpler algorithms.

5 Conclusion The article shows and proposes one of the approaches to implement the idea of the estimating methodology of the strengthening distribution with a general formula to rationalize the procedure of making an algorithm for calculating building structures. The proposed approach to the final equation making for strengths determining in bendable elements allows to combine the discrete form of the task into a general form expression with the possibility of subsequent analysis of the stress–strain state. The algorithm of the general equation for beams provides the possibility of the proposed methodology extending to solve problems with other design schemes of structures.

References 1. Smirnov AF, Alexandrov AV, Lascenikov BYa, Shaposhnikov NN (1984) Structural mechanics, dynamics and stability of structures. Moscow 2. Smirnov AF (1947) Static and dynamic stability of structures. Moscow 3. Smirnov MS (2006) Building dynamics. Determination of frequencies and modes of natural oscillations of the structure. St. Petersburg 4. Rzhanitsyn AR (1991) Structural mechanics. Moscow 5. Korenev BG, Rabinovich IM (1984) Dynamic calculation of buildings and structures. Moscow 6. Kazemahvary S, Radford D, Deshpande VS, Fleck NA (2007) Dynamic failure of clamped circular plates subjected to an underwater shock. J Mech Mater Struct 2:2007–2023

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7. Qiu X, Deshpande VS, Fleck NA (2004) Dynamic response of a clamped circular sandwich plate subject to shock loading. J Appl Mech 71:637–645 8. Allachverdov BM, Ribina II (2017) Modern problems of the dynamics of structures. St. Petersburg 9. Maslennikov AM (2016) Dynamics and stability of structures. Moscow 10. Bolotin VV (1956) Dynamic stability of elastic systems. Moscow 11. Onundi LO, Matawal DS, Elinwa AU (2010) The influence of Euler critical load on the method of unicial parameters for the dynamic analysis of multi-story buildings subjected to aerodynamic forces. Cont J Eng Sci 5:1–13 12. Bosokov SV (2021) The mixed method of construction mechanics in the problems of plate dynamics. Struct Mech Anal Constr 3:66–70 13. Timoshenko SP (1955) Stability of elastic systems. Moscow 14. Alfutov NA (1978) Basics of calculating the stability of elastic systems. Moscow 15. Kornoukhov NV (1949) Strength and stability of rod systems. Elastic frames, trusses and combined systems. Moscow 16. Solovyova AA, Solovyov SA (2021) Structural reliability analysis of steel truss elements on buckling using p-box approach. Struct Mech Anal Constr 1:45–53 17. Pattel VI (2013) Nonlinear inelastic analysis of concrete-filled steel tubular slender beamcolumns. Dissertation doctor of philosophy. Melbourne 18. Prokofiev IP (1948) Theory of structures. Moscow 19. Volmir AS (1956) Stability of deformable systems. Moscow 20. Sobakin AA, Nikolaeva DA, Androsov VA (2020) General formula of displacements in bending elements. In: IOP conference series: materials science and engineering. International multi-conference on industrial engineering and modern technologies, vol 1079, p 032014. https://doi.org/10.1088/1757-899X/1079/3/032014 21. Bronstein IN, Semendyaev KA (1981) Reference book in mathematics for engineers and students of universities. Moscow 22. Goulet J (1985) Resistance des materials. Reference book. Translated from French by A.S. Kravchuk. Moscow

Determining the Water Demand of Fine Aggregates I. L. Kostiunina(B) , A. L. Rozovskii, and S. N. Pogorelov South Ural State University, 76 Prospect Lenina, Chelyabinsk 454080, Russia [email protected]

Abstract. For the effective design of concrete and mortar compositions, it is important to know the quantitative and qualitative characteristics of their components, in particular, aggregates, including artificial aggregates. One of the essential characteristics affecting the quality of fine aggregates is water demand. Determining the water demand of sand in a solution using well-known methods depends on the composition of the solution and its liquid phase and cannot objectively characterize its quality. Water demand, defined as the amount of water held by the surface forces of water particles, is more suitable for assessing the quality of fine aggregates. The wetting power of grains is a determining factor in the water demand of dense sands, such as sands for heavy concretes. When developing a new method for determining the water demand of sand, our task was to use the positive aspects of two methods–drying and measuring electrical conductivity. The advantage of the proposed method is the continuous change and recording of dehydration parameters and the clear distinction between free and bound moisture at standard temperatures. The developed method consists in the continuous measurement of the electrical conductivity of pre-moistened sand during dehydration with a room temperature air flow, recording a characteristic point on a graph of conductivity over time, and determining the moisture content corresponding to the water demand of the sand using the weight method. We proved that the method is sufficiently accurate and reproducible when using sands with a wide range of grain compositions. Keywords: Fine aggregate · Concrete · Water demand · Method for determining · Electrical conductivity · Conductometric method

1 Introduction Numerous international studies confirm that artificial aggregates can fully replace natural aggregates in concretes [1–8]. The ability to obtain stronger concrete than similar concrete based on natural aggregates has been proven. However, lower compressive strength (10–30%), tensile strength (10%), elastic modulus (10–40%) and higher creep (50–100%) and water absorption (25–50%) are observed in most cases. The consequence of higher water absorption is a decrease in the frost resistance of concrete (3 times higher

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_13

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weight loss). The high water absorption of these concretes is explained by the higher permeability of the aggregates. Previous studies on the physical and mechanical properties of concrete based on crushed concrete aggregate have shown that in certain conditions we can intentionally influence the physical and mechanical properties and achieve the required quality [6, 7, 9–11]. This will allow us to fully replace structural concrete based on natural aggregates [12]. Several research papers state that the design of the concrete compositions is similar for recycled and natural aggregates, but the amount of mixing water should be adjusted experimentally [1, 4, 13, 14]. There is no available proven method for designing the composition of a concrete mix based on recycled aggregates, which takes into account their higher water demand and reduced durability [15]. The wide variety of characteristics of concrete aggregates serves as an obstacle to determining the theoretical indicators of water consumption. In particular, recycled aggregates are quite heterogeneous and their characteristics depend on the material used for their production [1, 12]. Thus, it is impossible to determine the demand for mixing water in a concrete mix based only on the fraction of aggregates and the consistency of the concrete mix. This once again proves the need to experimentally assess the water demand of aggregates. The source [16] studied the influence of the properties of produced sand on the water demand of mortar and concrete. Experiments were carried out using purpose-made sands with a wide range of particle angularity and the fine sand fractions content. The authors examined the various properties of sand and their effect on the workability of concrete, including the influence of sand’s properties on water demand and workability. A test phase using mortars rather than full-scale concrete mixes allowed the authors to isolate the characteristics of the sand and assess the influence of each attribute (particle angularity, particle size, and the content of fine particles) on water demand. Their experiments confirmed that the angularity of particles and the degree of dispersion of sand (quantified by the fineness modulus) influence the water demand of mortars. These results were used in subsequent testing, wherein the authors studied the influence of the properties of the produced sand on the water demand of full-scale concrete mixes. A statistically valid model of water consumption was developed for normal strength concretes. A mathematical regression model allowed the authors to evaluate the contribution of each component, as well as their relative importance and statistical significance. They proved that the angularity of sand particles is the dominant factor influencing water demand, followed by the degree of sand dispersion quantified by the particle size modulus and the number of very fine particles. The source [17] notes the importance of the water content of concrete mixes and presents data on the sand-to-coarse aggregate ratio and water content. Based on the Bingham model, the authors derived formulas for the sand-to-coarse aggregate ratio and water content and then carried out experiments to verify the formulas. They proved that the proposed theoretical calculations are correct. The water demand of sand and sandy soils is related to the sand hydraulic conductivity. Evaluation of water permeability properties is crucial for hydraulic conductivity calculation of waterworks and foundation beds. Hydraulic conductivity, which characterizes water permeability of sand soils, greatly depends on the evaluation method.

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The hydraulic conductivity of sandy soil depends on a variety of factors: test apparatus design, head, test specimen conditioning method, chemical composition of water and and other factors [18–22]. The source [23] studies the influence of the water demand of sand on the properties of the mortar. Extensive experiments on various types of sand were conducted to characterize and quantify this influence. The experiments that sand type had a significant effect on the properties of the mortar, which was essential for designing the concrete mix. The water demand of different types of sand was investigated. Sand properties, such as particle size modulus, specific surface area, average dry density, and bulk density, were taken into account. The studies demonstrated that there is a relationship between the water demand and the average density and bulk density of sand and determined the influence of the type of sand on the rheological and strength properties of the solution. Thus, all researchers note the importance of taking into account the water demand of sand for the design of concretes and mortars.

2 Theoretical Part Most artificial sands used in concrete are produced from several varieties of rocks with slightly varying mineralogical composition and properties. Therefore, the requirements for the grain size of sands obtained from natural raw materials are identical. Industrial waste with a wide range of properties can be used to expand the range of raw materials for construction sands, but the requirements for the grain composition of new fine aggregates must be determined. Granulated slags of non-ferrous metallurgy (copper and nickel industries) differ from conventional raw materials in poorer wetting power and higher density. Let us consider the influence of these factors on the rheological and technological properties of a concrete mix, namely, on structural viscosity and sedimentation stratification. Let us imagine a sand grain of regular spherical shape with radius R, density Qg , surrounded by a layer of bound water σ, moving at a constant velocity V in a cement paste with viscosity η and density Qp . We will consider the cement paste as a homogeneous medium with the properties of a heavy liquid due to its thixotropic liquefaction. Then, at small values of the Reynolds number, i.e. at low grain velocities, according to Stokes’ law: V = (2R2 (Qg − Qp )g)/9η

(1)

Assuming the velocity to be constant, we negin varying the properties of the grain and the medium to find out their mutual influence: (a) We increase the grain density: Q g > Qg . In this case, to maintain equilibrium, we should either decrease the grain radius or increase the viscosity of the medium: R < R or η > η; (b) We decrease the thickness of the bound water layer, i. e. the grain wetting power: σ < σ. In this case, the released water will increase the W/C ratio and the viscosity of the cement paste, since according to [24]: W

η = A · e(C· C )

(2)

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where A and C are constant values; W/C is the water/cement ratio, i. e. η’ < η. At the same time, increasing the W/C ratio decreases the density of the cement paste: Q g < Qg . In both cases, to maintain equilibrium, we should decrease the grain radius or its density: R < R or Q g < Qg . (c) We decrease the grain radius: Rg  < Rg . In this case, to maintain equilibrium, we should decrease the viscosity of the paste or increase the density of the grain: η < η or Q g > Qg . We can conclude that with an increase in the density and a decrease in the wetting power of the aggregate grain, we should decrease the grain radius or increase the viscosity of the paste to maintain its equilibrium in the cement paste, i.e., to prevent sedimentation stratification. Based on the example of slag sands, we have established that along with the geometric characteristics, the surface properties determining water demand play a significant role and should be taken into account when setting the requirements for the grain sizing of waste-based artificial fine aggregates. The use of by-products in the production of concrete aggregates (slags in particular, which have a wide range of material composition) necessitated the development of advanced methods to determine their physical and technical properties. One of the most important characteristics of fine aggregates which affects their quality is water demand, measured as the amount of water bound by sand grains due to surface and intracapillary forces. The need to determine the water demand of fine aggregates in real operating conditions led to the development of several methods. The most widely used method was developed by Bazhenov [25], which defines water demand as the amount of water necessary to achieve a certain mobility in the mortar mix, minus the water demand of cement. However, as indicated by the author, the results of this method depend on the cementto-sand ratio and the rheological characteristics of the mix chosen by the workable criterion. Bazhenov’s method takes into account the wetting power of the aggregate in a particular mix, the liquid phase of which has a well-defined composition. Water demand may change alongside any changes in the composition, for example, when using another binder. Due to the current lack of a reference cement to test aggregates in concrete, this method cannot be used to determine water demand as one of the specified parameters of sand quality. The water demand of sand determined in a concrete mix according to existing, well-known methods depends on the composition of the mix and its liquid phase and cannot objectively characterize its quality. Determining water demand as the amount of water held by the surface forces of sand particles provides a constant value more suitable for assessing the quality of sand. The wetting power of grains is the determining factor of water demand for almost dense aggregates, such as heavy concrete sands. There are several methods for determining different types of moisture, among which we can distinguish the continuous drying method and the electrical conductivity method. The continuous drying method is based on the use of different binding energies of capillary and bound water and consists in determining the characteristic points corresponding

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to the types of moisture on a graph of moisture content versus drying rate [21]. Drying is generally performed in thermostats at elevated temperatures (up to 105 °C). However, when assessing the water demand of sand, we are interested in the content of bound water at standard temperatures, which cannot be determined by the above method due to the excessive drying period. The electrical conductivity method is based on the difference in the electrical properties of several types of moisture in soil. The relationship between electrical conductivity and moisture content is generally expressed as a power function [26] L R = A · BK

(3)

where R is the electrical resistance; B is the moisture content; A, k are the coefficients depending on the measurement conditions and the type of the material being studies. When moving from one type of moisture to another, the coefficients in formula (3) change when the material is dehydrated. A method for determining the water demand of an aggregate using its influence on the structural characteristics of a hardening concrete mix was developed in [27]. This method is based on the experimentally established dependence of the formation period of the cement paste structure on the water-cement ratio. When the aggregate is introduced into the cement paste, the period of structure formation changes because it binds part of the mixing water. After comparing the time of the structure formation of concrete mix and cement paste prepared with several W/C values, we can determine the water-cement ratio of the concrete, and consequently, the volume of water bound by the binder. The difference between the amount of mixing water and the volume of water bound by the binder relative to the mass of the aggregate will give the water demand of the aggregate. According to the above method, the water demand of an aggregate is determined at the end of the structure formation period, while concrete mixes are laid much earlier. In the first 20 min after mixing, the immobilization of water by a dense aggregate reaches 90% of the value obtained at the end of the concrete structure formation, which allows us to estimate the water demand during laying and compaction with certain accuracy. The method for determining the water demand of an aggregate by its structural characteristics is based on an assumption that the periods of structure formation in a cement paste hardening in an unrestricted state and in a cement paste in a concrete mixture are equal if their water-cement ratios are equal. However, as shown by Argunova [27], due to the pressure difference in the system, this rate is different and depends on the intergranular space, which restrains the use of this method for determining the water demand of fine sands. Methods for determining the characteristics of aggregates, concrete mixes, and concretes by measuring electrical conductivity are of interest [28–30]. Silchenko used changes in the electrical conductivity of sand based on the presence of various types of moisture on its grains to determine the water demand of fine aggregates [31]. A weighted sample of dry sand was mixed with a given amount of water, placed in a

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mold, and compacted, after which the resistance of the mix was determined using electrodes fixed on the mold and an R-38 zero-balance bridge. Then the sand was removed and mixed with a new portion of water, and the operation was repeated. The electrical resistance was determined by changing the moisture content of the sand from 1–2 to 4–7% at 0.2% intervals. The moisture content of the sand equal to its water demand was determined by a characteristic point on a graph of moisture content versus resistance. However, this method is laborious (15–25 operations for one type of sand) and has critical weaknesses. The swelling effect of wet sand does not allow it to be compacted equally with different moisture contents, and the void ratio and size of the sand pores affect the electrical resistance, which is especially noticeable when working with fine sands.

3 Test Procedure When developing a new method for determining the water demand of sand, we aimed to use the positive aspects of the two above methods (drying and measuring the electrical conductivity)–the continuous change and recording of dehydration parameters and the clear distinction between free and bound moisture at standard temperatures. The developed method consists in the continuous measurement of the electrical conductivity of pre-moistened sand during dehydration with a room temperature air flow. The conductivity is recorded as a point on a graph of conductivity versus time. We then determine the moisture content corresponding to the water demand of the sand using the weight method. Figure 1 shows a diagram of our installation.

Fig. 1. Installation for determining the water demand of sand.

Our method for determining water demand includes the following operations. A weighted sample of sand is placed in cylindrical glass tumbler 1 with a perforated bottom covered with paper filter 2. Two stainless steel electrodes 3 mounted on the perforated

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cover 4 are inserted into the sand. The sand in the glass tumbler is compacted on a vibrobench and the glass tumbler is hermetically sealed to funnel 5 connected to a vacuum system and a water supplying tube. When the valve of the vacuum system is closed, water valve 6 opens and the sand sample is moistened to full saturation, without changing its package. A vacuum of about 60 kPa is generated in the vacuum system, valve 6 is closed, valve 7 opens, and the sand begins to dehydrate. Using conductometer 8, recorder 9 continuously registers changes in electrical conductivity. OK102 conductometer measures conductivity at a voltage of 0.20 V in the circuit and a high AC frequency of 3–10 kHz, which reduces measurement errors associated with the polarization of the electrodes. Figure 2 shows a typical electrical conductivity curve plotted by the recorder during the experiment.

Fig. 2. Conductivity of sand versus dehydration time.

When the electrical conductivity curve transitions into a straight line, the devices and the vacuum system are turned off and the characteristic point and the corresponding dehydration time are determined graphically. Then the sand sample is again saturated with water and the experiment is repeated with the vacuum system turned on for the previously determined time. Then the sand sample is removed from the glass tumbler and dried to determine the moisture content corresponding to the water demand of the sand. Studies have shown that the variation coefficient of the water demand determined for different sands does not exceed 3%. This indicates the sufficient accuracy and reproducibility of the method when using sands with a wide range of grain compositions.

4 Conclusion Our review of international studies allows us to conclude that it is essential to account for the properties of aggregates, in particular the water demand of sand, when designing concrete and mortar compositions. We noted the need to experimentally assess the physical and mechanical characteristics of aggregates (especially artificial aggregates) to

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obtain strong and durable concretes. We proposed a conductrometric method for determining the water demand of fine aggregates. The essence of the method is to measure the electrical conductivity of wet sand dried by an air flow and determine the moisture content corresponding to the water demand of the sand. We showed the advantages of this method. The obtained experimental data allow us to conclude that the proposed method for determining the water demand of fine aggregates method is accurate and efficient.

References 1. Ajdukiewicz A, Kliszczewicz A (2002) Influence of recycled aggregates on mechanical properties of HS/HPC. Cem Concr Comp 24:2 2. Barra M, Vazquez E (1999) Properties of concretes with recycled aggregates: influence of properties of aggregates and their interpretation. UK Thomas Telford Publishing, pp 19–30 3. Kikuchi M (1999) Application of recycled aggregate concrete for structural concrete, Part 1—experimental study on the quality of recycled aggregate and recycled aggregate concrete. UK Thomas Telford Publishing, pp 55–68 4. Kliszczewicz A (2002) High performance concrete with recycled aggregate (in Polish), Conference ‘Dni Betonu – Tradycja i Nowoczesnosc’, Polski Cement i Stowarzyszenie Producentów Cementu i Wapna, Szczyrk, Polski Cement, Cracow 5. Zielinski K (2005) Possibilities of using construction debris to produce cement concretes (in Polish), Politechnika Poznanska, Poznan 6. Jamrozy Z (2005) Concrete and its technologies (in Polish). PWN, Warszawa 7. Cichocka K, Małaszkiewicz D (2004) Properties of concrete with recycled aggregate (in Polish), Zeszyty naukowe Politechniki Bialostockiej, p 25 8. Pawluczuk E (2009) Recycled aggregates influence on defined concrete properties (in Polish), Zeszyty naukowe Politechniki Bialostockiej, Bialystok 9. RILEM 121-DRG (1994) Specification for concrete with recycled aggregates. Mater Struct 27:557–559.https://doi.org/10.1007/BF02473217 10. ECCO (2002) Recycling concrete and masonry. Environmental Council of Concrete Organizations, Skokie, Illinois 11. Bretschneider A, Ruhl M (1998) The influence of recycled aggregate of the compressive strength and the elastic modulus of concrete. Aus dem Berichtsband zu Darmstadt Concrete 12. Padmini AK, Ramamurthy K, Mathews MS (2009) Influence of parent concrete on the properties of recycled aggregate concrete. Constr Build Mater 23:829–836 13. Boltryk M, Pawluczuk E (2011) Modification of selected properties of cement concretes on recycled aggregates (in Polish). In˙zynieria i Budownictwo R 67:6 14. Koper M (2013) Forming of properties of recycled aggregate concrete (in Polish). Warsaw University of Technology, Warsaw 15. Boltryk M, Pawluczuk E (2008) Method of determining effective water in concrete mixture on recycled aggregates (in Polish), 54 KN KILiW PAN “KRYNICA 2008”, Krynica 16. Kubissaa J, Kopera M, Kopera W, Kubissaa W, Kopera A (2015) Water demand of concrete recycled aggregates. Proc Eng 108:63–71. https://doi.org/10.1016/j.proeng.2015.06.120 17. Dilek U (2015) Effects of manufactured sand characteristics on water demand of mortar and concrete mixtures. J Test Eval 43(3):20130321. https://doi.org/10.1520/JTE20130321 18. Wang L, Ai H (2002) Calculation of sand–aggregate ratio and water dosage of ordinary concrete. Cem Concr Res 32(3):431–434. https://doi.org/10.1016/S0008-8846(01)00696-2 19. Bazhenov YuM, Gorchakov GI, Alimov LA, Voronin VV (1972) Structural characteristics of concretes. Beton i zhelezobeton (Concrete and Reinforced Concrete) 9:19–21

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20. Spragg R, Villani C, Snyder K, Bentz D, Bullard J, Weiss J (2013) Factors that influence electrical resistivity measurements in cementitious systems. Transp Res Rec 2342:90–98 21. Rangelov M (2018) Nassiri S (2018) Evaluation of methods to correct the effect of temperature on electrical conductivity of mortar. Adv Civ Eng 5:1–9. https://doi.org/10.1155/2018/932 7528 22. Kasperov GI, Levkevich VE, Pastukhov SM (2015) Results of sand soil permeability studies to evaluate the operational safety of sludge dump waterworks. Bulletin of Officer and Engineer Institute of the Republic of Belarus’ Emercom 2:68–72 23. Goldberg VM, Skvortsov NP (1990) Impact of physical, chemical and thermodynamic conditions on the formation of clayey soil filtration properties. In: Earth’s crust research challenges, pp 133–139 24. Weshe K, Berg W (1973) Rheologishe eigen shaften von zementein und frishbeton. Beton 1 25. Bazhenov YuM (1977) Methods for determining the composition of various types of concrete. Stroyizdat, Moscow 26. Larionov AK, Alekseev VM, Lipson GA (1962) Moisture content of soil and modern methods for its determination. Gosgeolototechizdat, Moscow 27. Argunova LI, Olginsky AG (1972) Study of the properties of hardened cement paste depending on the intergranular space of the aggregate in concrete. In: Proceedings of the VII conference on concrete and reinforced concrete. Kharkov 28. Kasianov AE (2012) Method of measuring hydrophysical properties of running soils. Land Improv Rehabil, Ecol 2:26–28 29. Levkevich VE, Mikanovich DE, Tsedic VA (2014) Laboratory test methods to determine sand soil permeability factor. Probl Saf Emer Situat 1(3):63–65 30. Zharnitskii VIa, (2010) Quick determination of permeability of clayey soil used for impermeable layer of dams. Environ Eng 4:37–44 31. Silchenko PG (1975) Water demand of sand in the composition of cement-sand concrete. Stroitelnyye materialy, detali i izdeliya (Building Materials, Parts and Products). Budivelnik, Kyiv

Increasing the Energy Efficiency of Buildings L. M. Vesova(B) and A. A. Churakov Volgograd State Technical University, 1, Akademicheskaya Ulitsa, Volgograd 400074, Russia [email protected]

Abstract. Current trends and perspectives on building construction and renovation are primarily concerned with a rational usage of energy resources, a comfortable indoor climate and a reduced impact on the environment. New requirements for consumer qualities of housing, modern trends in the field of energy and resource conservation require the development of new structural solutions of buildings, modern organizational and economic directions of the industry development based on progressive achievements of science and technology, which will allow to introduce modern efficient materials and technologies into production, to solve the issues of creating a comfortable living environment. The most promising way of tackling this problem is converting to energy-efficient houses. The main heat loss in buildings occurs in the enclosure structures, which account for 30– 35% of the total heat loss of a building. A high thermal protection of a building or a structure can be ensured by using efficient thermal insulating, structural building materials like cellular concrete. The unique thermal properties of cellular concrete are primarily due to porosity. Its structure produces a significant number (up to 90%) of artificially created air cavities, ensuring self-regulation comfort of living areas. The use of fiber-reinforced concrete structures in construction will help to reduce labor costs for reinforcement work, steel and concrete consumption by reducing the thickness of constructions, combine the technological operations of concrete mix preparation and its reinforcement. It has important properties for the construction industry, such as improvement of air exchange, moisture and thermal properties of the walls and sustainable structures. Keywords: Energy-efficient buildings · Cellular concrete · Fiber-reinforced concrete

1 Introduction The modern construction sector is one of the key branches of the economy and to a large extent determines the solution of social and economic problems of the country’s development. Modern trends and prospects for the construction and renovation of buildings primarily relate to a rational approach to the use of energy resources, a comfortable indoor climate and a reduced impact on the environment. The government has adopted a Strategy of Socio-Economic Development of the Russian Federation until 2030, with its extension until 2035, which provides for a significant increase in requirements for energy efficiency of capital construction projects [1]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_14

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The energy efficiency of a facility is a concept that covers its key parameters that ensure the consumption of resources within the established norm. According to the document, all new capital construction projects—residential, public and industrial—will be required to have a high energy efficiency class (A or A+). In existing buildings, “energy-efficient modernization” of engineering systems—heating, hot water supply, and lighting—is envisaged. New requirements for the consumer qualities of housing, current trends in energy and resource conservation require the development and introduction of fundamentally new construction solutions for buildings, modern organizational and economic trends in the sector based on progressive achievements of construction science and technology, which will allow in the near future to introduce modern, effective materials and technologies and solve problems of creating a comfortable living environment. In the current context of rising energy costs and the negative impact of energy technologies on the environment, the problem of energy efficiency becomes very important. Energy efficiency is the most important resource for accelerating economic growth in Russia. The most promising direction in solving this problem is the transition to the construction of energy efficient houses. Energy losses for buildings around the world constitute about 40% of all energy consumed, data cited by the Green Building Council (RuGBC). An energy-efficient building is a building in which energy consumption is less than the accepted normative standards by means of implementing a set of functional-planning, design and engineering solutions, using renewable energy sources, while ensuring the necessary level of environmental and sanitary and epidemiological safety [2, 3]. The basic principle of such houses is to maintain a comfortable environment while using the minimum amount of energy. The volume of energy resources during the maintenance of such a house is consumed less than the accepted normative standards. This is ensured by space-planning, constructive, engineering and technical solutions in the design and construction of such houses. The use of modern energy-efficient structures and materials makes it possible to create buildings not only with low energy consumption, but also with different price ranges, comfort and environmental friendliness, which is certainly relevant within the modern construction industry. Materials with high insulation properties are a priority in the construction market. Obsolete, heavy, metal and energy-intensive structures with insufficient thermal and sound insulation should be replaced by lightweight, energy-saving building envelopes, ceilings and coatings, façade systems, fixed formwork construction technologies with better sound and thermal insulation qualities and technical and economic indicators from durable, lightweight concrete [4–6].

2 Relevance of the Issue The main heat losses in buildings are in the building envelope, which accounts for 30– 35% of the total heat loss of the building. Currently, the minimum required value of the thermal resistance of the walls of residential buildings is Eq. 1 [7]. R = 3.0 − 3.5m2

◦C

W

(1)

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According to recommendations [8], walls with thermal resistance not less than 10.0 m2 °C/W should be used for so called passive houses. It means that the thickness of external walls made of traditional building materials (reinforced concrete, bricks) is not able to provide the required value of thermal resistance in a single-layer building envelope with a reasonable thickness of the envelope. High thermal protection of a building or structure can be achieved by the use of effective insulating, constructional building materials. Materials for building envelopes must have sufficient strength and frost resistance, high thermal insulation properties, high fire resistance and durability, and environmental safety, both in terms of the safety of people living in houses with building envelopes made of these materials and in terms of the safety of the materials for the environment. There are various building envelope solutions using energy efficient building materials. The choice depends on the specific climatic conditions and design solutions [9, 10]. Two main options for thermal insulation of building envelopes can be distinguished: 1. a multilayer wall with a structural layer and a thermal insulation layer (thermally heterogeneous building envelope); 2. a wall in which the thermal insulation layer and the structural layer coincide (thermally homogeneous building envelope). Single-layer building envelopes have 1.3–1.5 times higher thermal homogeneity than the currently used multi-layer ones. This is due to the structural heterogeneity of the latter, the presence of thermal bridges and water vapor condensation on them. The influence of heterogeneity is taken into account when calculating the thermal resistance of the envelope. The thickness of single-layer envelopes increases by a factor of 1.053 due to material heterogeneity, and that of multi-layer envelopes by a factor of 1.33.

3 Main Part Physical and technical properties of the used insulation materials have a decisive influence on the thermal efficiency and operational reliability of structures, labor intensity of installation, the possibility of repair during operation and largely determine the comparative technical and economic efficiency of different options for insulating buildings. One of the most efficient insulators in construction is air, so the energy efficiency of building materials is largely determined by the percentage ratio of the volume of air-filled pores to the volume of the frame structure that forms those pores. However, there is a direct correlation between the thermal conductivity of the material, its specific weight and its strength. Air can also be an independent insulation layer in multilayer walls and thus provide thermal insulation. Cellular concrete—fulfills these requirements to a much greater extent than other building materials [11–13]. Cellular concrete can be obtained with the required specific weight, specified strength, required thermal resistance. It is possible to make a wide range of construction products from cellular concrete. Cellular concrete can be produced as

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structural and thermal insulating material, structural (700–1200 kg/m3 ), structural and thermal insulating (500 and not exceeding 700 kg/m3 ) and thermal insulating (200– 400 kg/m3 ) [14–20]. By the method of porosity, cellular concrete is produced as a result: • gas-forming (aerated concrete, gas silicates); • foam-forming (foam concretes, foam silicates); • aeration (aerated cellular concrete, aerated cellular silicate). It is known that aerated concrete has both closed and open pores, while foam concrete has mainly closed porosity. The individual pore sizes of these cellular concrete types are similar; the average pore size ranges from 0.5…0.8 · 10−3 to 2…2.2 · 10−3 m. By the method of curing: • non-autoclave; • involving steaming, electric heating or other types of heating under normal pressure; • autoclave, which cure under increased pressure and temperature. When producing foam concrete, foam is first prepared from blowing agents and then mechanically injected into the concrete mixture. The composition is mixed, the gas in the pores does not leave the material and therefore a material with closed, evenly distributed air bubbles is obtained. These pores are very small compared to the pores in aerated concrete. The production of foam concrete is possible both in closed shops as well as on open construction sites in the immediate vicinity of the application site. In aerated concrete, the cellular structure is formed with aluminum powder, which reacts chemically with alkali and releases hydrogen. A gasification reaction takes place, the solution swells and turns the mass into gas concrete. As a result of the reaction, the gas forms numerous open pores of relatively large diameter. The process of manufacturing products from cellular concrete is one of the most important technological operations, as it is at this stage is the formation of the cellular structure of the material. The main condition in this process, which must be strictly observed is to ensure the necessary conditions for the favorable formation of the cellular structure. The unique thermo-technical properties of cellular concrete are primarily due to its porosity [21, 22]. In the structure of cellular concrete, a significant number (up to 90%) of artificially created air cavities (cells) filled with air or gas are formed, providing selfregulation of relative humidity and high comfort of living spaces (Fig. 1). The pores or cells are evenly distributed in volume, bounded by thin and strong partitions which form the load-bearing framework of the material. The size and character of the distribution of air pores in the volume, i.e., the microand macroporous structure of cellular concrete, is decisive in the process of composite formation. At the same time, the technology and, of course, the method of poritization determine the quality of the pore structure. It is known that aerated concrete has closed and open pores, and foam concrete, most often, has closed pores. Individual pore sizes in cellular concrete are approximately equal, and their average size is from (0.5…0.8)· 10–3 to (2…2.2)· 10–3 m.

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Fig. 1. Characteristics of the pore structure of cellular concrete.

Porosity affects average density of cellular concrete in the dry state. It can be within a fairly wide range: structural (700–1200 kg/m3 ), structural-insulating (500 and no more than 700 kg/m3 ) and insulating (200–400 kg/m3 ). Expanding the production and nomenclature of products made of insulating lowdensity cellular concrete requires increasing its physical and mechanical properties. Along with significant technical and economic advantages, which contribute to its wide use in construction, low-density cellular concrete has a number of drawbacks. These are primarily a low ability to absorb tensile forces, as well as reduced cracking resistance, which creates certain problems already at the stage of transportation of products. One of the rational ways to eliminate these drawbacks can be dispersed reinforcement with fiber additives. Dispersed reinforcement of cellular concrete can increase not only the bending tensile strength, but also the compressive strength. The percentage of strength increase depends on the type of fiber and on the specific composition of the cellular concrete mixture. Makarychev [23] in the early 80’s noted that while in heavy concrete fiber reinforcement is appropriate only in necessary cases, in cellular concrete due to its low tensile strength it is always appropriate. Fiber reinforced concrete is a new generation of modern high quality reinforced concrete, which is made up of different fiber materials. Fiber reinforced concrete differs from traditional concrete, or metal reinforced concrete, with higher tensile strength, flexural strength, shear strength, impact and fatigue strength, crack resistance, water resistance, frost resistance, heat resistance and fire resistance. Fiber reinforced concrete can outperform conventional concrete by up to 20 times in terms of fracture resistance. All this ensures its high technical and economic efficiency. All of the fibers currently in use can be classified in various ways. Low-modulus fibers have higher relative elongation at break, which increases the impact toughness of concrete. They include organic fibers—polyethylene, polypropylene, polyester, etc. High-modulus fibers increase the bending strength and stiffness of the material, as well as resistance to dynamic loads. This group includes steel, basalt and carbon fibers. There is also a classification of fibers by origin, according to which all fibers are divided into natural and artificial.

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Examples of natural fibers are wool, hair, cotton, linen, coconut (organic), wollastonite, basalt, chrysotile-asbestos fibers (mineral/inorganic). The group of artificial fiber includes: metal fiber, glass fiber, boron fiber, carbon fiber, polymer fiber, synthetic wollastonite fiber and mixed fiber. Metal fibers are divided into steel and aluminum. Steel fibers are made from wire of proper size, specially stamped, as well as milled and turned. The main role of reinforcing fibers is: forming a spatial framework; restraining the sedimentation and deformation phenomena; increasing the stability and plastic strength of the material. The use of the material is relevant in civil and industrial construction, where it is necessary to improve the properties of concrete. Dispersed reinforcement allows to reduce the weight of the structure and increase the thermal insulating qualities of the material. The fiber used in the manufacturing process determines the performance properties of concrete. Steel fiber—has high strength to loads, does not shrink and does not form cracks during service. The most important qualities—long operating time, density and resistance to wear and tear. Its properties are not lost under the influence of low temperatures, moisture and fire. Steel fiber concrete is used to produce: coatings for bridges, floors, tunnels, shore protection strips, foundations, sleepers, roads, runways, sidewalks, structural frameworks, curbs, drainage channels, dams, manhole shafts for sewers, wastewater treatment systems, fiber concrete floors. Fiberglass filaments are filaments made of inorganic glass, which are obtained by drawing the molten glass mass on special machines. The properties of filaments directly depend on the chemical structure of glass and the method of obtaining the material. Concrete of this type has high qualities of elasticity, which gives it plasticity. Fiberglass concretes are relevant for fiberglass facade finish of residential buildings, waterproofing of cleaning structures, noise shields, light decorative products for finishing coatings, industrial premises with frequently polluted coatings, benches, fences, flowerbeds. Basalt fiber is a mineral inorganic fiber of artificial origin, which is obtained from the mineral of volcanic origin melted in furnaces. Main properties: resistance to mechanical stress, resistance to acids and alkalis, resistance to combustion. Basalt fiber concrete is used in the construction of foundations, slabs, roads, dams, reservoirs, railway structures. Cellulose fibers are produced from cellulose derived from natural materials. Such fibers are characterized by high absorption of water-saturated compounds. Adding cellulose fiber to the mortar promotes better and more uniform drying of the screed, reduces shrinkage, eliminates the appearance of cracks, increases the vapor permeability of polymer coatings. Synthetic fiber is an auxiliary reinforcing additive in the form of discrete multidirectional fibers that significantly improve the structure and technical characteristics of the finished concrete structures. The obvious advantage of fibers is their three-dimensional

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distribution in the mixture, which cannot be provided by reinforcement bars. The most common types of synthetic fiber in cement concrete matrix are acrylic, polyamide, polypropylene, carbon, nylon and others. In concrete, fiber creates a grid structure, guaranteeing a significant improvement of the technical characteristics of fiber concrete. It shows good resistance to impact and chemical influences. The drawbacks are such as poor resistance to compression and tension, high temperatures, variability in the quality of raw materials. Synthetic fibers are used for the manufacture of cellular concrete, foam blocks of low specific gravity. The considered types of fibers are not universal, each fiber allows to give the material some or other characteristics depending on the purpose of the material and conditions of use. Only cellular concrete makes it possible to make single-layer exterior walls of an acceptable thickness to provide the required thermal resistance.

4 Practical Value In the last years the interest in non-autoclave foam concrete as a durable, environmentally friendly and cheap building material has increased [24–28]. The production of foam concrete products has a number of advantages: • lower initial investment in setting up production; • significantly lower energy costs due to the elimination in some cases of grinding processes, vibration processes in the preparation of mixtures and products, as well as the “thermos” method of curing the products; • the ability to manufacture products and structures both in the factory and on site; • the possibility of a significant increase in the strength of non-autoclaved foam concrete products over time. The research showed, that durability of non-autoclave foam concrete in 3–3.5 months of hardening increases in 1.2 times, and in 2 years the durability increases in more than 2 times in comparison with durability indices of foam concrete in 28-days old age. The tests of physical and technical properties of foam concrete, which have been used as thermal insulation in freezing chambers for more than 65 years, showed, that even after thousands of cycles of freezing and thawing the durability of foam concrete grade of medium density D 400 exceeded 30 kg/cm2 , which is 3–3.5 times higher than the durability of this concrete in 28-days old age. The durability of non-autoclaved foam concretes, characterized by frost resistance, is significantly higher than that of autoclaved foam concretes. It is also important that the technology allows a number of additional options for the production of non-autoclaved foam concrete products. These include: • use of a variety of raw materials, including carbonate rocks, unmilled quartz sand, slag, ash; • extensive use of various chemical additives to intensify the production process and improve the physical and technical properties of foam concrete;

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• use of highly effective cutting equipment, providing high precision products, suitable for the installation of structures on the glue. The development of technological parameters of products manufacturing under production conditions showed that non-autoclave foam concrete products can be made not only in the individual forms, but also by cutting technology through the use of effective accelerators and temperature conditions of maturing arrays, allowing to make their dismantling and cutting into products of desired size in 3.2–2.5 h after production. Single-layer walls are used as curtain walls after installation to the load-bearing structures. In low-rise buildings these walls can be self-supporting. Two-layer non-load-bearing, bearing and self-supporting curtain constructions, are made of D200…D250 foam concrete with an outer shell of 15–30 mm thick fiber concrete or an outer shotcrete layer. The load from the weight of the wall is transferred to the slab via the projecting brackets. On the inside, the envelope is grouted or plastered with cement-sand mortar over a steel grid. The grid is connected to the outer layer by flexible galvanized steel ties that pass through the foam concrete layer. Three-layer walls are supported by slabs. They can also be non-load-bearing curtain walls. These structures are manufactured with an insulating middle layer made of lightweight concrete with low average density, strength and thermal conductivity. The outer layers are made of structural concrete. Cellular concrete is known to have a high bonding strength with heavy concrete, but this requires the sequential laying of layers in a single process cycle to form a monolithic cross-section. This technology eliminates the installation of any inter-layer bonds. There is a three-layer curtain wall with outer and inner layers of plaster or shotcrete more than 20 mm thick on a metal grid. The inner layer is made of D200…D250 foam concrete. Three-layer curtain wall with thermal insulation of D200 foam concrete or less between the inner and outer layers of half-brick masonry, which are connected by galvanized metal rods. Three-layer load-bearing walls can have an inner load-bearing layer of reinforced concrete; structural lightweight concrete; prefabricated reinforced concrete panels; of brickwork. And the outer protective layer is made of reinforced concrete shells; brickwork or other materials.

5 Conclusion The use of fiber reinforced concrete structures in construction will help to reduce labor costs for reinforcement work, reduce steel and concrete consumption by reducing the thickness of structures, and combine the technological operations of concrete mixture preparation and its reinforcement. The advantages of fiber reinforced concrete include its high-performance characteristics. It is resistant to abrasion and chemical influences, does not deform during use and has a high tensile and breaking strength. Fiber reinforced concrete has practically no shrinkage or cracking. The use of fiber reinforced concrete as a reinforcing material can significantly reduce the labor intensity of concrete products. Such structures do not need additional reinforcement by means of metal carcasses and grids.

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Fiber reinforced concrete, unlike conventional concrete, is resistant to extreme temperature fluctuations. Fiber reinforced concrete has properties that are important in the construction industry, such as improved air exchange, moisture and thermal resistance of the walls, as well as sustainable structures that increase the comfort of the dwelling. The high technical characteristics of fiber reinforced concrete contribute to the strength and durability of the structure. Summarizing the above, we can conclude that the operational energy efficiency of buildings is formed primarily by its thermal energy efficiency, which in turn depends on the thermal protection properties of the building envelopes.

References 1. Russia’s energy strategy to 2030. Ministry of energy of the Russian federation. http://minene rgo.gov.ru/aboutminen/energostrategy/. Accessed 11 Jun 2022 2. Tabunshchikov YA, Brodach MM, Shilkin NV (2003) Energy efficient buildings. AVOKPRESS, Moscow, p 200 3. Markov DI (2012) Peculiarities of the formation of energy-efficient residential buildings of medium storey. Build Mater, Equip, Technol XXI Century 5(160):29–33 4. Yundin AN, Tkachenko GA, Izmalkova EV (2001) About a design technique of composition of non-autoclaved foam concrete with one-stage preparation of a foam concrete mixture. Izv. vuzov. Constr 7:21–26 5. Zavadsky VF (1999) Complex approach to solving the problem of heat protection of walls of heated buildings. Stroitelnye Mater 2:7–8 6. Gorlov YP (1989) Technology of heat insulation and acoustic materials and products. Higher School, Moscow, pp 77–89 7. SP 50.13330.2012 Thermal protection of buildings. SaintGobain Construction Products Rus LLC 8. Faist W (2011) Basic provisions for the design of passive houses. ASV, Moscow, p 144 9. Deryabin PP (2001) Cellular concretes with coarse aggregate. Proceedings of NGASU. NGASU, Novosibirsk 4(15):171–174 10. Vylyazagin VP, Pinsker VA (2004) The walls of the building in the permanent formwork of heat-insulating foam concrete. In: Collection of reports of the International scientific-practical conference “Aerated concrete in modern construction”, St. Petersburg 11. Vinogradov VP (1992) Small enterprises for the production of building products from nonautoclave foam concrete. Stroitelnye Mater 10:5–6 12. Heat Insulation Materials in the focus of attention of Gosstroy of Russia (2000). Stroitelnye Mater 4:38–39 13. Bazhenov YM (1987) Technology of concrete. The Higher School, Moscow, p 415 14. Morgun LV (2005) Analysis of structural features of foam concrete mixtures. Stroitelnye Mater 12:44–46 15. Ukhova TA (2011) Present and future of cellular concrete in Russia. Ves Beton Constr J 16. Serova RF, Kasumov ASh, Velichko EG (2016) Problems of production and application of cellular concrete. Fundam Res 7–2:267–271 17. Mitina NA, Lotov VA Thermal insulation materials based on dispersion-reinforced gas concrete non-autoclave curing. http://www.sts54.ru/public/13.php. Accessed 20 Oct 2013 18. Danilov BP, Bogdanov AA (1973) Enclosing structures of cellular concrete of variable density. Stroyizdat, Moscow, p 102

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19. Akhundov AA, Gudkov YV (2000) State and trends of development of light concretes in Russia. In: Concrete and reinforced concrete in the third millennium. Materials of international scientific-practical conference, Rostov-on-Don, pp 50–55 20. Kondratiev VV (2003) Structural and technological bases of obtaining “extra light” foam concrete: abstract of the thesis. Cand. of Science of Technology, Kazan, 22 p 21. Pukharenko YV (2004) Principles of structure formation and prediction of fibrocrete strength. Stroitelnye Mater 10:47–51 22. Kurbatov VL et al (2000) Energy-resource-saving multilayered structures of wall blocks. Izv Higher Educ Inst Const 9:4–9 23. Makarychev VV (1979) About fiber-reinforced cellular concrete. Sb. NIIZhB “Fibroconcrete and its application in construction”. NIIZhB Gosstroy of the USSR, Moscow, pp 85–88 24. Kurbatov VL et al (2000) Energy-saving multilayer construction of wall blocks. Izv Higher Educ Inst Constr 9:4–9 25. Kazakov YN. Low-rise urban development with energy-saving building systems and cellular concrete. Cellular concrete in modern construction: collection of papers, an international scientific-practical conference, pp 54–61 26. Cellular concretes in modern building: collection of papers of international scientific and practical conference, pp 6–8 27. Kondratyev VV (2003) Structural and technological bases of obtaining “ultralight” foam concrete: abstract of Ph. PhD. Kazan, 22 p 28. Pinsker VA (2004) State and problems of the production and use of cellular concrete. In: Cellular concrete in modern construction: collection of reports, international scientific and practical conference, pp 1–5

The Use of PVC Waste in Concrete with the Addition of PVAc S. Sokolnikova(B) , A. Puzatova, and M. Dmitrieva Immanuel Kant Baltic Federal University, 14, Nevskogo St, Kaliningrad 236016, Russia [email protected]

Abstract. Studies of the flexural and compressive strength of concrete were carried out with the replacement of 20% of the volume of sand with crushed waste from PVC (polyvinyl chloride) panels and the addition of polyvinyl acetate (PVAc) in the amount of 10% of the mass of cement. The tests were carried out on the 28th day of hardening of the samples in the mode of changing relative humidity from 90–95% in the first two days to 55–60% in the rest of the hardening time. The TiO2 photocatalyst was applied to the surface of the concrete to protect polymer concrete from UV irradiation and give it photocatalytic properties. A decrease in the workability of the mixture was recorded when PVC waste was added to the concrete composition, but the addition of PVAc to the mixture increased the workability to the minimum required value. The flexural strength of samples with PVC waste and the addition of PVAc decreased by 23.3%. Compressive strength decreased by 26.5% for these samples, and by 13.5% for concrete with PVC waste without the addition of PVAc. Keywords: Polymer concrete · Plastic waste · Photocatalytic concrete · Photocatalyst · Workability · Flexural strength · Compressive strength

1 Introduction Concrete is one of the most common building materials, characterized by versatility of application and low cost. At the same time, aggregates usually are 70–80% of the volume of this material [1]. These can be sand, crushed stone, gravel, as well as light aggregates such as diatomite, pumice, perlite, expanded shale, sintered pulverized fuel ash and plastic waste. The latter are of the greatest relevance due to accessibility in almost any part of the world and environmental benefits. The application of plastic in concrete is one of the available methods of reuse of various types of polymer waste, since concrete structures have a long service life and can later be recycled and reused as an aggregate [2]. Moreover, it is known that the concrete industry for the extraction of natural aggregates requires high energy consumption, thus, when using plastic waste as part of the aggregate, CO2 emissions and the rate of resource depletion are reduced. To date, many studies have been conducted on the use of PVC, PET, HDPE, PP and PE waste in concrete [3–6]. However, there is no detailed work on the joint use of bonding components, such PVAc and plastic waste. PVAc has a low cost, moreover, it © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_15

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is possible to use PVAc waste in concrete, which is formed during the production of water-based lacquers and paints [7]. It is known that concrete with the addition of PVAc effectively gains strength when kept in dry conditions, which is an important advantage in practice. This composite, when selecting the optimal polymer concentration, achieves maximum strength indicators when hardening for 1–2 days in a humid environment and subsequent hardening in a dry environment with a relative humidity of 30–60% [8]. When manufacturing polymer concrete with a high concentration of PVAc, it should be taken into account that photodegradation of the polymer occurs under conditions of active exposure to sunlight. This process can be significantly slowed down by adding titanium dioxide (TiO2 ). TiO2 is able to reflect and absorb UV light, thereby protecting the material from photodegradation [9]. Moreover, when a TiO2 photocatalyst is added to concrete, a material with photocatalytic properties is obtained that oxidizes ecotoxicants dangerous to humans to safer substances when exposed to sunlight or artificial light [10]. Earlier, the authors conducted research on the development of a method for applying TiO2 to the concrete surface. The photocatalyst was applied to a metal mold pretreated with machine oil for the manufacture of concrete. Then the mixture was immersed into the mold, and vibration compaction was carried out. The effectiveness of the TiO2 deposition method was evaluated by measuring the concentrations of solutions of representatives of polycyclic organic hydrocarbons (PAHs). Photocatalytic concrete samples were immersed in pyrene and anthracene solutions and exposed to UV irradiation. It was found that the efficiency of photodegradation of PAHs increases by 10% when TiO2 is applied to the mold compared to the method of adding TiO2 directly to the composition of the concrete mixture. The method of applying the photocatalyst to the mold can be used in the manufacture of paving slabs, facade and road panels. Crushed PVC waste can be effectively used as a substitute for a part of the natural aggregate in concrete due to their physicochemical properties and accessibility due to the high complexity of chemical processing. The environmental hazard of PVC is also higher than that of other polymers due to the presence of chlorine [3]. Thus, there is a serious need for the reuse of PVC waste. Crushed PVC panels, pipes, sheets, doors, window profiles, furniture, packaging and other products can be used as aggregates. For example, in [3], crushed PVC sheets were used, which replaced 5, 15, 30, 45, 65 and 85% of the volume of fine and coarse aggregates. The authors found that when replacing 5% of a coarse aggregate, the compressive strength increased by 12%, in other cases the strength decreased by 4–80%. At the same time, the workability of the mixture did not decrease when using up to 15% of PVC waste. The authors also note an increase in abrasion resistance up to two times when replacing coarse aggregate. In the study [11], sand in the amount of 5, 15, 30 and 45% by volume was replaced by crushed PVC pipes. With an increase in the PVC content, a decrease in compressive strength by 5–50% was recorded, at the same time, an improvement in other properties of concrete was observed, there were a decrease in shrinkage by 18–72% and a decrease in the permeability of chlorine ions by 12–36%. The decrease in concrete strength when PVC waste is added is primarily due to weak adhesion between cement and PVC particles, as well as the rapid appearance of cracks in cement around PVC particles under load due to a significant difference in elasticity modules [11]. The influence of these factors on the strength of concrete can be reduced

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by adding PVAc. At the same time, it is important to choose the concentration of the PVAc binder component and the necessary conditions for curing polymer concrete, since when hardening only in wet conditions, the strength of polymer concrete can significantly decrease [8]. In this work, concrete samples were made with the substitution of 20% sand by volume for crushed PVC panel waste and the addition of PVAc 10% by weight of cement. Before the production of samples, TiO2 photocatalyst powder was applied to metal molds for concrete to impart photoprotective and photocatalytic properties to concrete. The purpose of this work is to study the workability of the obtained mixtures, flexural and compressive strength on the 28th day of hardening, while the samples hardened in a humid environment only for the first two days.

2 Materials and Methods 2.1 Cement, Sand and Water Portland cement CEM I 42,5H (LLC “Peterburgcement”, Russia), sand for construction works, the size of fraction is 0–2 mm and tap water were used. 2.2 Characteristics of PVC Waste The PVC waste used in this work was obtained from panels crushed to a size of 0.2– 1.5 cm. Figures 1 and 2 show the panels before and after grinding.

Fig. 1. Waste from PVC panels before grinding.

2.3 Characteristics of PVAc Polyvinyl acetate glue was used (Bolars, AJ stroymarket, Russia) TU 2242-03356852407-09.

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Fig. 2. Crushed PVC panel waste.

2.4 Characteristic of TiO2 In this work, a TiO2 photocatalyst was used (Promchem, Russia). The average diameter of the particles was 21 ± 5 microns. The photocatalyst was applied to the surface of a metal mold for the manufacture of concrete, pretreated with machine oil. The consumption of TiO2 was 40 g per 1 m2 . 2.5 Composition of the Mixture The following ratios were used: cement/aggregate = 1/3, W/C = 0.4 and PVAc/cement = 0.1. At the same time, PVC waste was replaced by 20% of sand by volume. Also, in the manufacture of samples, water in the composition of PVAc was taken into account. The components of mixtures for the manufacture of three samples-beams with dimensions of 40 × 40 × 160 mm are presented in Table 1. In the manufacture of PVAc-PVCwaste samples, PVC waste was pre-mixed with PVAc before being added to the concrete mixture. In the manufacture of PVAc samples (without PVC), the PVAc binder component was added to water and thoroughly mixed. The vibration time of the mixture was 2 min with an amplitude of vertical vibrations (0.35 ± 0.03) mm and a frequency of 3000 per minute. 2.6 Hardening Conditions For the first two days, the hardening of the samples took place at a temperature of 20 ± 2 °C and a relative humidity of 90–95%. Then, for 26 days, the samples were kept at a temperature of 20 ± 2 °C and a relative humidity of 55–60%.

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Table 1. Components of mixtures for the manufacture of three samples-beams. Composition (g)

Mix code PVAc + PVCwaste

Control

PVAc

PVCwaste

Cement

500

500

500

500

Sand

1500

1500

1200

1200

Water

200

180

180

180

PVAc

–

50

–

50

PVC waste

–

–

58

58

2.7 Determination of Workability and Strength The determination of the workability and strength of concrete samples was carried out in accordance with GOST 310.4-81 [12], but the arrangement of the samples was changed during the bending test. The upper surface of the sample was sanded and placed horizontally during the test. Flexural and compressive strength was measured on the 28th day of concrete hardening using a ToniNorm testing machine (ToniTechnik, Germany).

3 Results and Discussions 3.1 Workability The results of studies of the workability of mixtures are shown in Fig. 3. The greatest decrease in workability is observed when replacing part of the sand with PVC waste. However, when PVAc is added to PVC waste, the workability of the mixture increases to the minimum value of 106 mm required by GOST 310.4-81 [12]. At the same time, it is worth noting a decrease in the workability of the mixture when adding PVAc without PVC. A similar effect may be associated with the influence of modifiers that are part of the PVAc, and their interaction with cement particles. In [8], on the contrary, the authors note an increase in the workability of mixtures with the addition of PVAc in the amount of 10 and 20% by weight of cement. 3.2 Flexural Strength In the previous work, when studying the cross sections of samples tested for bending, it was found that most of the PVC waste plates are located parallel to the base of the sample during its manufacture. It is assumed that this is due to the vibration compaction of the mixture. Thus, when testing samples according to GOST 310.4-81 [12], when the upper surface of the sample is vertical during testing and, consequently, the PVC waste plates are located parallel to the load and can cause large stress concentrations in concrete. In this work, the samples were arranged so that the surfaces of the PVC waste plates in concrete were perpendicular to the load during bending. The results of the bending strength tests are shown in Fig. 4. A decrease in the strength of samples with the addition of PVAc, as well as samples with PVC waste, was

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Fig. 3. Workability of mixtures.

found by 16.3%. At the same time, the decrease in the strength of the samples PVCwaste + PVAc was 23.3%. It is worth noting that after testing, beam samples with the addition of PVC and beam samples with PVCwaste + PVAc did not split into two parts (Fig. 5), as PVC waste plates were reinforcing components. To separate them, an additional effort of about 100 N had to be applied.

Fig. 4. Flexural strength.

Photo of the fracture surfaces of the sample PVCwaste + PVAc after bending test is shown in Fig. 6. It is established that the PVC plates are distributed sufficiently over the cross-section of the sample, there was no concrete segregation. At the same time, in the samples of PVAc and PVCwaste + PVAc recorded an increase in large pore, which significantly affect the strength of concrete. A similar effect may be associated with the effect of PVAc on the structure of the mixture [8]. According to the study of the surfaces of the destroyed samples (Fig. 5), it can be concluded that the adhesion strength of cement and PVC waste plates is insufficient, since the destruction of PVC plates did not occur, in all samples they were torn out of concrete. The use of PVAc under these conditions did not lead to a significant increase in adhesion between PVC plates and cement.

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Fig. 5. Sample PVCwaste after bending test.

Fig. 6. Photo of the fracture surfaces of the sample PVCwaste + PVAc after bending test.

3.3 Compressive Strength When placing the samples during the compression test such a way that the upper (during manufacture) surface was horizontal, there was a significant decrease in strength due to insufficiently smooth surface grinding. In this regard, the samples were placed in the press according to GOST 310.4-81 [12]. Figure 7 shows a photo of the test of the PVCwaste + PVAc according to GOST 310.4-81 [12], while the upper (during manufacture) surface was positioned vertically (Fig. 7, the back side of the sample) and most of the PVC waste plates are located in the direction of the compressive strength. Sharp edges of PVC waste plates arranged in this way can cause significant stress concentrations in concrete. Thus, in practice, it will be relevant to add PVC waste to concrete products, taking into account the directions of action of vibration compaction and the action of the load.

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Fig. 7. Testing of the sample PVCwaste + PVAc.

The results of compressive strength tests are shown in Fig. 8. A decrease in the strength of samples with the addition of PVAc by 11.3% was recorded. Samples with PVC waste and samples PVCwaste + PVAc showed a decrease in strength by 13.5% and 26.5%, respectively. A decrease in the compressive strength of samples with PVAc may be associated with an increase in the porosity of samples, in particular, an increase in the size of large pores [8].

Fig. 8. Compressive strength.

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A photo of the samples after the tests is shown in Fig. 9. It is worth noting that samples with the addition of PVC waste and PVCwaste + PVAc were visually less damaged.

Fig. 9. Photo of samples after compression tests. From left to right samples: control, PVAc, PVCwaste, PVCwaste + PVAc.

4 Conclusion In this work, studies were carried out on the workability of mixtures and strength during bending and compression of concrete with the replacement of 20% of the volume of sand with PVC waste and the effect of the PVAc binder component on the manufactured composite. At the same time, the TiO2 photocatalyst was applied to the surface of the samples using molds for the manufacture of concrete. The following conclusions can be drawn from the results obtained: 1. The mixture with the addition of PVC waste had less workability, the slump was 104 mm. At the same time, the addition of PVAc made it possible to make the mixture with PVC waste more fluid, the slump increased to 106 mm. 2. On the 28th day of hardening, of which 2 days were at 90–95% humidity and 26 days at 55–60% humidity, the flexural strength of concrete with PVC waste is reduced by 16.3%. At the same time, the addition of PVAc to PVC waste leads to a decrease in strength by 23.3%. 3. Compressive strength under similar hardening conditions of samples with PVC waste is reduced by 13.5%. Strength of samples with PVCwaste + PVAc is reduced by 26.5%. 4. PVC particles were fairly evenly distributed over the volume of the sample beams. It is noteworthy that most of the PVC plates were parallel to the horizontal plane of the sample, which may be the result of vibration during its manufacture. It is worth noting that the use of PVAc waste obtained as a result of the activities of the paint and varnish industry will be environmentally and economically efficient in the composition of concrete mixtures [7]. To protect the surface of such composites from exposure to UV irradiation and give them photocatalytic properties, it is proposed to apply a TiO2 photocatalyst to the surface of the mold during the manufacture of the composite.

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This work will be continued in the field of concrete strength research with an increase in the percentage of replacement of PVC waste and selection of the optimal amount of PVAc. It is also necessary to determine suitable conditions for curing polymer concrete, taking into account the fact that in practice it seems relevant to achieve sufficient concrete strength at a relative humidity of 40–70%.

References 1. Haghighatnejad N, Mousavi SY, Khaleghi SJ, Tabarsa A, Yousefi S (2016) Properties of recycled PVC aggregate concrete under different curing conditions. Constr Build Mater 126:943–950. https://doi.org/10.1016/j.conbuildmat.2016.09.047 2. Craciun V, Voinitchi D, Badanoiu A, Voinitchi R (2017) Effect of mixing method and polyvinil acetate addition on the mechanical properties of concretes with recycled concrete aggregates. Rev Chim 68:1528–1531. https://doi.org/10.37358/rc.17.7.5709 3. Mohammed AA, Mohammed II, Mohammed SA (2019) Some properties of concrete with plastic aggregate derived from shredded PVC sheets. Constr Build Mater 201:232–245. https:// doi.org/10.1016/j.conbuildmat.2018.12.145 4. Gu L, Ozbakkaloglu T (2016) Use of recycled plastics in concrete: a critical review. Waste Manag 51:19–42. https://doi.org/10.1016/j.wasman.2016.03.005 5. Sharma R, Bansal PP (2016) Use of different forms of waste plastic in concrete—A review. J Clean Prod 112:473–482. https://doi.org/10.1016/j.jclepro.2015.08.042 6. Alfahdawi I, Osman S, Hamid R, Al-Hadithi A (2016) Utilizing waste plastic polypropylene and polyethylene terephthalate as alternative aggregates to produce lightweight concrete: a review. J Eng Sci Technol 11:1165–1173 7. Ismail M, Noruzman AH, Bhutta MAR, Yusuf TO, Ogiri IH (2015) Effect of vinyl acetate effluent in reducing heat of hydration of concrete. KSCE J Civ Eng 20:145–151. https://doi. org/10.1007/s12205-015-0045-5 8. Geist JM, Amagna SV, Mellor BB (1953) Improved Portland cement mortars with polyvinyl acetate emulsions. Ind Eng Chem 45:759–767. https://doi.org/10.1021/ie50520a031 9. Zhang B, Han J (2016) Preparation and UV-protective property of PVAc/ZnO and PVAc/TiO2 microcapsules/poly(lactic acid) nanocomposites. Fibers Polym 17:1849–1857. https://doi. org/10.1007/s12221-016-6679-1 10. Lee BY, Jayapalan AR, Kurtis KE (2013) Effects of nano-TiO2 on properties of cement-based materials. Mag Concr Res 65:1293–1302. https://doi.org/10.1680/macr.13.00131 11. Kou SC, Lee G, Poon CS, Lai WL (2009) Properties of lightweight aggregate concrete prepared with PVC granules derived from scraped PVC pipes. Waste Manag 29:621–628. https:// doi.org/10.1016/j.wasman.2008.06.014 12. GOST 310.4-81 (2003) Cements. Methods of bending and compression strength determination. Standartinform, Moscow

Bearing Capacity and Deformability of Connections of Wooden Structures on TGC Dowel Plates S. A. Isupov(B) Vyatka State University, 36, Moskovskaya Str., Kirov 610000, Russia [email protected]

Abstract. The results of a rather large selection of experimental studies on the determination of the bearing capacity and deformability of connections of wooden structures on plates with cylindrical dowels TGk 5 mm in diameter with a symmetric and no symmetric test scheme are presented. The relevance of the study is due to insufficient data on the bearing capacity and deformability of these joints in relation to some parameters when pressing composite wooden beams. Based on the data obtained, a statistical analysis of all the test results on determining the ultimate strength connections and the deformation connections by loading levels. The results of comparing the experimental data and calculations of the nagel joint according to the previously obtained calculated diagram of the deformation of the wood of the nagel nest with the nonlinear diagram of the deformation of the nagel for symmetric and no symmetric joints are also presented. Good convergence of calculation results with experimental data is obtained. The purpose of these studies is to obtain a short-term diagram of the deformation of the connections on the nagel plates of TGk for the possibility of a refined calculation of composite beams, to identify the patterns of strength and stiffness of the connections from the technological factors of pressing the nagel plates into the beams. Keywords: Nagel plate · Nagel · Test scheme · Deformation diagram · Statistical analysis · Nagel nest · Symmetric connection · No symmetric connection

1 Introduction In the conditions of modern production of wooden structures, the validity of the thesis that the degree of perfection of structures is determined by the perfection of the means of their connection is obvious. Connections on metal cylindrical nagels are the most common ones in the world practice [1–6]. The most promising direction for improving nagel joints is associated with the transition from traditional methods of making joints, which are characterized by the sequential installation of several single nagels, to technologies based on the simultaneous installation of a group of nagels—nagel plates [7–11]. One of the most common ways to implement this approach is the use of metal stamped plates in joints [12–16]. The simplicity of the main technological operations © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_16

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and the high productivity of the manufacturing processes of both plates and structures have led to their wide distribution. The main disadvantage of stamped toothed plates is their limited bearing capacity. Stamped metal plates are suitable for the manufacture of plank structures with a relatively small span. An increase in the bearing capacity and rigidity of such joints can be achieved by replacing short teeth with a rectangular cross section with cylindrical nagels with an increased cross section. Among such means of joint there are the nagel connectors proposed at Vyatka State University [17–20], which are connecting elements containing a group of cylindrical nagels fixed on a common base. A characteristic feature of nagel connectors is pointed cylindrical nagels of increased diameter on a common basis with a more saturated arrangement. Connectors of the basic type (Fig. 1)—TGk nagel plates [18, 19] are mainly intended for the manufacture of composite wooden elements of an increased cross section.

Fig. 1. TGk connectors plates.

The following two approaches are used in the analysis of work and the subsequent calculation of nagel connectors: analytical, in accordance with which the patterns of deformation of nagel -type joints are studied using a calculation model inherent in bending elements made of materials with certain mechanical characteristics; experimentaltheoretical, in which the numerical values and the nature of the distribution of the parameters of the stress–strain state in the nagel and the supporting base are taken on the basis of calculated assumptions that do not contradict the experimental data. In accordance with the provisions of the limit state design method, which is fundamental for the design standards in force in Russia SP 64.13330, the calculated bearing capacity of nagel joints numerically corresponds to the loading level, the excess of which cannot but lead to a violation of one of the partial inequalities of the system of equations τmax < Tc σmax < Nc δmax < δadd

(1)

where τmax —maximum shear stresses on the contact layer; σmax —maximum normal stresses over the base section; δmax —displacement of the base in relation to the connected elements; δadd —allowable displacement.

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The use of solutions involving the analytical model of the nagel as a beam on a deformable base for normalization is significantly difficult due to their complexity and the lack of exhaustively complete data on the patterns of nonlinear deformation of connectors materials. For these reasons, this approach can only be used for a theoretical analysis of the operation of joints and a refined control of the standard values of the design parameters. Under these conditions the main tool for normalization is the second solution, according to which the calculated values of the bearing capacity per one cut of the connection are determined on the basis of the limit equilibrium method, with the replacement of the actual mechanical characteristics of the joint materials with their calculated values. In general terms, the proposed apparatus for normalizing the bearing capacity and deformability of joints of wooden structures on nagel plates, partially implemented in the Recommendations [20], is as follows: • design load-bearing capacity per one cut of the connection with nagels of a given diameter and a certain working length is determined based on the limit equilibrium method; • deformation of nagel joints under the action of the indicated force effects is determined from the calculation of the nagel as a beam on a deformable base, taking into account variations in the stiffness characteristics of the nagel socket.

2 Preliminary Data Based on the previously performed preliminary experimental and theoretical studies to determine the strength and stiffness characteristics of joints on nagel plates [21], it can be concluded that there is a well-defined range of reasonable values for the working length of the nagel, within which a sufficiently high load-bearing capacity is achieved with a sufficiently low material consumption. The lower limit of this range for given mechanical characteristics of wood and nagel is determined by the value of the length αmin , which is minimally sufficient for the formation of only one plastic hinge (in the most stressed section of the nagel). For nagel plates of the base type TGk, in which the nagels are rigidly fixed relative to a rigid base, the minimum length is determined from the expression  Rn.b (2) αmin = 0.44 · d Rαcr.n where Rn.b. —is the design resistance of the nagel to transverse bending; Rα cr.n. —calculated average resistance of the wood of the dowel nest to buckling at an angle α to the fibers. The design load-bearing capacity per one cut of the nagel, with the specified length α = αmin , is determined from the expression  Rn.b α 2 Tn = 0.44 · d (3) Rαcr.n

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The upper limit of the expedient range is limited by a certain maximum length αmax , sufficient for reliable nagel pinching and formation of two plastic hinges in the state of ultimate equilibrium. For nagels fixed on a rigid unifying base, we have  Rn.b (4) αmax = 1.41 · d Rαcr.n The design load-bearing capacity per one cut of the nagel of this length  Rn.b Tnα = 0.63 · d 2 Rαcr.n

(5)

The design load-bearing capacity per one cut of the nagel with an intermediate length αmin < α < αmax , is determined from the expression Tn.a = Tn · Ka · Ks

(6)

where T n.α —the design load-bearing capacity per one cut of the nagel recessed to the recommended minimum length amin ; K α —coefficient determined depending on the working length of the nagel α; K s —coefficient determined depending on the conditions of deformation of elements from the connection plane. The coefficient Kα takes into account the effect of increasing of the bearing capacity of the nagel when the accepted working length of the nagel exceeds the minimum allowable; its numerical values range from 1.0 to 1.4 depending on the reduced length α = 0.44 α/αmin . The numerical values of the coefficient Ks , which takes into account the influence of the deformation conditions of the connected elements from the plane of their connection, are determined as follows: • in the presence of bonds from the connection plane (such as tie bolts), or force actions in the indicated direction (in the form of a transverse load on bent rods of a composite section), the value of this coefficient is taken equal to, Ks = 1.00, regardless of the relative working length of the nagel α ; • in the absence of such bonds or forces capable of absorbing the expansion forces caused by the bending deformation of the nagel and the connected elements, the values of this coefficient range from 0.8 to 0.95, depending on its relative working length α . In the manufacture of composite wooden elements, it is possible to turn the nagels relative to the plates, due to which the deformations of the joint increase, therefore, it becomes expedient to introduce a coefficient of working conditions during the transition from symmetric to no symmetric loading. With simultaneous pressing of a sufficiently large number of nagel plates, residual gaps between the plates and the wood inevitably occur. Therefore, in the calculations it is necessary to take into account additional deformations of the joints, which depend on the actual operating conditions of the plates in the composite elements, by introducing additional coefficients of operating conditions.

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3 Experimental Research To obtain more reliable information about the work of shear bonds in relation to compound wooden elements; revealing the influence of the technology of pressing TGk dowel plates on the magnitude of deformations; determining the deformability of bonds by statistical analysis of the stiffness characteristics of the entire population, determining the average values and the limits of the scatter of experimental data for various test schemes, short-term tests of several series of samples were carried out according to the procedure [22]. Experimental determination of the strength and deformation characteristics of joints on TGk dowel plates installed between wooden elements when pressed into solid wood without pre-drilling holes can be performed using two main test schemes. Scheme 1 in Fig. 2a is a double-cut symmetric nagel joint with a metal gasket, usually with a small number of nagels. The force on the nagels is applied through the metal base, which extends beyond the dimensions of the wooden elements, and the deformations of the mutual shear of the wood relative to the plate are measured using digital indicators ICH-10, fixed on both sides on the wooden elements with the legs of the indicators resting against the protrusions of the dowel plate, which makes it possible to obtain two results for both nagel plates in a tensile test specimen. Crimp clamps are used to prevent expansion phenomena from the plane of the sample. To eliminate friction forces between the wooden elements and the metal plate, a layer of lubricant is used or fixed gaps of up to 0.5 mm are left. Such a scheme is the main one when testing nagel joints with a metal gasket. The test results according to scheme 1 (strength and stiffness of joints) are quite well predicted in theoretical calculations with known mechanical characteristics of wood and nagel material.

Fig. 2. Test schemes: a symmetric connection—scheme 1; b skew-symmetric double shear connection—scheme 2; c no symmetric single shear connection—scheme 3.

Schemes 2 and 3 in Fig. 2b, c are the same type of skew-symmetric double-shear and no symmetric single-shear connections. Dowel plates are made for real beams with the appropriate orientation. The force on the nagel transferred through the wooden elements, the deformation of the connection is determined by measuring the mutual displacement by clock type indicators ICh-10. To eliminate the tilting effect when testing specimens under scheme 3, additional fastening from the plane using movable supports is carried out. Diagrams 2 and 3 reflect to a greater extent the real operation of the nagel plates in joints to increase the cross section of the bars with their inherent features: (a) no

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symmetric load application scheme impairs the operation of the weld that attaches the dowel to the plate; (b) during the simultaneous pressing of a sufficiently large number of dowel plates, there are nagel deviations from the perpendicular to the wood, due to which residual gaps between the plates and the wood are possible, which leads to increased deformation of the joint. Consequently, the real strain characteristics of shear bonds in composite elements can be obtained using test schemes 2 and 3. When using the basic scheme 1, it is necessary to take into account the listed features by introducing transient working conditions coefficients for the strains of the nail connection. The performance of the connections when tested according to scheme 2 and 3 was evaluated at the stage of preliminary tests. The test results confirmed the identity of both schemes, so all further tests of asymmetrical connections were performed according to the simpler scheme 3. Analysis of strength and strain characteristics of joints in order to study the peculiarities of no symmetric loading was carried out when testing 26 specimens (52 results) according to scheme 1 and three groups of specimen series according to scheme 3: 1 group—18 specimens were pressed with a minimal possible deviation of dowels from the axis perpendicular to the plane of fusion with gaps not exceeding 0. 5 mm; the 2nd group—44 specimens were cut from the composite beams with the joint pressing of 17 dowel plates with the gap left to 1 mm and the fixed deflection of dowels to 10°; the 3rd group—7 specimens also from the beams, but with the gaps to 3 mm. Samples during tests and nagel failure under symmetrical and non-symmetrical loading are shown in photos of Fig. 3.

Fig. 3. a symmetric joint—scheme 1; b unbalanced joint—scheme 3; c failure of the nagel under symmetric and no symmetric loading.

All tests were performed in accordance with the recommendations [22] on pine wood with an average compressive strength along the fibers Rz = 51.3 MPa (determined according to the GOST 16,483.10 method) at a moisture content of 7…10%. Preliminarily, samples were tested on the same wood to determine buckling resistance the wood of the dowel nest Rcr.n [23].

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When testing according to scheme 1, plates with two nagels (4 cuts) with a diameter of 5 mm and a length of 60 mm were installed; according to scheme 3—plates with 5 of the same nagels. The tests were carried out at a constant load increment rate of 0.100…0.125 kN per minute per nagel shear on a R-100 kN testing machine. Based on the data obtained, statistical processing of the results was performed and diagrams of the deformation of the connections T− (force on the shear of the nagel−total deformations) were plotted for groups of samples for average values—Fig. 4.

Fig. 4. Diagrams of deformation of joints.

The data of the graphs show that the deformations of the connections on the TGk plates depend on the operating conditions of the plate in the joint. Thus, testing samples according to scheme 3 causes the nagels to rotate relative to the plate, due to which the deformations of the joint increase, therefore, it becomes expedient to introduce a coefficient of conditions for deformations during the transition from symmetric to no symmetric loading. The value of the coefficient within the calculated forces can be taken on the basis of the experiments carried out equal to mc = 1.45. The deformations of connections for the 2nd group of specimens cut from composite beams are significantly higher than those of the connections of the 1st group of specimens. This is due to the complexity of simultaneous pressing of a sufficiently large number of dowel plates, which inevitably results in plate skewness and residual gaps. The influence of these additional technological factors will be taken into account by introducing one more coefficient for the deformations of joints—the manufacturability factor, the value of which according to experimental data we will take mt = 1.40. Tests of the samples of the third group showed a 3…4—fold increase in the deformability of joints, which indicates the unacceptability of large gaps between the dowel plate and the wood.

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4 Results 1. In order to obtain a calculation diagram based on the results of the experiment, a general statistical analysis of the obtained data was performed, taking into account previous processing of Rz and Rcr.n. [24]. The most typical distribution law is γdistribution. The following experimental data were processed: the strength of the connections for all main series and the deformation of the joints by loading levels. Histograms and distribution curves are shown in Fig. 5.

Fig. 5. Histograms and distribution curves: a strength of connections; b joint deformations.

2. According to the obtained design diagram of the deformation of the wood of the nagel nest [23], calculations were performed with a nonlinear diagram of the deformation of the nagel M−χ according to the methodology [24] for a symmetric according to scheme 1 and no symmetric according to scheme 3 joints. The calculation results and comparison with experimental data are shown in Tables 1 and 2. According to Table 2 for no symmetric loading the experimental values of deformations exceed the estimated values in the operating range by 1.4 times, that is, by the value of the manufacturability factor of the pressing. Consequently, the estimated short-term diagram is formed by multiplying the calculated values by the coefficient mt = 1.4. Note that the estimated values of deformations according to the tables differ by ~1.45 times, by the value of the coefficient mc , when comparing half values of deformations from Table 2. Graphs of Fig. 6, built on the basis of the tables, clearly show good convergence of the calculation results with the experimental data, the maximum discrepancy is up to 20%.

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Table 1. Experimental and calculated values of deformations of symmetric connection. Load steps, kN/cut

Experimental values, mm ˙ Xmin … Xmax X

Estimated values, mm ˙ Xmin … Xmax X

0.25

0.006

0.002 … 0.013

0.018

0.011 … 0.025

0.50

0.028

0.006 … 0.066

0.049

0.031 … 0.069

0.75

0.072

0.022 … 0.151

0.092

0.058 … 0.129

1.00

0.149

0.044 … 0.315

0.149

0.095 … 0.205

1.25

0.260

0.069 … 0.577

0.222

0.143 … 0.304

1.50

0.429

0.153 … 0.848

0.324

0.201 … 0.472

1.75

0.710

0.266 … 1.368

0.546

0.285 … 0.918

2.00

1.175

0.449 … 2.245

1.046

0.433 … 1.922

Td , kN

2.68

2.23 … 3.13

Table 2. Experimental and calculated values of deformations of no symmetric connection. Load steps, kN/cut

Experimental values, mm × 2 ˙ Xmin … Xmax X

Estimated values, mm ˙ Xmin … Xmax X

0.25

0.040

0.023 … 0.072

0.044

0.034 … 0.070

0.50

0.148

0.096 … 0.205

0.130

0.090 … 0.192

0.75

0.330

0.240 … 0.443

0.252

0.172 … 0.358

1.00

0.590

0.484 … 0.703

0.418

0.276 … 0.590

1.25

1.020

0.816 … 1.259

0.646

0.414 … 0.906

1.50

1.598

1.200 … 2.123

0.992

0.590 … 1.432

1.75

2.494

1.663 … 3.653

1.572

0.842 … 2.386

2.00

–

–

2.556

1.348 … 4.200

Td , kN

2.54

2.05 … 3.09

5 Conclusion Based on the results of experimental and theoretical studies, the following main conclusions can be drawn regarding the joints of wooden structures on plates with cylindrical nagels TGk. 1. A calculation diagram of the deformation of a symmetric and no symmetric joint on nagel plates with a nagel diameter of 5 mm has been obtained, which will be used for further calculations of composite wooden rods with a joint on TGk nagel plates. 2. It has been established that when assigning the design short-term deformations of the connectors, one should take into account the operating conditions of the plate in

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Fig. 6. Deformation curves: a symmetric connection; b unbalanced connection.

the joint and use the transition coefficients mc and mt for deformations obtained by calculation. It has been established that gaps between the dowel plate and wooden elements larger than 1 mm are not allowed, the maximum angle of inclination of the nagels during pressing should be limited to 10°. 3. The design load-carrying capacity of joints with regard to the technological factors of presses the nagel plates TGk has been determined.

References 1. Markovich FS (2015) The theory of calculating the yield strength of wooden joints with cylindrical dowels. Vestnik MGSU. Des Constr Build Syst 15:41–46 2. Zhilkin VA (2015) Study of the deformed state of a cylindrical nagel in a symmetric two-shear connection of wood plates. Bull ChGAA 71:29–41 3. Smirnov PN (2013) Comparison of methods for calculating dowels joints of wooden structures. Domestic and foreign experience. Struct Mech Calc Struct 6:68–72 4. Orlovich RB (2004) Trends in the development of joints of wooden structures in construction abroad. University News. Constr Archit 11:12–18 5. Smirnov PN, Pogoreltsev AA (2013) Determination of the bearing capacity of nagel joints based on standard material characteristics. Modern Build Struct Made Metal Wood 17:247– 253. http://nbuv.gov.ua/UJRN/sskmd_2013_17_44 6. Johansen KW (1949) Theory of timber connections. International Association of Bridge and Structural Engineering, pp 248–262 7. Zhuk VV, Shchevchuk VL, Antiporovich AV (2019) Experimental study of the operation of joints of wooden elements on rigid nagel plates. In: Problems of modern construction: materials of the international scientific and technical conference of BNTU, Minsk, May 28, 2019, pp 60–65. https://rep.bntu.by/handle/data/60589 8. Sawata K, Sasaki T, Kanetaka S (2006) Estimation of shear strength of dowel-type timber connections with multiple slotted-in steel plates by European yield theory. J Wood Sci 52:496– 502. https://doi.org/10.1007/s10086-006-0800-9 9. Gappoev MM, Bazenkov TN (1987) Investigation of the operation of nagel connections with metal gaskets. In: Collection of scientific papers of MISI. Study of the strength and efficiency of modern structures made of wood and plastics, pp 45–48

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10. Blass Hans J, Martin S, Harald L, Barbara W (2000) Nail plate reinforced joints with doweltype fasteners. In: World conference on timber 199 engineering 2000. Whistler, British Columbia, Canada. Proceedings, pp 8.6.4-1–8.6.4-8 11. Isupov SA (2016) Connections of wooden structures on the basis of dowel connectors. Reg Archit Constr 2:100–104 12. Labudin BV, Karelsky AV, Melekhov VI (2015) Shear test of elements of wooden structures connected by metal toothed plates. Civ Eng J 1:11–16 13. Gattescoa N, Macorinib L (2014) Ln-plane stiffening techniques with nail plates or CFRP strips for timber floors in historical masonry buildings. Constr Build Mater 58:64–76 14. Blaz HJ, Schadle P (2011) Ductility aspects of reinforced and non- reinforced timber joints. Eng Struct 33:3018–3026 15. Loskutova DV (2008) Experimental studies of nodal connections of wooden elements on metal toothed plates in bending. Vestnik TGASU 4:74–80 16. Ermolaev VV, Tsepaev VA (2006) Estimated characteristics of wood in joints of building structures on metal toothed plates. Hous Constr 2:14–15 17. Piskunov YuV (1988) Bearing wooden structures with connections on nagels plates and elements. The Bulletin of Higher. Constr Archit 6:13–17 18. Piskunov YV (1992) Connections of the nail group type and ways of their use for the manufacture of complete delivery structures. In: Proceedings in the international symposium CIB/W18/TG6 technology, equipment, production. Kirov-Blacksburg, p 11 19. Isupov SA (2020) Experimental substantiation by choosing basic variant of plates with cylindrical dowels. In: iop conference series. materials science and engineering, vol 962 20. Recommendations for the design and manufacture of wood structures with connections on plates with cylindrical nagels of the TsNIISK-KirPI system (1988) TsNIISK, Moscow 21. Chernyavsky SM (1987) Connections of elements of wooden structures on nagels fixed in metal plates. Dissertation, MISI 22. Recommendations for testing the connection of wood structures TSNIIS named after Kucherenko (1981) Stroiizdat, Moscow 23. Isupov SA (2021) Mechanical characteristics of materials for joints of wooden structures on TGk dowel plates. Abstracts of the 2nd international conference Modeling and methods of structural analysis, MGSU, Moscow, November 11–13 24. Piskunov YV, Burov EV, Zvorygin AV (1986) Determination of the stress-strain state of the nagel in the composition of the nagel plate, taking into account physically nonlinear behavior of materials. Moscow, VNIIS 6948:9

Increasing the Resistance of Chloromagnesian Composites to Cracking Under Prolonged Water Saturation G. Averina(B) , V. Koshelev, and L. Kramar South Ural State University (National Research University), 76, Lenin Ave, Chelyabinsk 454080, Russia [email protected]

Abstract. This article presents the results of a study devoted to determining the effect of sodium tripolyphosphate (STPP) additives on the properties of magnesium chloride composites, in particular, on their resistance to long-term water saturation. Magnesium oxychloride cements (MOC), especially based on dolomites, are highly prone to cracking when exposed to water for a long time. This effect depends on the degree of crystallization of the main active component—magnesium oxide, which is part of their composition. With an improper degree of crystallization, an artificial stone is formed, which individual phases are capable of creating internal stresses leading to destruction during long water saturation. In this paper, we consider the ability of the STPP modifier to stabilize these phases, as well as its effect on some physical and mechanical properties of chlorine magnesia composites. During the research, methods of mathematical planning of the experiment, standard methods for studying strength characteristics and water absorption by weight were used. It has been shown that the introduction of STPP additive reduces the strength of composites, but contributes to an increase in their resistance to cracking during prolonged water saturation. Keywords: MOC · STTP · Phase composition · Stabilization of phases · Resistance to long-term water saturation · Resistance to cracking

1 Introduction Binders based on magnesian rocks, which are waste products of the mining industry, have a high potential due to the high environmental efficiency of their production processes [1–3]. The mineral composites obtained on their basis also stand out against the traditional building materials due to their inherent unique technical characteristics [4–8]. The development of methods for obtaining such binders and their use in the production of building materials is still a relevant and popular research topic in the field of materials science. Numerous methods are known for obtaining magnesium composites with a stable phase composition, not subject to cracking and recrystallization due to the achievement © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_17

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of initial magnesium crystallites in sizes ranging from 38 to 45 nm [9–11]. A significant disadvantage of these methods is their difficult application in industrial conditions for the production of relatively large batches of products. For example, as practice has shown, the combined method of intensified roasting of a fractionated charge actually makes it possible to obtain binders with magnesium oxide crystallites in the specified range, which do not contain calcium oxide impurities on an industrial scale. However, due to the peculiarities of the firing equipment, it is practically impossible to exclude the periodic appearance of batches of products containing weakly crystallized magnesium crystallites of high activity. The presence of such crystallites has practically no effect on the setting time and normal density of the binder, as well as on the strength of magnesium composites based on it. However, the phases formed during the its hydration are susceptible to high humidity. The processes that occur when these phases come into contact with water cause internal stresses and the appearance of characteristic cobweb-like cracks throughout the entire volume of the composite [12]. An alternative way to obtain stable phases of magnesium composites can be methods that involve changing the processes of structure formation of magnesium composites that occur during the hydration reaction. The processes of structure formation, in turn, can be influenced by the following factors: reaction conditions, the presence of inert finely dispersed fillers—krents in the composition of the mixture, or the presence of active mineral and organic additives that can enter into exchange reactions with hydration products, thereby changing their composition [13–17]. The purpose of this study is to determine the effect of STPP additives on the physical and mechanical properties of chlorine magnesia composites obtained on the basis of a binder containing weakly crystallized magnesium oxide crystallites.

2 Materials and Research Methods For making samples of magnesia composites, a dolomitic magnesium binder was used. This binder was obtained by the method of intensified roasting of a fractionated charge [18] in an industrial rotary kiln at a temperature range of 600…750 °C. As a stabilizing phosphate-containing additive, sodium tripolyphosphate additive of analytical grade was used. To reveal the stabilizing effect of this additive in the control and modified composites, we studied the resistance to cracking during prolonged water saturation. The study was carried out on samples-cubes 2 × 2 × 2 cm in size, made from chlor-magnesia paste of normal density. This paste was obtained using a solution of bischofite with a density of 1.2 g/cm3 at the same water-binding ratio. The first series of samples was made without an additive; for the second series, an STPP additive was used in an amount of 0.25 and 0.5% by weight of the binder. To determine the optimal dosage of the STPP additive and the optimal density of the bischofite solution, a two-factor experiment was carried out, where these indicators were variable factors. The amount of additive introduced into the composition was 0.1%, 0.25% and 0.4% by weight of the binder. The densities of the bischofite solution were taken to be 1.18, 1.19 and 1.20 g/cm3 . Rectangular prisms 4 × 4 × 16 cm in size were used as samples.

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As responses, the bending strength on the 9th day of hardening, the compressive strength on the 9th day of hardening in the dry and water-saturated state, the coefficient of water resistance and the percentage of water absorption by weight were taken. The structure of the modified composites was studied using an SM-6460LA scanning electron microscope. To compare the mineralogical composition of the samples, we used the method of synchronous thermal analysis on a Netzsch Lux 409 instrument.

3 Results The samples tested for resistance to cracking hardened and gained strength under normal conditions for 7 days, thereafter they were placed in water for another two days. At the end of the test, the samples were removed from the water and subjected to visual inspection. Control samples of dolomitic magnesium binder were covered with a network of cobweb cracks. Samples with different content of sodium tripolyphosphate additive retained their integrity (Fig. 1).

Fig. 1. Samples subjected to water saturation for two days: a control, b with a sodium tripolyphosphate content of 0.5% by weight of binder.

The results of the two-factor experiment are shown in Table 1. Graphical interpretation of the results is shown in Figs. 2–4. Figure 2 shows the dependence of the compressive strength on the 9 day of hardening of the samples, on the concentration of the bischofite solution and the amount of the modifier additive in the composition. According to the dependences obtained, an increase in the content of the additive contributes to a decrease in the strength of the composites. With an increase in the density of bischofite, the strength characteristics of the composites increase, as well as with a decrease in the amount of STPP additive. The increase in the strength of magnesium chloride composites with an increase in the density of the bischofite solution is consistent with the known literature data [19, 20]. Therefore, the main process of structure formation proceeds according to the standard scheme.

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Table 1. Matrix and experimental results. Factor X

Factor Y

7 days

9 days

Rben, MPa

Rcomp dry., MPa

Wm, %

−1

−1

8.1

28

11.1

0.40

7.97

−1

−1

6.3

25.5

13.6

0.53

6.85

−1

−1

5.6

21.4

7.4

0.34

6.32

0

−1

8.0

28.3

12.2

0.43

6.37

0

−1

7.1

23.2

14.9

0.64

6.13

0

−1

8.4

19.6

10.2

0.52

5.45

1

−1

9.2

26.2

17.6

0.67

5.45

1

−1

7.1

21.3

13.5

0.63

5.49

1

−1

7.8

18.5

14.3

0.77

4.81

−1

0

10.0

31

7.7

0.25

6.13

−1

0

5.0

28.9

16.8

0.58

6.64

−1

0

9.2

23.2

11.5

0.50

5.51

0

0

8.9

32.3

14.1

0.44

6.21

0

0

8.0

23.3

15.7

0.67

5.75

0

0

8.8

23.5

15.6

0.66

5.50

1

0

9.2

26.8

16.36

0.61

5.31

1

0

7.8

22.6

18.9

0.84

5.18

Rcomp wet., MPa

Kwr

1

0

8.2

23.4

18.5

0.79

4.61

−1

1

10.5

38.4

5.9

0.15

4.48

−1

1

7.3

27.7

14.7

0.53

6.45

−1

1

9.7

25.4

11.9

0.47

5.46

0

1

10.5

36.4

16

0.44

5.59

0

1

7.6

26.3

19

0.72

5.69

0

1

7.9

30.2

23.4

0.77

4.14

1

1

10.5

32.3

17.1

0.53

5.66

1

1

9.4

24.2

17.4

0.72

5.17

1

1

7.6

19.5

19.1

0.98

4.77

Figure 3 shows the dependence of the water resistance coefficient of the samples on the concentration of the bischofite solution and the amount of the modifier additive in the composition. According to the data received, its indicator varies from 0.18 to 0.66. Increasing the content of the sodium tripolyphosphate additive contributes to an increase in the water resistance index. The concentration of the bischofite solution has little effect on this indicator.

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Fig. 2. The dependence of the compressive strength on the 9th day of hardening of samples of modified magnesium composites.

Fig. 3. Water resistance coefficient of samples of modified magnesium composites.

For chlorine magnesia stone obtained on the basis of an unmodified binder, consisting of magnesium oxide crystallites, the size of which is in the range of 38…45 nm, the typical water resistance coefficient is in the range of 0.5…0.66. The lower index of the coefficient of water resistance of the modified compositions based on a magnesian binder of high activity can be associated with the formation, during prolonged water saturation, of microcracks that are invisible to the naked eye. Thus, it can be concluded that the content of the sodium tripolyphosphate additive in an amount of less than 0.25% by weight of the binder is probably insufficient for the complete stabilization of the magnesium phases. Figure 4 shows the dependence of the water absorption of the samples on the concentration of the bischofite solution and the amount of the modifier additive in the composition. The highest water absorption rates are observed in compositions containing a modifier additive in the range from 0.15 to 0.375% by weight of the binder at a bischofite solution density in the range from 1.18 to 1.19 g/cm3 . This fact may also

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Fig. 4. Water absorption by weight of samples of modified magnesium composites in the 9th day of hardening.

indicate the presence of microcracking in composites with an insufficiently stabilized phase composition. Also, the low density of of the bischofite solution is the reason for the predominant content of the phases of magnesium trioxyhydrochloride, which is characterized by a lower density in the composition of the magnesia stone. An increase in the density of the curing agent at a constant amount of the STPP additive content and, in the opposite case, leads to a decrease in the water absorption of the samples. An example of a micrograph and the results of a probing X-ray analysis of a magnesium composite sample modified with the addition of sodium tripolyphosphate are shown in Fig. 5.

Fig. 5. a Micrograph of a sample of magnesium composite modified with STPP, b X-ray analysis of block No. 1, c X-ray analysis of block No. 2.

The results of this complex analysis indicate the presence in the structure of blocks consisting mainly of calcium-filled magnesium oxyhydrochlorides (1) and chloride salts, in particular potassium chloride (2). Thermal effects are recorded on thermograms (Figs. 6 and 7), corresponding to the following main minerals of chlor-magnesian stone based on dolomite binder: • 3MgO*MgCl2 *11H2 O—magnesium trioxyhydrochloride with endo-effects at the intervals of 150…180 °C and 200…220 °C; - SiO2 —silicon dioxide with endoeffect at 670 °C;

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Fig. 6. Thermogram of a sample of chlormagnesian stone based on dolomite binder without additives-modifiers.

Fig. 7. Thermogram of a sample of chlor-magnesian stone based on dolomite binder with TPPS.

• 5MgO*MgCl2 *13H2 O—magnesium pentoxyhydrochloride with endo-effects at the intervals of 160…170 °C and 350…370 °C; • Mg(OH)2 —magnesium hydroxide with endo effect in the range of 400…550 °C. • CaCO3 —calcium carbonate with endoeffect in the range of 725…830 °C. The nature of the curves is almost identical, which indicates the presence of all the listed minerals in the composition of both samples. At the same time, the total mass loss of a sample of chlorine magnesia stone with the addition of sodium tripolyphosphate is 3% less than that of a sample of chlorine magnesia stone based on dolomite binder without additives.

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4 Discussion Obviously, the introduction of an additive of sodium tripolyphosphate contributes to a change in the physical and mechanical properties of magnesia composites due to its influence on the processes of structure formation of oxyhydrochloride phases. It is also obvious that the process of structure formation of the composite with the addition of sodium tripolyphsate differs from the typical hydration process of magnesia oxychloride cement. According to the most common theory, if high-activity magnesium oxide crystallites (less than 38 nm in size) are present in the binder powder, during the formation of the composite structure, magnesium oxyhydrochloride blocks are formed. Free magnesium hydroxides are formed at their boundary. When magnesium hydroxides are saturated with water, their volume increases. In this case, the volume of the oxyhydrochloride matrix, apparently, changes insignificantly. Thus, due to the appearance of internal stresses, the samples crack in a cobweb-like pattern, repeating the contours of oxyhydrochloride blocks. The additive of STPP in the magnesium chloride solution probably reacts with highly active magnesium oxide crystallites to form magnesium phosphate compounds. The increase in volume under the influence of water saturation of this phase is approximately comparable to the increase in the volume of the oxyhydrochloride matrix of the composite. Consequently, the entire system expands evenly, while maintaining its integrity. When comparing the areas of weight loss with areas of endothermic effects on termograms, it can be concluded that the differences in weight loss are due to magnesium hydroxide (12% for the composition without additives, 9% for the composition with the addition of sodium tripolyphosphate). This partially confirms the theory about the neutralization of magnesium oxide of high activity and the prevention of the formation of a web-structure of potential stress centers. To confirm this hypothesis and to clarify the processes of structure formation, it is necessary to conduct a study of the chemical and mineralogical composition of magnesium oxychloride stone modified by additives and compare the results with the compositions of control samples.

5 Conclusions 1. The introduction of an additive of sodium tripolyphosphate in an amount of at least 0.25% by weight of the binder makes it possible to stabilize the magnesium chloride composite obtained on the basis of a dolomitic magnesia binder containing weakly crystallized magnesium oxide of high activity. 2. The addition of sodium tripolyphosphate affects the basic physical and mechanical properties of magnesium chloride composites. In particular, an increase in the proportion of sodium tripolyphosphate contributes to a decrease in the strength characteristics of the samples. This effect is more pronounced at the maximum concentration of bischofite solution (1.2 g/cm3 ) than at the minimum one (1.18 g/cm3 ).

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3. However, the water resistance index increases with increasing dosage of this type of additive in chlorine magnesia composites. At the highest dosage, the water resistance coefficient of the modified composite approximately corresponds to the standard water resistance coefficient of magnesia composites obtained on the basis of magnesium oxide crystallites of the optimal degree of crystallization (0.5…0.6).

References 1. Vinnichenko VI, Ryazanov AN (2015) Resurso-i energosberegayushchie vyazhushchie iz othodov dolomita (Resource and energy saving binders from dolomite waste) In: Energy and resource saving environmentally friendly chemical-technological processes of environmental protection. Belgorod, pp 22–32 2. Pyzhov EV (2020) Ocenka vozmozhnosti ispol’zovaniya othodov gornodobyvayushchej promyshlennosti v proizvodstve stroitelnyh izdelij (Evaluation of the possibility of using mining waste in the production of building products) In: International scientific and technical conference of young scientists, pp 3185–3191 3. Miryuk OA (2014) Perspektivy ispolzovaniya othodov v tekhnologii magnezialnyh stroitelnyh materialov (Prospects for the use of waste in the technology of magnesian building materials). Sci World 11:41–44 4. Lebedeva NS, Nedayvodin EG, Sukhikh SD (2017) K voprosu povysheniya ognestojkosti stroitelnyh materialov na osnove magnezialnogo vyazhushchego (On the issue of increasing the fire resistance of building materials based on magnesian binder). Modern Probl Civ Protect 24:65–68 5. Nosov AV et al (2013) Vysokoprochnoe dolomitovoe vyazhushchee (High-strength dolomite binder). Bull SUSU: Series Arche Const 13:30–37 6. Uryasheva NN, Kovaleva OI, Kovalev NV (2018) Research of the magnesia cement stability to the impact of corrosive biological environments In: IOP conference series: materials science and engineering, IOP Publishing, vol 451, p 012035 7. Lauermannová AM et al (2021) High-performance magnesium oxychloride composites with silica sand and diatomite. J Market Res 11:957–969 8. Khalil A, Wang X, Celik K (2020) 3D printable magnesium oxide concrete: towards sustainable modern architecture. Addit Manuf 33:101145 9. Nosov AV, Chernykh TN, Kramar LY (2014) Dobavki-intensifikatory obzhiga dolomita (Additives-intensifiers for dolomite firing). Sci SUSU 1:998–1002 10. Tyukavkina VV, Gurevich BI (2014) Vliyanie rezhimov obzhiga dolomita na svojstva magnezialnogo vyazhushchego (Influence of dolomite roasting regimes on the properties of magnesian binder). Dry Constr Mix 1:33–36 11. Khuziakhmetov RK (2013) Tekhnologiya magnezialnyh vyazhushchih iz dolomitovogo poroshka i ocenka kachestva produktov obzhiga (Technology of magnesian binders from dolomite powder and assessment of the quality of roasting products). Bull Kazan Tech Un 7:101–107 12. Kramar LY (2007) Teoreticheskie osnovy i tekhnologiya magnezialnyh vyazhushchih (Theoretical foundations and technology of magnesian binders and materials). South Ural State University, Chelyabinsk 13. Kramar LY, Nuzhdin SV, Trofimov BY (2007) Compositions based on magnesian binder, not prone to cracking during operation. Bull SUSU: Series Arche Const 14:15–17

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14. Yelenova AA, Krivoborodov YR (2016) Vliyanie gidrodinamicheski aktivirovannoj dobavki kristallogidrata na gidrataciyu i tverdenie cementnogo kamnya (Influence of hydrodynamically activated additive of crystalline hydrate on hydration and hardening of cement stone). Adv Chem Chem Technol 30:36–38 15. Krivoborodov YR, Boyko AA (2011) Vliyanie mineralnyh dobavok na gidrataciyu glinozemistogo cementa (Influence of mineral additives on the hydration of aluminous cement). Tech Technol Silic 18:12–15 16. Guvalov AA, Kabus AV, Usherov-Marshak AV (2013) Vliyanie organomineralnoj dobavki na rannyuyu gidrataciyu cementa (Influence of organomineral additives on the early hydration of cement). Build Mater 9:94–95 17. Ba H, Guan H (2009) Influence of MgO/MgCl2 molar ratio on phase stability of magnesium oxychloride cement. J Wuhan Univ Technol-Mater Sci Ed 24:476–481 18. Averina GF, Koshelev VA, Kramar LY (2019) Combined roasting of raw materials modified by additives-intensifiers in form of low humidity sludge. In: IOP conference series: materials science and engineering, IOP Publishing, vol 687, p 022038 19. Matcovic B et al (1977) The mechanism of the hydration of magnium oxide. J Am Ceram Soc 60:504–507 20. Rogic V, Matkovic B (1972) Phases in magnesium oxychloride cement (in Serbo-Croat). Cement (Zagreb) 16:61–69

Steady-State Nonlinear Heat and Mass Transfer in Multilayer Enclosing Structures of Buildings and Constructions R. A. Sadykov1 and A. K. Mukhametzianova1,2(B) 1 Kazan State University of Architecture and Engineering, 1, Zelenaya Street, Kazan 420043,

Russia [email protected] 2 Kazan Federal University, 35, Kremlyovskaya Str, Kazan 420008, Russia

Abstract. For various canonical forms, a generalized mathematical model of a nonlinear stationary convective-molecular process of heat transfer through multilayer enclosing structures is suggested. A one-dimensional boundary value problem of heat and mass transfer processes in the multilayer enclosing is formalized, which takes into account the processes of infiltration and exfiltration of the vaporair mixture through the multilayer enclosing, as well as the presence of positive or negative and surface heat sources. Analytical closed solutions of the boundary value problem are obtained under conditions of unambiguity. Solutions of physical processes are analyzed depending on variable or constant thermophysical characteristics, sinks or heat sources. Boundary value problems of unrelated nonlinear stationary transfer and some algorithms for their solution for various bodies of classical forms are considered. Mathematical models are formalized, analytical and approximate solutions of boundary value problems of transfer are reduced to a dimensionless criterion form, which is convenient for large-scale transitions, practical applications, formulation of optimization problems and automation of control systems. Based on the results of closed general analytical solutions of a number of applied boundary value problems of heat and mass transfer, their physical interpretation is carried out. The results obtained make it possible to use them for practical calculations in the design of enclosing structures of buildings and constructions, thermal, engineering and electrical networks, the development of construction regulations for thermal protection of buildings, as well as in the calculations of multilayer structures of industrial thermal power and mechanical engineering equipment. Keywords: Heat transfer · Mass transfer · Enclosing structure · Condensation · Air permeability · Drying

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_18

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1 Introduction Depending on the purpose of the room (construction), climatic conditions and the time period of the year, the processes of heat and moisture transfer, filtration of the vapor—air mixture and liquid through the capillary-porous solid layers of the enclosing structure are accompanied by such physical phenomena as condensation heating or evaporative cooling. Therefore, the processes of molecular-molar heat and mass transfer through piecewise homogeneous media are quite complex and interrelated [1–5]. Structural solutions made of a dense outer layer of enclosing structures are possible only for individual constructions (bridges, monuments, gas and water reservoirs, etc.), and for residential and industrial buildings, such solutions can only worsen the humidity state of the multilayer enclosing structures (MES) due to the difficulties of air permeability, and consequently, the drying of the MES during the year with positive temperatures. Modern energy-saving buildings and constructions are built mainly from capillaryporous and capillary-porous-colloidal materials, which are used not only in civil and industrial construction, but also in industrial heat and power engineering (thermal and electrical networks, high-temperature heat exchangers, turbine blades, brickwork heatand electric generating units, systems of nuclear reactors with internal cooling, etc.), the aerospace industry (casing of high-speed flying vehicles, rocket nozzles, etc.) an d others, where various elements of heating equipment are subjected to high thermal stresses arising under the influence of high gradients of transport potentials [6–9].

2 Materials and Methods The transfer of thermal energy in the enclosing structures (ES) occurs through the solid skeleton of the material, liquid and vaporous moisture, which are contained in capillaryporous and capillary-porous-colloidal bodies. The differential equation (DE) of steadystate nonlinear transfer taking into account filtration (vapor–gas mixture and liquid) in the presence of internal volumetric negative or positive heat sources (HS) under generally accepted assumptions in relation to classical forms in Cartesian, cylindrical and spherical coordinate systems (CS) can be written in the form of an ordinary differential inhomogeneous equation (ODIE) of the second order: [λ(t)t  ] +

 [λ(t)t] + sgn[G]G(t)cp (t)t  + sgn[I ]I (t) = 0, r

(1)

where t(r)—the temperature; r—the current coordinate r ∈ [0, h], h—the thickness of the MES; λ—the coefficient of thermal conductivity OK (possibly taking into account its volume porosity ); —the shape constant ( = 0.2, respectively, “0”—unlimited plate, “1”—cylinder or square bar, “2”—ball or cube); cp – the isobaric heat capacity of the steam–air mixture; G—the flow density of the steam–air mixture, here “+” means the process of exfiltration, “–”—infiltration of the steam–air mixture; I(t)—the capacity of the internal (+) or sink (–); “ ” (upper stroke)–differentiation with respect to r; sgn[.]— (signum) “sign” function.

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If I = const, then a continuously uniformly distributed positive or negative HS acts in the considered region of thermal resistances. If I (t) = const, then local, concentrated, or distributed positive or negative HS acts in this region. With a generalized physical description of the processes of cooling the MES (possibly evaporative) or heating (possibly condensing), similar to Eq. (1), heat balances can be drawn up for both the region r ∈ [−∞, 0], and the region r ∈ [0, +∞], which lead to new DE of gas (or liquid) flows entering the ES and outgoing from the ES with boundary conditions (BC) corresponding to the new closed intervalsr. In this case, one or two more second-order ODIE and, respectively, two or four BC are added to the DE (1), depending on the conditions of the boundary value problem (BVP). Therefore, in order to obtain an unambiguous solution, the set BVP of the transfer processes in the MES will have to contain three second-order DEs of the and six BCs. The temperature field t(r) in this case can be expressed in terms of the ambient air temperatures from both sides of the MES. In a more simplified version, these boundary DE for the MES are replaced by BC of the third kind, with possible consideration of surface sinks or HS at the boundary of the MES surfaces [10, 11]. Therefore, Eq. (1) with BC of the third kind can be replaced by simpler BC of the first kind, provided that constant fictitious (equivalent) boundary layers are introduced. The analysis of the molar heat transfer showed that in this case, the BC of the third kind can be written as the BC of the first kind. Then, when solving the ODIE (1) and the presence two isothermal surfaces in the BC, it is convenient to apply the Kirchhoff transformation [12, 13], which, through a new auxiliary variable θ and the average coefficient of thermal conductivity λc leads the ODIE (1) to formalize the following BVP: ⎧ G(θ)c (θ) ⎪ θ  + r θ  + sgn[G] λcp θ  + sgn[I ] I λ(θ) = 0, ⎪ ⎪ c ⎨ θ (0) = θ1 = t1 , (2) ⎪ θ (0) = θ2 = t2 , ⎪ ⎪  ⎩ λc θ  = λ(t)t , t where λc = (1/t) t12 λ(ξ )d ξ , t = t2 − t1 , t2 > t1 , t1 t2 and the temperatures of the opposite surfaces of the MES. The direction of the heat flow relative to r ≥ 0 is determined by the BC of the BVP. The formalized BVP (2) can be rewritten in a criterial form using the Peclet (Pe) and Pomerantsev (Po) criteria and dimensionless scales of temperature (T ) and thermal resistant R, which is especially convenient, since it allows converting a MES into a single-layer one. In this case, omitting intermediate transformations, BVP (2) can be written as: ⎧    ⎨ T + r T + sgn[Pe]Pe(T )T  + sgn[Po]Po(T ) = 0, (3) T (0) = 0, ⎩ T (1) = 1, where T = (θ − θ1 )/(θ2 − θ1 ) ∈ [0, 1]- dimensionless temperature, R = R/R0 ∈ [0, 1] [0, 1]—dimensionless thermal resistance, here R = r/λ—current thermal resistance, R0 —total thermal resistance (total, reduced, required or multilayer wall), which is

Steady-State Nonlinear Heat and Mass Transfer in Multilayer

181

selected depending on the accepted BC; Pe = G(T )cp (T )R0 (in construction thermophysics the expression Gcp R0 is called the relative coefficient of filtration heat transfer, which characterizes the ratio of the thermal capacity of the air flow Gcp to the heat transfer coefficient of the enclosure structure K = 1/R0 ). If we take into account the volumetric porosity of the MES, then Pe = [G(T )cp (T )R0 ]/[1 − ]; Po = [I (T )h2 ]/[λc T ], in this formulation of the BVP T in the Pomerantsev criteria can be omitted, since the maximum temperature difference is equal to one; “ ” (upper stroke)—differentiation according to R. If the limits of variation of the similarity criteria Pe and Po are set, then the sign of the signature in ODIE (3) can be omitted, provided that Pe and Po are specified in the interval [0,1]. In this case, Pe and Po can be written as: Pe = [Pe − inf(Pe)]/[sup(Pe) − inf(Pe)], Po = [Po − inf(Po)]/[sup(Po) − inf(Po)] ∈ [0, 1]. Therefore, all dependent and independent variables and parameters of the generalized BVP are and they will belong to the four-dimensional normalized unit  dimensionless  space T , R, Pe, Po and the BVP (3) will be rewritten as: ⎧     ⎪ ⎨ T + R T + Pe(T )T + Po(T ) = 0, (4) T (0) = 0, ⎪ ⎩ T (1) = 1. Therefore, the above transformations significantly simplify the mathematical formalization of the BVP, eliminate physical dimensions and signs, and solve the issues of scale transition. However, the physical interpretation of the BVP becomes more complicated, especially when a graphical solution of the BVP is constructed in the above space, where the direction of the flow (G) and the sign of HS (I) are actually “lost” due to the absence of negative values of the problem parameters in the closed interval [0,1], but this complication is easily eliminated by the reverse transition to the initial parameters of the set BVP. Let us consider as examples several simplified special cases of solving the stated BVP. I.

For  = 1, λ(t), Pe = const, Po = const and an artificially omitted sign of the signature (since Pe, Po ∈ / [0, 1] the BVP (3) can be written in the form: ⎧  ⎨ T + PeT  + Po = 0, (5) T (0) = 0, ⎩ T (1) = 1, where at Pe < 0 there is infiltration in the MES, at Pe > 0– exfiltration, at Pe = 0– there is no air filtration or infiltration and exfiltration compensate each other; at Po < 0 the negative HS acts, at Po > 0– positive HS acts, at Po = 0– there are no sinks and heat sources, or they compensate each other.

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The analytical solution to BVP (4)–(5) is obtained in the form:

exp(−PeR) − 1 Po Po T (R) = R, 1+ − exp(−Pe) − 1 Pe Pe

(6)

which already covers all combinations of the above special cases of transfer parameters (Pe, Po) under the given single-valuedness conditions. Therefore, depending on the sign and value of the Pe or Po, we have different mathematical model (MM) reflecting the corresponding physical processes or phenomena. If the Pe, or Po ∈ [0, 1] are entered into Eq. (5) the generalized physical interpretation of the problem and the solution obtained at this scale becomes somewhat more complicated due to the absence of negative values of the Pe, or Po in MM and its solution. In addition, it should be noted that the particular solution (6), despite its apparent simplicity, was still obtained with the functional dependence of the thermal conductivity coefficient on temperature λ[t(r)]. Therefore, if λ(t) = const, then to obtain the profile t(r) it is necessary to initially translate the obtained solution T (R) into θ (r), and then, by the reverse transition through the Kirchhoff transformation (2), find the temperature field t(r) in the original notation of the BVP. The algorithm for such a transition is considered in the following example. II. For  = 2, λ(t) = λ0 (1 + βt) (λ0 - the known coefficient of thermal conductivity at the control temperature t0 , β- the temperature coefficient of thermal conductivity), Pe = 0 and Po = 0 we obtain an intermediate known solution of BVP (2) in the form: θ (r) = t1 + (t2 − t1 )

ln(r/r1 ) . ln(r2 /r1 )

(7)

The original dependent variable t(r) is found using semidefinite integration (2) and for the case of linear dependence λ(t) we obtain a quadratic equation of the form βt 2 /2 + t = t1 + βt12 /2 − λc (t1 − θ )/λ0 ,

(8)

λc = λ0 [1 + β(t1 + t2 )/2],

(9)

where

solving which with respect to t (the root from physical considerations is taken with the positive sign of the radical) taking into account (7) and (9), we obtain   

(1 + βt2 )2 ln(r/r1 ) 1 −1 . (10) t= (1 + βt1 ) 1 − 1 − β (1 + βt1 )2 ln(r2 /r1 ) Mathematical analysis of the results for constant λ and variable λ(t) showed that the variability of λ(t) at β > 0 increases, and at β > 0 decreases heat transfer, and the formula for calculating the increase in the relative change in the heat flow due to the variability of λ(t) will be q = [q(β) − q]/q (for β > 0) or q = [q − q(β)]/q(β) (for β < 0).

(11)

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Due to the fact that thermal stresses strongly (especially for high-intensity and high-temperature processes) depend on depend on the gradients of transfer potentials (temperature, pressure, moisture content, etc.), it follows from (11) that variable thermal conductivity can significantly affect not only the temperature distribution and heat transfer, but also the magnitude and distribution of thermal stresses, which is confirmed by numerous practical examples from the field of aircraft and mechanical engineering, construction industry, industrial and nuclear energy. III. For  = 2, the linear dependence λ(t), Pe = 0 and Po = const the general solution of the DE (2) by intermediate replacement of the variable U = θ + Ir 2 /4λc can be reduced to the solution of the DE for the previously considered case II (when Po = 0). Then the general solution of Eq. (2) for Po = const considering the indicated replacement, can be written as θ (r) = c1 ln r − Ir 2 /4λc + c2 ,

(12)

and after determining c1 and c2 from the BC (2), the solution θ (r) is θ (r) = [t2 − t1 + I (r22 − r12 )/4λc ]

ln(r/r1 ) − I (r 2 − r12 )/4λc + t1 , ln(r2 /r1 )

(13)

For a more simplified presentation of the algorithm for moving to the source variables of the BVP, we take t1 = t2 = 0. Then Eq. (13) takes the form θ (r) = [I (r22 − r12 )/4λc ]

ln(r/r1 ) − I (r 2 − r12 )/4λc , ln(r2 /r1 )

(14)

and the quadratic equation with respect to t is βλ0 t 2 /2 + λ0 t − λc θ = 0, from the solution of which it follows  t = ( 1 − 2βγ − 1)/β, where

 2 2 ln(r/r1 ) 2 2 − (r − r1 ) /4λ0 . γ = I (r2 − r1 ) ln(r2 /r1 )

(15)

(16)

(17)

For β = 0 it follows that t = γ , and for β > 0 it follows β ≤ 1/2 max γ . From the analysis of the obtained solutions, similarly to example II, an estimate of the temperature profile is derived depending on λ(t) both at β > 0, and at β < 0. IV. For  = 1, λ = const, Po = const and Pe = 0 the solution to the BVP (3) will be  (18) T = R( 1 − 2βγ − 1)/β, and if the heat flow coincides with the positive direction of the axis r, it will be T = (1 − R)(1 + PoR/2).

(19)

184

R. A. Sadykov and A. K. Mukhametzianova Table 1. The values of the relative temperature T (R).

R Po

0

0.1

0.2

0.3

0.4

6

1

1.17

1.28

1.33

4

1

1.08

1.12

1.12

1.08

1

0.88

0.72

0.52

0.28

0

3

1

1.035

1.04

1.015

0.96

0.875

0.76

0.615

0.44

0.235

0

2

1

0.99

0.96

0.91

0.84

0.75

0.64

0.51

0.36

0.19

0

1

1

0.945

0.88

0.805

0.72

0.625

0.52

0.405

0.28

0.145

0

0

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

−1

1

0.855

0.72

0.595

0.48

0.375

0.28

0.195

0.12

0.055

0

−2

1

0.81

0.64

0.49

0.36

0.25

0.16

0.09

0.01

0

−3

1

0.765

0.56

0.385

0.24

0.125

0.04

−0.015

−0.04

−0.035

0

−4

1

0.72

0.48

0.28

0.12

0

−0.08

−0.12

−0.12

−0.08

0

−6

1

0.63

0.32

0.07

−0.12

−0.25

−0.32

−0.33

−0.28

−0.17

0

1.32

0.5 1.25

0.6 1.12

0.7 0.93

0.8 0.68

0.04

0.9 0.37

1 0

Table 1 presents the values of the relative temperature T (R) calculated by Eq. (19) for −6 ≤ Po ≤ 6. The numerical results of changes in the relative temperature T (R) for various Po criteria showed that depending on the Po criterion, the temperature of the ES can be significantly higher than the maximum surface temperature of the ES at Po ≥ 3 and less than the minimum surface temperature of the ES at Po ≤ −3. Therefore, the higher the moisture content of the MES (negative HS), the deeper the moisture condensation front shifts into the MES (the period of the year with negative temperatures) and the wider the condensation zone. Similarly, the displacement of the evaporation front and the narrowing of the condensation zone (CZ) are found in the opposite direction, i.e., to the outer surface of the MES, when the MES dries out (decrease in moisture content and, accordingly, in heat sink during the period of the year with positive temperatures). The exact location of the front and the condensation (evaporation) zone can be found from the conditions for the existence of the extremum of the function T (R) The rate of displacement of the front and the CZ (evaporation) in one direction or another depends on ∇t, the moisture content and the energy (form) of the connection of moisture with the ES material. The specific heat flow is found from the equation q = −dT /dR and in the initial notation, when the heat flow coincides with the positive direction of the axis r, it takes the form q = λc (t1 − t2 )/h − I (h/2 − r).

(20)

From (20) it follows that q can be with the “+” sign when it coincides with the positive direction of the abscissa axis r (when t1 > t2 ), and with the “−” sign when the direction is decreasing r (when t1 < t2 ).

Steady-State Nonlinear Heat and Mass Transfer in Multilayer

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For values Po = 0, we have a linear law of change t(R): t = tv − (tv − tn )R/R0 .

(21)

The heat flow density will be q = (tv − tn )/R0 + IR0 /2 − IR.

(22)

The density of the heat flow entering through the internal thermal boundary (considering the resistance to heat perception Rv ) is determined by substituting R = 0 into (22). We get: qent = (tv − tn )/R0 + IR0 /2.

(23)

The density of the heat flow exiting through the outer thermal boundary is obtained at R = R0 : qexit = (tv − tn )/R0 − IR0 /2.

(24)

The difference (qent − qexit ) will give the density of the heat flow required for heating and evaporation of the moisture in the summer season, contained in the MES: qent − qexit = IR0 .

(25)

In the presence of air filtration in the MES, the analytical solution of the BVP is represented by Eq. (6). In this case, the dimensionless temperature depends on the independent variable R and two transfer parameters Pe and Po. Graphical dependences T (R) at different values of Pe and Po are shown in Fig. 1.

Fig. 1. Change in the dimensionless temperature along the wall thickness for various physical processes in the ES: a 1—infiltration (−3 ≤ Pe ≤ 0.01; Po = 0); 2—infiltration (−3 ≤ Pe ≤ 0.01) and heat source (Po = 3); 3—infiltration (−3 ≤ Pe ≤ 0.01) and heat sink (Po = −3); b 1— exfiltration (0.01 ≤ Pe ≤ 3; Po = 0); 2—exfiltration (0.01 ≤ Pe ≤ 3) and heat source (Po = 3); 3—exfiltration (0.01 ≤ Pe ≤ 3) and heat sink (Po = −3).

Figure 1 shows that with a certain combination of two opposite processes (infiltration and heat source or exfiltration and heat sink), they can equalize each other. In this case,

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T varies approximately linearly. For example, when Pe = −3 and Po = 3 (Fig. 1a), or Pe = 3 and Po = −3 (Fig. 1b). This situation is observed in cases where the Po and Pe criteria are close in modulus and opposite in sign, and the solution (6) takes the form (21). The generalized formulation of BVP (4) allows us to consider many other variations of the parameters λ(t), Pe(T ), Po(T ) taking into account the direction of gas flows (or droplet liquid) and the sign of HS, but the solution algorithm will be similar to those considered above. The initial ODIE (1) with variable transfer parameters [λ(t), Pe(T ), Po(T )] and BC of various kinds (possibly mixed and nonlinear), taking into account surface positive (or negative) HS (sinks), in the most general case, is solved by numerical or approximate methods of solving ODIE, and under certain conditions of the indicated transfer parameters, it can be reduced to solving the well-known DE of Bessel, Legendre or to solving a linear inhomogeneous DE of the n-th order (in our case—of the 2nd order) with variable coefficients of the form n 

an−i (r)t (i) (r) = f (r),

(26)

i=0

where ai (r)—are the variable coefficients of an inhomogeneous n-order DE;(i)—the superscript at t means the number of the derivative, t (0) = t; a0 = 1. The general solution of ODIE (26) is sought in the form t(r) = t00 (r) + tchn (r),

(27)

where t00 (r), tchn (r)– respectively, the general solution of the homogeneous DE (f (r) = 0) and some particular solution of the inhomogeneous DE. If a linearly independent fundamental system of solutions ti (i = 1; n) of the corresponding homogeneous DE (26) is known on some interval, then the general solution of the inhomogeneous DE can be found by the method of variation of arbitrary constants. In this case, the solution to Eq. (26) is sought in the form [14]. t(r) =

n 

ci (r)ti (r),

(28)

i=1

where ci (r)– unknown functions are found from the system of n equations: ⎧ n  ⎪ ⎪ ci (r)ti (r) = 0, ⎪ ⎪ ⎪ i=1 ⎪ ⎪ n  ⎪ ⎨ ci (r)ti (r) = 0, i=1 ⎪ ⎪ ⎪ − − − − −− ⎪ ⎪ n ⎪  ⎪ (n−1)  ⎪ ci (r)ti (r) = f (r), ⎩

(29)

i=1

Solving system (29) with respect to ci (r), we obtain ci = Yi (r),

(30)

Steady-State Nonlinear Heat and Mass Transfer in Multilayer

from where

187

 ci =

Yi (r)dr + ci ,

(31)

where ci – arbitrary constants of integration determined from the BC of the BVP. Further, substituting the obtained values ci (r) into (28), we obtain the general solution of the inhomogeneous DE (26). For example, for a second-order equation, system (29) takes the form   c1 t1 + c2 t2 = 0, (32)  c1 t1 + c2 t2 = f (r), 



Solving it with respect to c1 and c2 , we find:  ⎧ t2 f (r) ⎪ ⎪ dr + c1 , ⎨ c1 (r) = − W [t1 , t2 ] (33) ⎪ ⎪ ⎩ c (r) = −  t1 f (r) dr + c , 2 2 W [t1 ,t2 ]    t (r) t2 (r)  – Wronskian for functions ti (r), i = 1, 2. where W (r) = W [t1 , t2 ] =  1  t1 (r) t2 (r)  Figure 2 shows some typical distribution profiles t(R) in the ES depending on the transfer parameters [λ(t), Pe(T ), Po(T )] and their signs.

Fig. 2. Typical partial graphical dependences of the distribution in the MES: (1)—excluding air filtration, HS and λ = const; (2)—taking into account air infiltration; (3)—taking into account air exfiltration; (4)—taking into account air infiltration and heat sink (the presence of moisture in the ES); (5)—taking into account the exfiltration of air and HS; (6)—curve (4), (6) - curve (4), but taking into account the linear dependence λ(t) at β < 0; (7)—curve (4), but taking into account the linear dependence λ(t) at β > 0.

For linear inhomogeneous DE with constant coefficients and with the right-hand side of the form: f (r) = eαR [Pe (r) cos βr + Qm (r) sin βr],

(34)

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R. A. Sadykov and A. K. Mukhametzianova

where Pe (r) and Qm (r)– respectively, the polynomials of degree e and m with indefinite coefficients, a particular solution of the inhomogeneous Eq. (2) can be found more simply—by the method of indefinite multipliers (selection method) [15–18]. In this case: ˜ k (r) sin βr], tchn (r) = r s eαR [P˜ k (r) cos βr + Q

(35)

˜ k (r)– polynomials of r kth degree of the general where k = max (m,e); P˜ k (r) and Q form with indefinite coefficients; s—is the multiplicity of the root γ = a ± iβ of the characteristic homogeneous equation (if γ = a ± iβ is not the root of the characteristic equation, then s = 0). Therefore, depending on the moisture content, the structure of the capillary-porous materials, the thermophysical characteristics of the MES, and other factors, the function f (r) can be selected as a special case of expression (34). Particular solutions for various types f(r) of Eq. (26) for ai = const, i = 1, n are presented in Table 2. Table 2. Particular solutions for different types of right-hand sides of the DE (26). No

f(r)

Roots of the characteristic equation

Types of the particular solutions

II

Pm (r)

1. The number 0 is not a root of the characteristic equation

P˜ m (r)

III

Pm (r)eαr

IIII

Pm (r) cos βr + Qm (r) sin βr

2. The number 0 is the root of r s P˜ m (r) the characteristic equation of multiplicity s 1. The number α is not a root P˜ m (r)eαr of the characteristic equation 2. The number α is the root of r s P˜ m (r)eαr the characteristic equation of multiplicity s 1. The numbers ± iβ are not P˜ k (r) cos βr + roots of the characteristic ˜ k (r) sin βr Q equatio 2. The numbers ± iβ are the r s (P˜ k (r) cos βr + roots of the characteristic ˜ k (r) sin βr) Q equation of multiplicity s

* I-III are special cases of Eq. (29).

When finding particular solutions ODE (26), it is sometimes convenient to use the principle of superposition, ti (r) is a solution to ODE (26) at f (r)= fi (r), j = 1, p, i.e. p p then the function t(r) = j=1 tj (r) is the solution to (26) at f (r) = j=1 fj (r). Let’s move on from general solutions to specific ones. As an example, consider the case when a uniformly distributed “+”—positive or “−”—negative HS operates in a MES. The results of comparing the obtained solutions with the work [19], where only

Steady-State Nonlinear Heat and Mass Transfer in Multilayer

189

the effect of transverse air filtration was taken into account in the original equation, are presented in Table 3. Further, based on the constructed temperature fields, considering the infiltration (or exfiltration) of air and negative (or positive) HS, it is possible to calculate the humidity regime of the MES. For this purpose, the saturated mixing ratios E[t(x)] are determined for each layer of the MES. Then, according to the dependencies E(x) or E(Rvap ), (where Rvap - water vapor permeability resistance in the MES) and the relative humidity of the inside air and the external atmospheric environment surrounding the MES, the presence or absence of CZ moisture in the MES is graphically determined [20–22]. In the presence of CZ, the amount of moisture condensing in the MES under stationary conditions of water vapor diffusion is determined. Then, the densities of mass flows of moisture of air entering the CZ from the room (J m1 ) and leaving the CZ outside (J m2 ) are found. Then the specific density of the amount of condensing moisture in the MES (J k ) will be: Jk = |Jm1 − Jm2 |.

(36)

The considered method for calculating the humidity conditions of the MES also allows to calculate the rate of drying or desiccation of the MES after the cessation of moisture condensation in it during the period with positive outside atmospheric air temperatures [23].

3 Results and Discussion 1. Based on the physical and mathematical description of the processes of heat and mass transfer in the MES, which are caused by the action of external climatic factors and the operation of engineering systems for the life support of buildings and constructions (heating, ventilation, and air conditioning), the generalized BVP of the steady-state nonlinear convective transfer in piecewise homogeneous media is formalized in a criterial form. 2. The set BVP allows us to calculate, regardless of the scale of the objects and the direction of the flows: heat and mass transfer fields, flows and transfer coefficients (heat transfer, thermal resistance, vapor permeability resistance, steam and filtration cooling, etc.), taking into account the changes in the thermophysical properties of the MES from their transfer potentials, as well as the Cartesian SC—for plates and walls; in the cylindrical SC—for heat supply systems, heating, ventilation and electrical networks; in the spherical—for spherical gas storage tanks, etc. 3. The analogy of the processes of heat and mass transfer allows, with an accuracy to the transformation of symbols, to use the obtained analytical closed solutions of the BVP for other processes, for example, mass transfer, replacing only the temperature symbol “t”with the symbol of moisture content “u” (in the processes of the MES drying), and instead of heat exchange, use mass exchange similarity criteria with the corresponding physical interpretation of the set BVP. 4. The results of the research can be used for practical calculations of the MES and for improving the existing regulatory documentation on thermal and moisture protection of buildings and constructions.

Suggested option

[19]

Classic option

cp Gr

−1

p

(continued)

cp Gr t = tn + (tv − tn ) ecp Gr0−1 + c rG λ3 I

Heat source e

(ecp Gr − 1) ecp Gr0 t = tn + (tv − tn ) c Gr (e p 0 − 1) ecp Gr r + λ3 I cp G

cp GR

t = tn + (tv − tn ) ecp GR0−1 − c RG λ3 I p e −1

(ecp Gr0 − 1) ecp Gr

(ecp Gr − 1) ecp Gr0

t = tn + (tv − tn )

Exfiltration

Heat sink

t = tn + (tv − tn ) ecp Gr0−1 e −1

Infiltration

(ecp Gr − 1) ecp Gr0 t = tn + (tv − tn ) c Gr (e p 0 − 1) ecp Gr r λ3 I − cp G

t = tn + (tv − tn ) rr0

Comparison of temperature fields

Table 3. The results of comparing the obtained solutions with the work [19].

190 R. A. Sadykov and A. K. Mukhametzianova

Suggested option

[19]

Classic option

c Ge

cp Gr 0

qv

Heat source

Heat sink

+

cp G kexf ,W = c Gr p 0 −1 e λ3 I 1 + (tv −tn ) cp G

cp Gecp Gr0

ecp Gr0 −1

λ3 I 1 (tv −tn ) cp G

ecp Gr0 −1

λ3 I 1 (tv −tn ) cp G

kinf ,W =

−

cp G λ3 I 1 − (t −t v n ) cp G ecp Gr0 −1

cp G kexf ,W = c Gr p 0 −1 e λ3 I 1 − (tv −tn ) cp G

kexf =

Exfiltration

cp G + cλ3GI p ecp Gr0 −1

cp G − cλ3GI p ecp Gr0 −1

cp Gecp Gr0

cp Ge ecp Gr0 −1

kinf ,W =

kinf =

cp Gr 0

v qexf ,W = (tv −tn )

cp Gecp Gr 0 + cλ3GI p ecp Gr0 −1

v qinf,W = (tv −tn )

Heat source

Infiltration

v qexf ,W = (tv −tn )

cp Gecp Gr 0 − cλ3GI p ecp Gr0 −1

K = (t −t ) , r 0 = K1 v n

c G

p v = (t −t ) qexf v n cp Gr0 e −1

Exfiltration

v qinf,W = (tv −tn )

v = (t −t ) p qinf v n cp Gr0 e −1

Infiltration

Heat sink

n) qv = (tv r−t 0

Comparison of heat transfer coefficients

Suggested option

[19]

Classic option

Comparison of heat flow densities

Table 3. (continued)

Steady-State Nonlinear Heat and Mass Transfer in Multilayer 191

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R. A. Sadykov and A. K. Mukhametzianova

Acknowledgements. The second author acknowledges the support of the Kazan Federal University Strategic Academic Leadership Program (“PRIORITY-2030”).

References 1. Ilyinsky VM (1974) Building thermal physics (enclosing structures and microclimate of buildings). High School, Moscow 2. Fokin KF (2006) Thermal engineering enclosing parts of the buildings. AVOK-PRESS, Moscow 3. Bogoslovsky VN (2006) Building thermal physics (thermophysical foundations of heating, ventilation and air conditioning): Textbook for universities, 3rd edn. AVOK North-West, St. Petersburg 4. Gagarin VG, Kozlov VV (2005) Method of engineering calculation of the moisture state of enclosing structures, taking into account the transfer of vaporous and liquid moisture. In: Reports materials of the international scientific and technical conference “Theoretical foundations of heat and gas supply and ventilation”. MGSU, Moscow, pp 49–53 5. Hugo H (2007) Building physics—Heat air and moisture. John Willey & Sons Limited, Leuven 6. Kozdoba LI (1975) Methods for solving nonlinear problems of heat conduction. Science, Moscow 7. Isachenko VP, Osipova VA, Sukomel AS (1981) Heat transfer. Energoizdat, Moscow 8. Eckert ER, Drake RM (1961) Theory of heat and mass transfer. Gosenergoizdat, Moscow 9. Isaev SI et al (1979) Theory of heat and mass transfer. In: Leontiev AI (ed). High school, Moscow 10. Set of rules (SP) 50.13330.2012 (2012) Thermal protection of buildings. Updated edition of SNiP 23-02-2003 (with Amendment No. 1). Ministry of Regional Development of Russia. Moscow, p 95 11. Set of rules (SP) 23-101-2004 (2004) Design of thermal protection of buildings. Ministry of Regional Development of Russia. Moscow, p 167 12. Lukanin VN, Shatrov MG, Kamfer GM et al (2000) Heat. High School, Moscow 13. Vatin NI, Glumov AV, Gorshkov AS (2011) Influence of physical, technical and geometrical characteristics of plaster coatings on the moisture regime of plaster walls made of aerated concrete blocks. Inzhenerno-stroitelnyj zhurnal 1(19):28–33 14. Matveev NM (1967) Methods of integration of ordinary differential equations. High school, Moscow 15. Gagarin VG, Kozlov VV, Mekhnetsov IA (2005) Longitudinal air filtration in modern enclosing structures. AVOK 8:60–69 16. Ezerskiy VA, Kuznetsova NV (2005) Providing vapor protection for the outer walls of workshops with a saline industrial environment. Promyshlennoe i grazhdanskoe stroitel’stvo 12:25–27 17. Guidelines for calculating the moisture regime of building envelopes (1984) Stroyizdat, Moscow 18. Rakhimov RZ, Shelikhov NS, Smirnova TV (2010) Thermal insulation of their stone wool. ASV, Moscow 19. Ushkov FV (1969) Heat transfer of enclosing structures during air filtration. Stroyizdat, Moscow 20. Rakhimova GM, Lantsov AE (2010) Selection and calculation of thermal insulation of pipelines of heating networks. Study guide. KGASU, Kazan

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21. Stroy AF, Skalsky VA (1984) Calculation and design of heating networks. Budivelnik, Kiev 22. Sadykov RA, Krainov DV, Medvedeva GA (2020) Thermal physics of buildings. Study guide. KGASU, Kazan 23. Sadykov RA (2022) Modeling of heat and mass transfer in piecewise homogeneous media depending on physically coupled irreversible processes. In: XVI Minsk international forum on heat and mass transfer, Minsk, 16–19 May 2022

Modeling of Construction Objects When Considering Repair Characteristics Ya. Lvovich1 , I. Lvovich2 , A. Preobrazhenskiy2(B) , and Yu. Preobrazhenskiy2 1 Voronezh State Technical University, 14, Moscow District, Voronezh 394026, Russia 2 Voronezh Institute of High Technologies, 73a, Lenina Street, Voronezh 394043, Russia

[email protected]

Abstract. The paper considers the possibilities of modeling construction projects, when repair processes are implemented for them. An analysis of the significance of the parameters of construction objects when considering their maintainability is carried out. It was suggested that assessments of the significance of the maintainability status parameters should be carried out, and the selection of the optimal set of indicators was required. Nine indicators were selected. The method of extreme grouping was used in the selection of indicators for modeling. This is due to the fact that the cost of computing resources increases as the number of parameters increases. The formation of classification models of repair is carried out. The results are given, which provide standards for the parameters of repair models, as well as the minimum permissible degree of similarity by models. Based on the results of the classification, there are opportunities for the state of construction projects to be determined. The analysis demonstrated good performance of the proposed models. Keywords: Model · Repair characteristics · Construction objects · Classification · Validation

1 Introduction When considering construction projects, in many cases there are tasks related to their maintainability. Consideration should be given to assessing the importance of risk factors in terms of how they would affect maintainability. During the consideration of construction sites, it is necessary to strive to ensure that the number of measured parameters is minimized [1, 2], when sufficient information content in the building system under analysis will be ensured. To do this, you should rely on classification models of repair. The purpose of the work is to develop models and algorithms that allow classification by construction sites during the repair processes on them.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_19

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2 Analysis of the Significance of the Parameters of Construction Objects When Considering Their Maintainability In order to assess the degree of influence of the status parameters associated with the repair on the severity of the industry, we examined the relationship (pair correlation coefficients) between the change in the values of the analyzed indicators for construction projects requiring repair and the calculated value of “Points” (Table 1). There was a ranking of all indicators by the absolute value of the correlation coefficients. Evaluations of the significance of the maintainability status parameters are required to justify the choice of the optimal set of indicators that are applied to evaluate damage and determine the appropriate repair [3, 4]. Table 1. Assessment of the significance of risk factors by the degree of influence of maintainability. No

Name of the indicator

Correlation coefficient

Rank According to the correlation coefficient

Division “do not require repairs “−” requiring repair”

1

2

3

4

5

1

Number of years of building object

0.4164

1

2

2

The material from which the object is made

−0.209

4

11

3

Qualification of builders, %

0.2306

3

20

4

Built-up area

−0.191

5

38

5

Number of floors

0.1699

8

23

6

Type of building object—residential or non-residential

0.172

7

4

7

Power supply

0.3022

2

29–30

8

Soil under construction object

0.1899

6

5

9

Engineering communication

−0.167

9

19

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In the course of obtaining such estimates, we proposed the following approach: (1) using the Student’s t-test, the reliability of the difference in indicators among the compared groups of construction objects was assessed; (2) all indicators were ranked for each pair in the compared groups of construction objects based on the Student’s t-statistics module; (3) the calculation of the sum of ranks was carried out, which are obtained if three groups are compared: “Not requiring repair”, “Requiring repair”, “Repaired”. A ranking of all indicators was carried out in accordance with the fact that the amount received is decreasing; the obtained ranks demonstrate the significance of indicators in the course of solving the problem of determining the maintainability of objects; (4) the sum of the ranks was calculated, which are obtained by comparing four groups that correspond to the degree of destruction: “Initial repair”, “Repair of the 1st degree”, “Repair of the 2nd degree”, “Repair of the 3rd degree”. Ranking is carried out for all indicators in accordance with the fact that the amount received is decreasing; the calculated ranks demonstrate the significance of indicators in the course of solving the problem of assessing the required repair for construction projects [5, 6]. The calculation results are given in Table 1. Its analysis shows that, from which it can be seen that the assessment of maintainability is interconnected to the maximum extent with such indicators as the age of the object, the material from which the object was created, the qualifications of the builders (%), the built-up area, the number of floors, type of object—residential or non-residential, power supply, soil under the construction site, engineering communications [7, 8].

3 Application of the Method of Extreme Grouping When Choosing Indicators for Modeling Analysis of the processes associated with the repair is possible when classification procedures are used, which are based on the methods of cluster analysis. The number of parameters taken into account will affect the accuracy of models that are formed using statistical methods. The cost of computing resources will increase as the number of parameters grows. As an optimality criterion, the minimization of the number of measured parameters is considered under the condition of ensuring sufficient information content of the selected parametric system [9, 10]. In the course of research of objects of building systems, one can be convinced that when some integral factor changes, this will have a different effect on the measured characteristics. For example, in a primary set of p features, a partition can be found in a small (when compared with p) number of groups. Then the features that change will be associated with a particular group. In this case, one common factor comes into play [11, 12].

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The parameters that we place in one group should have a strong correlation, in different groups—a weak correlation. The formation of a random variable is carried out, which will correspond to the partition for each group of features. It will be considered as a determining factor that has a strong correlation with the parameters of the analyzed group [13]. Then we rely on an approach that uses factor analysis. It is required to provide extremization with respect to some functionals, which are heuristically defined. The extreme grouping of parameters is associated with partitions, which allow optimizing the functional J1 or J2 . The set of random variables x(1) , x(2) , ..., x(p) will be grouped in an extreme way by  the number of classes p in those cases when a set of subsets S1 , S2 , ...S p is found. This  set is connected by a series of numbers 1,2,:p, provided that ∪pl=1 Sl = {1, 2, ..., p}, also  Sl ∩ Sq = 0 for l = q and such p normalized factors f (1) , f (2) , ..., f (p ) , (corresponding (i) to the variance Df = 1). These factors lead to the fact that some optimality criterion will be maximized. Let us dwell on one of the algorithms for a specific optimality criterion. Functional J1 =

2 2   corr(x(i) , f (1) ) + ... + corr(x(i) , f p ) i∈S1

i∈S

p

(1)



is considered as the optimality criterion. In the course of modeling, corr(x, f ) is considered in the form of a paired correlation coefficient between feature x and factor f .  We believe that Ai = x(i) , i ∈ Sl , l = 1, 2, ..., p . The maximization of the functional J1 (both by splitting features A1 , ..., Ap into groups, and by choosing factors f (1) , f (2) , ..., f (p ) ) will show that the parameters will be split in such a way that a large correlation shows “close” features. Then, if the functional J1 , will be maximized, for each set of random variables, for the l-th group we observe signs that are strongly correlated with the value f (l) . In this case, the required set f (1) , f (2) , ..., f (p ) is chosen so that any of them, on average, is closest to all the features of its group. The optimal set of factors [14], f (1) , f (2) , ..., f (p ) if classes S1 , S2 , ...Sp are specified, is provided when there will be a maximization of each of the terms in the expression 

(i)

corr(x , f

(l)

2



) , (l =

1, p ),

i=S l

max

f (1) , f (2) , ...,f (l)

J1 =

p 

λ2l

(2)

l=1

When implementing modeling processes λl - the maximum eigenvalue of the matrix Rl . It is formed using the correlation coefficients of the variables that determine Al . The set of factors f (l) , l = 1, 2, ..., p , which is optimal, will be determined in the following way  i∈Sl

f (l) =  

i,j∈Sl

(l)

αi x(i) αi(l) αj(l) rij

l = 1, 2..., p .

(3)

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If modeling processes [15] are implemented, then rij = corr(x(i) , x(j) ), and α (l) = (l) (l) α2 ), ..., αml is an eigenvector of the matrix Rl , which is associated with the maximum eigenvalue λl , then Rl ∗ α (l) = λl ∗ α (l) . Also, based on known factors f (1) , f (2) , ..., f (p ) , there are possibilities for forming a partition S1 , S2 , ...Sp . It will (l) (α1 ,

give the maximum J1 when f (1) , f (2) , ..., f (p ) are specified. That is, the relation is true

 (4) Sl = i : corr 2 (x(i) , f (l ) ) ≥ corr 2 (x(i) , f (q) ) for all q = 1, 2, ...., p .

To ensure the maximum J1 , the fulfillment of (2) and (3) is required. The paper proposes an iterative algorithm for determining [16] the optimal partition S1 , S2 , ...Sp  and the optimal set of factors f (1) , f (2) , ..., f (p ) . Let at the γ -th iteration step, a partition of the parameters into groups A1 , ..., Ap . (l) For each such group of parameters, factors fγ are built according to the formula (2) and (γ +1) (γ +i) a new partition γ + 1 of the parameters A1 , ..., Ap in accordance with the rule: (γ +1)

the parameter x(i) belongs to the group Al

if

corr 2 (x(l) , fγ(l) ) ≥ corr 2 (x(l) , fγq ) (q = 1, 2, ..., p ).

(5)

If for some parameter x(i) there are two or more factors such that for x(i) and these factors in (4) is equal, then the parameter x(i) belongs to one of the corresponding groups arbitrarily. Obviously, at each iteration step, the functional J1 does not decrease, so this algorithm will converge to a maximum. The maximum may be local.

4 Formation of Classification Repair Models To solve the problem of assessing the maintainability of construction objects, it is proposed to use formalized models [17]. On their basis, it is possible to present different types of repairs in an understandable and accessible form—in our case, we divide the groups “Not requiring repair”, “Requiring repair”, “ Repaired “, and also distinguish among the objects requiring repair, the groups “Initial repair”, “Repair of the 1st degree”, “Repair of the 2nd degree”, “Repair of the 3rd degree” (Fig. 1). The formulation of the modeling problem has the following form. There is an initial set of building objects G=

N 

gn ,

(6)

n=1

During the simulation, we considered that N is the size of the initial sample. Each construction object is characterized on the basis of a set of indicators:

∀n : gn → Pn = Pn1 , Pn2 , ..., Pni , ..., PnI , (7) When modeling i = 1, I - the index of the indicator, n = 1, N - the serial number of the construction object.

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199

Fig. 1. Illustration of the scheme for assessing the maintainability of construction objects.

Then each of the building objects will be associated with a point in the feature hyperspace P i . Any of the elements gn in the set G is associated with a linguistic variable (type of repair). The construction of repair models consists in the fact that many construction objects are divided into homogeneous groups [18]. The description of the model of each group Mj j = 1, J is as follows:

(8) Mj = Zji , Lj , i = 1, I , j = 1, J , When modeling Zji - the value of the model parameters (parameter standard), Lj linguistic description of the model (type of repair). To solve this problem, we propose two approaches. The first uses direct processing of statistical information. The second uses a classification technique [19]. When statistical data processing is implemented, then the linguistic variable shows the classification criterion. The number of classes (J) corresponds to the number of building objects [20] possible for a given set (set G). In order to determine the parameters of the model, it is necessary to calculate: Lj —classification criterion for each of the groups; Zji =

1  i · Pn ,i = 1, I , j = 1, J , Nj ∀n∈

(9)

Gj

where Gj is the set of construction objects corresponding to the j-th group; Nj —the number of construction objects corresponding to the j-th set. This approach requires the implementation of many routine operations. Then, due to the fact that the parameters lj are estimated in a subjective way, there will be a noticeable probability of error when the initial set is partitioned into groups. In this case, there will be a possibility of inaccurate estimation of the parameters associated with the model. These shortcomings are not in the classification method, which is associated with cluster analysis. The implementation of classification approaches is due to the fact that

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the minimax criterion is used. The criterion that clustering is qualitative is determined by the requirements: (a) for groups, building objects must be closely related [21]; (b) building objects in different groups should be far from each other; (c) the distribution of building objects relative to groups must be uniform. It is required to specify a metric when considering cluster analysis, which shows how close construction objects will be during grouping. It is suggested to use indicators. If the indicators are quantitative, then linear distance is used dLab

=

I  i Pa − Pbi ,

(10)

i=1

euclidean distance. dEab

I  2 1/2  i i = , Pa − Pb

(11)

i=1

generalized Minkowski power distance.

dPab

I  p 1/p  i i = Pa − Pb

(12)

i=1

or Mahalanobis distance. i

i

i

i

T −1 dMij = (P˜ a − P˜ b ) W (P˜ a − P˜ b ),

(13)

i where Pa(b) —the value of the i-th indicator of the a(b)-th object, i = 1, I , a, b = 1, N , i P˜ a(b) —column vector of values of all indicators on a(b)-th object, W −1 —matrix inverse to covariance. If the indicators are qualitative, then the Hamming coefficient is proposed

μhab = Sab /I ,

(14)

During the modeling, Sab – the total number of matching property values (zero and singular: 1—the presence of the property, 0—the absence) is considered. Normalized data, which do not depend on the sample, are used in cases where the analysis has shown that there is no preference for a certain scale for the indicator. Adjustment for normalized values is carried out if there is a different significance in individual indicators P i (i = 1, I ). Expert assessments were used to determine the degree of significance wi (i = 1, I ). Its values correspond to the range [0,1]. We consider J to be the number of distinct values of a linguistic variable lj that is associated with the primary sample (considered as a set G). We consider J groups in the course of classification processes. The main stages of classification will be as follows:

Modeling of Construction Objects When Considering

1. Based on the selected metrics (7–11), the matrix of mutual distances S =

201



sij

i,j

(∀i, j = 1, N ) is calculated. Distances correspond to information messages gn ∈ G. 2. The process of selecting objects gk1 and gk2 , which correspond to the expression Sk1 k2 = max Sij (i, j = 1, N ), is carried out. ∀i,j

3. The set G is represented as a set of subsets Gk1 and Gk2 taking into account the fact that:  gi ∈ Gk1 , if Sik 1 < Sik 2 , (15) ∀i : gi ∈ Gk2 , if Sik 2 < Sik 1 4. Parameters of classes and are calculated as follows:  t Ptj Zji =

∀t j

Nj

, j = 1, 2,

(16)

During the simulation, it is considered that tj - the set of objects of the construction sphere, which corresponds to the j-th class, Nj - the number of objects of the construction sphere, which correspond to the j-th class. 5. The calculation of the vector of total distances S = {S1 , S2 , ..., Sn , ..., SN } is carried out, which corresponds to each object gn ∈ G to the points mj that correspond to the parameters Zji , j = 1, c − 1, (c -1 is considered as the number of classes during the simulation). 6. The construction object gkc corresponding to the expression skc = max Si , i = 1, N ∀i

will be selected during the simulation. 7. The set G is partitioned into subsets Gkj (j = 1, c) according to the rule (Sik j is the distance from the object gi to the point mj ). 8. Based on expression (12), an estimate Zji (j = 1, c) is made. 9. Steps 5–8 are performed until the logical expression c ≥ J becomes true. As a result of the classification, we obtain repair models of type (9), the parameters of which are calculated as follows: Lj —set by the expert for each group; Zji —is determined by the formula (12). The criterion of adequacy (A) of the obtained models is the percentage of patients from the set G with a diagnosis, in groups with the same value of the linguistic description of the model Lj : N 100  an , · A= N

(17)

n=1

where

 an =

1, if ln = Lj ∀ ln ∈ Gj 0, if ln = Lj ∀ ln ∈ Gj

, j = 1, J .

(18)

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At the first stage, the necessary set of indicators corresponding to the problem being solved is taken:

(19) X = qx1 , qx2 , ..., qxi , ..., qxI , where qxi is the value of the i-th parameter for patient X. To correlate the building object with the model j mj , the expression is used: ⎧ ⎨ mj | rxj = max rxj ∀j , (20) X → ⎩ 0 | rxj ≤ r0 In the course of modeling—shows how the building object X corresponds with the model; r0 is the lower limit of this indicator. The evaluation rxj is carried out in the following way: rxj = 1 −

dxj , J  dxj

(21)

j=1

Calculation of dxj is carried out using the selected expression (10)–(16).

5 Results After confirming the chosen alternative, the set of indicators X and the corresponding alternative are included in the sets G and L in order to carry out the learning processes of the system. Models (6) are adjusted due to the fact that the parameters Zji will be updated taking into account the indicators of the building object gx . The resulting standards of parameters of formalized disease models are given in Table 2. The results of the classification can be used to determine the condition of building objects. The determination of the minimum acceptable degree of similarity, at which the classification is made, was determined based on the histograms of the distribution of the degree of similarity of construction objects from the training sample. The results are shown in Table 3. In the case when a building object cannot be attributed to any of the models, the final decision must be made by the doctor himself based on an analysis of the degree of similarity of the object with each of the models. The constructed models were tested using the appropriate sample. It examined the presented 12 construction sites that did not require repairs and 53 construction sites that require repairs at the age of 15 to 35 years.

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203

Table 2. Standards of parameters of repair models. Parameter name

Model name Initial repair

Repair of the 1st degree

Repair of the 2nd degree

Repair of the 3rd degree

Number of years of building object

0.42

0.44

0.49

0.53

The material from which the object is made

36.22

41.13

40.41

42.63

Qualification of builders, %

14.71

17.25

15.67

16.61

7.86

9.05

8.92

10.36

Number of floors

64.78

60.63

65.46

53.62

Type of building object—residential or non-residential

18.56

25.33

20.26

22.01

Power supply

241.23

275.56

265.95

246.26

Soil under construction object

329.44

366.88

360.12

364.63

70.0

100.0

90.0

90.0

Built-up area

Engineering communication

Table 3. Minimum acceptable degree of similarity by models. Model name

Value of r0

Valuation models Not requiring repair

0.87

Requiring repair

0.82

Repaired

0.76

Models for assessing the type of repair Initial repair

0.75

Repair of the 1st degree

0.84

Repair of the 2nd degree

0.81

Repair of the 3rd degree

0.78

Based on the results obtained, the performance of the generated models was confirmed. The accuracy of the forecast according to the characteristics of the repair was 89.7%.

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6 Conclusion The paper deals with the problems of modeling construction objects in the course of repair processes. An integrated approach based on a combination of optimization methods, classification, statistical analysis has been developed. Classification models of repair are formed, their efficiency is demonstrated.

References 1. Odu G (2013) Review of multi-criteria optimization methods—theory and applications. IOSR J Eng 3(10):01–14 2. Sorokin SO (2018) Optimization modeling of the functioning of the system of homogeneous objects in a multidimensional digital environment. Model, Optimiz Inf Technol 6(3):153–164 3. Orlova D (2018) Stability of solutions in ensuring the functioning of organizational and technical systems. Model, Optimiz Inf Technol 6(1):325–336 4. Lvovich I, Preobrazhenskiy A, Lvovich Y, Choporov O (2021) Modeling and optimization of processing large data arrays in information systems. In: Proceedings of ITNT 2021—7th IEEE international conference on information technology and nanotechnology, vol 7, p 9649229 5. Liu C, Fan J, Branch J, Leung K (2014) Toward QoI and energy-efficiency in Internet-ofThings sensory environments. IEEE Trans Emerg Top Comput 2(4):473–487 6. Shah A and Ghahramani Z (2015) Parallel predictive entropy search for batch global optimization of expensive objective functions. Adv Neural Inf Process Syst 3330–3338 7. Neittaanmäki P, Repin S, Tuovinen T (eds) (2016) Mathematical modeling and optimization of complex structures; series: computational methods in applied sciences. Springer International Publishing AG Switzerland 8. Sokolov AA, Tyukov AP, Shcherbakov MV, Yanovskiy TA (2019) Multi-level architecture of the intellectual support system for management decisions in resource supporting systems of industrial productions. Model, Optimiz Inf Technol 7(1). https://doi.org/10.26102/23106018/2019.24.1.027 9. Salnikov VV, Frantsuzova YuV (2019) Energy analysis of control programs for multi-purpose machines. Model, Optimiz Inf Technol 7(2). https://doi.org/10.26102/2310-6018/2019.25. 2.019 10. Lopota AV, Tsyrkov AV, Tsyrkov GA (2017) Methods and tools of project-operational management of an machine-building enterprise. In: Proceedings of the 2017 international conference quality management, transport and information security, information technologies (IT&QM&IS). IEEE, pp 536–539 11. Groefsema H, Beest NRTP (2015) Design-time compliance of service compositions in dynamic service environments. In: International conference on service oriented computing and applications, pp 108–115 12. Tsyrkov AV, Tsyrkov GA (2017) Intelligent components to support workflow in the design and production activities. In: Proceedings of the 2017 international conference quality management, transport and information security, information technology (IT&QM&IS), pp 764–768 13. Rios LM, Sahinidis NV (2013) Derivative-free optimization: a review of algorithms and comparison of software implementations. J Global Optim 54:1247–1293 14. Talluri S, Kim MK, Schoenherr T (2013) The relationship between operating efficiency and service quality: are they compatible? Int J Prod Res 51:548–2567 15. Tal D, Altschuld J (eds) (2021) Working with 3D models. In Drone technology in architecture, engineering and construction. Wiley & Sons Ltd

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16. Santoši Ž, Budak I, Šokac M, Pavleti´c D (2019) Bridging the symmetry-related gap between physical and digital sculpting by application of reverse engineering modeling. FME Trans 47:304–309 17. Lvovich IYa, Lvovich YaE, Preobrazhenskiy AP, Preobrazhenskiy YuP, Choporov ON (2019) Modelling of information systems with increased efficiency with application of optimizationexpert evaluation. J Phys: Conf Ser Krasnoyarsk Sci Tech City Hall Russ Union Sci Eng Assoc 33079 18. Dorofeyuk AA (2009) Expert-classification analysis methodology in control and complex data processing problems (history and future prospects). Contr Sci 3(1):19–28 19. Veiga MR (2005) Characteristics of repair mortars for historicbuildings concerning water behaviour. Quantification and requirements. In: International workshop Repair mortars for Historic Masonry, RILEM, Delft, 26–28 de Janeiro 20. Wang T, Xu D, Elsworth D, Zhou W (2016) Distinct element modelling of strength variation in jointed rock masses under uniaxial compression. Geomech Geophys Geo Energ Geo Resour 2(1):11–24. https://doi.org/10.1007/s40948-015-0018-7 21. Li L, Liang WG, Lian HJ, Yang JF, Dusseault MB (2018) Compressed air energy storage: characteristics, basic principles, and geological considerations. Adv GeoEnergy Res 2(2):135–147

Static Three-Point Bending Tests on 3D Printed Multilayer Composite Plates I. A. Solovev1 , M. V. Shitikova1,2(B) , and A. V. Mazaev1 1 Voronezh State Technical University, 84, 20-Letiya Oktyabrya Street, Voronezh 394006,

Russia [email protected] 2 Moscow State University of Civil Engineering, 26, Yaroslavskoye Shosse, Moscow 129337, Russia

Abstract. The article presents the results of static tests for three-point bending of composite three-layer plates with continuous outer layers and tetrachiral honeycomb core. The plates were made using 3D printing (stereolithographic printing), and the procedure of laboratory additive manufacturing has been described in detail. Four series of samples were tested, varying in the discretization (number of elementary cells) of the filler. Samples within the series differ in the thickness of tetrachiral honeycombs, but the volume of their solid body is the same. As a result of the tests, graphs of the displacement dependence of the load were obtained. It has been shown that the thickness of the honeycomb core significantly affects the strength of the composites, despite the decrease in the thickness of the ribs of the honeycomb core, namely: the thicker the sample, the greater the bending strength it has, even with the decrease in the thickness of the walls of the honeycomb core ribs. Keywords: Stereolithographic printing · Tetrachiral honeycombs · Composite plates · Static testing

1 Introduction In recent years, researchers in many fields of science and technology are paying great attention to auxetics (material with a negative Poisson’s ratio) [1–3]. These materials have an unusual deformation mechanism: they expand in the direction perpendicular to the application of force when stretched, and similarly contract when compressed. The existence of natural materials with these properties has long been known [4–8], but the study and creation of artificial materials with auxetic properties was almost impossible due to the difficulty of reproduction. Nowadays when 3D printing technologies have been widely developed, the creation of a synthetic auxetic is no longer difficult. Today the attention of materials scientists is attracted by the methods for improving the performance characteristics of traditional materials by creating structures with significantly nonlinear and anomalous deformation properties, up to obtaining an adaptive © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_20

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mechanical response of materials to external influences. These materials include auxetics. Compared to classical materials, auxetic materials have a number of advantages: increased energy absorption, increased resistance to crack formation and crack opening, and better indentation resistance. The improvement of these advantageous properties in the material is of constant interest to manufacturers of various structures. Often these mechanical properties are found in composites. This paper discusses methods for studying composite plates, the materials from which they are made of, the technology for manufacturing, and conducting an experiment on three-point bending of composite plates. Thus, Arbaoui et al. [9] considered the effect of core thickness and the number of core layers on the mechanical properties of a multilayer honeycomb core sandwich structure and cladding under three-point bending. According to the experimental results, which are consistent with numerical calculations, it was concluded that the mechanical properties of multilayer plates (in particular, the shear modulus) increase with the increase in number of filler layers and decrease with the increase in thickness of the honeycomb core. Usta et al. [10] investigated low-velocity impact on composite sandwich panels with various types of auxetic and non-auxetic prismatic core structures. For the manufacture of the auxetic core, 3D printing technologies were used. According to the results of the tests on dropping the striker on the samples, they concluded that composites with an auxetic layer have a higher impact resistance than non-auxetic fillers. Composites with auxetics can better absorb energy and resist indentation more strongly. This means that an impact with more energy is required to destroy the material. Hou et al. [11] conducted a comparative study of the reliability of composites with auxetic and non-auxetic fillers. The sample in question consists of two outer solid sheets and a 3D printed polymer core. According to the results of the study, they concluded that a layer with a negative Poisson’s ratio gives composites greater reliability and durability. Moreover, during repeated impacts on the composite, a stable behavior of plates with auxetic filler was revealed. Smardzewski et al. [12] considered compression and low-velocity impact responce of wood-based sandwich panels. The cladding sheets are made of fibreboard and the auxetic lattice core is 3D printed using biocomposite fiber. Based on the results obtained, they concluded that depending on the tasks, it is required to adjust the angles of inclination of the ribs of the lattice filler: for example, for better compression resistance, 65° angle of inclination of the ribs is required, while for maximum energy absorption it should be 30°. The possibility of developing options to eliminate the shortcomings of auxetic structures, namely, relatively low rigidity and stability, was studied in [13]. To solve this problem, they proposed to fill the auxetic frames with soft materials. The chiral-type auxetic framework was fabricated using 3D printing technologies. The samples were tested under quasi-static compression. According to the results of the research, it was concluded that the filling foam could reduce auxeticity, while significantly increase the rigidity of the material. The bending behavior and free vibrations of a rectangular multilayer plate with an auxetic honeycomb core were studied in [14]. The plate is a rectangular structure of two thin solid slabs and a honeycomb core with a hexagonal hourglass unit cell. In [14], only

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numerical studies were carried out, in so doing plates with different angles of inclination of the side edge of the cell relative to the vertical were considered. It has been shown that the tilt angle of the unit cell of auxetic honeycombs has a significant effect on the natural frequency. Brischetto et al. [15] presented the results of the development of simple and inexpensive polymeric multilayer plates using a home desktop 3D printer and evaluated their bending properties. The focus was on a single material configuration, in which both the inner honeycomb core and the outer shell are made from PLA using a single extruder. Five samples were tested, four of which showed identical results, except for one, since the bottom surface of the sample was chosen as the load application surface, in contrast to the other four, while prestressing was created due to the heat generated by the printed floor. Anil Kumar et al. [16] investigated the influence of the unit cell size of a regular hexagonal honeycomb core, as well as the influence of the width of a three-layer multilayer composite on the stiffness characteristics of the composite plate. The honeycomb structure is made of Kevlar, the outer layers are made of carbon fiber. Numerical calculations were made using ANSYS and a series of three-point bending tests were carried out. Based on the results, it has been observed that the cell size of the honeycomb core does not significantly affect the stiffness properties of the composite sandwich panel. The analysis also showed that as the panel width increases, the rigidity of the composite panel increases significantly. The results obtained in [16] are in good agreement with the studies carried out in [17], wherein numerical models of composite plates with two full-bodied front plates and a honeycomb core were developed. Honeycomb structures with different degrees of discretization (unit cell size) were considered. According to the calculations, structures with lower discreteness show higher strength compared to structures with higher discreteness. In so doing, with the increase in the relative density of honeycombs from 14 to 71%, the difference between the maximum stresses in cells with different discreteness has a pronounced area of increase and subsequent decline. The influence of the thickness of the auxetic filler and the characteristics of the material of the front layer of the composite on the stiffness characteristics of the material, as well as on its ability to absorb energy, was studied in [18]. Various wood-based materials were considered as the front material. Materials were tested under three-point bending. Experimental studies have shown a significant effect of the type of wood composites used as facings on the stiffness and strength of beams with auxetic filler. Mazaev and Shitikova [19] performed a numerical analysis of the strength of layered composite plates with continuous outer layers and a tetrachiral honeycomb interlayer under static bending. Aluminum alloy was chosen as the plate material. For honeycomb layers, discretization (number of unit cells) and relative density varied at a constant thickness. Calculations were carried out with rigid clamping of the ends and three-point bending in the framework of the theory of elasticity by the finite element method. The strength analysis has provided the load magnitudes at which the maximum stresses were equated to the conditional elastic limit of the material. The results of numerical calculations have shown that tetrachiral honeycombs with a relative density of honeycomb cores from 20 to 70% have a significantly higher strength in relation to solid slabs with

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an equal volume of a solid body. Honeycombs with a larger unit cell are stronger than honeycombs with a smaller unit cell at the same relative density. Based on the brief review above, it could be concluded that the study of composite plates is an actual topic. The aim of this work is to evaluate the strength characteristics of three-layer composite plates, in which the middle layer is a cellular structure of the tetrachiral type exhibiting auxetic properties. In so doing, the created composite samples were divided into 4 series, differing in the degree of discretization. Within each series, the plates differ from each other in the thickness of the walls and the thickness of the cellular filler by maintaining a constant volume of the solid body of honeycomb filler.

2 Sandwich Production with LFS Technology and Test Unit We have carried out the studies for four series of composite plates, each of which contains nine samples. Series of samples differ from each other in unit cell sizes. The following d a parameters were taken for analysis: 1.0, 1.3, 1.6, and 1.9 mm. Within the series, the honeycomb thickness t cl varies from 0.7 to 3.58 mm. Figure 1 shows a view of a honeycomb structure of the tetrachiral type.

Fig. 1. Honeycomb structure of tetrachiral type.

For manufacturing the samples, 36 3D models of the honeycomb structure (for each discretization and wall thickness) and a model of the front plate have been developed. Creating samples includes the following steps: 1. 2. 3. 4.

Printing honeycomb core and faceplates on a 3D printer; Cleaning of printed elements in an ultrasonic bath; Pre-curing in an ultraviolet chamber; Bringing the honeycomb filler to the required dimensions and evenness of the surface by grinding; 5. Cleaning of polished elements from dust; 6. Applying an adhesive to the faceplates; 7. Gluing the elements into a single sample in an ultraviolet chamber. Let us consider the steps in more detail.

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1. The elements were printed using a Formlabs Form 3 3D printer with LFS (Low Force Stereolithography) printing technology. This printer completely immerses the print platform in resin, and then, using a laser, cures the specified elements in layers. The cellular filler on the platform is positioned such that excess resin does not accumulate in the holes and could be freely cleaned after the platform is lifted from the resin. The faceplates were arranged in such a way that the layers were parallel to the long side. For the manufacturing these samples, the thickness of the curing layer was 100 μm. Figure 2a shows the printer in use.

Fig. 2. Stages of manufacturing the composites: a the Formlabs Form 3 3D printer; b the ultrasonic bath for washing in isopropyl alcohol; c the ultraviolet chamber with the samples; d the process of mechanical refinement of the elements using sandpaper.

2. When the printer finishes, the elements are removed from the resin. Since they were completely submerged, washing the samples with isopropyl alcohol in an ultrasonic bath is required to get rid of resin residue. Isopropyl alcohol corrodes uncured resin, and ultrasound helps speed up and improve the process. To obtain clean samples, it

Static Three-Point Bending Tests on 3D Printed Multilayer

3.

4.

5.

6.

7.

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is required to keep the elements in the bath for 5 min. Figure 2b shows the structure cleaning process. After receiving clean elements, we place them into an ultraviolet chamber. When printed, the elements do not gain strength characteristics, and to obtain the required values, the elements are additionally cured. The required time under UV light is ten minutes. This process is carried out in several stages; at the beginning after washing, to simplify machining, and at the end when gluing the elements into a single sample. To obtain the required characteristics, in addition to the ultraviolet exposure itself, the application of pressure on the samples to align them is also required. Since the test specimens are small enough, their geometry may change from a slight heating or physical impact. In order not to lose a certain required structure, during curing, the samples are clamped between two quartz glasses, and a weight of 1 kg is placed on top. In this case, the load is positioned so as not to block ultraviolet radiation. Figure 2c shows an ultraviolet chamber with the samples. We use transparent resin to make samples. In this regard, when printing the first layers of elements, part of the laser radiation goes beyond the boundaries of the required element, and resin flows are formed on them. So some mechanical refinement of the samples is required before their further study. To do this, first we use sandpaper with a fraction of 240 to remove large irregularities, and then a fraction of 1000 to complete smoothness in order to ensure the maximum contact area of the surfaces during subsequent gluing. Figure 2d shows the process of finishing the elements. After the samples have been refined, they need to be washed again, as dust and pieces of sandpaper settle and get stuck in the narrow places of the structure. This stage completely repeats all the actions performed during stage 2. Upon completion of all preparatory stages, we proceed to the assembly of the composites. To do this, we apply a thin even layer of resin to the front solid plates using a brush. After that, all three components of the composite are assembled and carefully laid on quartz glass, preventing the layers from moving from each other. The last step in creating the plates is to cure the samples between the quartz glasses under the pressure of the load, as in point 3. The composites are in the chamber for 5 min. During this time, the elements still gain strength, and the resin, which acts as a link between the elements, hardens to the required strength due to the thinness of this layer. Since in each series all samples differ from each other in the thickness of the honeycomb core, only three samples are cured at the same time: one sample from each series with the same honeycomb thickness of the honeycomb core, since they have the same dimensions. For the curing of the samples of the fourth series, additional elements with the required thickness are made so that the curing process of all samples took place under the same conditions. Figure 3 shows the composites of series 1.6.

3 Test Unit The test was carried out in partial compliance with the procedure illustrated in ASTM D790 [20]. The thickness and width of each sample were measured; the collected results

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Fig. 3. a Composites of series 1.6: top view; b Composites of series 1.6: end view.

are necessary to verify the performance of the process and to obtain geometric characteristics for calculating mechanical properties. Also, each sample was weighed to control the amount of solid. Table 1 shows the masses of each sample. After evaluating the geometric characteristics, it was possible to conduct an experiment. Each test specimen was placed horizontally on two supports. Figure 4 shows an example for a sample during testing. The load was given by a punch, which is symmetrically located between two supports and acts on the upper surface of the composite. The deflection of the sample at the stage of loading was measured using information obtained from the position of the traverse. The movement of the punch was set using a constant strain rate of 8 mm/min. The supports are metal cylinders with the diameter of 10 mm, and the punch has the diameter of 4 mm.

4 Preliminary Test Results and Mechanical Behavior of Multilayer Samples Figure 5 shows the raw load–deflection curves for all series of the samples. As a result of the tests, the bending strength and data for determining the modulus of elasticity were obtained. Bending strength is defined as the maximum value of the bending stress that the specimen could withstand. The modulus of elasticity indicates the resistance

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Table 1. Mass of the samples, g. Honeycomb thickness, mm

Sample series d a = 1.0 mm

d a = 1.3 mm

d a = 1.6 mm

d a = 1.9 mm

3.58

1.96

1.83

1.60

1.45

2.37

1.55

1.46

1.38

1.32

1.77

1.41

1.34

1.36

1.29

1.42

1.36

1.33

1.35

1.34

1.18

1.36

1.32

1.33

1.27

1.01

1.30

1.35

1.28

1.33

0.88

1.35

1.35

1.30

1.35

0.78

1.32

1.28

1.35

1.27

0.70

1.33

1.36

1.34

1.34

Fig. 4. View of the three-point bend test unit.

of a material to deformation under the load. Graphically, it indicates the slope of the stress–strain curve at a certain stress level. As expected, all samples initially exhibited Hookeian behavior; in this part of the graph, the trend of the stress–strain curve is almost linear. Table 2 presents the bending strength of all samples.

5 Conclusion In this work, four series of composite plates with an auxetic filler of the tetrachiral type were manufactured. Series of samples differ from each other in unit cell sizes. The following d a parameters were taken for analysis: 1.0, 1.3, 1.6, and 1.9 mm. Within the series, the honeycomb thickness t cl varies from 0.7 to 3.58 mm. They were tested for static three-point bending to study the effect of discretization and wall thickness of honeycomb ribs on the strength characteristics of the plates at a constant solid volume.

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Fig. 5. Raw load–deflection curves: a the samples of series 1.0.; b the samples of series 1.3.; c the samples of series 1.6.; d the samples of series 1.9.

Table 2. Ultimate bending strength, MPa. Sample no

Honeycomb thickness, mm

Sample series d a = 1.0 mm

d a = 1.3 mm

d a = 1.6 mm

d a = 1.9 mm

1

3.58

175.73

140.17

117.01

113.37

2

2.37

103.45

89.76

88.75

81.00

3

1.77

84.99

68.52

79.26

77.97

4

1.42

69.58

62.91

60.88

74.39

5

1.18

64.99

63.83

69.77

59.30

6

1.01

41.31

48.12

43.79

40.13

7

0.88

50.15

50.28

51.50

56.17

8

0.78

37.30

39.92

51.95

42.86

9

0.70

38.47

42.45

44.85

46.23

Having studied the test graphs in Fig. 5, the following conclusion could be drawn: the thicker the sample, the greater the bending strength it has, even with the decrease in the thickness of the honeycomb core walls. At the same time, in previous studies presented

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in [17], it was shown that the larger the solid body, and consequently the thicker the filler walls, the stronger the composite. Acknowledgements. The work was supported by the Ministry of Science and Higher Education of the Russian Federation, Project no. FZGM-2020-0007. The research was carried out using the facilities of the Center for Collective Use named after Professor Yu.M. Borisov, Voronezh State Technical University, which was recently retrofitted with the support from the Ministry of Science and Higher Education of the Russian Federation, Contract no. 075-15-2021-662.

References 1. Mazaev AV, Ajeneza O, Shitikova MV (2020) Auxetics materials: classification, mechanical properties and applications. IOP Conf Ser: Mater Sci Eng 747. https://doi.org/10.1088/1757899X/747/1/012008 2. Saxena KK, Das R, Calius EP (2016) Three decades of auxetics research—materials with negative Poisson’s ratio: a review. Adv Eng Mater 18:1847–1870. https://doi.org/10.1002/ adem.201600053 3. Ren X, Das R, Tran P, Ngo TD, Xie YM (2018) Auxetic metamaterials and structures: a review. Smart Mater Struct 27(2):023001. https://doi.org/10.1088/1361-665X/aaa61c 4. Rossow WB, Whitehead JA, Covey C, Walterscheid RL (1992) Elasticity of α-cristobalite: a silicon dioxide with a negative Poisson’s ratio. Science 257:650–652. https://doi.org/10. 1126/science.257.5070.650 5. Love AEH (2013) A treatise on the mathematical theory of elasticity. Cambridge University Press, Cambridge 6. Williams JL, Lewis JL (1982) Properties and an anisotropic model of cancellous bone from the proximal tibial epiphysis. J Biomech Eng 104:50–56. https://doi.org/10.1115/1.3138303 7. Veronda DR, Westmann RA (1970) Mechanical characterization of skin-finite deformations. J Biomech 3:111–124. https://doi.org/10.1016/0021-9290(70)90055-2 8. Frolich LM, LaBarbera M, Stevens WP (1994) Poisson’s ratio of a crossed fibre sheath: the skin of aquatic salamanders. J Zool 232:231–252. https://doi.org/10.1111/j.1469-7998.1994. tb01571.x 9. Arbaoui J, Schmitt Y, Pierrot JL, Royer FX (2014) Effect of core thickness and intermediate layers on mechanical properties of polypropylene honeycomb multi-layer sandwich structures. Arch Metall Mater 1:59. https://doi.org/10.2478/amm-2014-0002 10. Usta F, Türkmen HS, Scarpa F (2021) Low-velocity impact resistance of composite sandwich panels with various types of auxetic and non-auxetic core structures. Thin-Walled Struct 163:107738. https://doi.org/10.1016/j.tws.2021.107738 11. Hou S, Li T, Jia Z, Wang L (2018) Mechanical properties of sandwich composites with 3dprinted auxetic and non-auxetic lattice cores under low velocity impact. Mater Des 160:1305– 1321. https://doi.org/10.1016/j.matdes.2018.11.002 12. Smardzewski J, Maslej M, Wojciechowski KW (2021) Compression and low velocity impact response of wood-based sandwich panels with auxetic lattice core. Eur J Wood Prod 79(4):797–810. https://doi.org/10.1007/s00107-021-01677-3 13. Zhang XG, Ren X, Jiang W, Zhang XY, Luo C, Zhang Y, Xie YM (2022) A novel auxetic chiral lattice composite: Experimental and numerical study. Comp Struct 282:115043. https:// doi.org/10.1016/j.compstruct.2021.115043

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14. Thang NT, Van Long N, Tu TM, Nam NH (2022) Navier solution for static and free vibration analysis of sandwich plate with auxetic honeycomb core resting on Pasternak elastic foundation. J Sci Tech Civil Eng (STCE)-HUCE. https://stce.huce.edu.vn/index.php/en/article/ view/2297 15. Brischetto S, Ferro CG, Torre R, Maggiore P (2018) 3D FDM production and mechanical behavior of polymeric sandwich specimens embedding classical and honeycomb cores. Curved Layer Struct 5(1):80–94. https://doi.org/10.1515/cls-2018-0007 16. Kumar A, Angra S, Chanda AK (2021) Analysis of effect of variation of honeycomb core cell size and sandwich panel width on the stiffness of a sandwich structure. Res Eng Struct Mater 8(1):45–56. https://doi.org/10.17515/resm2021.308me0606 17. Mazaev AV, Shitikova MV (2021) Numerical analysis of the stressed state of composite plates with a core layer made of tetrachiral honeycombs under static bending. Comp Part C: Open Access 6:100217. https://doi.org/10.1016/j.jcomc.2021.100217 18. Peli´nski K, Smardzewski J (2020) Bending behavior of lightweight wood-based sandwich beams with auxetic cellular core. Polymers 12(8):1723. https://doi.org/10.3390/polym1208 1723 19. Mazaev AV, Shitikova MV (2021) Static bending strength of sandwich composite plates with tetrachiral honeycombs. Int J Comput Civil Struct Eng 17(3):102–113. https://doi.org/10. 22337/2587-9618-2021-17-3-102-113 20. ASTM, I (2007) Standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials. ASTM D790-07

Stress–Strain Properties of Concrete at Early Freezing R. T. Brzhanov(B) , M. K. Suimenova, G. I. Esbolay, K. M. Shaikhieyva, and B. S. Akmurzaeva Non-commercial Joint Stock Company Caspian University of Technology and Engineering named after Sh. Yessenov, 32 Microdistrict, Aktau City, Republic of Kazakhstan [email protected]

Abstract. Studies show that the influence of negative temperatures is manifested both in the strengthening of the concrete structure and in its destruction. The destruction of concrete is associated primarily with the formation of ice in the pores. The resulting forces act destructively on the concrete structure if it does not have a certain strength. Strengthening of concrete occurs due to microcracks, a decrease in the concentration of tensile stresses at the mouths of cracks. Thus, it has been established that concrete, due to the presence of a liquid phase, continues to harden even at negative temperatures, but the quantitative side of this phenomenon has not been studied enough. The article provides an analysis of temperature deformations and changes in the structure of concrete during freezing, which depend on the resulting action of two groups of mutually opposite forces—freezing forces at the phase boundaries and internal pressure forces of the formed ice that violate the internal connection of concrete components. In this article, the products formed during the hydration of silicate minerals at low positive and negative temperatures are also considered, which differ markedly in their composition from those arising under normal conditions. Keywords: Structure of concrete · Deformation of concrete · Intensity of loading · Cement hydration · Thermodynamic properties

1 Introduction The properties of concrete, which is a complex system, are largely determined by its structure. The structure of concrete is constantly changing when concrete is hardened under the influence of physical, physical–chemical, mechanical influences. Since hydration processes intensify when the temperature of the medium increases, it weakens when it falls. The mechanical path is based on the compaction of concrete and the change in its structure from external forces applied at various stages of hardening. At the same time, the degree of hydration is strongly influenced by the concrete storage conditions, as due to the significant loss of moisture in the frost, there is a decrease in the final strength of the concrete. The phase composition of neoplasms in frozen concrete does not differ from conventional concrete, irreversible structural changes are caused only by © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_21

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early freezing. With an increase in the period of concrete curing at positive temperatures, structural changes appear to a lesser extent, there is no decrease in strength. Studies also show that the influence of negative temperatures is manifested both in the hardening of the concrete structure and its destruction. The destruction of concrete is associated primarily with the formation of ice in the pores. The resulting forces are destructive of the concrete structure if it does not have a certain strength. Concrete hardening occurs due to microfractures, reducing the concentration of tensile stresses in the mouth cracks. Thus, it is established that concrete, due to the presence of liquid phase, continues to harden and at negative temperatures, but the quantitative side of this phenomenon is not sufficiently known. A complex indicator of the resistance of concrete to various types of impacts is its deformable properties. Deformations of concrete are divided into two types: power (external) and proper (temperature-shrink). Complete deformations of concrete consist of elastic and plastic, which in turn arise first at concrete loading and second, arising at prolonged action of load, shrinkage and temperature. Among [1] these deformations, the most interesting are the creep of concrete and temperature deformations.

2 Relevance of the Article When concrete is frozen [2] at an early age, its deformability increases. The relative deformations of the frozen creep immediately after preparation are 15–20 times higher than the deformations of concrete with graded strength. When the temperature drops below zero, the sample at the beginning decreases in volume, then lengthens and after a certain time its dimensions stabilize. The initial decrease is due to increased water density, compression of solids and loss of moisture. Due to the decrease in the rate of cement hydration, water is in a disjoint state before turning to ice, so the intensity of its evaporation increases. Expansion (lengthening) of freshly prepared concrete is a consequence of the transition of water into ice. When the concrete thaws, there is a slight increase in its size, and at the moment of melting ice shrinks. The amount of deformation depends significantly on the time of preconditioning of concrete. Early loading brings a certain change in the tensile state of the structures, as in the case of plastic deformation of concrete there is a relaxation of stresses and their redistribution in the concrete. The influence of this type of load is manifested in the change of the mutual arrangement of cement particles in concrete, increasing the adhesion of cement stone with aggregate, mechanical modification of the structure, selfhealing of cracks. All of these factors work together and manifest themselves in a kind of deformed concrete behavior: the weakening caused by the stress of microfractures and the hardening caused by the increase in density and the change in the concrete structure. With axial compression, the density of concrete increases over time, but the intensity of the process decreases. The strength of concrete increases faster than the density and the hardening curve rises until the maximum transverse deformation reaches the limit. If under compression it is quite natural to compact concrete under load, then at a stretch, it would seem to be possible to expect a decrease in the density of concrete and particle separation at their contact points. However, when stretched along with longitudinal, transverse deformations occur, which at a certain intensity of loading cause cement

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stone to be compacted in this direction as well. The creep of concrete also leads to the relaxation of stresses and the extinguishing of the harmful action of shrinkage stresses. The important thing is the re-orientation of the particles, by changing the shape of the micro-defects [3]. The increase in strength depends on the time and intensity of the load. The greatest increases in strength are observed at an intensity of 0.3–0.4 from the grade strength of concrete at the time of loading. Increased strength at early loading is obtained for a tensile compression state of 20–40%, a tensile state of 30–70%, a bending state of 25–55% of the grade strength of concrete. It has also been established that in dynamic loading, the hardening effect is higher the earlier loading age, and the optimal time for concrete loading is the period between the beginning and the end of the clawing. At the same time, not all researchers have a clear assessment of the impact of early loading. Some authors show that such effects are particularly effective in low-strength concrete, while others show that the degree of hardening of concrete increases with the consumption of cement.

3 Objective of the Job Early freezing of concrete may not cause destructive processes, even though increase its strength if all the water in the cement gel is in a bound state. This state means the end of the induction period of cement hydration, since at this time the liquid phase is intensely saturated and bound by dissociated ions. This is accompanied by the formation of embryos of the crystalline cement stone structure. The freezing of the liquid phase immediately after the end of the induction period is accompanied by the transition of a part of the connected water into free water, turning it into ice. The less water is contained in the cement gel before freezing, the faster the saturation and significant increase in the strength of the concrete after thawing. Theoretical study of influence on deformation properties of concrete.

4 Theoretical Part Comprehensive coverage of the negative temperature effect on the properties of the concrete structure at its early freezing is reflected in the work [4, 5]. Thus, in these studies 17 regularities of liquid phase content in cement gel were established, as well as a set of strength of cement at negative temperatures. The properties of thin water films and changes in their physical properties are shown in [6, 7]. Such water freezes at negative temperatures, and being in a liquid state can react with the minerals of cement. As a result, gradually slowing down, the hydration process of C3S, C3A and C4AF is observed at a temperature of 90–15 °C, aβC2S to—10 °C [8, 9]. At the same time, the products produced by hydration of silicate minerals at low positive and negative temperatures differ markedly in their composition from those produced under normal conditions. However, the influence of temperature is noticeable on the size of the crystals. As the temperature decreases, the size of the crystals of calcium hydrosilicate decreases, and Ca(OH)2 increases. As the CSH (II) crystals decrease, the specific surface of the hydrosilicate increases. Water transition from liquid to solid does not occur immediately at zero degrees. This is facilitated by the water-soluble compounds in the cement reducing

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the freezing temperature of the liquid phase of the concrete, as in other porous materials, part of the water in the liquid state at temperatures up to minus 90–75 °C [10, 11]and in some fine soils—even at temperatures up to minus 90–190 °C [12]. Hydration and heating of cement, as well as hardening of concrete in the cold, are treated differently by various researchers. So some researchers consider electrical forces of attraction; that act at very close distances from the surface of particles. In a monomolecular layer of water, the forces of surface stress are enormous. And water is treated as a solid. In the following layers, the influence of electrical forces of attraction rapidly drops to zero, and the properties of adsorbed water as the particles move away from the surface approach those of ordinary water. According to other works [13], it was stated that the topochemical theory is considered the most appropriate for explaining the complex process of formation of the cement stone structure. Here is the opinion of a number of researchers that the important role in solidification is played by structured water, located at the surface of neoplasms. Taking into account the physicochemical properties of structured water on the surface of hydrosilicates, it is assumed that it is the carrier of cement strength. And since the surface of the products of 18 hydration is increasing all the time, it should be assumed that the strength of the cement stone is the result of a combination of physical (adsorption) forces, usually called the forces of Van der Waals and the forces of chemical bonds [14]. The size of neoplasms of cement hydration products is hundreds of times larger than microcrystals of calcium hydrosilicates. In the early stages of solidification, when the amount of hydrosilicate is still small, the hydroxide crystals, calcium sulfonate and calcium hydroaluminate are in contact with the cement stone gel, as though binding several clinker grains simultaneously. These provisions do not contradict the chemical theory of cement hardening. So calculated according to the thermochemical section of thermodynamics in the work [15], where the enthalpy of formation, Gibbs energy, entropy and heat capacity of polymer silicates were calculated using the method of ion increments. The increments or conditional constituents of the thermodynamic indicator are convenient for the calculation of thermodynamic properties. The thermodynamic property of a substance is determined by the sum of the conventional thermodynamic constants of its components. The model of the polysilicate compound, accompanied by an increase of SiO3 -2 ions and SiO2 , is proposed. SiO2 2–SiO2 2− → Si2 O7 6–SiO2 2− → Si3 O10 8–SiO2 2 − → Si4 O13 10– …..(1 − n)…. Si2 O6 4–SiO2 → Si3 O8 4–SiO2 → Si4 O10 4–SiO2 → Si5 O12 4. On the basis of the principle of additivity, the increment of any ion of a series is determined by summing to the increment of the first member of the series the necessary amount of increment of the ion constant for each row. The results of the calculation based on ion increments are presented in Table 1. Analysis of these data shows that the relative error in the calculation of standard enthalpy of silicate formation does not exceed 4.2%, and for Gibbs energy from 0.05 to 2.5%, entropy and heat capacity does not exceed 0.5%. The good convergence of the results with the literature allows the use of the ion increment method calculations for the practical calculation of thermodynamic functions of silicates [16]. However, these calculations can be applied under standard conditions, in addition, it is necessary to take into account the process work during the concreting, which is to achieve the necessary usability of the concrete mixture requires excess water, exceeding the chemical

Stress–Strain Properties of Concrete at Early Freezing

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Table 1. Formation enthalpy, Gibbs energy, entropy, silicate heat capacity (data [9]) Connection

−f H298 kJ/mol

Fractional error, %

−f G298 kJ/mol By increments

By literary data

Fractional error, %

By increments

By literary data

K2 SiO3

1588.73

1590.34

0.1

1504.22

1498.03

0.41

K4 SiO3

2090.60

–

–

2233.96

–

–

Na2 SiO3

1565.17

1563.56

0.1

1463.40

1469.59

0.42

NiLiSiO4

2280.70

2279.70

0.1

2150.28

2150.28

0

Na2 Si2 O5

2414.81

2474.00

2.39

2266.02

2.67

2.67

requirements of cement clinkers by 2–3 times. Due to the fact that the complete separation of adsorbed and chemical bound water, which is part of the hydrosilicate structure, cannot be achieved. Studies have noted that the high dispersion at low temperatures of CSH (II) has a significant impact on the amount of water bound by chemical analysis methods. At temperatures below 20 °C, the aluminium containing materials are hydrated in a cement test to the hexagonal calcium hydroaluminate (C3A.aq), aluminium gel hydroxide (in the case of C3A) and 20 iron (in the case of C4AF) and solid hydrated calcium aluminate. The C3AH6 content decreases with the decrease in the solidity temperature of minerals. It is believed that the formation of calcium hydroaluminates of SSAN6 at low temperatures is unlikely. According to some researchers, this is possible due to the interaction with mineral water, due to the exothermic reaction in the local areas and the overheating of the mixture. The speed of hydration, as well as any chemical reaction, depends on the above factors and in addition depends on a number of factors—the fineness of the grinding, the cement of clinkers, the water cement ratio (WCR). WCR has little influence on the hydration rate during the first 3–4 days, but in the future the smaller the WCR the faster the hydration decreases are presented in Table 2. Table 2. Water content related at hydration of C2S in test (data [17]) Temperature hydration, (°C)

Amount of bound water in % over a period, (day) 1

3

7

14

28

3.82

6.07

20

2.13

2.82

2.93

5

2.68

2.79

5.30

−10

−0.57

0.58

0.59

0.95

1.73

−20

−0.62

0.32

0.55

0.78

0.89

Table 3 suggests that the hydration of different clinker minerals is different, the degree of hydration will depend on their ratio in Portland cement, the interaction of hydration products among themselves and can be assumed that some increase in hydration degree in a long time with an increase in WCR is due to the fact that with large WCR the thickness

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of hydrate shells around the grain clinker decreases. This phenomenon facilitates the water penetration to the non-hydrated part of the clinker grains. More water is used to prepare a concrete mix with the required workability than is required to hydrate the cement. As a consequence, this excess water, in a free or adsorbed state, makes the cement stone expand liable during evaporation. Depending on the size, age, humidity of the cement stone, ambient temperature, water in these pores and capillaries can be in a solid (ice), liquid and gaseous state. Water in this state in the cement stone is possible to have 30–60% of the original WCR. As the WCR decreases, so does the water volume, i.e. the porosity of the cement stone. Table 3. The degree of hydration of clinker minerals in Portland cement (data [15]) Mineral

Amount of bound water in % over a period 3 min

14 min

1 day

28 day

90 day

c3s

1–4

1–9

40–70

80–100

90–100

β-C2S

0.5–1

1–2

4–15

20–35

75–80

C3A

10–30

14–32

40–60

60–80

85–90

C4AF

8–20

11–23

20–40

50–70

80–89

However, when WCR is less than 0.4, the solubility of the concrete mixture is disturbed, when laying such concrete mixture may appear large pores and cavities. In addition, cement’s binder properties are not fully used due to reduced hydration. At any stage of hydration are characterized by neoplasms, which can be divided into gels, crystals. Ca(OH)2 , non-hydrated cement grains, pore volume. During solidification, the pore and capillary system changes continuously. The following classification of cement stone pores is currently adopted: Ultramicro pores (pores of gel) up to 0.01 microns; Micro-pores (contrast and micro capillary) of 0.01–0.1 microns; Pores of transition size 0, 1–1 μm; Macroprops of size I m. Many works are devoted to studying the influence of early freezing of concrete on the processes of firming and concrete structure formation [6, 9, 11, 17]. The causes of disturbance in the structure of early-frozen concrete have been identified, which are reduced to increasing the volume of water when freezing; the migration of moisture to the cooling surface; the accumulation of water at the large aggregate. Thus, research has found that early freezing of cement stone is harmful mainly for its macrostructure: destructive processes occur in pores larger than 0.1 μm. The most structural breakdown occurs in samples frozen at once, gradually decreasing with their retention until freezing, and when frozen at 24–72 h age, there is almost no violation. There are no abnormalities in the structure of the gel, as the water in the ultra-micro fluids does not freeze even at very low negative temperatures. These general provisions of structural changes in cement stone, do not take into account the concrete production technology and also the influence on the processes of chemical additives. In addition, some studies on the early freezing of concrete have noted that in the subsequent hardening of concrete at positive temperatures, they acquire even higher strength than the standard hardening twins [18, 19].

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5 Practical Significance The reaction rates in a multi-component system such as the hydration of cement clinker minerals in the presence of additives are very difficult to describe thermodynamically, since the speed of their interactions and the possibility of their interactions depend on the temperature, the concentration of compounds, water cement ratio. However, thermodynamic consideration of the problem becomes possible with the introduction of the following additional conditions: if one starts by taking the point in time when double and base salts with the additive are complete. If the concrete temperature is reduced to 0 °C…−20 °C. In this case, the cement hydration processes proceed very slowly. With the adoption of such limitations, a thermodynamic approach is not only possible, but also very useful. It has been possible to formulate an important provision that the hydration of cement during the use of additive in low-eutectic insulated conditions to the gradual melting of ice [20, 21]. This fact is explained by the fact that even at—20 °C in concrete there is a liquid phase in the pores and capillaries—an aqueous solution of the electrolyte, therefore the ability to hydrate cement remains. At the same time, part of the water is bound into crystalline binders, which leads to an increase in the concentration of the additive, the balance of the additive system and water is disturbed. Under insulated conditions, this causes ice to melt to restore the balance in the system. The material balance equation is as follows: C = ±/δ

(1)

where δ is the transition coefficient from the adsorption (desorption) of the capillaryporous body surface unit to the volume concentration of the substance.  = (C/RT )(d σ/dc)

(2)

 is adsorption by Gibbs equation; C is concentration of additive; σ —interphase energy; In real conditions, these equations are not completely fulfilled, because continuous cement hydration produces smaller pores [22].

6 Conclusions The main factor in the level of intra-structural stresses in cement concrete is the wet shrinkage, which develops during the hardening and operation of concrete and reinforced concrete products and structures in the air. Air conditions associated with reduced humidity cause significant anomalies in the development of the structure and strength of cement stone and cement concrete. In general, a lack of moisture reduces the hydration rate of the binder, leads to a deterioration in the differential porosity of the cement stone and the development of intra-structural stresses, which generally negatively affects strength.

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References 1. Golovnev SG (1999) Winter concreting technology. Optimization of parameters and choice of methods. Publishing House of SUSU, Chelyabinsk, p 156 2. Brzhanov RT (2018) Forecast of cooling of monolithic concrete. In: Features of the current stage of development of natural and technical sciences, pp 7–10 3. Antonina Y, Rafael O (2017) Technology of winter concreting of monolithic constructions with application of heating cable. Archit Eng 2(2):43–48 4. Brzhanov RT (2009) Re-vibration as a factor in increasing the strength of concrete. Bull PSU 1:25–35 5. Tzarenko A, Yurgaytis A (2020) Possibilities for intensifying construction work’s dynamic on objects of the annual production program by winter concreting technology. IOP Conf Ser: Mater Sci Eng 753(3):032072 6. Svintsov AP et al (2020) Effect of nano-modified additives on properties of concrete mixtures during winter season. Constr Build Mater 237:117527 7. Brzhanov RT, Pikus GA, Traykova M (2018) Methods of increasing the initial strength of winter concrete. IOP Conf Ser: Mater Sci Eng 451(1):012083 8. Lazarev A (2021) The technology of winter concreting of monolithic frame structures with substantiation of heat treatment modes by solutions of the differential equation of thermal conductivity obtained by the method of group analysis. Int J Comput Civ Struct Eng 17(4):115–122 9. Zhuravlyov EG (2020) Review and analysis of winter concreting methods, used on construction sites in Russia. IOP Conf Ser: Mater Sci Eng 880(1):012029 (IOP Publishing) 10. Brzhanov RT (2010) Causes of destructive processes during winter concreting. In: Proceedings of the international scientific and technical conference “Modern problems of geotechnics, mechanics and construction of transport facilities”, pp 235–238 11. Golovnev SG (2010) Modern construction technologies: monograph. South Ural State University Publishing Center, Chelyabinsk 12. Melnik AA (2017) Calculation of concrete strength in winter conditions based on heat exchange processes modeling. Procedia Eng 206:831–835 13. Brzhanov RT (2018) Methods of increasing the initial strength of winter concrete. IOP Conf Ser: Mater Sci Eng 451:012083 14. Karpenko NI et al (2020) On the determination of the influence of low negative temperatures on deformability and the development of the microcracks forming process in concrete elements under axial compression. IOP Conf Ser: Mater Sci Eng 753(2):022056 15. Manos GC, Naxakis D, Soulis V (2015) The dynamic and earthquake response of a two story old r/c building with masonry infills in Lixouri-Kefalonia, Greece including soil-foundation deformability. In: Proceedings of the 5th international conference on computational methods in structural dynamics and earthquake engineering, pp 435–459 16. Brzhanov RT (2020) The study of the duration of the set of winter concrete critical strength. Sci Technol Kazakhstan 1:48–54 17. Giussani F (2009) The effects of temperature variations on the long-term behavior of composite steel—Concrete beams. Eng Struct 31(10):2392–2406 18. Jia H et al (2020) Influence of pore water (ice) content on the strength and deformability of frozen argillaceous siltstone. Rock Mech Rock Eng 53(2):967–974 19. Korzeniowski W, Skrzypkowski K, Zagórski K (2017) Reinforcement of underground excavation with expansion shell rock bolt equipped with deformable component. Stud Geotech Mech 39(1)

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20. Brzhanov RT, Aldabergenov MK (1996) Thermodynamic properties of alkali aluminates and alkaline earth aluminates. Abstracts of reports of the Republican scientific. In: Practical conferences “Biologochemical and physico-tech. methods and means in modern research”, Kustanai, pp 112–113 21. Bakhodir R, Adkhamjon M, Bakhtiyorovich MM (2022) Shrinkage deformations of concrete in natural conditions of the republic of Uzbekistan. Univ: Tech Sci 2–7(95):20–24 22. Medina NF et al (2017) Mechanical and thermal properties of concrete incorporating rubber and fibers from tire recycling. Constr Build Mater 144:563–573

A Modified Implicit Scheme for the Numerical Dynamic Analysis of Beam Elements Considering Nonlocal in Time Internal Damping V. N. Sidorov1,2 , E. S. Badina1,2,3(B) , and E. P. Detina1 1 Moscow State University of Civil Engineering, 26, Yaroslavskoye Sh., Moscow 129337,

Russia [email protected] 2 Russian University of Transport, 9b9, Obrazcova St., Moscow 127994, Russia 3 Institute of Applied Mechanics of Russian Academy of Sciences, 7, Leningradsky Ave., Moscow 119991, Russia

Abstract. In the present paper, the problem on numerical dynamic simulation of bending structural elements made of orthotropic materials, such as composites and nanomaterials, is considered. The modeling of damping properties of such materials, including those that are initiated by internal friction in the material, is of particular concern. Damping parameters of the proposed numerical model are nonlocal in time. Such a model provides the results allowing one to approximate enough reliably the dissipative properties of constructional elements made of composite materials. The nonlocal in time damping model, known as “damping with memory”, is embedded into the finite element method algorithm. An equilibrium equation for a beam element in motion is solved numerically utilizing an implicit scheme. The damping matrix for the proposed model is derived from the condition of stationarity of the total deformation energy of the moving mechanical system. The provided analysis of the one-dimensional nonlocal in time design model has shown that the modified implicit scheme allows one to increase the accuracy of the experimental data approximation. Keywords: Nonlocal damping · Composite materials · Nonlocal mechanics · Finite element analysis · Newmark method

1 Introduction Application of modern composites and nanomaterials reveals wide opportunities for building and construction. Due to its controllable properties such materials can be adjusted for various goals. Mathematical modeling of dynamic behavior of mechanical systems made of structurally complex materials is a nontrivial problem. In order to ensure satisfactory compliance of numerical modeling results to data derived from experiment, it is required to apply specialized hypotheses and approaches. At the same time, the selected hypotheses and approaches should not lead to excessively complicated and tedious models. Application of the fractional order operators allows one to get © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_22

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perspective results for solution of this problem [1]. Another approach for modeling the properties of structures is based on the principals of nonlocal mechanics [2, 3]. The nonlocal elastic model was proposed in [4] and in [5] it was applied for the problem of the bar in tension. In article [6] the damping mechanism is considered for the cantilever beam. Four different damping models are studied: Kelvin-Voight viscous damping [7], external air damping, time hysteresis and spatial hysteresis. The last two models are nonlocal in time and in space respectively. The results of the dynamic experiment are used for obtaining the damping coefficients by least squares method. In [3] a nonlocal damping model is used for the analysis of Euler-Bernoulli beams and Kirchhoff plates. The damping model under consideration belongs to the class of “damping with memory” models, and it is nonlocal in time. It is satisfactory for numerical calculations of structures made of structurally complex materials when they subjected to dynamic loading [8]. It is considered that damping of the structure at the current time moment t is assumed to be dependent not only on instant value of strain rate at this moment ε˙ (t), but also on the values of strain rates ε˙ (t) of the previous time history τ = 0 ÷ t [4]. The longer is the gap between the two time points the lower is the influence that one of them has on the other. In the present article, the nonlocal in time damping model is embedded into finite element analysis (FEA). In the FEA algorithm, the equilibrium equation for a mechanical system, deformed in motion, is presented in the matrix form and usually is written in displacements [9]: M V¨ (t) + DV˙ (t) + KV (t) = F(t)

(1)

Here K, M , and D are, respectively, the stiffness matrix, the mass matrix, and the damping parameters matrix of the finite element model (FE) model, F(t) is the vector of external forces at the considered moment of time t, V (t), V¨ (t), and V˙ (t) are, respectively, unknown vectors of nodes’ displacements, velocities and accelerations at the considered moment of time t. Equation (1) could be solved using the FEA algorithm based on the implicit scheme using the modified Newmark method [9]. A distinctive feature of this method is that dynamic equilibrium of the design model is analyzed in a certain moment of time t+t = ti+1 (where i is the number of the current time step), depending on values of displacements V (t), velocities V˙ (t) and accelerations V¨ (t) calculated on the (i − 1)-st and i-th time steps.

2 A Modified Newmark Method with Nonlocal in Time Internal Damping The damping matrix D is derived from the condition of stationarity of the total potential energy of a deformed system, including the energy dissipation function (at an arbitrary point of a structure) due to the internal friction in the material 21 d ε˙ 2 , where d is a

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structural damping parameter, ε denotes deformations in the material. Let us present the components of the velocity vector V˙ (t) within the time interval (ti−1 , ti+1 ) as     V¯ (ti+1 ) − V¯ (ti ) + V¯ tti − V¯ (i − 1) 1 1 ˙ = V˙¯ (ti+1 ) + V˙¯ (ti ) (2) V¯ (ti+1 ) = 2t 2 2 Then Eq. (1) for the time step (i + 1) could be presented as 1 1 M V¨ (ti+1 ) + DV˙ (ti+1 ) + DV˙ (ti ) + KV (ti+1 ) = F(ti+1 ) 2 2

(3)

Let us accept now the kernel function G(t − τ ) [3] that characterizes diminishing influence of the damping factor in time and satisfies the condition t G(t − τ )d τ = 1

(4)

0

Substituting relationship (4) in Eq. (3) provides the local damping model in the form 1 1 M V¨ (ti+1 ) + DV˙ (ti+1 ) + DV˙ (ti ) 2 2

ti G(ti − τ )d τ + KV (ti+1 ) = F(ti+1 )

(5)

0

In order to account for diminishing influence of damping factors on the velocities of t nodes V˙ (t) at preceding time steps, let us integrate in (5) the term V˙ (ti ) 0i G(ti − τ )d τ by parts, resulting in 1 M V¨ (ti+1 ) + DV˙ (ti+1 )+ 2 ⎡ t ⎤ ⎤ ⎡ i ti ti 1 ⎣ G(ti − τ )V˙ (ti )d τ + ⎣ G(ti − τ )d τ ⎦V¨ (ti )d τ ⎦ + KV (ti+1 ) = F(ti+1 ) + D 2 0

0

0

(6) In order to derive the damping operator core, let us apply the Laplace integral, i.e., the error function [8]. Then G(t − τ ) could be presented as 2μ 2 2 G(t − τ ) = √ e−μ (t−τ ) π

(7)

where μ is a parameter characterizing the degree of non-locality of material damping in time. The control of the nonlocal damping model by the parameter μ was studied in [10]. Obviously, the higher μ, the closer the nonlocal model to the classic local model (Fig. 1). In order to transform Eq. (6) into a computational scheme due to the Newmark method, it could be rewritteb as follows:

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229

Fig. 1. Kernel function based on Laplace integral for different values of μ.

⎡ ⎤ ⎤ ⎡ i i i



1 1 ⎣ M V¨ i+1 + DV˙ i+1 + D⎣ G(j)V˙ j d τ + G(j)d τ ⎦V¨ i d τ ⎦ 2 2 j=1

j=1

j=1

+KV i+1 = F i+1

(8)

Suppose that within the analyzed time steps i − 1 and i + 1, the elements of the acceleration vector V¨ (t) are changed according to the linear law [11] (Fig. 2). Let us consider the time point (ti ± θ ) lying within the time interval (ti−1 , ti+1 ) between the points ti−1 ti+1 . Due to the smallness of the interval (ti−1 , ti+1 ), accelerations V¨ (ti ± θ) on the span between the points ti − θ ti + θ of the time axis considering for the assumption accepted above can be deemed constant: V˙ (ti+1 ) − V˙ (ti−1 ) V¨ (ti ± θ ) = 2t

(9)

where t is a time increment. Location of the point (ti ± θ ) in the case of numerical integration according to the Newmark method with the analyzed interval is expressed by parameters a, b, c (Fig. 2). When establishing dependence (9) between the acceleration at the point (ti ± θ) and velocities at node points, the condition a + b + c = 2t should be accepted, ensuring the location of the point (ti ± θ ) inside of the interval (ti−1 , ti+1 ). A sum of multipliers in (8) at the vector V (ti+1 ), which should be sought for at every time step ti+1 , could be named as the effective stiffness matrix Kef and is calculated by the formula Kef =

1 2(t)

2

M+

1 D+K t

(10)

Let us put together the remaining terms of the sum in (8) into a single vector and name it as the effective force vector Ref (t). Then, numerical transformations based on the implicit scheme allow one to present an equilibrium equation in the matrix form: Kef V (ti+1 ) = Ref (ti+1 )

(11)

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Fig. 2. A scheme of the elements of the acceleration vector V¨ (t) within the analyzed time steps ti−1 I ti+1 .

The solution of the set of Eqs. (11) gives the values of elements of the displacement vector V (ti+1 ) at the (i + 1)st time step, with due account for structural damping properties, nonlocal in time.

3 Estimation of the Model Accuracy Increase When Using the Modified Newmark Method As an example, let us consider vibrations of a composite beam. The beam is simply supported and is loaded by a concentrated force, suddenly applied in an initial moment of time in the midspan. General parameters of a beam structure and its material, engaged in calculations, and values of instantly applied distributed load are presented in Table 1 [12–14]. Table 1. General parameters of a beam made of vinylester fiber glass. Young’s modulus for the material [Pa]: E = 1,720,000 Beam length (m): L = 12 Material density (kg/m3 ): ρ=1900 Cross section area of the beam (constant along the entire length) (m2 ): A = 0.006 Moment of inertia of the beam section (m4 ): I = 1840e-8 N ): q = 0.1 Instantly applied distributed load ( m

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Consider beam vibrations on the time interval lt . Let us divide the interval lt by a finite number of sections, in so doing the quantity of node points should be equal to nt , while the step length per time t = lt /(nt − 1) should not be changed within the interval lt . The technique for calibrating the damping model with memory by defining a value of the parameter μ, resulting in the better approximation of experimental data, was √ suggested in [10]. In Figs. 2 and 3, with an accepted value μ = π/2, we assess a capability of additional model flexibility by selecting the position of the point ti ± θ .

Fig. 3. Assessing the influence of the point ti ± θ location in the general scheme of the Newmark method on the solution of equilibrium equation for a beam made of composite material (solution for the first nine node points of the time interval t).

In Table 2 the middle section of the beam deflections are presented. The deflections are obtained by solving the Eq. (8) using modified Newmark method for different positions of the ti ± θ point. a-parameter is constant and equal to t. In Table 2 nine first points of the time interval lt = 3.6s are considered. The Table 2 shows that the deflection value can be changed up to 10% by moving the ti ± θ point. On the Fig. 3 the middle section of the beam deflection is shown during the time period of 0.09 s. Different curves correspond to different positions of the ti ±θ point: blue one for a = t; b = 0.1t; c = 0.9t; black one for a = t; b = 0.4t; c = 0.4t; red one for a = t; b = 0.5t; c = 0.5t. If b < c—the deflection vector rate increases; if b > c the deflection vector rate decreases. Figure 4 shows the change of displacement values at the center section of a vibrating beam for the first sixty node points of the analyzed time interval. The stationary value of the deflection (deflection at the moment of time 0.5 s) can be compared with the deflection value v in a center section from the static force F calculated

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Table 2. The middle section of the beam deflection for different positions of the ti ± θ point. Time ti , s 0 0.000 0.017 0.026 0.036 0.044 0.052 0.061 0.070 Values of b and c parameters Deflections, m b = 0.0000, c = 1.0000

0 0.000 0.031 0.043 0.060 0.079 0.086 0.085 0.073

b = 0.0003, c = 0.0084

0 0.000 0.031 0.043 0.060 0.079 0.087 0.087 0.076

b = 0.0004, c = 0.0083

0 0.000 0.031 0.043 0.060 0.080 0.087 0.087 0.077

b = 0.0005, c = 0.0082

0 0.000 0.031 0.043 0.060 0.080 0.087 0.087 0.077

b = 0.0006, c = 0.0081

0 0.000 0.031 0.043 0.060 0.080 0.087 0.088 0.078

b = 0.0008, c = 0.0079

0 0.000 0.031 0.044 0.061 0.080 0.088 0.089 0.080

b = 0.0017, c = 0.0070

0 0.000 0.031 0.044 0.061 0.080 0.088 0.090 0.084

b = 0.0026, c = 0.0061

0 0.000 0.031 0.045 0.062 0.080 0.088 0.091 0.086

b = 0.0035, c = 0.0052

0 0.000 0.030 0.045 0.062 0.079 0.087 0.091 0.087

b = 0.0044, c = 0.0044

0 0.000 0.030 0.045 0.062 0.078 0.086 0.090 0.087

b = 0.0052, c = 0.0035

0 0.000 0.029 0.045 0.061 0.078 0.085 0.089 0.086

b = 0.0061, c = 0.0026

0 0.000 0.029 0.045 0.061 0.077 0.084 0.087 0.085

b = 0.0070, c = 0.0017

0 0.000 0.028 0.044 0.060 0.075 0.082 0.085 0.083

b = 0.0079, c = 0.0008

0 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

Fig. 4. Assessing the influence of the point t ± θ location in the general scheme of the Newmark method on the solution of equilibrium equation for a beam made of composite material (number of node points nt = 60).

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using the well known formula: v=

qL4 ≈ 0.0698[m] 384EI

From Fig. 3 it is seen that by changing the position of the point ti ± θ a phase of vibrating process could also be controlled.

4 Conclusion The numerical dynamic analysis of a bending structural element made of a composite material has been carried out. In so doing its damping properties have been defined by the nonlocal in-time damping approach, resulting in the flexible model for solving the equations of motion for beam elements by the Newmark method on the general time interval (ti−1 , ti+1 ). It has been shown that the general implicit scheme parameters could be calibrated using data of a physical experiment. Such an approach to the dynamic analysis of bending elements is novel and is considered to be rather perspective in applications to dynamic analysis of structures made of structurally complex materials, such as composites. It is shown that accuracy of the results of numerical calculations could be improved by managing parameters of the suggested modifications of the Newmark method, including by varying the location of the point (ti ± θ ) on the current time interval (ti−1 , ti+1 ). Acknowledgements. This research is supported by the Russian Science Foundation, Project No. 21-19-00634.

References 1. Rossikhin YA, Shitikova MV (2010) Application of fractional calculus for dynamic problems of solid mechanics: novel trends and recent results. App Mech Rev 63(1):010801. https://doi. org/10.1115/1.4000563 2. Potapov VD (2012) Ustojchivost’ sterzhnej pri stokhasticheskom nagruzhenii s uchetom nelokal’nogo dempfirovaniya (Stability’ of bars under stochastic loading, taking into account non-local damping). Problemy mashinostroeniya i teorii nadezhnosti 4:25–31 3. Lei Y, Friswell MI, Adhikari S (2005) A Galerkin method for distributed systems with non-local damping. Int J Solids Struct 43:3381–3400. https://doi.org/10.1016/j.ijsolstr.2005. 06.058 4. Eringen AC, Edelen DGB (1972) On nonlocal elasticity. Int J Eng Sci 10(3):233–248. https:// doi.org/10.1016/0020-7225(72)90039-0 5. Pisano AA, Fuschi P (2003) Closed form solution for non-local elastics bar in tension. Int J Solids Struct 40(1):13–23. https://doi.org/10.1016/S0020-7683(02)00547-4 6. Banks HT, Inman DJ (1991) On damping mechanisms in beams. J Appl Mech 58(3):716–723. https://doi.org/10.1115/1.2897253 7. Voigt W (1966) Lehrbuch der Kristallphysik (mit Ausschluß der Kristalloptik). B.G. Teubner Verlagsgesellschaft Johnson Reprint Corporation, Stuttgart-New York

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8. Sidorov VN, Badina ES (2021) Nelokal’nye modeli dempfirovaniya v dinamicheskikh raschetakh konstruktsij iz kompozitnykh materialov (Non-local damping models in dynamic analysis of structures made of composite materials). Promyshlennoe i grazhdanskoe stroitel’stvo 9:66–70 9. Bathe KJ, Wilson EL (1976) Numerical methods in finite element analysis. Prentice-Hall 10. Sidorov VN, Badina ES, Detina EP (2021) Nonlocal in time model of material damping in composite structural elements dynamic analysis. Int J Comput Civil Struct Eng 17(4):14–21. https://doi.org/10.22337/2587-9618-2021-17-4-14-21 11. Sidorov VN, Detina EP, Badina ES (2022) Modificirovannyi metod Newmarka pri dinamicheskom raschete kompositnyh elementov s uchetom dempfirovaniya s pamyat’u (Modified Neshmark method in the dynamic calculation of composite elements, taking into account damping with memory). Mehanika kompositnyh materialov i konstrukciy 28(1):98–111. https://doi.org/10.33113/mkmk.ras.2022.28.01.098_111.05 12. Landherr JC (2008) Dynamic analysis of a FRP deployable box beam. Master of applied science thesis. Queen’s University 13. Lim RA (2016) Structural monitoring of a 10 m fibre reinforced polymer bridge subjected to severe damage. Master of applied science thesis. Queen’s University 14. Xie A (2007) Development of an FRP deployable bridge. Master of applied science thesis. Royal Military College of Canada

Optimizing the Structure of Construction Mixes for 3D Printing V. A. Solonina1(B) , I. A. Surovtsev1 , and M. D. Butakova2 1 Tyumen Industrial University, 38, Ul. Volodarskogo, Tyumen 625000, Russia

[email protected] 2 South Ural State University, 76, Lenin Avenue, Chelyabinsk 454080, Russia

Abstract. The paper presents experimental studies on optimizing the structure of a polydisperse fine grain concrete mix for 3D printing of structures with the production of a dense cement conglomerate providing high plastic and cement strength, as well as stable geometry of the layers and the structure in general. Optimization was performed at the micro level by introducing limestone meal as a filler with a grain size of up to 60 microns, and at the macro level by selecting the ratios between the three basic fractions of quartz sand (0.16–0.315: 0.315–0.63: 0.63–1.25) according to the maximum bulk density of the fraction mix. Arranging the fine grain mix components according to their proportionality at each scale level of the structure allowed us to obtain a conglomerate with 40% higher bending strength and 23.8% higher compressive strength than the control composition. The grain packing density and obtained fractal structure also allowed us to halve water absorption during capillary suction. The resulting composition of the polydisperse fine grain concrete mix serves as a basis for further modification with chemical additives to obtain a viscous-plastic mix with specified rheotechnological characteristics meeting the requirements of additive 3D printing by layer-by-layer extrusion. Keywords: Grain sizing · Filler · Grain composition · Optimal structure · Polydisperse mix · Strength

1 Introduction Development within the construction industry is based on the principles of increasing rationality in the production of building materials, products and structures, as well as on construction sites. Optimizing the use of all resources, including human resources, is also a significant factor. The most promising technology which meets this trend and is implementable in the construction industry is additive 3D printing [1–4]. Over the past decade, additive technologies have been developed significantly in many industrial sectors; however, the introduction of additive technologies in construction has not yet become sufficiently widespread. The most convenient base in this case is fine grain (sandy) composites based on mixed cementitious binders with reduced cement consumption [5, 6]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_23

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The predominantly fine grain compositions of concrete mixes currently used for layer-by-layer extrusion are not adapted to the design features of construction 3D printers, which is reflected in the poor rheotechnological characteristics of mixes and the performance of products based on them. The most typical defects of products molded by layer-by-layer extrusion are geometry deterioration caused by the low plastic strength of layers; the presence of gaps, voids, and fractures; increased porosity, low crack resistance, high shrinkage deformations, etc. [7, 8]. The properties of composites, including capillary porosity, largely depend on the structure of the disperse systems from which they are composed [9]. Cement-sand conglomerates at macro to nano levels of the structure are composed of hardened cement paste, cement substance, newgrowths of this cement substance, solid phase of newgrowths, the substance of a single structural element of the newgrowth [10, 11]. The organization of the elements making up the composite is preconditioned by their proportionality at each level of the structure [12, 13]. High strength indicators of the conglomerate can be achieved by combining several factors: increasing system density by optimizing the grain composition; decreasing the number of pores of the hardened cement paste by reducing the W/C ratio; filling the pores between cement grains, and improving the rheology of the lubrication effect; forming hydration by-products during the reaction with calcium hydroxide when microfillers are added into the mix [14–16]. The purpose of the paper is to select the composition of a polydisperse fine grain concrete mix with the optimal ratio of components for 3D printing of building structures to obtain a dense cement conglomerate.

2 Materials and Methods Prototype samples were made using CEM II/V-Sh 32.5 N Portland cement. We enhanced fiber reinforced hardened cement paste by adding finely dispersed additives (fillers): 1. Ground quartz sand obtained by grinding washed quartz sand in a laboratory ball mill. 2. MP-1 limestone meal from Minyarsky Quarry OOO. To control the dispersion ability of the material, we used a FRITSCH—ANALYSETTE 22 NanoTec laser analyzer, which determines grain sizes from 0.01 to 2000 µm using 57 measuring channels. The physical and mechanical characteristics of the samples were determined using standard methods.

3 Results Filler grains actively reinforce the structure of the matrix material by serving as a cementitious binder [17]. The effect of creating a fractal structure in the binder matrix by introducing fillers is revealed at certain percentages of cement and filler grain sizes. Changes in the strength of the hardened cement paste samples depending on the amount of additives and water introduced is attributed to the interaction between the

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grains of dispersed mineral additives and the forming hardened cement paste. In this case, both the specific surface area (average grain size) of the finely ground additive and the distribution of grains by fractions and the grain size composition of the material are important. The results of the grain size analysis of the raw materials are presented in Table 1 and Fig. 1. The use of mineral fillers is effective in a limited range both in terms of their dispersion ability and the amount that can be combined with a hydraulic binder without reducing its strength [18]. To determine the optimal content of mineral fillers in the composition of the cement-filled binder, we made two series of compositions based on cement with ground sand and cement with ground limestone with varying weight ratios (from 0 to 40%). Mixing water was selected to ensure constant paste consistency (by the flow of a standard cone on a flow table). Figure 2 shows the influence of the consumption and type of the finely-ground filler on the water demand of the composite binder.

Fig. 1. Graphs of the grain size composition of materials: a Portland cement, b ground quartz sand; c limestone meal.

When the percentage of fillers is high, the water demand of the particulate-filled binder is significantly reduced due to the change in the total specific surface area of grains in the mix. A significant reduction in water consumption is observed with the introduction of fillers up to 15%. A further increase in the content of mineral additives does not significantly affect the water demand of the mix. 20 mm edge cubes were formed from the prepared compositions to serve as samples. Figure 3 shows the compressive strength of the samples from particulate-filled mixes depending on the content of the filler and the hardening time. The obtained results indicate that the optimal content of fillers in the hydraulic binder mix is 10–15%. At the same time, the increase in the strength of the particulatefilled binder was 14% with the introduction of ground quartz sand and 23.4% with

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# of item

Grain content, %

Grain size (microns) Portland cement

Ground quartz sand

Limestone meal

1

5

1.71

2.38

0.93

2

10

4.09

4.62

1.85

3

25

9.68

11.90

7.85

4

50

20.01

25.98

16.52

5

75

32.11

45.95

26.73

6

90

43.46

69.10

37.63

7

95

50.36

84.25

44.65

8

99

62.32

112.26

57.32

Fig. 2. The influence of the filler content on the water demand of the mix.

the introduction of ground limestone. This can be explained by the optimal grain size composition of finely dispersed mixes, which leads to a denser packing of binder grains and increased strength even at lower cement content. With the introduction of over 15% of fillers into the binder mix, strength decreases; at up to 30%, the strength of the 28 days old cement composite does not exceed the strength of pure Portland cement. The strength of the samples with ground limestone is 8.2% higher. The carbonate rock has a chemical affinity with the minerals of the Portland cement clinker, and tight contacts are formed during natural hardening. An important feature of carbonate rocks is that they enter into active physical and chemical interaction with cement clinker minerals, thus participating in the formation of the hardened cement paste structure [19]. When grinding carbonate fillers, they are activated, some chemical bonds are broken, and groups of free radicals and ions are formed on the grain surface. The freshly formed grain surface has increased reactivity and is predominantly positively-charged. The finely dispersed filler fills the cavities between calcium sulfate dihydrate crystals, which increases the strength of contacts between crystals and density and, as a result, the strength and durability of hardened compositions [20]. Finely-ground limestone helps to reduce water gain,

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Fig. 3. Kinetics of developing compressive strength of the samples a with ground quartz sand; b with ground limestone.

stratification of mixes, increase their water-retaining capacity, plasticity, and uniformity, reduce shrinkage, as well as improve water, frost, and acid resistance of the solution [21]. Shifting to the macro level of the fine grain concrete structure, we considered the optimization of the grain size composition of the filler–quartz sand. The fractal arrangement of grains depends on the grain composition and configuration of the filler grains. The void content can be reduced by introducing additional, smaller fractions of filler grains. In fractal packing, it is important that the diameter of the finer fraction grains

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does not exceed the size of the voids between the larger grains. Otherwise, larger grains will inevitably separate, which increases the void content and, as a result, leads either to a porous structure of the composite or an increased consumption of binder. The use of two or more filler fractions in the composition of the cement-sand mix reduces the consumption of cementitious binder due to a decrease in the void content of the filler without compromising the construction and technical characteristics of the material. Most authors point to the ratio of near-gravity fractions from 1:2 to 1:1.6 [11, 12, 22]. The main task of optimizing the grain size composition of the filler was to select the ratios between the three main sand fractions (0.16–0.315: 0.315–0.63: 0.63–1.25). The optimal ratio of 1.89:1:2.67 was experimentally determined by the maximum bulk density. Several mixes were prepared to confirm the effectiveness of the resulting polydisperse mix with the maximum grain packing at the micro level (filler-binder) and macro level (filled binder and quartz sand), see Table 2. Table 2. Polydisperse mortar mix compositions. Mix #

Cement (g)

Ground limestone (g)

Quartz sand (g) Non-fraction

1.25–0.63

0.63–0.315

0.315–0.16

Water (ml)

0

500

–

1,500

–

–

–

240

1

425

75

1,500

–

–

–

215

2

500

–

–

720

270

510

225

3

425

75

–

720

270

510

195

To obtain mortar mixes of normal consistency, mixing water was selected by cone flow on a flow table. We noted a regular decrease in consumption during fractionation of the dispersed system components. When fractionated quartz sand was used in the polydisperse mix, mixing water consumption reduced by 10.4%. With a filled binder, water consumption reduced by 6.25%. The combined use of optimal percentages of the dispersed components allowed us to reduce water consumption by 18.75%. 4 × 4 × 16 cm beams were formed from solutions of normal consistency. After 28 days of hardening under normal conditions, the samples were tested for bending and compressive strength. The optimization of the grain composition of the polydisperse mix at the micro and macro levels allowed us to increase in the bending strength of the solution by 40% and the compressive strength by 23.8% (Fig. 4). Cement-based composite materials have a capillary-porous structure [10]. Upon contact with moisture, it is sorbed into the material body, which decreases the strength of the artificial stone and develops corrosion. To assess the structure of the obtained compositions and predict the applicability of the material without a significant decrease

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Fig. 4. Strength gain of mortar mix compositions.

in strength during alternate freezing-thawing and moistening-drying, we should control its hydrophysical characteristics. The obtained samples were tested for water absorption during capillary suction (Fig. 5).

Fig. 5. Water absorption during capillary suction of mortar mix compositions.

Analyzing the data in Fig. 5, we can conclude that the lower the water consumption for obtaining a mortar mix with constant rheological parameters, the lower the water absorption of the hardened mortar rock during capillary suction.

4 Conclusion Organizing the components of a fine grain mix according to their proportionality at each level of the structure allowed us to obtain a conglomerate with 40% higher bending strength and 23.8% higher compressive strength than the control composition. The obtained grain packing density with fractal structure also allowed us to halve water absorption during capillary suction. We found the optimal grain sizing of both finely

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dispersed mixes and fine fillers, which allowed us to obtain a denser packing of binder grains and its increased strength even at lower cement content. The resulting composition of the polydisperse fine grain concrete mix can serve as the basis for further modification with chemical additives to obtain a viscous-plastic mix with specified rheotechnological characteristics meeting the requirements of additive 3D printing by layer-by-layer extrusion.

References 1. Zhang J, Wang J, Dong S, Yu X, Han B (2019) A review of the current progress and application of 3D printed concrete. Compos Part A Appl Sci Manuf 125:105533. https://doi.org/10.1016/ j.compositesa.2019.105533 2. Roussel N (2018) Rheological requirements for printable concretes. Cem Concr Res 112:76– 85. https://doi.org/10.1016/j.cemconres.2018.04.005 3. Denisova YV (2018) Additive technologies in construction. Stroitelnye materialy i izdeliya (Build Mater Prod) 1(3):33–42. https://doi.org/10.34031/2618-7183-2018-1-3-33-42 4. Luneva DA, Kozhevnikova EO, Kaloshina SV (2017) The use of 3D printing in construction and its development prospects. Bull Perm Natl Res Polytech Univ Build Arch 8(1):90–101 5. Torshin AO, Borovikova SO, Korchunov IV, Potapova EN (2018) The development of a building mix for 3D printing. Uspekhi v khimii i khimicheskoy tekhnologii (Advances in Chemistry and Chemical Technology) XXXII(2):164–166 6. Poluektova VA, Kozhanova EP (2019) Improving the production technology of dry building mixes for 3D printing. Tekhnologii additivnogo proizvodstva (Add Manuf Technol) 1(1):14– 23 7. Lesovik VS, Elistratkin MYu, Glagolev ES, Shatalova SV, Starikov MS (2017) The formation of composition properties for construction printing. Bull Belgorod State Technol Univ named after V.G. Shukhov 2(10):6–14 8. Slavcheva GS, Artamonova OV (2019) Rheological behavior and mix design for 3D printable cement paste. Key Eng Mater 799:282–287. https://doi.org/10.4028/www.scientific.net/ KEM.799.282 9. Artamonova OV, Slavcheva GS, Chernyshov EM (2017) The effectiveness of using complex nano-sized additives for cement systems. Neorganicheskie materialy (Inorgan Mater) 53(10):1105–1110. https://doi.org/10.7868/S0002337X1710013X 10. Chernyshov EM (2011) Structural heterogeneity of building composites: issues of materials science generalization and theory development (part 2). Russian Academy of Architecture and Building Sciences, Moscow-Orel-Kursk 11. Svidersky VA (2008) The influence of the grain size parameters of the filler on the structure of the composite material. Sukhiye stroitel’nyye smesi (Dry Build Mixes) 4:46–48 12. Makeev AI (2008) The concept of harmony in controlling the homogeneity/heterogeneity of the conglomerate structures of building composites. In: Proceedings of the science and innovations in construction SIB-2008 international congress volume 1, Modern problems of building materials science and technology Book 1 (A-N), Voronezh, pp 311–320 13. Bazhenov YuM, Chernyshov EM, Korotkikh DN (2014) Structural design of modern concretes: defining principles and technology platforms. Stroitelnye materialy (Build Mater) 3:6–14 14. Ramachadran V, Feldman R, Baudouin J (1986) The science of concrete: physical and chemical concrete science, translated from English. Stroyizdat, Moscow 15. Solomatov VI, Vyrovoy VN (1988) Physical features of the structure formation of composite building materials. Izvestiya Vuzov (News Higher Educational Institutions), Construction 10:59–64

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16. Kaprielov SS (1995) General regularities in the structure formation of hardened cement paste and concrete with the addition of ultrafine materials. Beton i zhelezobeton (Concrete and Reinf Concrete) 4:16–20 17. Makarova NB (2001) A study of the physical and mechanical properties and analysis of the microstructure of the filled cement-sand composite. Izvestiya Vuzov (News of Higher Educational Institutions), Construction 5:21–27 18. Kalashnikov VI, Suzdaltsev OV, Dryanin GP, Sekhsposyan GP (2014) The role of dispersed fillers in new generation concretes. Izvestiya Vuzov (News of Higher Educational Institutions), Construction 7:11–21 19. Kalashnikov VI (2001) Polymer-mineral dry mortar mixes. Izvestiya Vuzov (News of Higher Educational Institutions), Construction 5:41–46 20. Ivashchenko YuG (2010) Evaluation of the influence of natural and technology-related mineral additives on the kinetics of the formation of the fine grain concrete strength. Bull Saratov State Tech Univ 4(3):25–29 21. Plugin AA (2011) The use of carbonate additives in cement compositions for waterproofing and restoration of buildings and structures. In: Proceedings of the institute of construction and architecture of Moscow State University of Civil Engineering, pp 224–227 22. Entin ZB (2009) On the relationship between grain sizing and cement strength. Tsement i yego primeneniye (Cem Appl) 6:111–113

Evaluation of Deformation Properties of Portland Cement Mortars Modified with Microfiber V. A. Dmitrienko(B) , S. A. Maslenikov, O. V. Pashkova, and N. A. Dmitrienko Institute of Service and Business (branch) of DSTU in Shakhty, 147, Shevchenko Str., Shakhty 346500, Russia [email protected]

Abstract. The flooding of old mine workings after the closure of coal mining enterprises in Shakhty provoked the development of deformation processes of the rock mass This, in turn, is accompanied by uneven deformations of the soil mass in the foundations and the formation of cracks in the stone structures of buildings. Based on the analysis of studies in the field of concrete and mortar modification, as well as experimental studies, the positive effect of poly-propylene microfiber additives on the deformation characteristics of Portland cement mortars has been revealed. A significant in-crease in the water demand of the mixture with microfiber additives and, accordingly, a decrease in the rate of strength gain was revealed. A specially developed method for measuring deformations made it possible to evaluate the deformation of samples when testing solutions for uniaxial compression. The growth of the limit value of deformation of modified solutions in comparison with the control one by three times has been established. This will reduce the stress concentration in the masonry and the likelihood of cracks in the structures. Keywords: Microfiber · Solution · Fiber concrete · Strength · Deformation

1 Introduction Despite the popularity and large volumes of using concrete in the construction sites, many researchers continue the experimental studies on improvement of composition properties [1–3]. A peculiar place in many studies has the fibro concrete. The scientists carried out the studies at the beginning of the last century. However, despite high performance qualities of fibro concrete, as well as its physical and mechanical properties; high frost resistance, moisture resistance, crack resistance, resistance to impact loads, adhesion and abrasion resistance [4, 5], there is no tendency to increase in the volume of its usage at present [6]. Nevertheless, due to the unique operational properties of the fibro concrete many scientists continue the research work [7–12] to determine its new properties and justify its practical benefits in various areas in building various facilities [13–17]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_24

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Foreign experience testifies to the widespread use of fibro concrete in earthquakeprone areas, for construction: tunnels, roads, bridges, industrial structures, etc. [18, 19], as the main building material.

2 Relevance of the Research Most of the territories of coal-mining regions are problematic from the point of view of construction facilities safety. The territory of the town Shakhty in Rostov region is no exception, since about two dozen mines worked out the fields of several coal seams for many decades. This was accompanied by significant deformation of the ground surface in the most of the places of the town and consequently by the appearance of defects on various structures. During the design and construction of new construction facilities in the 70 and 80 s of the last century, special design solutions were applied to minimize the problem of cracking of load-bearing structures. However, at the end of the 90 s of the last century, all coal enterprises were closed on the territory of the town. The cessation of pumping water from old mine workings led to the flooding of the worked-out spaces, the rise of the groundwater level and even their exit to the surface. The negative consequences of the “wet conservation” of the mining enterprises provoked not only flooding. In the stratigraphic structure of the region, there are layers of clay rocks, which became water barriers. The mining of coal seams with a complete collapse of the roof was accompanied by bad deformations and destruction of rock formations. This led to the hydraulic connection of aquifers and moistening of the entire rock mass at a depth of more than one kilometer. Experimental studies of moistened destroyed rocks indicate significant changes in the physical and mechanical properties of clay rocks. Significant deep rock pressure is accompanied by deformations of the destroyed zones of the massif and, accordingly, uneven shrinkage of the bases of building foundations. Many buildings on the territory of the town are built with load-bearing walls made of ceramic or silicate bricks. Since the brick and Portland cement mortar do not allow significant deformations, so the deformations in the building foundations lead to the formation of cracks. Therefore, cracks have begun to appear on buildings in various parts of the town in recent years. Even in the central part of the town, new cracks appeared on the buildings, which were protected by whole coal, and the previously formed ones are opened up to 4–5 cm or more (Fig. 1). To prevent crack formation in the design of objects in the 70–80 s of the last century, special measures were applied to strengthen structures in the former mining working out territories. However, cracks have also begun to appear on a number of new objects at present (Fig. 2). This means that even the use of special structures does not exclude the formation and development of cracks due to significant deformations of the foundation base.

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Fig. 1. Crack on the building of the drama theater in Shakhty.

Fig. 2. Crack on a residential building built in 1989.

There are many examples of appearing cracks on buildings built in 2010–2015 with the installation of monolithic reinforced concrete strips on the sole of the foundation and the basement (Fig. 3). Moreover, violations occur in areas under which coal mining was completed more than half a century ago.

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In addition, violations often appear in places which are not typical for stress concentration (in the door corners and window openings), and between windows (Fig. 4) and even between deformation seams. Under conditions of significant deformations of the foundations, an important factor in the reliability and durability of stone structures is crack resistance. Therefore, for the redistribution and equalization of stresses in masonry, the resistance of masonry mortar to the formation and development of cracks becomes important.

Fig. 3. Crack formation in stress concentration zones.

Fig. 4. Crack formation on new buildings.

The analysis of the current research in the field of application of various modifiers for regulating the properties of mortars and concretes, allows us to note that mortars modified with polypropylene fiber show a sufficiently high resistance to cracking [20–22].

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3 Methods and Materials Determining the effect of micro-reinforcement on the properties of the mortar was carried out by comparing bending and compressive strength of control samples without additives made in accordance with the GOST 310.4-81 and modified with microfiber. When preparing compositions with a ratio of cement and aggregate of 1:3, Portland cement of the Sebryakov Plant CEM I 42,5 and sand with Mk = 1.81 were used. Before determining the granular composition, the required amount of sand was mixed to reduce the influence of grain composition in different compositions. Polypropylene microfiber with a diameter of 20 µm and a length of 12 mm was used as a modifying additive for solutions. The water content was determined by the spread of a standard cone on a shaking table, which corresponded to the normal consistency of the mortar. For the control composition, the water-cement ratio was 0.45, with a cone spread of 108–110 mm. The amount of water in the modified compositions was initially determined from the condition of equal mobility with the control composition, which is, with a cone spread of 108–112 mm. The optimal amount of microfiber was determined by introducing fibers into the compositions in an amount of 1–3.0% by weight of cement, according to the strength characteristics. For bending and compression tests, the volume of the mortar was calculated from the condition of preparing 6 beam samples from each composition. The tests were carried out after 28 and 40 days after mixing. The increase in the hardening time before testing is explained by the fact that in order to obtain equal mobility in the modified compositions, it was necessary to increase the amount of water, which reduced the rate of hardening. However, a significant increase in strength was pointed out among samples after 28 days of hardening. Each composition was prepared and tested three times. Bending strength was determined by using the PI fixture (Fig. 5) as the arithmetic mean of the two largest values of the test results of three samples. The halves of the beams obtained after the bending test were used to determine the compressive strength.

Fig. 5. Bending test of samples.

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For loading the samples in determining bending and compressive strength, an E160N press was used, which has the function of recording and storing test results (loads) in digital format. Since the determination of the samples deformation is not provided by the press design, a special device was made for fixing the watch-type indicators on the ball bearing press. Since the ball bearing changes its position relative to the horizontal surface, the deformation value was determined as the average value of three indicators located at an angle of 120° relative to each other. Since there is no possibility of automatic fixation of the strain value in the ICH indicators, video recording of the indicators and a stopwatch was used, which made it possible to accurately record the strain values of the sample every second during the processing of the video file. The E160N press has the ability to continuous record the values of load and stress until the destruction of the sample, but the count is made every 0.05 s. The loading process sometimes takes more than a minute, so several hundred values are recorded in the press memory. In order to reduce the time spent on processing the results of research, the process of starting the hydraulic system of the press and the stopwatch was carried out simultaneously, which made it possible to synchronize the readings of the load and deformation of the samples. At the same time, a special program was used to process information from the memory of the press, which ensures the selection of every twentieth value, this makes it possible to obtain a sample of loads with an interval of 1 s.

4 Results To determine the optimal dosage of polypropylene microfiber, samples containing from 1 to 3.0% fiber by weight of cement were tested. To assess the effect of the dosage of polypropylene microfiber on the strength of the solution, six compositions were tested with an interval of increasing the dosage of the fiber by 0.5%. Based on the results of tests of samples of beams for bending and compression with polypropylene fiber, graphs of the dependence of the strength of the solution samples on bending (Fig. 6) and compression (Fig. 7) are constructed. The research results shown in Fig. 6 indicate a significant increase in bending strength with an increase in fiber dosage. At the same time, the compression test is characterized by a decrease in the effect on strength indicators with an increase in the dosage of microfiber over 2% by weight of cement (see Fig. 7); therefore, an increase in dosage over 2% is not advisable. During a visual inspection of the beam samples after bending tests, it was noted that most of the fibers do not break during the formation of a crack during bending; therefore, despite the opening of the crack, the halves are firmly connected and partially retain their load-bearing capacity. Moreover, most of the fibers do not break during the formation of a crack during bending, but are pulled out. This indicates a low adhesion of the fibers to the cement stone and, accordingly, the low efficiency of the use of the strength properties of the fibers.

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Fig. 6. Dependence of the bending strength of the solution samples on the microfiber content.

Fig. 7. Dependence of the compressive strength of the solution samples on the microfiber content.

It was also established that the values of deformations at limiting stresses of solutions modified with polypropylene microfiber are several times higher than the deformations of the control ones. Therefore, after determining the optimal dosage of microfiber, studies were carried out on the deformation of halves of sample beams of the composition modified with polypropylene microfiber in an amount of 2% by weight of cement. The tests were carried out to determine the compressive strength of the samples (Fig. 8). The obtained test results of the control and one of the modified composition are shown in Table 1 and in the graphs (Fig. 9 and 10). The test results of equally mobile Portland cement solutions show that the introduction of polypropylene microfiber is accompanied by an increase in water demand and a decrease in strength growth with a hardening period of 28 days. With an increase in the hardening period, the bending strength is 17,4% higher than the control samples, and the compression strength is only 3,0% higher.

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Fig. 8. Measurement of deformations of samples under loading.

Fig. 9. Loading graph of the control sample.

However, according to the results of the research, it was found out that, the destruction of the halves of the beams during compression of without additives occurs with a deformation of more than 0.45 mm, and the modified 1.24–1.50 mm, that is, three times higher than the control ones. During compression, the destruction of control samples occurs with the formation of a prism and separation of the upper parts of the sample (Fig. 10). At the same time, samples with a microfiber content of 2% during compression testing do not split into parts even when deformed up to 2 mm. On all tested samples (Fig. 11), the prints of load plates up to 0.95 mm deep are clearly visible. Moreover, the stratification of the sample does not occur until the press stops while reducing the load by 30% of the maximum. Reduced mobility, even with small doses of microfiber, significantly complicates the laying and requires an increase in the water-cement ratio. Therefore, to design the

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Fig. 10. Loading graph of the modified sample.

Table 1. Results of determining the deformability of mortar samples. Control sample

Modified sample

Voltage, MPA

Deformations, mm

0.3082

0.03

Voltage, MPA 0.2165

Deformations, mm 0.06

0.6057

0.04

0.3508

0.15

1.3158

0.05

0.6622

0.26

2.6509

0.07

1.2988

0.37

4.6972

0.08

2.4995

0.45

7.0598

0.1

4.276

0.52

9.4877

0.12

6.3216

0.58

11.8633

0.14

8.4879

0.65

14.1104

0.17

10.675

0.72

16.1933

0.19

12.8176

0.78

18.1236

0.22

14.9019

0.84

19.9016

0.25

16.8807

0.9

21.4978

0.29

18.7203

0.96

22.8604

0.32

20.3972

1.03

24.0043

0.34

21.9264

1.09

24.9232

0.37

23.3106

1.16 (continued)

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Table 1. (continued) Control sample

Modified sample

Voltage, MPA

Deformations, mm

Voltage, MPA

Deformations, mm

25.5739

0.4

24.5368

1.22

26.1215

0.42

25.5935

1.28

26.5536

0.45

26.4281

1.33

26.8754

0.49

27.0401

1.39

27.1449

0.58

27.5267

1.43

27.3620

0.79

27.8748

1.46

27.2823

0.98

28.0897

1.48

28.1846

1.5

28.1366

1.52

27.9773

1.54

27.7733

1.56

27.4034

1.6

composition of the masonry mortar with the required mobility, it is necessary to calculate the amount of mixing water. Studies of the effect of the microfiber content on the mobility of the solution and the water-cement ratio (W/C) were performed in accordance with GOST 28,013 by immersion in the composition of the reference cone of the PGR device (STROITSNIL Cone). As a result, a large variation in the immersion of the cone was revealed when testing one composition—up to 1.8 cm, which in some cases exceeded the influence of the modifier. In addition, it was found that an increase in the amount of water in the compositions for obtaining the mobility of Pk 2 and Pk 3 leads to a significant decrease in the strength and deformation characteristics of the solutions and a correspondingly positive effect of the modifier. Therefore, determining the required amount of water in formulations with different microfiber content, to obtain the mobility of Pk 1 with a cone immersion up to 4 cm, a technique with a statistical evaluation of the results was adopted. To do this, each composition was made three times on different days. When preparing the first batch, the amount of water was taken in such a way that the average value of the cone immersion was 3.5–4.0 cm. In the next two batches, the water content was not changed. The cone was immersed in a vessel with a solution seven times. The largest and smallest precipitation values were removed from the sample. From the three tests of each composition, after calculating the measurement error, a sample was selected with the smallest measurement error, but not more than 25%. In this sequence, tests of all compositions were carried out.

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The average results of three tests of each mortar mixture are shown in Table 2 and Fig. 12. The measurement error in the samples of modified solutions is 19.88–24.74%, and the error of the average values of all samples is 3.39%.

Fig. 11. Destruction of the half of the beam without microfiber.

Fig. 12. Trace from the load plate during compression testing of a sample modified with microfiber.

The analysis of the obtained results of the above studies indicates an increase, with a microfiber content of 1–2% by weight of cement, of the water-cement ratio is directly

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proportional to the dosage of the modifier. The accepted research methodology allowed for a high degree of reliability (see Fig. 13) establish the dependence of the water-cement ratio on the dosage of microfiber.

Fig. 13. Dependence of the water-cement ratio on the microfiber content with an average mobility of 3.54–3.64 cm.

Table 2. Results of determining mobility of modified mixtures. Fiber content, %

W/C

Cone shrinkage, cm

Average value, cm

Measurement error, %

0

0.733

3.4

3.62

8.84

3.60

23.79

3.54

23.64

3.7 3.6 3.9 3.5 0,5

0.770

3.6 4.3 3.8 2.9 3.4

1

0.797

3.1 4 3.8 3.9 2.9

(continued)

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V. A. Dmitrienko et al. Table 2. (continued)

Fiber content, %

W/C

Cone shrinkage, cm

Average value, cm

Measurement error, %

1,5

0.823

4

3.60

19.88

3.64

24.74

3.2 4.1 3.5 3.2 2

0.873

4.1 3.9 4 3.4 2.8

5 Conclusion According to the results of studies of sand-cement mortar, it was found out: the introduction of polypropylene microfiber into the composition of sand-cement mortars in an amount of more than 2% by weight of cement leads to a significant increase in the water demand of the mixture and a decrease in compressive strength: • the presence of microfiber eliminates the separation of solution particles during the destruction of beam samples with deformations up to two mm; • during the compression test of the halves of the control samples-beams, the maximum deformations (at the moment of destruction) do not exceed 0,45 mm; • the ultimate deformations of samples of solutions modified with polypropylene microfiber were 1,24–1,50 mm • an increase in the ultimate deformations of modified compositions in masonry will allow redistributing stresses and, accordingly, reduce the likelihood of cracking; • the obtained dependence of the water-cement ratio W/C on the microfiber content is approximated by a linear function, and allows determining the required amount of mixing water during experimental studies of modified formulations.

References 1. Abrahamyan SG, Iliev AB, Lipatova SI (2018) Modern additive construction technologies. Part 2. Engineering Bulletin of the Don, 1. https://ivdon.ru/ru/magazine/archive/n1y2018/ 4748 2. Nizina TA, Balykov AS, Saraykin AS (2015) Acad Bull UralNIIproekt RAASN 4:91–95 3. Perfilov VA, Kotlyarevskaya AV, Kanavets UV (2016) Bulletin of the Volgograd State University of Architecture and Civil Engineering. Ser: Build Archit 44–2(63):111–118

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4. Leone M, Centonze G, Colonna D, Micelli F, Aiello MA (2018) Fiber reinforced concrete with low content of recycled steel fiber: shear behavior. Constr Build Mater 161:141–155. https://doi.org/10.1016/j.conbuildmat.2017.11.101 5. Ortiz J, De la Fuente A, Pérez IS (2017) Steelfibre-reinforced self-compacting concrete with 100% recycled mixed aggregates suitable for structural applications. Constr Build Mater 156:230–241. https://doi.org/10.1016/j.conbuildmat.2017.08.188 6. Gorb AM, Voilokov IA, Fibrobeton—The history of the issue. Regulatory framework, problems and solutions. https://monolitpol.ru/files/monolitpol026.pdf 7. Ibe EE, Shugurova AV (2017) Prospects for the use of fibroblast in the construction of hydraulic structures. Online J “Sci Stud” 9(1). https://naukovedenie.ru/PDF/61TVN117.pdf 8. Novikov NS (2016) Fire resistance and strength of fiber-reinforced concrete structures. Technosp Secur Technol 3(67):122–127. https://academygps.ucoz.ru/ttb/2016-3/2016-3.html 9. Stradanchenko SG, Pleshko MS, Armeiskov VN (2013) Development of effective fiber concrete compositions for underground construction. Eng Bull Don, 4. https://ivdon.ru/ru/mag azine/archive/n4y2013/1994 10. Klyuev SV, Netrebenko AV, Durachenko AV, Pikalova EK (2014) Monolithic fiber concrete for floors of industrial buildings. Collect Sci Pap Sworld 19(1):29–32 11. Klyuev SV, Avilova EN (2013) Fine-grained fibroconcrete using polypropylene fiber for covering highways. Bull V.G Shukhov BSTU 1:37–40 12. Klyuev SV (2014) High-quality fiber concrete for monolithic construction. Int Sci Res J 11(2):29–32 13. Klyuev AV, Klyuev SV, Netrebenko AV, Durachenko AV (2014) Fine-grained fiber reinforced with a new fiber. Bull BSTU named after V.G Shukhov 4:67–72 14. Klyuev SV (2012) The use of composite binders for the production of fiber-reinforced concrete. Technol Concr 1–2(66–67):56–57 15. Klyuev SV (2014) Development of dispersed-reinforced fine-grained concrete based on technogenic sand and composite binder. Int Sci Res J 11(2):27–29 16. Pothisiri T, Soklin C (2014) Effects of mixing sequence of polypropylene fibers on spalling resistance of normal strength concrete. Eng J 18(3):55–64 17. Enfedaque A, Alberti M, Galvez JC, Beltran M (2018) Constitutive relationship of polyolefin fibre-reinforced concrete: experimental and numerical approaches to tensile and flexural behavior. Fatigue Fract Eng Mater Struct 41(2):358–373. https://doi.org/10.1111/ffe.12688 18. Gafarova NE (2016) Fibroconcrete for earthquake-prone construction areas. Int J Appl Fundam Res 9–2:179–181. https://applied-research.ru/ru/article/view?id=10213 19. Kamal MM, Safan MA, Etman ZA, Kasem BM (2014) Mechanical properties of selfcompacted fiber concrete mixes. HBRC J 10(1):25–34 20. Panda B, Paul SC, Tan MJ (2017) Anisotropic mechanical performance of 3D printed fiber reinforced sustainable construction material. Mater Lett 209:146–149. https://doi.org/10. 1016/j.matlet.2017.07.123 21. Miroshnichenko KK, Savitsky NV (2011) Technology of preparation of high-quality nonshrinkable fiber concrete of high mobility in the conditions of a construction site for the device of gravy for structures and technological equipment. Visnik PDABA 11–12:73–78 22. Yemelyanova IA, Shevchenko VI (2014) Modeling of the mixing process of concrete mixture with polypropylene fiber. Technol Concr 3:36–38

Energy-Saving Technologies for the Construction and Operation of Buildings in the Arctic Zone of the Russian Federation E. P. Sharovarova1,2,3(B) and V. N. Alekhin1,2,3 1 Ural Federal University, 19, Mira St., Ekaterinburg 620002, Russia

[email protected]

2 Ural State University of Architecture and Art, 23, K. Liebknecht St., Ekaterinburg 620075,

Russia 3 TECHCON Ltd, 50A, Lenina St., Ekaterinburg 620075, Russia

Abstract. This article provides a brief description of the climate, resources, and problems of energy supply, construction and operation of the Arctic zone. Harsh climatic conditions significantly complicate the development of infrastructure and the development of resources. In recent decades, there has been a decrease in the population of the Arctic zone due to negative migration and a decrease in the rate of natural increase. Active exploration and development of the Arctic zone is hampered by numerous socio-economic problems of the territory, the lack of a centralized energy supply, and a high level of unemployment. To solve these problems, it is necessary to create comfortable conditions for people to live and attract the able-bodied population. The problem of energy supply to decentralized areas can be partially solved by using the generated thermal energy in the process of mining. The authors proposed the concept of utilization of thermal energy of production for the energy supply of buildings. As examples of enclosing structures for prefabricated buildings in hard-to-reach areas, a multilayer panel with an air gap and a hemisphere house made of three-layer panels mounted on a metal frame are given. The given structures of buildings reduce the resource intensity of construction and fully comply with the heat and power requirements for buildings. The paper presents the results of thermotechnical calculation of a fragment of a wall made of a multilayer panel with an air gap. Keywords: Energy-saving technology · Energy efficiency of buildings · Heat recovery · Renewable energy sources · Arctic zone

1 Introduction The Arctic zone plays an important role in the socio-economic development of the Russian Federation. The Arctic zone includes the territories of the Murmansk region, the Nenets Autonomous Area, the Chukotka Autonomous Area, the Yamal-Nenets Autonomous Area and parts of the territories of the Republics of Karelia, Komi, Sakha, the Krasnoyarsk Territory and the Arkhangelsk Region [1]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_25

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The territories of the Arctic zone of the Russian Federation contain reserves of natural gas, oil, platinum, tin, nickel, titanium, apatite ores and ores of rare earth metals [2]. Within the framework of the current state program “Socio-economic development of the Arctic zone of the Russian Federation”, mechanisms for state support and stimulation of entrepreneurial activity have been developed, measures have been taken to create new jobs, improve the quality of life and develop human capital [1, 3, 4]. The Arctic zone is characterized by an extremely harsh climate, with strong winds, low rainfall and very low temperatures. The average temperature of the warmest month is about 0 °C. Severe climatic conditions significantly complicate the development of infrastructure and the development of resources [5–8]. The area of the Arctic zone of the Russian Federation is about 3 million square kilometers (approximately 18% of the territory of the Russian Federation), where about 2.4 million people live (less than 2% of the population of the Russian Federation). The average population density is about 0.8 people per square kilometer, which is about 10 times less than the Russian average. In recent decades, there has been a decrease in the population of the Arctic zone due to negative migration and a decrease in the rate of natural increase. Active exploration and development of the Arctic zone is hampered by numerous socio-economic problems of the territory, the lack of a centralized energy supply, and a high level of unemployment. To solve these problems, it is necessary to create comfortable conditions for people to live and attract the employable population.

2 Prospects for the Development of Renewable Energy in the Artic Today, one of the factors hindering the development of renewable energy sources (RES) in Russia is their low competitiveness in various regions of the Russian Federation. If we consider the Arctic and its features (climate, high cost of imported fuel, high tariffs for electricity and heat), which were mentioned above, then the competitiveness of the introduction of renewable energy sources is higher compared to most regions of Russia. The use of renewable energy sources will shortly reduce the cost of building and maintaining public infrastructure. Due to the very cold climate of low population density and the remoteness of settlements from each other, it is very expensive to build new energy facilities; in some areas, it is almost impossible. Thanks to the use of renewable energy, it will be possible to significantly improve the ecological situation in the region. The entire energy system of the Arctic operates on imported coal, fuel oil, diesel fuel, harmful emissions from which pollute the environment. The main directions for the development of alternative energy in the Arctic regions can be projects in the field of wind, solar energy, biofuels and marine energy. It is known that in the coastal areas of the White and Barents Seas, as well as in the Novaya Zemlya and Franz Josef Land archipelagos, the wind speed reaches 5–8 m/s. In the near future, the first wind power plant in the North with a capacity of 201 MW will start operating in the Kola district near Murmansk, it will be the largest wind power plant in Russia. The total capacity of all Russian Arctic wind farms is 210 MW. Usually the units are used either separately or together with solar panels and diesel generators [9–12]. In the eastern subarctic regions of Yakutia, installations for the generation of solar energy may be involved. In cold climates, the potential for solar energy

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production increases. The lower the ambient temperature, the more efficient the solar cells work: at 0 °C, the solar cell will have a 10% higher efficiency than at 20 °C. Geothermal energy is considered very promising. The most perspective for heat and power purposes are thermal waters, which occur at a depth of 1 km. It is advisable to build geothermal stations in remote settlements, especially if wells have been drilled for oil and gas production there: power plants can be installed without large capital costs [13].

3 The Concept of Utilization of Thermal Energy of Production for Heating Buildings Currently, there is an active development of mineral deposits in the Arctic zone with the participation of engineers, surveyors, mechanics and other specialists. To create comfortable conditions for long stays, prefabricated buildings with energy efficient fences can be built. The problem of energy supply to decentralized areas can be partially solved by using the generated thermal energy in the process of mining. For example, in the processing of nickel ores, technologies with significant heat release are used. First, the ore is dried in furnaces, the resulting mass is diluted with coal coke and melted into an intermediate product of metallurgy—matte. The slag obtained in the process of remelting is sent to the dump, the matte is then blown in the convector. The resulting white nickel matte, containing a significant amount of nickel, is again crushed and ground, after which it is sent for firing. Next, electrolytic refining is carried out to obtain nickel [14, 15]. Most processes occur with the release of thermal energy. For heat recovery in industry, waste heat boilers (2) are used, which use the heat of waste gases from metallurgical units (1), industrial furnaces, and power plants to heat the coolant [16, 17]. The exhaust gases used in such boilers have a temperature of 350–1500 °C. The heated coolant (4) can be used in heating systems (3), as well as used in the gap of the warm contour of buildings (Fig. 1).

Fig. 1. The concept of the use of thermal energy in nickel production for heating buildings.

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4 Design of Energy Efficient Buildings in Harsh Climatic Conditions The shape and enclosing structures of the building should be designed in such a way as to minimize heat losses and reduce the resource intensity of construction and transportation of building materials. One of the examples of buildings designed for living is the project of a compact hexagonal house in the form of a dome with a metal load-bearing frame on a pile foundation [18, 19]. Enclosing structures are made of sandwich panels 250 mm thick. Typical small metal elements and low weight of structures allows the assembly of the building frame in the shortest time with minimal use of construction equipment. Figure 2 shows the layout of the coating structures and the cross-section. Figure 3 shows the following design solutions: a constructional unit for supporting roof structures on the pile head and a connection with a beam (1), a constructional unit for connecting metal elements of the roof structure (2), a constructional unit for connecting roof elements in the area of the upper ring.

Fig. 2. The layout of the coating structures and the cross-section.

Low-rise buildings of administrative and amenity complexes, hotels, residential complexes in the Arctic zone are proposed to be built from prefabricated structures (Fig. 4). Foundations (2) on permafrost soils (3) are often designed in such a way as to preserve the frozen state of the soil, in which it has a high bearing capacity. At the same time, it is important to design the thermal insulation of the lower floor of the building to prevent soil heating. To reduce the complexity of construction in the Arctic zone, metal columns and beams (1) can be used as a supporting frame, enclosing structures are proposed to be made of prefabricated multilayer panels with an air gap (4). When an excessive amount of heat is generated during production processes, the heated coolant can be used to maintain a positive temperature inside the building envelope.

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Fig. 3. Constructional units.

Fig. 4. The scheme of building construction in the arctic zone.

The design of the multilayer panel is an inner and outer sandwich panels (3, Fig. 5), interconnected by a metal frame made of perforated profiles (2). The fixing element (1) is installed at the corners of the inner sandwich panel [20–22]. Depending on the

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methods of heat recovery, heated air can be supplied to the panel gap, or tubes with a coolant can be installed in a closed gap.

Fig. 5. General view of a sandwich panel with an air gap.

The duration of the heating period in the Arctic zone is about 10 months. Building heating systems should be designed based on the characteristics of production process technologies and methods of heat recovery. The design of panels with an internal gap allows the use of both a heating system with antifreeze and air heating systems, as well as a combination of them.

5 Thermal Analysis of Sandwich Panels with a Gap The thermal analysis was carried out in the ANSYS software package. A fragment of a wall without windows was chosen for the calculation. The analysis model made in SOLIDWORKS (Fig. 6) consists of three panels for three floors (with dimensions of 1.2 × 3 m (H)), a parapet panel (with dimensions of 1.2 × 0.9 m (H)) and a distribution tray under the panel of the 1st floor. In the course of the calculation, it was found that at an outdoor air temperature above minus 18 °C with a single air exchange in the building, heating devices are not required. At temperatures below minus 18 °C, additional measures must be taken to ensure that these requirements are met. It was determined that with a single air exchange and an outdoor temperature of minus 32 °C, it is sufficient to install a “warm floor” with a specific power of at least 70 W/m2 . It was also determined that at the same outdoor air temperature of minus 32 °C and a twofold increase in air exchange, the temperature of the inner wall corresponds to the

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Fig. 6. SOLIDWORKS model.

standard temperature without the use of a “warm floor” device. It should be noted that an increase in the air exchange rate in the building and, accordingly, an increase in the mass flow rate in the ventilated gap of a multilayer panel is less effective than a floor heating device. The calculation was made for a three-story building. Figure 7 shows that when the number of storeys is reduced to 1–2 floors, the temperature at the exit from the panel gap will be higher: about 21 °C for 2 floors, about 23 °C for 1 floor.

6 Conclusions Improving the efficiency of energy supply in hard-to-reach and isolated areas based on modern technologies is an important state task. Most settlements in the Arctic zone are heated and lit by separate power units. There are no alternatives to diesel in many parts of the Russian Federation yet. At the same time, fuel still needs to be delivered to navigation with northern delivery, which further increases its cost. As a rule, residents of Arctic settlements receive energy via a local network from substations operating on diesel generating installations. The high cost of energy obtained with such labor is one of the main problems for the budgets of the northern regions. Other heat and power facilities in the Arctic are needed of repair, and widespread diesel fuel is considered too expensive and harmful to the environment. One of the potentially effective methods of modernizing local energy in isolated areas is the partial or complete replacement of diesel power plants with energy facilities based on renewable energy sources and small nuclear power.

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Fig. 7. Air temperature distribution in the ventilated gap of the panel (at outside temperature minus 13.7 °C).

Acknowledgements. The work was supported by Act 211 Government of the Russian Federation, contract no. 02.A03.21.0006. Thanks to everyone who made useful comments on the text.

References 1. Resolution of the government of the Russian Federation 484 (2021) On approval of the state program of the Russian Federation: socio-economic development of the Arctic zone of the Russian Federation. https://docs.cntd.ru/document/603154509. Accessed 25 June 2022 2. Bortnikov NS, Lobanov KV, Volkov AV, Galyamov AL, Murashov KY (2015) Arkticheskie resursy cvetnyh i blagorodnyh metallov v global’noj perspective (Arctic Resources of Colored and Noble metals in a global perspective). Arktika: ekologiya i ekonomika 1(17):38–46

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3. Priorities of the Chairmanship of the Russian Federation in the Arctic Council (2021–2023). https://arctic-council-russia.ru/. Accessed 19 June 2022 4. Investment portal of the Arctic zone of Russia (2022). https://arctic-russia.ru/. Accessed 14 June 2022 5. Sherstyukov BG (2016) Klimaticheskie usloviya Arktiki i novye podhody k prognozu izmeneniya klimata (The climatic conditions of the Arctic and new approaches to the forecast of the climate change). Arktika I Sever 24:39–61 6. Hon VC, Mohov II (2008) Analiz ledovyh uslovij v arkticheskom bassejne i perspektivy razvitija severnogo morskogo puti v XXI veke (Analysis of ice conditions in the Arctic basin and prospects for the development of the northern sea route in the 21st century). Problemy Arktiki i Antarktiki 1(78):59–65 7. Sedova NB, Kochemasova EY (2017) Ekologicheskie problemy Arktiki i ih social’noekonomicheskie posledstviya (Environmental problems of the Arctic and their socioeconomic effects). Vserossijskij ekonomicheskij zhurnal EKO 5:160–171 8. Rudenko D (2015) Analiz demograficheskih processov v Rossijskoj Arktike (The population dynamics in the Russian Arctic). M.I.R. (Moderniz Innov Res) 6(4):51–57 9. Alternative energy in the Arctic (2020). https://goarctic.ru/work/alternativnaya-energetika-varktike/. Accessed 15 June 2022 10. Potravniy IM, Yashalova NN, Boroukhin DS, Tolstoukhova MP (2020) Ispol’zovanie vozobnovlyaemyh istochnikov energii v Arktike: rol’ gosudarstvenno-chastnogo partnerstva (The usage of renewable energy sources in the arctic: the role of public-private partnership). Ekonomicheskie i social’nye peremeny: fakty, tendencii, prognoz 13(1):144–159 11. Berdin VH, Kokorin AO, Yulkin GM, Yulkin MA (2017) Vozobnovlyaemye istochniki energii v izolirovannyh naselennyh punktah Rossijskoj Arktiki (Renewable energy sources in isolated communities in the Russian Arctic). WWF: World Wildlife Fund, p 80 12. Zmieva KA (2020) Problemy energosnabzheniya arkticheskih regionov (Problems of energy supply in the Arctic regions). Rossijskaya Arktika 8:5–14 13. The predominant types of alternative energy sources in the Arctic region of Russia (2020). https://magazine.neftegaz.ru/articles/arktika/543629-preimushchestvennye-vidyalternativnykh-istochnikov-energii-v-arkticheskom-regione-rossii/. Accessed 9 June 2022 14. Informacionno-tekhnicheskij spravochnik: proizvodstvo nikelya i kobal’ta (Information and technical reference: Nickel and cobalt production) (2016). Buro NDT, Moscow, p 202 15. Kablov EN, Ospennikova OG, Sidorov VV, Rigin VE, Kablov DE (2011) Osobennosti tekhnologii vyplavki i razlivki sovremennyh litejnyh vysokozharoprochnyh nikelevyh splavov (Features of the technology of smelting and pouring modern foundry high-temperature nickel alloys). Vestnik MGSU im. N.E. Baumana. Ser. “Mashinostroenie” (Series “engineering”), p 68–78 16. Di Maria A, Merchan M, Marchand M, Eguizabal D, Garcia de Cortazar M, Van Acker K (2022) Evaluating energy and resource efficiency for recovery of mettalurgical residues using environmental and economic analysis. J Clean Prod 356:131790 17. Zuo Z, Feng Y, Dong X, Luo S et al (2022) Advances in recovery of valuable metals and waste heat from copper slag. Fuel Process Technol 235:107361 18. Makarov AV, Zhuravlev AV, Tyan VU (2019) Osobennosti stroitel’stva fundamentov v vechnomerzlyh gruntah (Features of the construction of foundations in permafrost soils). Inzhenernyj vestnik Dona 1(52) 19. Krylov DA, Fedotov AA (2013) Temperaturnyj rezhim vechnomerzlogo grunta pod zdaniem so svajnym fundamentum (Temperature regime of permafrost soil under a building with a pile foundation). Vestnik MGSU im. N.E. Baumana. Ser. “Estestvennie nauki” (Series “Natural Sciences”) 3:106–116

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20. Sharovarova E, Alekhin V, Shcheklein S, Novoselova N, Hussein A (2022) Geothermal power supply of buildings in harsh climatic conditions. In: Proceedings of the 5th international conference on construction, architecture and technosphere safety—ICCATS 2021, Lecture Notes in Civil Engineering, vol 168. Springer, pp 181–189 21. Sharovarova E, Alekhin V, Skachkov A (2020) Multilayer facade panel structure analysis. IOP Conf Ser: Mater Sci Eng 962(2):022076 22. Sharovarova E, Alekhin V, Avdonina L (2020) The potential for the development of renewable energy generation in Russian territories where the power supply system is decentralized. IOP Conf Ser: Mater Sci Eng 962(2):022075

Influence of Surface Tension Forces of Modifiers on Some Properties of Composite Materials A. Pichugin1 , A. Pchelnikov1 , O. Smirnova2(B) , and S. Tkachenko2 1 Novosibirsk State Agrarian University, 160 Dobrolyubova Str., Novosibirsk 630039, Russia 2 Novosibirsk State University of Architecture and Civil Engineering (Sibstrin), 113

Leningradskaya Str., Novosibirsk 630008, Russia [email protected]

Abstract. The influence of surface tension forces of various types of vegetable oils on the light transmission of wood has been studied. The results of testing for light transmission, physical-chemical and physical-mechanical properties of more than 25 compositions that provide light transmission after wood bleaching are presented. Graphs of the light transmission of wood from some properties of vegetable oils have been constructed and a regularity of the properties of oils on the light transmission of wood has been established, which consists in a decrease in light transmission with an increase in the surface tension force. Based on the studies carried out, it was concluded that when impregnated with vegetable oil modified with turpentine, a high light transmission result can be obtained. A binary composition of vegetable oil with 10–20% turpentine is recommended, which provides significantly better light transmission with a fairly low deformability and high thermal stability. Used in this composition, corn or sunflower oil are quite affordable and widespread products, and turpentine is also a non-deficient chemical product that is well combined with both oil and wood. Options for reducing these indicators due to the introduction of thinning components are proposed. Keywords: Surface tension · Light transmission · Vegetable oil · Wood · Fluidizing components

1 Introduction The molecules of a substance in the liquid state are located at a certain fairly close distance from each other and have great freedom. Each liquid molecule, although sandwiched between other neighboring molecules, can make oscillatory movements around its centers of equilibrium. In this case, the molecules are not tied to certain points and can move throughout the entire volume of the liquid, which is called the phenomenon of fluidity. At the junction between the liquid and the gas, an interface is formed, which is under special conditions compared to the rest of the liquid mass. The molecules in the boundary layer of the liquid are not surrounded by other molecules of the same liquid from all sides and are attracted only by the molecules of the inner layers, i.e., under the action of the resulting attractive force, they are drawn into the liquid. The number © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_26

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of molecules remains on the surface, at which the surface area of the liquid is minimal for a given volume. The molecules of the surface layer exert molecular pressure on the liquid, pulling its surface to a minimum. This effect is called surface tension. Surface tension is a phenomenon of molecular pressure on a liquid caused by the attraction of molecules of the surface layer to molecules inside the liquid in a state of equilibrium. Such an equilibrium is possible only by reducing the distance between the molecules of the surface layer and the underlying particles of the liquid [1–4]. Special conditions for finding the liquid are noted in the capillaries, which is typical when impregnating wood with various modifiers. Complex processes are formed here, because capillary phenomena occur in the narrow space of cylindrical tubes with a diameter of less than a millimeter, called capillaries. The liquid, passing through the capillaries or being absorbed into the porous body, rises up or falls down in the capillaries. This process is called capillarity. In the case of a wetting liquid, the forces of attraction between the molecules of the liquid and the solid exceed the forces of interaction between the molecules of the liquid, so the liquid is drawn into the capillary, and the liquid rises in the capillary until the resulting force acting on the liquid upwards is balanced by the gravity of the liquid itself. At the same time, it should be noted that the speed of liquid movement through the capillaries is influenced by the physical properties of the liquid itself, including viscosity and surface tension force. Thus, one of the important components in achieving light transmission is the optimal surface tension, which ensures uniform distribution of the modifier over the entire volume of wood [5–7].

2 Theoretical Substantiation of the Method for Determining the Surface Tension Forces of a Liquid The surface tension coefficient α is defined as the work that must be expended for an isothermal reversible increase in the unit area dS of the liquid surface at a constant volume [8, 9]. Consider an isothermal reversible increase in the surface layer of a liquid. The work of the external force will be α dS. , the film itself will do the work—α dS. According to the first principle of thermodynamics, the surface layer must be informed of the heat δQ∗ (* the sign δ indicates that the amount of heat is not a complete differential, since it depends not only on the initial and final states of the system, but depends on the transition path), which is spent on changing the internal energy dU and the work performed by the film: δQ = dU − ads

(1)

For a reversible process δQ = Tds, where T—is the absolute temperature, ds—is the entropy change. Therefore, Eq. (1) will be rewritten as: dU = Tds + ads

(2)

It is known from thermodynamics that all work in an isothermal process equal ta change in the free energy of the system. Since the free energy of the system: F = U − TS

(3)

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where U is the internal energy and TS is the bound energy, then from Eq. (3) the change in free energy: dF = dU − Tds − SdT

(4)

substituting the value of dU from expression (4) into Eq. (2), we obtain: dF = −SdT + ads

(5)

from here: SdT = −

dF ∂F ;a = dTs ∂ST

Substituting the value of S into Eq. (3), we find: F =U +T

∂F ∂Ts

(6)

Since the surface tension coefficient does not depend on the area of the film, but depends on the temperature and, according to the definition, F = as., substituting the value of F into Eq. (6), we obtain:   da s (7) U = a−T dT Dividing the left and right sides of Eq. (7) by the area s. , we similarly obtain: U =a−T

da dT

(8)

where U —is the total internal energy of a unit of area, a—is the free energy of a unit of da —is the bound energy of a unit of area. area, T dT From the first principle of thermodynamics, one can understand the physical meaning of Eq. (8). When an isothermal expansion of a film per unit area, it must be given heat: Q = U − a = −T

da dT

(9)

da The value of Q—is positive, since it follows from experience that dT < 0. It can be seen from (8) that by determining the surface tension, a of a liquid at a given temperature and the dependence of its surface tension on temperature, it is possible to calculate the free, bound and full energy. In this paper, the surface tension is measured by the elevation of this liquid in the capillary. When a wetted capillary of radius r is immersed in a liquid, its surface in the capillary will become concave and the pressure under it will decrease by 2a/r. Therefore, the liquid will rise to a height h at which:

2

a = pgh r

(10)

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here ρ is the density of the liquid, g is the acceleration of gravity. From (10) we get: a=

pghr 2

(11)

The calculation according (11) has the disadvantage that to measure the height of elevation, the cathetometer must be pointed twice—at the meniscus and on a flat surface, which is difficult and reduces the accuracy of the result. Therefore, they use two capillaries of different radii. If we denote the height of the liquid rise in one capillary by h1 , and in the other by h2 , then using the formula (10), we can write: 2a 2a ; h2 = r1 pg r2 pg   2a 1 1 − h1 − h2 = pg r1 r2 h1 =

therefore α=

pg(h1 − h2 )r1 r2 2(r2 − r1 )

(12)

3 Materials and Research Results Wood pretreated with chemical reagents turns white and after impregnation with polymer or oil compositions, the material becomes available for light to pass through the material. In our studies, various vegetable oils and other organic liquids with low viscosity were used for comparison, the use of which was found in domestic and foreign practice [10]. The light transmission indicators of wooden samples impregnated with various oils depend on the degree of moisture content of the material and have a fairly high degree of reduction during drying, amounting to several tens of percent. However, not all impregnating compositions have the same level of light transmission reduction of the material. Thus, polyethylene glycol has a large absolute decrease in the light transmission index— 78% or 353 lx out of the initial 455 lx. Olive oil, although it has a fairly significant absolute decrease in the light transmission index, however, compared to the initial value, this is less than 38%. The minimum decrease was noted for samples impregnated with linseed oil—16%. Original and little-used oils have average quality reduction rates of up to 30%. These are peanut, mustard, cotton, sesame oils. Important technological characteristics of impregnating oils are their viscosity and surface tension, which affect the completeness and speed of passage of the impregnating liquid through the capillaries in wood samples. Testing of rheological characteristics— viscosity—was carried out on a viscometer VZ-4. All tested formulations had viscosity values ranging from 18 to 23 c according to VZ-4 (Table 1). The exception was the compositions of polyethylene glycol and turpentine, the viscosity of which was 10–12 °C.

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Table 1. Light transmission of wooden samples impregnated with various oils indicators name of the impregnating substance. Refractive index at Density at conditional viscosity

Light transmittance in 20 °C

The dry in 20 °C, Kg/m3

The wet In, c

The unfiltered state, lk \|/ In the dry

In the wet

In the unfiltered state Sunflower oil 1.474–1.475

947

20.36

255

410

Corn oil

1.471–1.474

947

19.91

265

432

Mustard oil

1.470–1.474

920

20.89

210

282

Olive oil

1.466–1.471

914

22.78

338

540

Sesame oil

1.469–1.471

946

20.04

190

270

Rapeseed oil

1.472–1.476

912

22.40

172

310

Cottonseed oil

1.474–1.476

949

25.57

143

212

Linseed oil

1.488–1.487

940

18.82

145

172

Peanut oil

1.468–1.472

911

22.68

185

242

Rice oil

1.471–1.478

922

22.52

155

250

Polyethylene glycol

1.460–1.467

1100

11.73

99

455

Turpentine

1.460–1.482

866

10.23

87

164

The surface tension force was determined by the classical method of ring separation, the essence of which is as follows. A ring made of platinum wire, the plane of which is parallel to the surface of the liquid, is slowly lifted from the oil wetting it. The force observed at the moment of separation of the ring from the surface is the surface tension force of this liquid or surface energy. The method is suitable for measuring the surface tension of various oils and surfactants [11]. The correlation between the rheological characteristics of oils and light transmittance has not been established, but a relationship has been found between the amount of surface tension and light transmission. For most compositions, the influence of the light transmission of wood samples on the surface tension of oils was established (Fig. 1), i.e. with an increase in this indicator, a sharp decrease in light transmission was noted for both dry and wet samples. Therefore, the task was set to reduce the viscosity and surface tension forces of vegetable oils by modification with organic liquids. Polyethylene glycol and turpentine were used as diluents with low viscosity indices. Taking into account the fact that polyethylene glycol has the ability to reduce light transmittance between wet and dry samples very much (78–80%), the choice was made in favor of turpentine, especially since the decrease in these indicators for this component is less than 50%. The initial value of

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Fig. 1. Dependence of light transmission of wood samples on the surface tension of vegetable oils: 1—in the dry state; 2—in the wet state.

the surface tension force of turpentine is 32 mN/m, which can help reduce the surface tension of vegetable oil. Figure 2 shows the curves of the dependence of the decrease in viscosity and the strength of surface tension on the ratio of vegetable oil and turpentine.

Fig. 2. Dependences of viscosity reduction (1) and surface tension strength (2) on the ratio of vegetable oil and turpentine.

Analyzing the decrease in viscosity and surface tension of the impregnating composition of vegetable oil and turpentine, it can be concluded that a more detailed consideration is needed in the range of ratios of these components up to 20–25% turpentine. The resulting decrease in viscosity by more than 6 s and the value of surface tension by 5 mN/m could have an effect due to better penetration into the capillaries of wood, thereby improving the light transmission of samples. The proposed hypothesis was confirmed by the results of tests on the light permeability of wooden samples impregnated with compositions of vegetable oil and turpentine (Fig. 3), showing an increase in light permeability in the range from 10 to 20% with a maximum at 15% turpentine. At the same time, the convergence of light transmission indicators between wet and dry samples was noted from 40% for pure vegetable oil to

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20% at the marked maximum. In addition, it was found that in the future, with an increase in the proportion of turpentine in the impregnating composition, the gap increases.

Fig. 3. Light transmission of wooden samples impregnated with compositions of vegetable oil and turpentine: 1—wet samples; 2—dry samples.

Thermomechanical studies are one of the most important evaluation methods for the characterization of wooden products. The results of thermomechanical tests, which represent one of the directions of physic-chemical research methods and are one of the most accessible and simple in laboratory practice. This method makes it possible to detect structural changes in the volume of wood after processing at various stages of chemical influences. Thermomechanical studies were carried out using the method of measuring uniaxial compression deformation under the influence of a continuously acting load under conditions of heating the sample at a constant rate in the temperature range from room temperature to +300 °C. To remove the thermomechanical characteristics, samples were prepared from treated wood with a diameter of 8 mm and a thickness of 3 mm. The value of the compressive load on the thermomechanical scales of Academician V. A. Kargin was 8.3 g/mm2 . The heating was carried out at a rate of 3 degrees per minute, the curves were plotted from the points read from the device [12, 13]. Figure 4 shows thermomechanical curves of wooden samples impregnated with a composition of vegetable oil and turpentine. Depending on the type of character of the impregnating liquid for wood processing, the thermomechanical curve will mix towards lower or higher temperatures, moving away from the curve of pure wood, which may indicate a decrease in its quality indicators or an increase in thermal stability and, as a result, an increase in physical and mechanical properties. The sample impregnated with vegetable oil has increased deformation, and thermal stability is limited to 220 °C (Fig. 4, curve 1). Samples impregnated with vegetable oil with turpentine have lower deformation values and their thermal stability is higher (Fig. 4, curves 2.3), which indicates better packaging of impregnating liquids and chemical interaction with the inner surface of the

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Fig. 4. Thermomechanical curves of wooden samples impregnated with vegetable oil with turpentine: 1—vegetable oil without additives; 2—the same, with the addition of 5% turpentine; 3—the same, —the same, with the addition of 10% turpentine; 4—the same, with the addition of 15% turpentine.

wood capillaries. Wood samples impregnated with vegetable oil with 15% turpentine have the lowest deformation rates, and the temperature transition to a fluid state occurs after 260 °C, which indicates a high degree of thermal stability and, as a result, sufficiently strong crosslinking of the components.

4 Conclusions Based on the conducted studies, it was concluded that when impregnated with vegetable oil modified with turpentine, a high light transmission result can be obtained. Therefore, a binary composition of vegetable oil with 10–20% turpentine is recommended, which provides significantly better light transmission with a sufficiently low deformability and high thermal stability. Corn or sunflower vegetable oil used in this composition are quite affordable and widespread products, and turpentine is also a non-deficient chemical product that is well combined with both oil and wood.

References 1. Detlaf AA, Yavorsky BM (2002) Course of physics. Higher School, Moscow 2. Kuhling H (1982) Handbook of physics. Higher School, Moscow 3. Landsberg GS (2012) Elementary textbook of physics. Volume 1: mechanics. Warmth. Molecular Physics. Book on Demand, Moscow 4. Matveev AN (1987) Molecular physics. Higher School, Moscow 5. Trofimova TI (2007) Course of physics. Academy, Moscow 6. Nanazashvili IK (1990) Building materials from wood-cement composition. Stroyizdat, Moscow

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7. Pichugin AP, Denisov AS, Khritankov VF et al (2014) Experience and possibilities of using vegetable raw materials in the construction of objects for various purposes. Innov Food Secur 3(5):22–28 8. Khozin VG, Shekurov VN, Petrov AN (1997) Complex use of vegetable raw materials in the production of building materials. Build Mater 2:12–14 9. Schlegel IF, Makarov SG (2017) Sawdust processing issues. Build Mater 10:56–57 10. Pichugin AP, Khritankov VF, Pchelnikov AV et al (2020) Thermomechanical studies of protective impregnating compositions with nanoscale and special additives. Eng Constr Bull Caspian Sea 3(33):53–58 11. Lukutsova N (2012) Influence of micro- and nanodispersed additions on qualities of wood-and cement compositions. SITA J Israel 3(14):70–75 12. Lukash AA (2016) Glued wood concrete made of soft hardwood. Build Mater 8:63–66 13. Stenin AA, Eisenstadt AM, Shinkaruk AA et al (2014) Mineral surface modifier for the protection of building materials from wood. Build Mater 10:51–55

Methodology of Determination of the Platform Joint of Reinforced Concrete Large-Panel Buildings Stiffnesses Z. Abaev, A. Valiev(B) , and M. Kodzaev North Caucasian Institute of Mining and Metallurgy, Nikolaeva St. 44, Vladikavkaz 362021, Russia [email protected]

Abstract. This paper aims to develop a method for platform joint stiffness determination. The joint flexibility factor is the value numerically equal to the deformation of the joint caused by a single concentrated or distributed force. The difficulty in assessing the actual work of joints is a complex stress-state is that different types of bonds (distributed and discrete) can be applied in one joint with the variety of their design solutions. For joints having several characteristic stages of operation (e.g. before and after cracking in the joint), the joint compliance (stiffness) coefficients must be taken for each stage in a differentiated manner. In this case, the deformation of the connection is determined as the sum of the deformations of the force increments in the individual stages. The practical implementation of the method is also presented using LIRA-SAPR Software with the new types of finite elements specifically for modelling the horizontal joint of the panels. These are: FE-59 to account for the linear behaviour of the joint and FE-259 to account for physically non-linear work. Keywords: Platform joint · Finite element · Joint flexibility

1 Introduction Prefabricated structural systems can be classified into (i) large panel wall systems (LP), (ii) frame systems, (iii) slab-column systems with shear walls, and (iv) dual frame-wall systems. Prefabricated RC large-panel buildings (LPB) are widely spread thought the territory of Russia because of the industrialization policy implementation in USSR [1–5]. LPB system consists of RC wall and floor panels which are connected at discrete points and form a boxlike structure. LPB has been exposed to several damaging earthquakes, including the 1976 Gazli, Uzbekistan (Soviet Union); 1977 Vrancea, Romania; and the 1988 Spitak, Armenia earthquake. The performance of these buildings was satisfactory, without evidence of significant damage or collapse. However, there is a lack of technical resources that document the seismic design philosophy for this construction technology [6–10]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_27

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The main difference between prefabricated buildings and monolithic buildings is that they have a special feature—the joint of the prefabricated elements and the need to adequately represent it in the calculation scheme. For large-panel buildings it is the vertical joint between the wall panels (may be free, without connections along the floor height, or may contain point welded connections on the embedded parts, dowels or continuous monolithic loop or welded joints) and the horizontal joint between the wall panels and floor slabs (may also have a different design: platform, contact, etc.). The stiffness and strength characteristics of the joint are determined by many factors: the mortar grade, the gap sizes between the panels, the presence, placement and characteristics of the embedded parts and much more [11–14]. There are many papers devoted to the problems of modelling the joints of panel buildings and determining their stiffness [15–18]. Special attention should be paid to the calculation of panel buildings for progressive collapse (accidental impact, avalanche-like collapse) [19, 20]. Existing technologies allow creating a calculation diagram of a panel building taking into account the work of joints (with certain simplifications and assumptions), but require a lot of painstaking work. Schemes created in this way are usually difficult to edit. Therefore, calculations involving a change in the type of joint or its stiffness characteristics are time-consuming, highly skilled and require careful attention to the smallest details. Considering these difficulties this paper aims to develop a methodology for platform joint stiffness determination.

2 Calculation of the Stiffness of the Platform Joint 2.1 Initial Data For FE platform joint stiffness calculation materials taken from [21]: Panel’s concrete class − B30 (E b = 32,500 MPa, Gb = 0.4, 32,500 = 13,000 MPa). Mortar class (according to USSR classification) − 200 (E b = 19,500 MPa, Gb = 0.4, 19,500 = 7800 MPa). Conversion from the USSR class to the new class is made by design: B = 0.778 M (M—is USSR class, B—new class). Shear modulus G determined according clause 6.1.15 of the SP 63.13330.2018 Concrete and reinforced concrete structures. General provisions. Dimensions of the case study platform joint and finite element model of the joint are shown on Figs. 1 and 2 respectively (Table 1). 2.2 Coefficient of Flexibility During determining the platform joint flexibility, is taken into account that flexibility depends on the stresses in the joint that are caused by outer loads. Only the mortar flexibility is taken into account, because slab has much higher stiffness than mortar. −2/3 and its thickness is from 10 to 20 mm, If stress in mortar joint σ ≤ 1.15Rm platform joint flexibility is determined by Eq. 1 [22]. 



λm = λm = 1.5 · 10−3 · R−2/3 · tm . m

(1)

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Table 1. Types of wall connections. Coefficient for

Symbol

Tension

λt

Stress

λc

Shear

λτ

Rotation

λφ

Connection diagram

Fig. 1. Dimensions of the case study platform joint.





λm = λm = 1.5 · 10−3 · 20−2/3 · 20 = 0.004 mm3 /N. For platform horizontal joint, in which compressive stress transmitted by reference areas of R/C slab and by two mortar joints between slab and joining elements, coefficient of flexibility is determined by Eq. (2).   hpl A   λc.pl = λm + λm + , (2) Epl Apl where hpl —height of cross-section, E pl —Young’s modulus of slab, A—cross-sectional area of the wall on the joint’s level, Apl —cross-sectional area of joint through which   compressive stresses are transferred, λm , λm —horizontal joint flexibility coefficient of

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Fig. 2. Finite element model of the joint.

upper and lower joints respectively, Rm —tensile strength of mortar.   180 160 = 0.0145 mm3 /N. λc.pl = 0.004 + 0.004 + 32500 180 − 20 −2/3

If the stresses in the joints σ ≥ 1.15Rm

, platform joint flexibility coefficient is: √ −b ± b2 − 4ac   (3) · t . λm = λm = 5 · 10−3 · R−2/3 m m 2a





λm = λm = 1.5 · 10−3 · 20−2/3 · 20 = 0.013 mm3 /N. For determining platform joint flexibility coefficient, design length was taken as 1 m. That’s why length value is missing in designs for A and Apl . Defined that slab’s shear flexibility is way less than mortar’s. Therefore, it can be neglected, due to its smallness. Thereby platform shear flexibility coefficient might be determined by Eq. 4:  A    λT = λT ,m + λT ,m . (4) Apl 



where λτ,m and λτ,m —horizontal mortar joint shear flexibility of upper and lower joints respectively: λT ,m = tm /Gm .

(5)

where Gm —mortar’s shear modulus, which might be taken as fine-grained concrete shear modulus of the closest concrete class by its strength characteristics. 20 = 0.00256 mm3 /N. 7800 180 = 0.00576 mm3 /N. λT = (0.00256 + 0.00256) 180 − 20 Defined, that platform joint shear flexibility depends on lots of parameters—compressive stresses in joints, quality of contact surfaces, joint production method, etc. That’s why the proper way to determine joint shear flexibility is to test their reaction to the shear action. One of the theoretical ways to determine flexibility was shown earlier. 



λT ,m = λT ,m =

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2.3 Determination of Stiffness Characteristics of FE Platform Joint for Short-Term Load In general, FE of platform joint work may be described by diagram σ − ε on Fig. 3:

Fig. 3. Diagram σ − ε. 2/3

2/3

On Fig. 3 σm1 = 1.15 Rm , σm2 = 2 Rm . Relative deformations εm1 , εm2 determined by platform joint flexibility coefficient during compression on each part of the diagram (Eqs. 6 and 7). εmi = εm(i−1) + εm1 =

σmi − σm(i−1) · λc.pl,i . hst

σm1 · λc.pl,1 λc.pl,2 ; εm2 = εm1 + (σm2 + σm1 ) . hst hst

(6) (7)

where hst —full joint’s height, mm (in proper case is the height of the slab and two joints). Relative deformation εm3 must be taken of such value, to make plots of the diagram σm2 –σm3 increase monotonously, for example it might be taken as εm3 = 10εm2 . Young’s modulus of FE for each plot of the diagram σ − ε is determined by Eq. (8): Ei =

σmi − σm,i−1 . εmi − εm,i−1

(8)

Shear modulus of FE of platform joint determined by Eq. (9): G=

hst . λT

(9)

where λτ —platform joint shear flexibility coefficient. To define the parameters of the diagram, we use the proper case of platform joint that was shown on Fig. 1. The height of FE platform joint hst = hpl + tm + t  m = 160 + 20 + 20 = 200 mm. Since the final stiffnesses of platform joint are determined according to a total height of FE of joint, the manual joint height changes in Vizor, respective stiffness characteristics must be corrected.

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Diagram’s characteristics for short-term load: • stresses: σm1 = 1.15 · 202/3 = 8.47 MPa. σm2 = 2 · 202/3 = 14.74 MPa. 1.01σm2 = 1.01 · 14.74 = 14.89 MPa. • relative deformations: 0.0145 = 0.000614. 200 0.0347 + 0.000614 = 0.001702. = (14.74 − 8.47) · 200 εm1 = 8.47 ·

εm2

εm3 = 10 · 0.001702 = 0.01702. • Young’s modulus for each sector: 8.47 = 13794.8 MPa. 0.000614 14.74 − 8.47 = 5762.8 MPa. E2 = 0.001702 − 0.000614 14.89 − 14.74 = 9.8 MPa. E3 = 0.01702 − 0.001702 E1 =

It should be mentioned that there are basically two methods of calculating the shear modulus of elasticity in codes, but no any recommendation which one to use. Shear modulus: G=

200 = 34722.2 MPa. 0.00576

or G = 0.4E1 = 0.4 · 13338.6 = 5335.4 MPa. 2.4 Analysis of the Results Diagram parameters of FE work during short-term load action are shown on the Table 2. These parameters should be uploaded to LIRA-SAPR software [23] for correct modelling. The process is shown on Fig. 4. The model of platform joint is shown on Fig. 5. This is the simplest way of uploading your parameters for every stiffness you have no model. They may be different for each material. There are currently several techniques for incorporating the operation of a platform joint into the design scheme of a large-panel building:

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Table 2. Diagram parameters of finite element. No

σmi , MPa

εmi

E ik , MPa

G, MPa 34,722.2

1

8.47

0.000614

13,794.8

2

14.74

0.001702

5762.8

3

14.88

0.01702

9.8

Fig. 4. Parameters of the joint.

• Equivalent column model, where the local yielding of mortar joints and floor slab is uniformly “smeared” over the height of the wall panel (this method simplifies the construction of the FE model, but introduces a number of inaccuracies into the calculation scheme. • The model of discrete bonds of finite stiffness—this approach specifies the joint behaviour in the building design scheme, but significantly complicates the model creation, as it leads to a significant increase of discrete bond stiffness types—for each joint type and FE step a separate stiffness, which entails both a large number of “manual” calculations, and complicates the control of given input data.

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Fig. 5. Finite element model of the joint (meshed).

The main disadvantages of those models are impossibility to take into account correctly the non-linear behaviour of the joint in the first case and extreme complexity of accounting for non-linearity in the second case (in fact the accounting of non-linear effects for the joint stiffnesses reduces to a series of sequential calculations with manual correction of the stiffnesses at each iteration). To avoid the above disadvantages LIRA-SAPR Software presents the new types of finite elements specifically for modelling the horizontal joint of the panels. These are tentativele: FE-59 to account for the linear behaviour of the joint and FE-259 to account for physically non-linear work. In the FEM model the platform joint is modelled by two rows of finite elements (Fig. 5).

3 Conclusion The proposed methodology might play an important role in improving the design solutions of the assessment of the operational reliability of the joints, analysis of joint failure in emergency situations and a further assessment of the seismic resistance of the LPB in general. The difficulty in assessing the actual work of joints is a complex stress-state is that different types of bonds (distributed and discrete) can be applied in one joint with the variety of their design solutions. This complicates the development of methods for determining compliance joints. Meanwhile, the description of the structural parameters of the joints should correspond to the level of the design model of the structural system of large-panel buildings in the

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volumetric setting, taking into account the work of the base, as well as taking into account the physical and geometric nonlinearity in the work of materials and structural system. Only in this case it is possible to fully estimate a number of important deformation and strength parameters of a large-panel building.

References 1. Andonov A, Deyanova M, Travanca J, Andreev S (2019) Development of analytical fragility and vulnerability functions of large-panel residential buildings typical of Bulgaria. In: Earthquake risk and engineering towards a resilient world 2. Gajera K, Lago BD, Capacci L, Biondini F (2021) Multi-stripe seismic assessment of precast industrial buildings with cladding panels. Front Built Environ 7. https://doi.org/10.3389/fbuil. 2021.631360 3. Guri M, Brzev S, Lluka D (2021) Performance of prefabricated large panel reinforced concrete buildings in the November 2019 Albania earthquake. J Earthq Eng 1–27. https://doi.org/10. 1080/13632469.2021.1887010 4. Chen S, Poongodi M (2020) An exhaustive research and analysis on seismic performance of prefabricated concrete shear wall structure. J Vibroeng 22:1871–1883. https://doi.org/10. 21595/jve.2020.21628 5. Bara´nski J, Berkowski P (2015) Computer modelling of precast large-panel buildings with degraded horizontal joints. In: Procedia engineering. Elsevier Ltd, pp 89–96 6. Nemchynov I, Maryenkov N, Khavkin A et al (2015) Seismic analysis of large-panel buildings. In: 3rd Turkish conference of earthquake engineering and seismology 7. Malakhova A, Davletbaeva D (2019) The consideration of compliance of structural joints in calculation of large panel buildings. In: E3S web of conferences. EDP Sciences 8. Vodopianov RY (2017) Simulation and computation of large-panel buildings in PC LIRASAPR 2017. Zhilishchnoe Stroitel’stvo [Housing Constr] 3:42–48 9. Gubchenko VE (2018) Work with the ‘Joint’ tool of software package LIRA-CAD. Zhilishchnoe StroiteTstvo [Housing Constr] 3:30–35 10. TsNIIEPzhilishcha (1985) Recommendations for design of large panel buildings in seismic areas 11. TsNIIEPzhilishcha (1989) Handbook for the design of residential buildings. Stroyizdat 12. Clough RW, Malhas F, Oliva MG (1989) Seismic behavior of large panel precast concrete walls: analysis and experiment. PCI J 34:42–66. https://doi.org/10.15554/pcij.09011989. 42.66 13. Makhviladze LS (1987) Earthquake-resistant large-panel housing construction. Stroyizdat 14. Toniolo G, Colombo A (2012) Precast concrete structures: the lessons learned from the L’Aquila earthquake. Struct Concr 13:73–83. https://doi.org/10.1002/suco.201100052 15. Magliulo G, Ercolino M, Petrone C et al (2014) The Emilia earthquake: seismic performance of precast reinforced concrete buildings. Earthq Spectra 30:891–912. https://doi.org/10.1193/ 091012EQS285M 16. Babiˇc A, Dolšek M (2016) Seismic fragility functions of industrial precast building classes. Eng Struct 118:357–370. https://doi.org/10.1016/j.engstruct.2016.03.069 17. Belleri A, Torquati M, Riva P, Nascimbene R (2015) Vulnerability assessment and retrofit solutions of precast industrial structures. Earthq Struct 8:801–820. https://doi.org/10.12989/ eas.2015.8.3.801 18. Velkov M (1981) Large panel systems in Yugoslavia: design, construction and research for improvement of practice and elaboration of codes. In: ATC—8 proceedings of a workshop on design of prefabricated concrete buildings for earthquake loads. Applied technology council

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19. Velkov M, Ivkovich M, Perishich Z (1984) Experimental and analytical investigation of prefabricated large panel systems to be constructed in seismic regions. In: Proceedings of the eighth world conference on earthquake engineering 20. Knowledge Base of LIRA-SAPR software. https://www.liraland.com/blog/. Accessed 3 June 2022 21. Emelyanov S, Nemchinov Y, Kolchunov V, Yakovenko I (2016) Details of large-panel buildings seismic analysis. Enfoque UTE 7:120–134. https://doi.org/10.29019/enfoqueute.v7n 2.100 22. Szulc J, Piekarczuk A (2022) Diagnostics and technical condition assessment of large-panel residential buildings in Poland. J Build Eng 50:104144. https://doi.org/10.1016/j.jobe.2022. 104144 23. LIRA-SAPR structural analysis software. LIRA LAND GROUP. https://www.liraland.com/ lira/. Accessed 3 June 2022

Special and Unique Structures Construction

Damping of Structures of Earthquake-Resistant Suspended Buildings T. Belash1(B) and I. Svitlik2 1 JSC Research Center of Construction, 6, 2Nd Institutskaya, Moscow 109428, Russia

[email protected] 2 Emperor Alexander I Petersburg State Transport University, 9 Moskovsky Pr.,

Saint-Petersburg 190031, Russia

Abstract. During the construction of multi-storey and high-rise buildings, the principle of suspension of floors has been frequently applied to create the main system of load-bearing structures. Such a solution makes it possible to reduce the loads in load-bearing structures caused by dynamic influences. The effectiveness of the use of suspended structures in earthquake-resistant construction was confirmed by studies of the behavior of such objects in earthquake conditions. The most widespread structural solution of suspended type buildings is a single-core system with a cantilever head. There are many approaches to the realization of floor suspension in buildings with rigid core, each of which has certain advantages and disadvantages. This article discusses some possible options for joining elements of suspended and load-bearing structures of buildings, as well as analyzes the effectiveness of their use. The analysis of the effectiveness of the proposed solutions was carried out by evaluating the displacements of elements and stresses in the load-bearing elements of the calculated models under seismic impacts with different frequency spectra. The parameters of the calculated models were determined in the LIRA 10.12 software package by the finite element method in the temporary realm. The results of computational research of these structural solutions are presented in the article. Keywords: High-rise buildings · Suspended structures · Seismic impact

1 Introduction The structural solutions of suspended type buildings with a rigid core are diverse. This can be used both to create a unique architectural image and to solve various engineering problems, for example, to ensure the earthquake resistance of a building. The most common structural solution of a suspended building is a load-bearing core with a cantilever head on it. Often, the floors are suspended from the head along the outer perimeter, and on the inside they are rigidly or hinged to the core of the building. An example of such a building is the ABSO building in the town of Povazhska Bystrica (Fig. 1). The floor beams are suspended from the cantilever beams of the head along the building outer contour. At the other end, they are installed on embedded parts in the core of the building. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_28

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Fig. 1. a Process of construction; b exterior.

In the built high-rise suspended buildings, free suspension of floors along the core of the building is not so common due to the danger of the rocking effect of the suspended floor block and subsequent damage to the integrity of the load-bearing structures. Significant displacements of suspended structures under wind influence led to cracks in the walls of the Trzonolinowiec building in Wroclaw (Fig. 2a, b). Forced modernization radically changed the structural solutions of the building (Fig. 2c).

Fig. 2. a Process of construction; b exterior; c steel supports.

It is worth noting that G. F. Penkovsky in his patent describes a building with a free suspension of floors as a system that is not subject to the effect of resonance under seismic impacts. This is explained by the fact that the mass of the overlying floor is a dynamic vibration dampener for the floor located below, due to the difference in the phases of forced oscillations [1]. The installation of shock-absorbing devices between suspended and load-bearing structures of buildings is still mainly a question of theoretical research. In one of the first Soviet patents concerning suspended type buildings, I. L. Korchinsky proposed

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connecting suspended ceilings with the core of a building by means of shock absorbers, which can be used as springs and other elastic connections made of damping materials [2]. In the future, such a decision was reflected in a number of other patents [3–6]. In modern studies, a positive effect is noted from the use of viscous dampers [7, 8], semirigid [9–11] and elastic [12, 13] joints in regulating vibrations of suspended building structures.

2 Methods Three calculation models of the building with suspended structures were created for the calculations (Fig. 3). The design models represent a 20-storey building with a height of 79 m with floors suspended from a metal head on 32 suspensions along the inner and outer contour. The floors and the rigid core of the building have a round shape. The diameter of the core is 8 m, the diameter of the floor is 16 m (Fig. 3a).

Fig. 3. a Axial section of the model; b the layout of the links; c fragment of a building with a load-bearing head.

The suspensions of the first calculation model are freely suspended along the core of the building without installing connections with the load-bearing walls (Fig. 3a). To account for the possible concussion of the structures of the core of the building and suspended ceilings, two-node finite elements of unilateral connection were used in the design scheme (Fig. 3b). These elements are included in the compression operation when the relative displacement of the nodes exceeds the established gap between the core and floor structures equal to 0.4 m. The second model is an original structure with the addition of elastic links between the floors and the core of rigidity on each floor of the building (Fig. 3b). The relative stiffness of elastic links varies from 5 to 20 t/m.

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The interaction of suspended ceilings and the core of the third model occurs by friction of the floor plate with a console made along the perimeter of the core (Fig. 4). Two-node friction elements of unilateral connection are installed between the floors and the rigid core on each floor of the building (Fig. 3b). In the work of finite elements, the Coulomb friction law is applied.

Fig. 4. Conditional scheme of the joint of the floor and the core of the building of the third model.

The relative stiffness of the tension-compression link was calculated by the formula (1). R = S · E,

(1)

S—the bearing area, E—the elastic modulus of the support material, as which fluorine plastic is adopted according to GOST 10,007-80. The relative stiffness of the clutch is adopted according to the formula (2). Q = R · γ,

(2)

G—the coefficient of statical friction of the support material. The accepted characteristics of the unilateral connection finite friction element are given in Table 1. Table 1. Characteristics of the unilateral connection finite friction element. Characteristic

Value

Relative stiffness of the tension-compression R, t/m

45,805

Relative stiffness of the clutch Q, t/m

1832,2

Coefficient of statical friction γ

0,04

For computational studies, seismograms of earthquakes with different response spectrum were selected in the web database on ground motion of the Pacific Earthquake Engineering Research Center (Fig. 5). The selected earthquakes have a wide frequency spectrum. Based on the prevailing oscillatory period Tn in the response spectrum, a conditional division of earthquake records into high-frequency (Tn < 0.3 s), mediumfrequency (0.3 s ≤ Tn < 1 s) and low-frequency (Tn ≥ 1 s) was adopted. Thus, the

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earthquakes that occurred in the city of Almiros and Friuli region are high-frequency, an earthquake in Griva is medium-frequency, and earthquakes in Chi-Chi and the St Elias mountains are low-frequency. The maximum horizontal displacements of the ground according to earthquake records are given in Table 2. Table 2. Maximum horizontal displacements of the ground, mm. Friuli, Italy

Almiros, Greece

Griva, Greece

Chi-Chi, Taiwan

St Elias, Alaska

19,8

13,3

12,8

141,2

134,1

Fig. 5. Earthquake response spectrum.

The selected earthquakes had a high magnitude and caused significant damage to many buildings. For example, the earthquake in the Italian region of Friuli, which occurred in 1976, had a magnitude of 6.5 and extreme intensity on the Mercalli scale. This earthquake led to the death of 990 people, and more than 157,000 people were left homeless (Fig. 6a). The 1999 Chi-Chi earthquake was the second most significant earthquake in Taiwan in history, killing 2,415 people and destroying the homes of more than 100,000 people (Fig. 6b). The magnitude of the earthquake was 7.7. The calculation was performed in the LIRA software package using the Dynamics plus module. This module allows you to simulate the response of the structure to dynamic impacts and perform calculations in the temporary realm using instrumental seismograms. In setting the dynamic loading, seismograms were attached to the bases of the calculated models as nodal loads. The joint effort of the building and the supporting ground was not taken into account as an assumption. The connection of the foundation plate and the supporting ground is conventionally assumed to be rigid.

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Fig. 6. Consequences of earthquakes a In the region of Friuli; b In Chi-Chi city.

3 Results and Discussion Criteria such as the forces occurring in the walls of the building core and load-bearing suspensions, as well as the movement of model elements in a global coordinates were chosen to analyze the behavior of calculated models with suspended structures. Changing the relative stiffness of the elastic links of the second model allows to influence both the forces in the core of the building and the movement of the model elements (Fig. 7). For further calculations, the relative stiffness of the links is assumed to be equal to 20 t/m.

Fig. 7. Graph of maximum a normal stresses of the core of the second model along the vertical axis; b horizontal displacements of elements of the second model.

Figure 8 shows the results of calculations concerning the movement of elements during an earthquake in the St Elias mountains to illustrate the behavior of calculated models under seismic impact.

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Fig. 8. Maximum displacement of structures under seismic impact in the St. Elias mountains of the a first calculated model; b second calculated model; c third calculated model.

Fig. 9. Diagram of the maximum normal stresses of the core walls of models along the vertical axis.

The calculation results are shown in Fig. 9, 10, 11 and 12.

4 Conclusions 1. The use of free suspension of structures in the model allows to achieve the smallest displacements of the floors. However, significant stresses in the walls, combined with a possible concussion of the core and floors, can lead to the destruction of load-bearing structures. 2. The use of elastic links in the second calculation model made it possible to reduce the displacements of the structures of the building core, as well as stresses in the load-bearing walls.

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Fig. 10. Diagram of the maximum moments acting on the section orthogonal to the vertical axis in the walls of the core.

Fig. 11. Diagram of maximum longitudinal forces in suspensions.

Fig. 12. Diagram of maximum horizontal displacements of suspended floors (left) and core elements (right).

3. The best results in reducing stresses in the building core were achieved in the third model. On the other hand, the use of friction elements led to an increase in the maximum displacements of suspended floors and longitudinal forces in load-bearing suspensions.

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References 1. Pen’kovskij GF (2017) Sejsmostojkoe zdanie s podveshennymi etazhami (Earthquakeresistant building with suspended floors). RU Patent 175,448 2. Korchinskij IL (1975) Podvesnoe zdanie (Suspended building). SU Patent 477,227 3. Dubrova EP (1985) Mnogoetazhnoe sejsmostojkoe zdanie (Multi-storey earthquake-resistant building). SU Patent 1,173,027 4. SHCHerbina VI (1985) Mnogoetazhnoe sejsmostojkoe zdanie (Multi-storey earthquakeresistant building). SU Patent 1,176,052 5. Talanov BP (1997) Sejsmostojkaya konstrukciya zdaniya (Earthquake-resistant structure of the building). RU Patent 2,074,303 6. Ostromenskij PI (2002) Sejsmostojkoe zdanie podvesnogo tipa (Earthquake-resistant suspended type building). RU Patent 2,186,183 7. Wang C, Lu Z, Tu Y (2011) Dynamic responses of core-tubes with semi-flexible suspension systems linked by viscoelastic dampers under earthquake excitation. Adv Struct Eng 14(5):801–813. https://doi.org/10.1260/1369-4332.14.5.801 8. Cai W, Yu B, Kaewunruen S (2019) Shaking table tests of suspended structures equipped with viscous dampers. Appl Sci 9(13):2612. https://doi.org/10.3390/app9132616 9. Cao W, Lu Z, Zhang J et al (2007) Shaking table test and analysis of core-tube partial suspension structures. China Civil Eng J 40(3) 10. Liu Y, Lu Z (2014) Seismic Performance and storey-based stability of suspended buildings. Adv Struct Eng 17(10):1531–1550. https://doi.org/10.1260/1369-4332.17.10.1531 11. Liu Y, Lu Z (2014) Seismic behavior of suspended building structureswith semi-rigid connections. Earthq Struct 7:415–448. https://doi.org/10.12989/EAS.2014.7.4.415 12. Belash T, Rybakov P (2016) Buildings with suspended structures in seismic areas. Mag Civil Eng 5:17–26. https://doi.org/10.5862/MCE.65.2 13. He Q, Yin A, Fan Z, He L (2021) Seismic responses analysis of multi-story suspended floors system. J Vibroeng 23:167–182. https://doi.org/10.21595/jve.2020.21478

The Design of Architectural Forms Based on Irregular Curves V. A. Korotkiy(B) , E. A. Usmanova, and L. I. Khmarova South Ural State University, 76, Lenin Avenue, Chelyabinsk 454080, Russia [email protected]

Abstract. Non-rectilinear shapes and smooth nature-like curves have been widely used in modern architecture. Such curve-based architectural forms are designed using the latest computational technologies and parametric digital modeling methods borrowed from the automotive and aviation industries. Graphically defined irregular curves are an essential component of architectural design. For the practical use of a graphically defined curve there are certain requirements: it should be approximated by a regular curve; the approximation error should not exceed 2%; the curve should pass through nodes and touch predefined direction vectors at these points; and the angle of the slope and curvature of the composite curve should change continuously. This article shows that these requirements can be fulfilled using a composite cubic Bézier curve. We have developed a graphicanalytical algorithm for the formation of the desired curve. A distinctive feature of the algorithm is that it takes into account the direction of the tangent vectors and the radii of the curvature at the nodes. Direction vectors are considered as a control for the constructed curve. We ensured second-order geometric smoothness at the nodes from the continuity of the slope and curvature. An experiment on the approximation of a nature-like curve (physical spline) of a composite cubic Bézier curve showed the approximation error was less than 1.5%. Keywords: Bézier curve · Nature-like curve · Approximation · Physical spline · Curvature · Smoothness

1 Introduction The widespread use of non-rectilinear shapes in architectural design is associated with the emergence of new building materials and the introduction of digital technologies into design [1–3]. Non-rectilinear architecture is in demand in many countries, especially in Asia (Fig. 1).

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_29

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Fig. 1. Harbin Opera Hause (China).

Curve-based architectural forms are designed using computing technologies and parametric digital modeling methods borrowed from the automotive and aviation industries [4, 5]. A parametric approach to the formation of curves and surfaces can be found in the work of the German architect Frei Otto (1925–2015). When designing, he used the “Search for Form” method by modeling nature-like curves and natural physical processes. Parametric methods are widely used in modern architectural design [6, 7]. Zaha Hadid Architects have become leading parametric designers, whose work includes the Heydar Aliyev Center in Baku (Fig. 2). Graphically defined irregular curves are an essential component of architectural design. For example, wave curves arbitrarily drawn by architects have become the basis for modern airport design (Fig. 3). Freely organized spaces limited by curved surfaces are used in recreation areas (Fig. 4).

Fig. 2. Heydar Aliyev Cultural Centrer (Baku). Architect Zaha Hadid (Iran).

For the practical use of a graphically defined curve, it should be approximated by a regular curve [8–10]. Modern computer aided design systems use the NURBS curve, which has become a standard tool for computer modeling. However, such a tool cannot always satisfy the designer, since it does not take into account the local geometric conditions imposed on the modeled line (tangents at nodes, radii of curvature, etc.).

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Fig. 3. Modern airport.

Fig. 4. Architectural fantasy.

Another approach is based on the use of a composite curve passing through the characteristic points of the modeled line and meeting the specified smoothness conditions. Cubic Bézier [11, 12] or Hermite [13, 14] curves are used as segments of composite curves. The main problem in forming a composite curve is to achieve a set degree of smoothness. G2 -geometric smoothness should generally ensure a continuous change in curvature. An abrupt change in curvature gives an unfavorable aesthetic impression [15–17]. Segments can be joined geometrically smoothly in various ways. The classical approach proposed by Bézier is based on joining segments of the same order [11, 12]. He obtained the condition for a G2 -smooth joining of segments of a three-dimensional cubic Bézier curve [18, 19]. Scientific novelty. We have developed a graphic-analytical algorithm for constructing a composite curve passing through given reference points and touching given lines at these points. A distinctive feature of the algorithm is that it takes into account the direction of the tangent vectors and the radii of the curvature at characteristic points of the curve. Direction vectors control the shape of the constructed curve. Relevance. Because of the widespread use of non-rectilinear shapes in architectural design, the emergence of new building materials, and the introduction of digital technologies into design.

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Practical significance. The proposed graphic-analytical algorithm allows the construction of a plane or spatial G2 -smooth composite cubic Bézier curve meeting set boundary conditions. Composite Bézier curves are used to approximate irregular (graphically defined) curves in architectural design. The approximation error is 1–2%.

2 Problem Statement An irregular curve is drawn in a space or on a plane. The curve passes through the nodes R0 , R1 , R2 , . . . , Rn . Direction vectors T0 , T1 , T2 , . . . , Tn are set at the nodes. The tangents and radii of the curvature are set at the boundary points. We should approximate the irregular curve by a set of smoothly interconnected cubic segments. The composite curve should pass through the nodes and provide an approximation accuracy of no less than 1–2%. We propose to use cubic Bézier segments to solve the problem ri (t) = (1 − t)3 Ri−1 + 3t(1 − t)2 Qi + 3t 2 (1 − t)Pi + t 3 Ri , t ∈ [0, 1]

(1)

where i = 1, 2, 3, . . . , n is the segment number. The symbol Ri denotes the node as a geometric object, and the symbol Ri denotes the radius vector of this point. We propose forming the desired curve sequentially, gradually adding segments. Each segment should meet the boundary conditions {Ri−1 , Ri , Ti−1 , Ti , Ki−1 }, i.e., pass through the points Ri−1 , Ri and touch the vectors Ti−1 , Ti . The curvature Ki−1 at the initial point of the segment should be equal to the curvature at the end point of the previous segment.

3 Geometrically Smooth Composite Cubic Bézier Curves A curve is called geometrically smooth if its curvature vector changes continuously in its modulus and direction with the change in parameter t. The smooth joining of segments provides for a common tangent and a common curvature vector at the junction point of the segments. The coincidence of the first and second derivatives on both sides of the junction point is not an obligatory condition of geometric continuity attributable to the slope and curvature continuity [20, 21]. Points R0 , R1 , R2 are set in the orthogonal coordinate system xyz with the tangents τ 0 , τ 1 , τ 2 indicated at these points. The control points Q1 ∈ τ0 , P1 ∈ τ1 of the segment R0 − R1 are fixed. The segment R1 − R2 should be added to the segment R0 − R1 , providing the common tangent τ1 and the common curvature vector K1 of the connected segments at the junction point R1 . The osculating planes Q1 P1 R1 and R1 Q2 P2 of the joinable segments should coincide at the junction point R1 ; therefore, the point P2 should be located in the osculating plane Q1 P1 R1 . The point P2 is incident to the predefined tangent τ2 , so the point P2 is defined at the intersection of the tangent τ2 and the osculating plane Q1 P1 R1 : P2 = τ2 ∩ Q1 P1 R1

(2)

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Thus, the control point P2 is fixed. To determine the control point Q2 , we find scalar values λ1 , μ1 meeting the known [8–10] smoothness condition: P2 = [(1 + λ1 )2 + 0.5μ1 ]R1 + Q1 λ21 − P1 [2λ1 (λ1 + 1) + 0.5μ1 ]

(3)

We mark the local coordinate system XY in the osculating plane Q1 P1 R1 initiating at point Q1 and having the axis X = Q1 R1 . All points meeting condition (3) lie on the XY plane, so this condition can be expanded along the X , Y axes. Taking into account that the local coordinates of point Q1 and the coordinate Y1 of point R1 (X1 , Y1 ) are equal to zero, we obtain:   YP2 XP1 XP2 −1 − (4) λ21 = 1 + YP1 X1 X1 Having determined λ1 , we mark the control point, Q2 , of the constructed segment R1 − R2 on the tangent τ1 . Thus, the practical use of smoothness condition (3) is reduced to constructing the intersection point of the line τ2 and the plane Q1 P1 R1 and calculating the parameter λ1 according to (4). In particular, if the curvature at the boundary point of the segment is equal to zero, the following theorem is correct. Zero-curvature theorem. If the vertices A, Q, P of the characteristic polyline AQPB of the Bézier segment are collinear, the curvature of segment AB at point A is equal to zero, regardless of the position of point B. Similarly, if the vertices B, Q, P are located collinearly, the curvature of segment AB at point B is equal to zero, regardless of the position of point A [8 − 10]. Corollary from the zero-curvature theorem. If control points Q, P of the characteristic polyline AQPB of the Bézier segment coincide, the curvature of the segment at end points A, B is equal to zero. The corollary of the zero-curvature theorem allows the construction of a geometrically smooth composite curve with zero curvature at the junction points. To this end, the control points of the segments should be coincided with the intersection points of the tangents at the end points of these segments.

Fig. 5. Architectural sketch and spation G2 smooth Bezier curve.

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Example 1. A spatial irregular curve drawn by an architect touches the xaxis of the coordinate system xyz at the initial point R0 . At the end point R3 (80, −65, 30), the curve goes up vertically (Fig. 5). The sketch passes through the points R1 (20, −30, 10) and R2 (50, −30, 20). The downward direction vector T1 (0.4575, −0.4575, −0.7625) is fixed at the point R1 . An almost horizontal unit direction vector T2 (0.8130, −0.5807, −0.04206) is set at the point R2 . We should find a smooth regular curve approximating the graphically defined curve (with an accuracy of 1–2%). We used a composite cubic Bézier curve to solve the problem. The advantage of such a solution is the small number of calculations and auxiliary constructions necessary. The shape of the first segment R0 − R1 is determined by modules ω0 , ω1 of the first vector derivatives at the boundaries of the segment. We achieve a satisfactory match between the sketch and the Bézier curve by changing these values. In particular, at we obtain a loop curve R0 − R1 deviating from the sketch by no more than 2%. Subsequent segments R1 − R2 , R2 − R3 are formed according to smoothness condition (3) and expression (4). For example, the segment R1 − R2 is described by the equations: x(t) = 20(1 − t)3 + 90.6750t(1 − t)2 + 106.0673t 2 (1 − t) + 50t 3 y(t) = −30(1 − t)3 − 120.6750t(1 − t)2 − 58.6184t 2 (1 − t) − 30t 3 z(t) = 10(1 − t) − 21.1251t(1 − t) + 62.2728t (1 − t) + 20t 3

2

2

(5)

3

Example 2. A characteristic polyline R0 (0, 0, 0) − Q1 (0, 0, 10) − P1 (−5, −25, 40) − R1 (5, −20, 30) of the cubic Bézier segment R0 − R1 is fixed in the coordinate system xyz. We should find the control points Q2 , P2 of the Bézier segment R1 − R2 (40, 0, 0) smoothly connected to the fixed segment R0 − R1 . The tangent τ2 at point R2 coincides with the x-axis (Fig. 6). Three-dimensional computer graphics indicates the characteristic polyline R0 Q1 P1 R1 of the fixed segment R0 − R1 , the end point R2 of added segment and the tangent τ2 = x at R2 . We mark a local coordinate system XY starting at Q1 and axis X = Q1 R1 in the osculating plane Q1 P1 R1 . We find the control point P2 = XY ∩ τ2 and its local coordinates P2 (XP2 = −3.04635, YP2 = −24.4330) by means of computer graphics. Graphics software helps to determine local coordinates of points R1 (X1 = 28.7228, Y1 = 0),P1 (XP1 = 37.4267, YP1 = 12.2165). We substitute the obtained local coordinates of points R1 , P1 , P2 into Eq. (4) and calculate the value λ1 = 0.7071. Given that Q2 R1 = λ1 |P1 R1 |, we mark the control point Q2 of the segment R1 − R2 on the tangent τ1 . Then, we return to the world coordinate system xyz and determine coordinates of Q2 (12.0711, −16.4644, 22.9289) and P2 (22.5, 0, 0) control points using graphic software. Distributing the Eq. (1) along the x, y, z axes, we find scalar equations of the spatial Bézier segment R1 − R2 . We change the parameter t within the range of 0–1 and calculate the coordinates of the segment points and obtain its visual image (see Fig. 6). Example 3 (Bézier curve with fixed curvature at its end points). The points R1 (x1 , y1 ), R2 (x2 , y2 ) with tangents τ1 , τ2 specified at these points are set in the plane xy. Circles of curvature ρ1 , ρ2 are given at the points R1 , R2 . We should find the control points of the Bézier segment satisfying the specified boundary conditions (Fig. 7).

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Fig. 6. Composite Bezier curve (Example 2).

We will search for the solution in coordinate form: x(t) = (1 − t)3 x1 + 3t(1 − t)2 xQ + 3t 2 (1 − t)xP + t 3 x2 y(t) = (1 − t)3 y1 + 3t(1 − t)2 yQ + 3t 2 (1 − t)yP + t 3 y2 , t ∈ [0, 1].

(6)

Given boundary conditions, we obtain formulae for the coordinates xP , xQ of the control points: 3η1 (xQ − x1 )2 sign(xQ − x1 ) + ψ, 2(d2 − d1 ) 3η2 (x2 − xP )2 sign(x2 − xP ) + ψ, xQ = 2(d1 − d2 ) xP =

(7)

where ψ is a constant coefficient: ψ=

(y2 − y1 ) + (d1 x1 − d2 x2 ) d1 − d2

(8)

4 Experiment (Simulation of a Nature-Like Curve) A nature-like curve, or a physical spline, is a curve characterized by the minimum energy of internal stresses and the minimum average curvature (for example, a thin metal ruler (see Fig. 8). The theoretical equation of a physical spline can be found only at small deflections. For large deflections, the solution is more complicated. Therefore, it is expedient to simulate a nature-like curve experimentally. We have an elastic ruler with free ends passing through points A, B, C (the simplest physical spline). We find an analytical function providing a satisfactory approximation to the shape of a ruler (Fig. 8a). The desired function should meet three groups of local conditions: incidence to the reference points A, B, C; touching the straight lines τA , τB , τC ; and zero curvature at the points A, C. The problem cannot be solved using a standard NURBS curve.

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Fig. 7. Bézier curve segments with fixed curvature at the ends.

Fig. 8. a Simplest physical spline photo; b Simplest physical spline approximation.

We search for a solution in the form of a composite G2 -smooth cubic Bézier curve. We break the elastic line into sections AB and BC, each of which is replaced by a Bézier cubic segment. To ensure zero curvature at the point A, we combine the control point P1 of the segment AB with the intersection point of the tangents τA , τB (see the zero-curvature theorem). We achieve the required accuracy of the approximation of the segment AB by moving the control point Q1 along the tangent τA . To ensure zero curvature at the point C, we combine the control point Q2 with the intersection point of the tangents τB , τC . We calculate the parameter λB according to the known ratio [5]: (2)

λB =

wB

(1) wB

=

|B − Q2 | |B − P1 |

(9)

Substituting λB into (4), we obtain the coordinates of the control point P2 . The control points of the segment BC are fully defined. The composite cubic curve AB + BC meets all boundary conditions. The approximation error does not exceed 1.5% (Fig. 8b). A physical spline of a general form. An elastic element with free ends passes through the supporting points 0, 1, ..., 4. We mark the tangents τ0 , ..., τ4 at the supporting points (Fig. 9). We should find a G2 -smooth approximation function passing through

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points 0, 1, ..., 4 and tangent to the lines τ0 , ..., τ4 . The curvature of the approximation function at the end points 0 and 4 must be zero. We will search for a solution in the form of a curve consisting of four cubic Bézier segments. The first segment. We coincide the control point P1 of the first segment 0 − 1 with the point of tangents τ0 , τ1 intersection. The result is that the curvature of segment 0 − 1 at the initial point is zero (see the theorem for zero mean curvature). Moving the control point Q1 along the tangent τ0 , we obtain satisfactory approximation of the first segment of the physical spline. The second segment. We specified the control point Q2 ∈ τ1 and found the control point P2 ∈ τ2 . The position of point P2 is functionally dependent on the position of point Q2 . Moving the point Q2 along tangent τ1 , we achieve satisfactory approximation of the second segment of the physical spline.

Fig. 9. Physical spline (general form) approximation.

The third segment. We specified the control point Q3 ∈ τ2 and found the control point P3 ∈ τ3 . The position of point P3 functionally depends on the position of point Q3 . Moving the point Q3 along the tangent τ2 , we achieve satisfactory approximation of the third segment of the physical spline. The fourth segment. We combine the control point Q4 with the intersection point of tangents τ3 and τ4 . The result is that Bézier segment 3–4 curvature at the end point 4 is equal to zero (see the theorem for zero mean curvature). The curvature at the ends of the fourth segment is fixed, so we cannot control its shape. Nevertheless, the Bézier segment 3–4 satisfactorily approximates the fourth segment of the physical spline. The approximation error is less than 2% (Fig. 10).

5 Conclusion Architectural graphics is the application of visual means to project implementation. Graphics is an essential part of the architectural design, from sketches to detailed drawings. A line arbitrarily drawn by the architect is used to form a surface [22–26]. We recommend replacing an approximate graphically defined curve with a regular algebraic curve. To approximate a graphically defined curve (flat or spatial), we propose using a composite cubic Bézier curve with continuous changes in slope and curvature. We

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Fig. 10. Physical spline (general form) approximation.

have proposed a graphic-analytical algorithm for constructing a composite Bézier curve, which provides an approximation accuracy of 1–2%. The algorithm can be implemented in any graphic suite supporting 3D graphics. Acknowledgements. The work was supported by Act 211 Government of the Russian Federation, contract № 02. A03.21.0011.

References 1. Kirichkov IV (2017) Krivolinejnost’ v arhitekture – analiz konstruktivnyh reshenij Harbinskogo opernogo teatra (Curvilinearity in architecture - analysis of constructive solutions of the Harbin Opera House). J Arch Des 1:53–71. https://doi.org/10.7256/2585-7789.2017.1. 22268 2. Adnan F, Yunus RM (2012) The influence of curvilinear architectural forms on environmentbehaviour. Procedia Soc Behav Sci 49:341–349 3. Kurshakova VN (2008) Problems of application of the latest membrane structures in modern architecture. Architecton: Izvestia VUZov, no 22. http://archvuz.ru. Accessed 17 Jan 2017 4. Farin G (1997) Curves and surfaces for computer aided geometric design. Implementation and algorithms. A practical guide, 4th edn. Academic Press, USA, San Diego, CA, p 499 5. Linn G (1993) Architectural curvilinearity. The folded, the pliant and the supple. J Arch Des (Willey Academy) 63(3/4):24–31 6. Schumacher P (2008) Parametricism—A new global style for architecture and urban design. AD Arch Des Dig Cities (London) 79(4) 7. Schumacher P (2007) Arguing for Elegance. In: Castle H, Rahim A, Jamelle H (eds) Elegance, architectural design, vol 77, no 1. Wiley-Academy, London 8. Korotkiy VA (2022) Irregular curves in engineering geometry and computer graphics. J Sci Visualiz 14(1):1–17. https://doi.org/10.26583/sv.14.1.01 9. Korotkiy VA, Usmanova EA (2020) Regular linear surfaces in architecture and construction. J Phys: Conf Ser 1441. https://doi.org/10.1088/1742-6596/1441/1/012065 10. Korotkiy VA, Khmarova LI (2020) Computer modelling of architectural forms based on ruled surfaces with imaginary axes. IOP Conf Ser: Mater Sci Eng 962:032026 11. Bézier P (1989) Geometric methods. Mathematics and CAD. Mir, Moscow, pp 96–257 12. Panchuk KL, Myasoedova TM, Odinets MN (2020) Construction of a discrete planar contour by fractional rational Bézier curves of second order. J Phys: Conf Ser 1546. https://doi.org/ 10.1088/1742-6596/1546/1/012039

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13. Panchuk KL, Myasoedova TM, Lyubchinov EV (2021) Spline curves formation given extreme derivatives. J Math 9(1):47. https://doi.org/10.3390/math9010047 14. Panchuk KL, Myasoedova TM, Lyubchinov EV (2021) Cyclographic model of generation of families of parallel curves to a multiply-connected (2021). Adv Intell Syst Comput 1296:152– 163. https://doi.org/10.1007/978-3-030-63403-2-15 15. Salomon D (2006) Curves and surfaces for computer graphics. Springer Science+Business Media Inc., New York, NY, USA, pp 11–164 16. Sorokin V, Kombarov V (2012) Comparison of the kinematic parameters of motion when modeling the trajectories of high-speed CNC machining with splines of the third and fifth degrees. Aerosp Eng Technol 8:11–17 17. Glaeser G (2014) Geometrie und ihre Anwendungen in Kunst, Natur und Technik. Springer Spektrum, p 508. https://doi.org/10.1007/978-3-642-41852-5 18. Foks A, Pratt M (1982) Computational geometry. In: Application in design and production. Mir, Moscow, p 304 19. Shikin EV, Plis AI (1996) Curves and surfaces on a computer screen. Dialog-Mifi, Moscow, Russia, pp 90–150 20. Gallier J (2018) Curves and surfaces in geometric modeling: theory and algorithms. University of Pennsylvania, Philadelphia, PA, USA, pp 61–114 21. Marsh D (2005) Applied geometry for computer graphics and CAD, 2nd edn. Springer, London, UK, pp 135–185 22. Korotkiy VA, Khmarova LI (2017) Kinematic methods of designing free form shells. IOP Conf Ser: Mater Sci Eng 262:011001. https://doi.org/10.1088/1757-899X/262/1/012109 23. Korotkiy VA, Usmanova EA (2015) Closed loop architectural shell. J Bull SUSU Ser “Construct Arch” 15(2):47–51 24. Korotkiy VA, Usmanova EA (2020) Wedge-shaped surfaces with constant length generators in architectural design. IOP Conf Ser: Mater Sci Eng 962:032027. https://iopscience.iop.org/ article/https://doi.org/10.1088/1757-899X/962/3/032027 25. Korotkiy VA, Khmarova LI, Usmanova EA (2016) Computer simulation of kinematic surfaces. J Geom Gr 3:19–26 26. Korotkiy VA, Usmanova EA and Khmarova LI (2016) Dynamic connection of secondorder curves. In: 2nd international conference on industrial engineering, applications and manufacturing (ICIEAM). IEEE Conference Publications, pp 1–4

“Healthy” Architecture: Synthesis of Humanistic Approaches T. Yu. Bystrova(B) , A. M. Postnikova, and A. V. Garas Ural Federal University, 19, Mira St., Ekaterinburg 620002, Russia [email protected]

Abstract. Ecological conditions, especially in large cities, active urbanization and the COVID-19 pandemic reinforced the importance of architecture, which exterior and interior both care about the human health, taking into consideration the influence of architectural forms on physical, mental and socio-cultural states of a person being around those structures, living in them or using them on a daily basis. The article clarifies the methodological foundations and conceptual apparatus of design, which can be referred to as the “healthy” architecture meaning it is aimed at maintaining the health of its users. The author refers to concepts of “healthy”, “sustainable” and “living” architecture, biomorphic approach and biophilia. It is implemented not only in the material environment (i.e. objectively) but also as an architect’s design setting, the design algorithms that are being used today require a change towards greater individualization of the form. It is dictated, on the one hand, by the characteristics of users and, on the other hand, by the natural and social context. Keywords: “Healthy” architecture · “Living” architecture · Adaptive architecture · Organic architecture · Universal design · Design model · Building form · Design algorithms

1 Introduction Ecological situation, especially in large cities, pandemic of 2020–22 strengthens and will strengthen the role of concepts that include the word “health”, not only in the sense of isolation or the speed of deployment of medical institutions. At the next development stage, cities will need architecture that sets humanistic goals and, to a certain extent, resists or compensates for the pressure of public measures aimed at combating the pandemic [1]. The comprehension of its qualities occurs at different levels, from experimental psychological [2] to urban [3, 4]. In modern architectural usage, “sustainable” architecture is too often reduced to a set of technological solutions, and the “sustainable” morphogenesis of buildings is not taken into account. Meanwhile, architecture, like any kind of “organized matter”, does not exist outside of form. That is why the essence of architectural design is the search for an adequately corresponded to functions, design, context, aesthetic preferences, economic © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_30

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conditions and construction technology form. Such form has a certain compositional and aesthetic independence in relation to technologies and construction. The concept of architectural form is applicable both to entire buildings and to their individual elements and even details, as well as to architecturally organized space. In parallel, those who develop the ideas of a “healthy home” are more likely to talk about cleanliness and safety in the building [5] (which is logical in certain social conditions) than about the whole complex of qualities, from visual ecology and aesthetics to energy efficiency. The processes of recent years are pushing us to return the concept of “architecture” to its original professional meanings and understand it as an activity to create harmonious objects that are adapted to the constitution and the needs of people and positively influence them. It is possible to restore architecture to its cosmic, demiurgic status only by synthesizing several concepts focused on human health and needs, “taking” their strongest and most viable qualities. These are organic architecture [6], adaptive architecture [7, 8], universal and inclusive design [9, 10], general aesthetic theory of harmony, sustainable design, sciences of complex systems [11–13]. All of them are critical of the unified architecture, all come to recognize the age, ethnocultural, regional, gender and other characteristics of users, but at the same time their representatives often act separately, without strengthening their positions by interacting with those who are nearby. They can be synthesized in models, the development and testing of which are presented in this text. The proposed in this article project model is a special “source code” of the project, taking into account both constructive and ethical characteristics of the architectural form. Their study is mainly carried out by specialists in project management in business and management, not related to the issues of morphogenesis. In architecture, many of these models have been and remain algorithmized. But, if before they were mainly set by standards and typologies, then at the moment it is necessary to develop other morphological models that differ from the previous ones, and also to change the algorithm of architectural design in the direction of working out specific places and tasks of the building, influencing the choice of expressive and technical means [14]. An architectural critic from the USA A. Betsky called this process “departure from the rules” [15].

2 Research Methodology We can agree with [16] that the basic concepts that reveal the topics of sustainability and health should be used as accurately as possible. Thus, according to the documents, the concept of “sustainability” cannot be reduced to only economic or only environmental aspects. It touches upon all aspects of human life and personality. Similarly, resulting from interaction with architecture or design, health is not limited only to hygiene, as, for example, it interprets one author [17]. Accordingly, as part of the sustainability program, a health-aimed architecture is an approach that takes into account all indicators of the user’s condition: mental, psychological, cognitive, physical, etc. The balance of technology, ecology and economics of the projects is shown by Ch. Alexander, M. Mehaffy, their followers and commentators [18]. Where the statements of the architects themselves are not enough, we turn to scientific research of their creativity and project programs [13, 19, 20].

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The development of the concept of sustainability in the 1970–2010s [21] leads to the expansion of the architectural “horizon”, including an assessment of not only technologies and materials, but also issues of their renewability, circularity, carbon footprint. Exactly in this volume it is present in this text. The main methodological orientation of the authors of the “healthy” architecture is aimed at the synthesis of viable productive concepts of architects of different periods, setting the task of ensuring human health by means of architecture, primarily organic architecture (from F. L. Wright and R. Steiner to S. Calatrava, I. Makovec and M. Budzinski), “sustainable” design, biophilia and “living” architecture (N. A. Salingaros, A. Duany, H. Viles, et al.), biomorphic approach (E. Saarinen, Yu. Lebedev). We selected those concepts in which there is a fixed connection between the properties of the architectural form and the physical, mental, socio-cultural parameters of the recipients. They need to be supplemented with data on architectural projects of the present time aimed at reducing morbidity, first of all, their technologies and structure [22]. In general, while intersecting with each other at the level of ideas, the authors do not always interact with like-minded people, which restrains the general movement towards an on health based architecture. Emphasizing the characteristics of the architectural form, we do not study buildings of the same typology, trying to determine the components of architecture that can be implemented with variable application of general principles. Strictly speaking, there are not yet enough objects to place restrictions on the search for empirical material. Values and principles that are adequate to the task of preserving and strengthening people’s health are important.

3 Results Concepts in which the model of a person is adequate to the level of tasks facing the “healthy” architecture are identified and systematically presented. Five components (temporal, formal, material, adaptive, aesthetic) of the design model for “healthy” architecture are identified and characterized. Being taken into account by the architect in the design, they significantly increase the positive impact of the object on the physical and mental state of a person. A design approbation of a health-aimed architectural design model was carried out. As the object was chosen the cultural center in a Ural small industrial settlement, which has a rich historical past and is partially changing its industrial functions today.

4 Discussion 4.1 General Understanding of Modern Architecture Striving for the universal significance of the results, it is necessary to recognize at the first step that today there are all opportunities to take the long discussion of the 1980s– 2020s about classics and modernism to a new qualitative level. The statement of their opposition has become a well-known and non-heuristic place. With all the skepticism about architectural modernism, which has lost, as N. Salingaros designates [23], the third

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dimension of form and turned into a mechanical multiplication of one-floor plans, devoid of facades, it is impossible to deny elements of humanistic design in it (for example, in the projects of the first Soviet “Khrushchevkas” in Moscow Cheryomushki—despite the very strict economic determination of the process). It is impossible to turn a blind eye to the ubiquity of modernist solutions, in which people have been living for at least the fourth generation and to which they have adapted to some extent. Quantitative and qualitative indicators of their familiar environments need to be studied and further taken into account in projects. Architecture as the creation of human-like forms—and not the way of making money has the most important goal. What is it? To save the person. To preserve the human in a person. The laws of matter organization, derived by architects from ancient Greece to modern times, are recorded in the works of Alexander [8, 14] and Salingaros [7, 23]. The calculated structural complexity, the presence of centers and scales, self-similar and fractal elements, the absence of monotonous surfaces and aggressive anti-gravity elements can serve as criteria for assessing the adaptability of an architectural object for any purpose. Universal laws of the harmonious structure of the world can be implemented in a modern mass residential complex, and in a “tree house”, and in the layout of a square or a block. Their implementation requires fewer automatisms, maximum consideration of the natural and anthropogenic environment, local traditions, terrain features, etc. The implemented projects of the supporters of “living architecture” prove that harmony is not necessarily solved only by a classical order. Respectively, modernism is not always automatically disharmonious or inhumane, and regional versions of the “classics” can be absolutely kitschy and disharmonious. You can start by revising the set of meanings of the concepts of “classics” and “modernism”, which are implied by default and very rarely voiced by most specialists. The search for a common plane of their existence in the modern world leads us to the characteristics of harmony and measure, which also have mathematical equivalents. This will be greatly hindered not only by the universal conviction that the economy “rules” architecture, but also by the lack of the habit of society to pay attention to architectural and environmental factors (“there is a roof, that is enough”). The pandemic brings us to a point where a person may not have enough strength to adapt to a weak or harmful architectural solution. The sooner all sides of the process understand this, the more optimistic its prospects can be. 4.2 Urban Context of Modeling Architecture Aimed at Health Design professions is going through difficult times. Digital technologies sometimes give the impression that it is possible to design without architects, economic shocks lead to the fact that their services look only “burdening” the budget. This leads to the spread of vernacular architecture in a number of regions of the world. So, D. Cerantonio says that “in Australia, only 2% of all new homes between 2012 and 2021 were designed by architects. We hope that by reducing the cost to the end-customer, we can increase this statistic and improve the standard of living through better designing buildings and environments” [24].

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It is accepted today that replanning and redesigning the processes of life in our cities is what worries both institutions and citizens. To be successful and meaningful, such processes must be supported by research [25]. Reliance on science becomes the slogan of the day, and science should respond to challenges of this kind. For example, researchers of the Austrian concern Baumut study the microclimate of premises in the VIVA research park depending on the materials of construction—exterior, thermal insulation, finishing [26]. They emphasize how important is the consumption of fresh air by residents (from 8 to 20 thousand litres per day), its humidity, including in connection with the development of microorganisms in the house. With all the importance of such physical studies, many other parameters must be added to them. They are noted not only by specialists. For example, one of the bloggers writes about Ch. Alexander’s buildings, “I’ve been to five of his built projects now, and have re-visited some of them on multiple occasions. In each of these places, the people involved told me the same three things: (1) that these places are becoming more beautiful through the passing of time; (2) that these structures, and the theory of space they’re predicated upon, are completely alien to what other architects and designers would have done; and (3) that people’s lives become more whole and beautiful as a result of their inhabiting of these structures, and dwelling in these places” [27]. The vocabulary of comments talking about beauty, perfection, structural integrity, brings an understanding of what people need from architecture in the modern world beyond the boundaries of the physical properties of materials. 4.3 Components of a Design Model for a Health-Aimed Architecture 4.3.1 Design Addressee The biosocial interpretation of a person as a part of the natural world and, accordingly, understanding of architecture in the unity of its physical, aesthetic, technological aspects (B. Fuller, Yu. Lebedev, Ch. Alexander, etc.) logically lead to the idea of a “good fit” of the architectural form to a person and his needs. It is important not to arbitrarily “fit” the form to some external criteria, but to find a solution that takes into account the interests and capabilities of all “participants” of the architectural process as much as possible. As the simplest example, one can repeat, following Ch. Alexander, the version of a gable roof in places where there is a lot of wood, very snowy winter or hot summer [8]. The intersection of climatic, biological and human principles gives rise to a construction that is possible, expedient, convenient to use and has a certain aesthetic. Through the study of the biological organization of man, architecture receives special impulses of morphogenesis, the value of which increases [9]. In projects where architects approach such unity, there are a number of interrelated characteristics that enhance their “usefulness” in the sense that this word is used in this text. Let’s list them as the main elements of the architecture model aimed at health. 4.3.2 Temporal Aspect of Architectural Form The pandemic has shown people overestimating the role of sustainable, stable structures in which they exist. The theme of home, hearth, synonymous with protection and health, came to the fore. Thus, there is a rejection of an unambiguously positive assessment of

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any architectural or urban innovations in favor of constants of spatial organization, laid very deeply. Of course, in the XX century, especially during the reign of modernism, architecture, as well as culture in general, put forward novelty as a priority. The pursuit of novelty as an end in itself does not contribute to health: the whole human-aimed architecture, even to the uninitiated, looks somewhat conservative (Fig. 1). It does not rush to the number of floors, is connected with the landscape and everyday practices of residents of a particular area, takes into account ethnic traditions—most often, without their literal reproduction. In the work “The Timeless Way of Building”, published in 1979, Ch. Alexander writes: “There is one timeless way of building. It is a thousand years old, and the same today as it has ever been. The great traditional buildings of the past, the villages and tents and temples in which man feels at home, have always been made by people who were very close to the centre of this way… And, as you will see, this way will lead anyone who looks for it to buildings which are themselves as ancient in their form as the trees and hills, and as our faces are” [14]. He plays with the meaning of the word timeless, which does not quite correspond to the word “eternal”, rather, it has gone beyond time, devoid of time. Ch. Alexander explains such “timelessness” of architectural objects by the presence of “live” patterns in them (there may be “dead” patterns [14, p. X]). This approach tending to sustainability makes sense. The American architecture researcher N. Salingaros believes that “living architecture” is possessed by cultures that are close to nature, do not prioritize technology or economics, are focused on pedestrians, not cars, and preserve their building traditions [23]. It is important that in the presence of quite objective parameters of “liveliness”, such an architecture is measured by criteria such as compliance with the needs and behavioral scenarios (patterns) of people, compliance with the laws of perception and assimilation of information, connection with the lifestyle and value system of a person [28, 29]. The forms of “living architecture” are diverse and complex, as life itself is complex, variable due to the presence of various deviations in them and cannot be reduced. Today, not only specialists but also politicians are calling for reliance on history and tradition [25]. Vernacular architecture is being studied more and more actively in various regions—the Middle East, North Africa, India, etc.—as a carrier of concentrated centuries-old experience in adapting a person to the conditions of existence in a particular climate and landscape. Today it is more important not to divide the history of architecture into stylistic or other periods, but to see the “through” laws of the organization of space. In addition, the temporal aspect of architecture suggests the possibility of changing the states of a person in a building. For example, the two-dome system of R. Steiner’s Goetheanum (1861–1925) is designed to create a sense of dynamics, development, movement of thought of the one who is in it [19]. The chronotope of architecture was also taken into account by the Austrian architect F. Hundertwasser, who spoke about the need for uneven floors and irregular windows, inherent not only in natural formations but also in early objects created by humans.

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Fig. 1. Examples of architectural forms of the last decades, approaching in proportions and even technologies to the traditional ones. a Theater. Mako, Hungary. 1996. Arch.: I. Makovecz; b “XXI century” private house. Beloilenka, Poland. 2003. Arch. M. Budzinski. c West Dean Visitor Center. West Sussex, United Kingdom. 1994–1995. Arch. Ch. Alexander partnered with CES with students from the Prince of Wales Institute of Architecture and from the University of Portsmouth.

4.3.3 The Formal Aspect of “Healthy” Architecture The ontology of architecture, the laws of its human-oriented structure are formulated by Ch. Alexander and his followers in the form of 15 fundamental properties or three laws, the main of which, from our point of view, are scaling, the presence of centers at all scale levels, taking into account the force of gravity when creating forms [7]. The ideas of S. Suzuki (1898–1998) about the integrity of the environment as a necessary condition for full human development are close to them. The strength of the approach is primarily due to the fact that these laws apply to all units of architecture, from building elements to urban planning codes (“new urbanism”). Architects directly and indirectly agree with them, speaking about the lack of development of the average scale of buildings, which today is taken away by advertising and signage [28], the need to strengthen the heterogeneity of architectural space [4]. The question of the average scale of buildings, filled today mostly with nonarchitectural elements, needs to be studied and to have special regulation [28]. An example is the law on the design of signage and navigation elements on facades, in force in Moscow. Small scale levels can be filled with the user’s personal items, and not with ornaments, as Ch. Alexander says. Augmented reality is able to fill a part of the architectural volume [9]. These phenomena must be carefully studied, otherwise you can slip into the same generalized typologies that these researchers rightly criticize. Along with the trend towards the actualization of the order architecture and the development of fractal shaping, one can point out the importance of archetypal forms that coincide with the inner mental structure of a person. 4.3.4 Adaptive and Aesthetic Aspects of “Healthy” Architecture The living world and the “living” architecture have a complex multi-level structure, where the proportions of objects fit into certain numerical sequences (the Fibonacci series, the “golden section”) and follow the laws of tectonics. The elements of the whole are variable, and the symmetries are devoid of absolute accuracy. When mastering them, the human brain works actively, whereas in “garbage” or monotonous environments it does not receive the necessary information. Our sensory system has evolved, tuning itself to connect with other forms of life, which means that natural geometry optimizes

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the state of the body and emotions. Accordingly, it underlies the ideas of harmony and beauty. In addition to these ideas formulated by researchers from different countries, the concept of inclusive design creates a good basis for health-aimed projects. Unlike mass architecture, which levels differences and creates “average” simplicity, this concept seeks to create a form that equally satisfies different categories of people. Instead of static parameters of a “standard” project, such indicators as human uniqueness and variability are used [10]. Initially, the possibility of coexistence of different positions and points of view on the projected object is recognized. Finally, the design does not end with the product itself—its long-term social consequences are also appreciated. This, perhaps the most complex kind of morphogenesis, is likely to grow out of the dialectical unity of invariant and individualized elements. A radical change in the project process contributes to the achievement of such a multiple variable whole. These are receiving feedback from users already at the preproject stage; co-participating design; “down-up” planning [3] and decentralization. 4.4 An Example of a “Healthy” Architecture In 2021, for one of the small towns of the Sverdlovsk region (Ural region, Russia), we have developed an object that implements installations of architecture aimed at health. • A cultural center is a multifunctional, universal space that can adapt to the physical, cultural, and communicative needs of city residents, including during difficult periods such as a pandemic (adaptive aspect). The project takes into concideration the requirements of accessibility of the building and its surrounding areas for lowmobility groups of the population, including the use of pedestrian ramps and tactile sidewalks. Also if the continuity of pedestrian paths connected with external transport communications is present. • During the design, it was determined that in the project of the cultural centre it is possible to interestingly and expressively implement architectural solutions that inherit the features of the wooden architecture of the region, strengthening its connection with the past, but without excessive archaization (temporal aspect). Particular attention was paid to proportioning and scaling, including work with local ornaments (Fig. 2). • The proportions and divisions of the volume of three blocks, united by two transitional spaces, are determined on the basis of 15 laws of sustainable architecture by Ch. Alexander—taking into account the features of local wooden architecture, such as low number of storeys, massiveness, the emphasis on windows, the presence of a gable roof (formal aspect). • The main material is wood. Local stone, metal and glass are used (material aspect). In addition, landscaping of the territory with local plant species adapted to the climatic conditions of this territory, which makes up more than 35% of the land plot, is provided. • The complexity of the color and texture palette, the use of thickening in places of compression, the use of asymmetry, ornaments and self-similar elements of different scale levels (small, medium, large) solve both adaptive and aesthetic problems. The brevity of the project, which was of an educational nature, did not make it possible

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Fig. 2. The project of a cultural centre for the Bilimbay village. Sverdlovsk region, Russia. Arch. O. Rodnova. Head: T. Yu. Bystrova. 2021.

to involve residents in the design, so the ideas of inclusive design were not fully implemented. The project proposal presents a scheme of the master plan, made taking into account the city development strategy, a functional zoning scheme and a planning scheme have been developed. Variants of engineering and technical solutions are proposed to improve the energy efficiency of the object. The analysis of the projected object according to the criteria of Green Zoom eco-certification is carried out.

5 Conclusion The presented model of architecture based on health takes into account the most fundamental and, at the same time, proven concepts, at the center of which is a person, his condition and development. The concretization of ideas can be carried out in the future in two ways: through the analysis of already existing objects declared as “sustainable”, “healthy”, etc. and in project practice.

References 1. Hosey L (2019) Six misunderstood terms in sustainable design. Architectural Lighting Industry. https://www.archlighting.com/industry/six-misunderstood-terms-in-sustainabledesign_s?utm_source=newsletter&utm_content=Article&utm_medium=email&utm_cam paign=AL_032420 2. Mehaffy MW (2007) Notes on the genesis of wholes: Christopher Alexander and his continuing influence. Urban Des Int 12(1):41–49 3. Gerfen K (2020) MASS design group asks: “What is the Role of Architecture in Fighting a Pandemic?”. https://www.architectmagazine.com/design/mass-design-group-asks-what-isthe-role-of-architecture-in-fighting-a-pandemic_o?utm_source=newsletter&utm_content= Article&utm_medium=email&utm_campaign=ABU_040720 4. Gray F (2014) Rudolf Steiner’s theories and their translation into architecture. Ph.D. thesis. Deakin University, p 334

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5. Silitonga S (2017) To be an affordable healthy house, case study Medan. In: IOP Conference Series: Earth and Environmental Science, Friendly City 4 “From Research to Implementation For Better Sustainability”, vol 126, Medan, Indonesia, pp 1–10. https://iopscience.iop.org/art icle/10.1088/1755-1315/126/1/012161 6. Inclusive Design Toolkit. University of Cambridge. http://www.inclusivedesigntoolkit.com/ whatis/whatis.html. Accessed 15 Feb 2022 7. CNU Congress for the New Urbanism. https://www.cnu.org/resources/what-new-urbanism 8. Alexander C (1979) The timeless way of building. Oxford University Press, p 552 9. Barbiero G (2011) Biophilia and Gaia: two hypotheses for an affective ecology. J Biourban 1:13–24 10. Seamon D (2005) Making better worlds: Christopher Alexander’s the nature of order, vols 2–4. Traditional Building, pp 186–188 11. Pickett S, Cadenasso ML, McGrath B (eds) (2013) Resilience in ecology and urban design linking theory and practice for sustainable cities. Springer 12. Ország Épít˝o (2012) Memoriam Imre Makovecz, # 4. Special edn 13. Betsky A (2020) Welcome to the postorthographic age. Architect. https://www.architectmag azine.com/practice/welcome-to-the-postorthographic-age_o?utm_source=newsletter&utm_ content=Article&utm_medium=email&utm_campaign=AN_032720& 14. Klyn D Einmal Ist Keinmal. Noteworthy—J Blog. https://blog.usejournal.com/einmal-ist-kei nmal-28afb7965ab3. Accessed 23 June 2020 15. Tokarev N, Architecture of direct action. Project Russia. https://prorus.ru/interviews/arhite ktura-pryamogo-dejstviya/. Accessed 31 Mar 2020 16. The Grass Roots Housing Process. Written in 1973 by Christopher Alexander (in homage with E. F. Schumacher). https://www.patternlanguage.com/archive/grassroots.html 17. Hess A (2006) Organic architecture: the other modernism. Gibbs Smith, Salt Lake City 18. Federidhi P (2020) Research and practices to reach a sustainable and healthy economic and social recovery post COVID-19—An invitation from Italy. Pascal International Observatory. http://pascalobservatory.org/pascalnow/blogentry/news/research-and-pra ctices-reach-sustainable-and-healthy-economic-and-social-re 19. Park G, Nanda U, Adams L, Essary J, Hoelting M (2020) Creating and testing a sensory well-being hub for adolescents with developmental disabilities. J Inter Des 45:13–32. https:// doi.org/10.1111/joid.12164 20. Banaei M, Ghaffari A (2011) What is healthy house? Housing Rural Environ 30(1):15–28 21. Pearce AR, Ahn YH (2017) Sustainable buildings and infrastructure: paths to the future. H, 2nd edn. Taylor & Francis, London, p 482 22. Batty M, Longley P (1994) Fractal cities. In: A geometry of form and function. Academic Press Inc., San Diego 23. Salingaros NA (2018) Adaptive versus random complexity. New Des Ideas 2:51–61. http:// jomardpublishing.com/UploadFiles/Files/journals/NDI/V2N2/SalingarosN.pdf 24. Bystrova T, Tokarskaya L, Vukovic DB (2019) Optimum virtual environment for solving cognitive tasks by individuals with autism spectrum disorders: the questions and methods of design. Int J Cogn Res Sci Eng Educ 7(1):63–72 25. Mehaffy MW, Salingaros NA (2021) The surprisingly important role of symmetry in healthy places. Planetizen. https://www.planetizen.com/features/112503-surprisingly-import ant-role-symmetry-healthy-places 26. Baumit simuliert Blackout im Viva Forschungspark. Baumit. https://www.ots.at/presse aussendung/OTS_20211111_OTS0099/baumit-simuliert-blackout-im-viva-forschungsparkbild. Accessed 11 Nov 2021 27. Caduff C, What Went Wrong: Corona and the World after the Full Stop. https://www.aca demia.edu/42829792/What_Went_Wrong_Corona_and_the_World_after_the_Full_Stop? email_work_card=view-paper. Access 22.06.2020

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28. Salingaros NA (2017) Unified architectural theory: form, language, complexity: a companion to Christopher Alexander’s the phenomenon of life—The nature of order, Book 1. Sustasis Press with Off the Common Books 29. The World‘s First Tokenized Architecture & Design Community Launches on the Blockchain. Yellowtrace (2022). https://www.yellowtrace.com.au/state-of-address-nft-architecture-com munity-on-blockchain// Accessed 17 Feb 2022

Features of Designing Unique Architectural Objects in Extreme Natural Environments: The Precedents of Application N. A. Saprykina(B) The Moscow Architectural Institute (State Academy), 11/4, Rozhdestvenka Street, Moscow 107031, Russia [email protected]

Abstract. This article discusses the features of designing unique architectural objects and their construction in extreme natural environments. It is noted that for these conditions, it is important to identify alternative approaches to solving this problem based on the search for new, including non-traditional solutions to unique architectural objects that use technological innovations of the future to ensure the security of existence. The features of creating a safe environment in extreme natural conditions, which are practically not used in modern architecture and construction practice, are revealed. The precedents of the construction of unique architectural objects in extreme conditions of the aquatic environment, the use of techniques for the formation of a virtual light environment in underground construction and the construction of unique objects to create an artificial habitable environment in space are presented. A selection of design proposals for unique architectural objects in extreme natural habitats is presented, which allows us to outline the directions for searching and conducting further promising research in this area. Keywords: Unique structures · Extreme conditions · Aqua-architecture · Terra-construction · Weightlessness architecture · Virtual environment · Innovative technologies

1 Introduction The design of unique architectural objects for conditions of extreme natural environments is associated with the vital need to create a comfortable living environment there [1]. Strict requirements for the design of such facilities necessitate a comprehensive and indepth study of this trend due to the exceptional complexity and relevance of the problem under consideration [2]. In Russian and foreign studies, the problem under consideration is of interest to scientists, philosophers, engineers, architects, physicians, ecologists, sociologists, psychologists and other specialists. In this regard, design and experimental developments of unique objects for the organization of a comfortable living environment in extreme © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_31

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conditions are proposed [3]. Especially important is the emergence of eco-oriented concepts of conservation of natural resources in extreme natural habitats [4], also, the human security strategy associated with the use of technological innovations for these purposes in the context of the direction of this study is brought to the fore [5, 6]. Despite these progressive trends, the practice of designing and constructing unique architectural objects for extreme natural environments does not yet have a methodology for comprehensive consideration of all requirements and solves only particular problems in this direction. In this regard, it is especially important to identify new concepts in theoretical research and design and experimental developments, takings into account the causes of the manifestation of dangerous factors and justifying the need to use innovative technical achievements in the design of unique architectural objects. 1.1 Relevance of the Issue The urgency of the problem lies in the modern needs of designing unique architectural objects in conditions of extreme natural habitats. The urgent need to create a safe habitat here is of particular importance for ensuring favorable living activity conditions. The modern solution to this problem is characterized by a one-sided approach that provides only for the current state of affairs without taking into account progressive trends in the development of architecture of unique objects for conditions of extreme natural habitats. The ongoing and projected changes in the environmental, socio-economic and especially energy nature, cause the need to search for new, including unconventional solutions to unique architectural objects and their life support systems. In this regard, it is important to note the need to revise the usual means of architecture in order to use the achievements of other fields of science and technology made possible by the latest developments in the field of innovative technologies. The present study attempts to identify new approaches and ways to develop concepts of formation habitat, as well as to clarify current trends in the design of unique objects in extreme conditions, which are practically not used in architecture and modern practice. 1.2 Problem Statement The purpose of the article is to gain new knowledge in the theory of architecture in the formation of a safe living environment as an alternative ecosystem for extreme natural environments. This will make it possible to identify individual strategic changes and alternative approaches to its formation in the conditions under consideration, as well as to clarify the current directions of research on this problem. The main scientific task of this article is to determine the design features of unique objects created for extreme natural environments that use technical innovations of the future to ensure the safety of existence. This will require solving the following specific research tasks: • Identification of the features of the construction of unique objects in extreme conditions of the aquatic environment. • Features of the use of techniques for the formation of a virtual light environment in underground construction.

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• Identification of the features of the construction of unique objects to create an artificial habitable environment in space. This approach to the study necessitates the identification of methods and techniques for designing unique architectural objects for conditions of extreme natural environments, which are practically not used in modern architecture and construction practice.

2 Theoretical Part 2.1 Aqua Architecture: Construction of Unique Objects in the Aquatic Environment Global warming, natural disasters, overpopulation of the planet—all these global problems require no less significant solutions from humanity, including in the field of construction of unique facilities in the aquatic environment. Due to the urgency of the development of the ocean’s riches and the use of its space, on the one hand, for the expansion of territories on land, and on the other, for the development of the economic potential of the ocean, great attention paid to construction for these conditions. The experience of exploring the ocean and its depths opens up new boundaries and provides precedents for the organization of artificial habitat in extreme aquatic environments: on the seashore, on the water and under water. This leads to the appearance of a large number of unique projects of mega-buildings on the seashore. For example, main threat to New Orleans (USA) is flooding as a result of the invasion of hurricanes (for example, Hurricane Katrina, which brought huge destruction in 2005). Therefore, the most logical thing is to place a floating “ark complex” on the shore of the bay. For these conditions, a mega structure on water in the form of a tetrahedron “New Orleans Arcology Habitat” 2009 (architect Kevin Schopfer) is proposed. The object is a spatial structure consisting of three separate towers, like the faces of a triangular pyramid, and is designed to accommodate up to 40,000 residents [7]. The shape of the triangular pyramid is chosen as the toughest and most durable construction. The structure is designed in such a way that a strong wind is not able to bring down this grandiose structure. This is ensured by the fact that the middle of the triangular pyramid is empty, its edges are additionally rounded, and the faces are inclined. The interior space of the “ark complex” provides for the placement of almost all the necessary facilities for a full-fledged life of the inhabitants: apartments, a hotel, a kindergarten, a school, offices, shops, restaurants, parking lots, casinos and even parks. The Ark complex is eco-sustainable, as it is a closed life support system that is able to provide itself with everything necessary. It is planned to place water and wind turbines, solar panels and water purification systems in the complex. For movement inside the mega-object, a system of horizontal and vertical elevators is provided, allowing you to move to different levels. According to the developers, such a self-sufficient complex will be a psychological support for people who have lost all their property in a disaster [8]. A similar mega structure of a floating multi-stores city near the shore of the reservoir “Boston Arcology Habitat” 2011 (architect Kevin Schopfer), designed for 15,000 residents, is proposed to be created near Boston. Rectangular in plan, the complex is located

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perpendicular to the coast line and is supported by a system of floating pontoons. It is equipped with installed solar panels and windmills, allowing restoring the ecological system and regulating the temperature inside the building. High-rise gardens, located every 30 floors, are the main public areas of the structure and include a set of sustainable energy-efficient components and life support systems. Energy is generated using photovoltaic panels, wind and water turbines. Instead of cars, horizontal moving sidewalks and stairs are installed. Translucent facade structures accumulate solar energy [9]. During the construction of unique objects on the water, a number of problems arise due to the need to overcome huge water spaces (construction of super bridges), due to the shortage of land area (floating cities and airfields), as well as in cases of mining (drilling of underwater oil wells). As the world’s population grows cities usually expand into surrounding areas, or because of infrastructure forming too high a density of cities, the question arises as to what alternatives can be offered after the depletion of land reserves. The proposed project of a skyscraper on the water “E Mare Libertas” (author Alexander Nikolas Walzer), 2018 (Austria), provides for a scenario of a vertically formed settlement in the port of Singapore. The idea of the project is to comprehend energy self-sufficiency to create open spaces on the water by using a modular construction system. Equipping the building with extensive greenery is due to protection from strong sun exposure throughout the year. To find the shape of the object, the coral growth algorithm was used, imitating their growth. The porosity of the structure helps to reduce the pressure of the crosswind, and at the same time, ensures the creation of open spaces that can be accessed through the appropriate block. Concrete floors and freely connected steel bears are used for the construction of the facility. This makes it possible to form a large habitable spatial frame. The structure can grow in several stages, with each stage representing a new floor. Vertical movement is carried out through elevators, which also have infrastructure, such as air circulation boxes and plumbing devices [10]. Another example of a unique object on the water is the floating power plant project “Civilization 0.000” (author Dimo Ivanov) 2018 (Switzerland), which is a high-tech structure using local renewable sources for energy generation. The power plant located at Cape Horn (Southern Chile) also uses wind, wave and tidal energy of this region. Electricity generation is just one of many important functions. The unique complex provides for the organization of space for energy storage, resource management, research and development. According to its water and aerodynamic features, the building consists of three structural main functional zones: a tower, a platform and a tidal power plant. The tower contains wind turbines, research laboratories, residential units, restaurants, sports facilities, social facilities, a control center, educational units, etc. [11]. One of the important tasks is to conduct underwater construction to create a comfortable and reliable artificial habitat in these conditions. It is associated with additional costs in ensuring the functioning of underwater objects and the adaptation of the human body. The project of the “Waterscraper” facility (author Mathias Koester) 2007 (Germany), created in the form of an inverted skyscraper in the sea, is a unique hotel with a combination of leisure and scientific research opportunities. The construction of the water skyscraper is equipped with an efficient ring structure capable of withstanding water

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pressure. The floor area of the complex decreases in size at the lower levels. The spatial solution of the facility meets the structural requirements and provides a combination of hotel rooms, laboratories, landscaped spaces and an observation deck on the 25th floor below sea level. The glazed dome on the top of the structure allows light to penetrate deeper into the inner atrium, which connects the public and private areas of hotel facilities. The lobby, restaurant and cafe of the hotel are located at levels above the sea, and conference rooms and hotel rooms are located below sea level with views of the rich underwater world. The surrounding ring of the water skyscraper, located on the surface of the water, accommodates a number of apartments with direct access to the beaches, covers the marina and connects to the main square in front of the main dome. The space under the open area is used to combine with its own underwater port and diving center. The unique water skyscraper can drift in the open sea, move to another location or moor to reach a fixed position [12]. The project of a unique underwater architecture object “Water-Scraper” (Malaysia), 2010 (author Sarly Adre Bin Sarkum) is an autonomous floating unit that will act as a floating city with a functional and self-sustaining space suitable for life. The underwater city is an eco-sustainable object, as it generates wave and wind energy, solar energy, etc. Food production has established through the organization of agriculture, aquaculture, and hydroponics. At the top of the floating volume of the city there is a small private forest, as well as organized places for the inhabitants to live and work in the water depths. To maintain the vertical position of the object and create a proper buttress, a system of ballast devices is used. Bioluminescent devices, due to their kinetic movement, collect energy, and also serve as balancing elements, constantly moving with the rhythm of the tide [13]. It is quite obvious that the main difficulty in organizing underwater facilities is construction and installation work. Therefore, all underwater houses are mainly created on land, and then lowered into the water, completely ready for operation. The high requirements for the creation of underwater habitable objects, in addition to purely technical requirements, include a large complex of architectural and psychological tasks. In addition to organizing all the necessary household amenities, they provide a favorable psychological atmosphere, which in turn determines the effectiveness of technological operations. 2.2 Terra-Construction of Unique Underground Facilities Using Techniques of Forming a Virtual Light Environment Underground construction, having certain advantages, both in organizational and economic terms, is gaining more and more recognition, and the modern state of technology contributes to its widespread development. The emergence of underground construction in cities is due to such urban planning factors as the lack of free territories, the need to decompress historically developed buildings, the creation of high-speed and continuous movement of public, special and individual transport, the preservation of historical and architectural ensembles, the development of cultural and communal services, etc. The experience of such construction gives examples of its versatile use in various fields of human activity, which has great prospects.

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A unique alternative direction in the conditions of underground space development is the use of techniques for the formation of a virtual light environment, which is especially relevant when organizing public facilities for exhibition functions, museum development, conservation and operation of natural and artificial underground formations—caves, geological parks, etc. [14]. An example of the use of virtual reality technologies is shown in the creation of the world’s first underground park “Lowline” with exotic plants brought from all over the world (design engineers James Ramsey and Dan Barash) in an abandoned terminal in Manhattan (New York) using a system of mirrors. The project provides for the reconstruction of underground space and the creation of infrastructure. It is assumed that the system of mirrors developed by the authors will accurately follow the movement of the Sun, collecting and transmitting sunlight to an underground oasis. Engineers managed to achieve a full light spectrum with an efficiency of about 70%, and the other 30% are absorbed during transmission [15]. Unique is the solution of the virtual light environment at metro stations in Stockholm (Sweden), which is not just a mode of transport, but a perfect gallery underground with unique murals, mosaics, sculptures and art objects. Many metro stations in Stockholm are cut right into the rocks and solved in various styles and images. Of great importance is the nature of the solution of the virtual light environment, made in various innovative ways and techniques [16]. Of interest is the new interactive underground museum of the history of the city of Lugo (Spain), which originated during the Roman Empire. To get acquainted with the history and life of the city, technologies are used through which audio and video installations are viewed (Company Nieto Soybean Arquitectos). The constructive system of the museum is formed by cylindrical volumes towering over green lawns. In the underground part of these volumes there are exhibition spaces equipped with installation equipment to create a virtual light environment. A spiral staircase leads visitors to a circular underground courtyard that unites all the rooms of the museum complex, which are both a park and a museum [17]. According to the concept of the “Underground Museum” by the American architect John Martin, it is planned to turn the Antwerp Central Station, closed in the 1970s, into an exhibition space. In the gallery project inside an abandoned tunnel, adjacent to the traditional details of the underground infrastructure, there are elements such as frames, beams, fasteners. In the interactive interior of the museum, the rays of film projectors may appear from some abandoned pipes, demonstrating the plots of various expositions on the inclined walls. According to the author, the spectacular visual range allows any visitor to feel like an “adventurer, scouring for adventures in abandoned dungeons” [18]. Within the framework of the issue under consideration, it is impossible not to dwell on the methods of forming the underground space of the Bolshoi Theater in Moscow and solving the virtual light environment of its premises. Underground there is a new Beethoven transforming hall at a depth of 27 m. Due to the fact that combustible materials are prohibited for use in the underground space, natural stone (granite, marble, and travertine) is used, as well as decorative plaster of various finishes, for example, imitation busier. When designing this space, the architects paid special attention to measures to suppress underground vibration noises transmitted from the subway through building

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structures, and acoustic treatment of internal surfaces, as well as the light environment of the space [19]. The use of virtual reality computer technologies in the formation of underground space gives such limitless possibilities as the ability to influence the inhabitant with light, color, sound and image. The capabilities of holographic technologies allow you to display a three-dimensional object directly in space, which allows you to create virtual museums and exhibition halls, as well as historical reconstructions. 2.3 Architecture of Weightlessness: Construction of Unique Facilities to Create an Artificial Habitable Environment in Space In extreme and aggressive conditions of cosmos, a specific factor in the formation of an artificial habitat is weightlessness, which creates certain difficulties for human life. This largely determines a special approach to the design of objects and affects the creation of habitable space. Depending on the distance from Earth, there are orbital objects (located in near-Earth space), interplanetary objects, as well as those launched into outer space, including planets of the Solar System and Galaxies. It is quite obvious that in conditions of vacuum and solar radiation it is impossible to apply the techniques of construction organization, design and manufacture of structures, as well as the usual building materials used in terrestrial circumstances. Despite this, due to the need to transport structural systems of space objects in a compact form, their manufacture takes place on Earth. This determines the use of transformable kinematic structures at all stages of the existence of a space object: manufacturing, transportation, construction and operation [20]. In addition, in space conditions, in order to ensure a comfortable life in a confined limited space, there is a need for the use of dynamic psychological rehabilitation techniques (light-color, sound and thermal climate, imitation of natural rhythms, etc.) in conditions of sensory hunger. Thanks to the use of transformation techniques, the possibility of multifunctional use of habitable space in space appears. Within the framework of this study, it is advisable to consider the developed original developments of interest in the context of the exploration of alternative space. So, the main idea of the 2010 “Space Skyscraper” project (author Kwonwoong Lim) is to create an object in space that will be in the plane of orbit, where the force of gravity is zero. The concept is to keep the median point of the structure on the plane of the orbit and build it until it almost reaches the surface of the Earth. This experiment is one of numerous studies on freeing a skyscraper for gravity and creating the highest-rise structure that could completely solve people’s housing problems. The building has a height of 1000 km, and its orbital plane is located 500 km from the earth [21]. The concept of creating a populated layer as a network of skyscrapers in the stratosphere at an altitude of several tens of kilometers is provided in the unique development “Stratosphere Network of Skyscrapers” (authors Mingxuan Dong, Yuchen Xiang, Aiwen Xie and Xu Han) 2013 (China). The first skyscrapers are meant to be built on supports, and when the network covers the entire earth, the need for supports will disappear, and interconnected buildings will be held at the ground due to its attraction. The project proposal is connected with an attempt to solve the problem of eliminating the catastrophic consequences of the ecological crisis and the growth of the Earth’s population.

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According to the authors, a horizontal mesh habitable layer of objects in the stratosphere can become the only platform for ensuring the continuity of human civilization [22]. An even more fantastic idea of “Space-scraper” was developed by American specialists (authors Richard Porter, Chris Allen, Cam Helland and Stephen Phillips) in 2007, offering to expand the urban space within the framework of NASA’s innovative research project “City in Space”. The studies obtained through a series of digital scenarios were initiated along with the study of the molecular structures of carbon. The space object is carried out in the form of a habitable biomimetic network in a geostationary orbit tied to the Earth’s atmosphere (35.786 km above its surface). As a “space elevator”, a system is proposed, which is a structure of carbon nanotube fibers woven together. Pretensioning of such carbon cables against the rotation of the Earth increases the strength of the cable, and numerous satellites deployed in extraterrestrial infrastructure make it possible to achieve equilibrium. The vital purpose of transport communications consists from local elevators with mass transit lines and nodes that run through the entire orbital network connecting several megacities. According to the authors, such a solution to the system of urban megacities in space can serve as a way out in the inevitable situation in the post-human period [23]. The creation of an artificial habitable environment in space illustrates the philosophy of understanding a new direction—architecture of weightlessness. The active development of atypical space in space can lead to the emergence of spatial objects with a new service infrastructure. It is assumed that such settlements will be built over existing cities within the troposphere and above the earth, where space shuttles can arrive and space elevators can reach. And the settlements located in near-Earth space will become a kind of buffers between the earth and the developed space [24]. The modern level of development of global telecommunication systems is sufficient to build a global information and operational environment of interaction. This can point to existing space systems that allow you to obtain data on the position of ground and cosmos objects equipped with appropriate equipment. In this regard, the use of space communication potential, which is closely related to the space information system, is of particular importance. Thus, the architecture of weightlessness is an area of limitless possibilities in shaping and organizing life outside the Earth.

3 Practical the Significance The techniques discussed above for the construction of unique architectural objects in conditions of extreme underwater, underground and space natural habitat, indicate an important problem of creating an artificial environment for life in these conditions. This will require an adjustment of the existing design method, since it cannot be solved by purely architectural means. This is due to the fact that the architecture of unique objects for extreme natural habitats, reacting to a new paradigm, opens up new knowledge, setting tasks for science to realize newly emerging unique objects, stimulates science to invent modern structures and materials, as well as construction technologies. The implementation of the theoretical provisions and practical recommendations set out in the article will allow us to outline directions for further research in this area and

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will contribute to the development of scientific and technological progress, which is of great socio-economic importance.

4 Conclusion The features of the formation of unique architectural objects in extreme natural environments in this review are outlined in the context of the following areas considered. • Aqua Architecture: the construction of unique objects in the aquatic environment is associated with the expansion of territories on land and the development of the economic potential of the ocean. It is advisable to organize energy supply using natural renewable energy sources. The creation of a comfortable and reliable artificial human habitat in these conditions is associated with the organization of an autonomous closed life activity support system. • Terra-construction of unique underground facilities which design techniques of forming a virtual light environment using is an alternative direction in architecture. It is especially relevant in the organization of unique public facilities for the implementation of exhibition functions, museum development, conservation and operation of natural and artificial underground formations, as well as in various fields of human activity, what has great prospects. • Architecture of weightlessness: the construction of unique objects to create an artificial habitable environment in space is determined by the specific conditions of weightlessness and requires the use of structures, materials and techniques that cannot be implemented in terrestrial conditions. The experience of designing in space allows to identify a new area in architecture, which has unlimited possibilities in shaping and organizing life outside the Earth. The principles of organization of architectural objects are similar, but they manifest themselves most vividly in extreme conditions during the design and construction of unique objects. The results of the research in the field of creating objects of extreme architecture will help not only in their design, but also in the formation of complex artificial habitats in a normal environment. The selection of project material carried out in the article in accordance with the proposed systematization will allow outlining directions for further research in this area.

References 1. Saprykina NA (2019) Formation of architectural objects for extreme habitat conditions in the context of innovative paradigms. In: International scientific and practical conference engineering systems. IOP Conf Ser: Mater Sci Eng 675:012017. https://doi.org/10.1088/1757899X/675/1/012017 2. Yesaulov GV (2012) Architecture and urban planning in conditions of extreme natural and techno genic impacts. Nestor-History, St. Petersburg, p 266 3. Galeev SA (2015) Adaptation of architectural systems to extreme environmental conditions. In: Electronic scientific journal «APRIORI. Series: Natural and technical sciences» 4. http:// www.apriori-journal.ru/index.php/journal-estesvennienauki/id/769

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4. Gasanov MA, Kolotov KA, Demidenko KA, Podgornaya EA, Kadnikova OV (2017) The concept of ecologically oriented progress and natural resource preservation. IOP Conf Ser: Earth Environ Sci 50(1):012025 5. Travush VI (2006) Security and sustainability in the priority areas of Russia’s development: national projects and their architectural and urban ACADEMIA. Arch Constr 2:9 6. Karimullin TA, Aidarova GN (2011) A safe city in an extreme world. Problem statement. Model. Izvestiya KazGASU. Theory and history of architecture, restoration and reconstruction of historical and architectural heritage 2(16) 7. Schopfer K (2009) New Orleans Arcology Habitat. http://www.archfacade.ru/2009/09/neworleans-arcology-habitat-noah.html 8. Yoneda Y (2009) NOAH: mammoth pyramidal arcology designed for New Orleans. https:// inhabitat.com/noah-mammoth-pyramidal-arcology-designed-for-new-orleans 9. Schopfer K (2011) Boston Arcology Habitat. http://ecotechblog.ru/architecture/plavuchiygorod-vblizi-bostona/ 10. Walzer AN (2018) E Mare Libertas: skyscraper on water. Austria. http://www.evolo.us/emare-libertas-skyscraper-on-water/#more-36125 11. Ivanov D (2018) Civilization 0.000: floating power station. Switzerland. http://www.evolo. us/civilization-0-000-floating-power-station/#more-36064 12. Koester M (2007) Waterscraper. Germany. http://www.evolo.us/waterscraper/#more-264 13. Sarkum SA (2010) Water-scraper: underwater architecture. Malaysia. http://www.evolo.us/ water-scraper-underwater-architecture/#more-2669 14. Saprykina NA (2021) Virtual light environment of underground spaces: an alternative to interaction. Light Eng 29(6):69–77. https://doi.org/10.83333/2021-065 15. Ramsey J, Barash D (2016) “Lowline” is an underground park of the future. Lighting with mirrors - reality. https://slavikap.livejournal.com/17578971.html 16. Mironova Y (2017) Gallery underground: 12 Stockholm metro stations. https://34travel.me/ post/metro-stocholm 17. Lapina G (2011) Underground museum. http://ais.by/news/13257 18. Martin J (2011) Underground museum in Antwerp. http://www.lookatme.ru/flow/posts/arcite cture-radar/137397-podzemnyy-muzey-v-antverpene 19. Martovitskaya A (2010) Underground part of the Bolshoi Theater Auditorium. https://archi. ru/russia/28681/bolshoi-podzemnyi-teatr 20. Saprykina NA (2021) Fundamentals of dynamic shaping in architecture. KURS, Moscow 21. Lim K (2010) Space skyscraper. http://www.evolo.us/space-skyscraper/#more-4056 22. Dong M, Xiang Y, Xie A, Han X (2013) Stratosphere network of skyscrapers. China. http:// www.evolo.us/competition/stratosphere-network-of-skyscrapers/ 23. Porter R, Allen C, Helland C, Phillips S (2007) Space-scraper. NASA. http://www.evolo.us/ competition/space-scraper/ 24. Saprykina NA (2020) Concepts of project forecasting in the formation of the architectural space of the future. In: Proceedings of the 2nd international conference on architecture: heritage, traditions and innovations (AHTI 2020), vol 471, pp 270–276. https://doi.org/10. 2991/assehr.k.200923.047

Optimization of Microclimate Parameters in Tent-Frame Buildings I. Yu. Shelekhov(B) and M. I. Shelekhov Irkutsk National Research Technical University, 83, Lermontova Street, Irkutsk 664074, Russia [email protected]

Abstract. The purpose of this work was to create favorable climatic conditions at workplaces in frame-tent buildings with limited energy capacities. A survey of a frame-tent building, located in harsh climatic conditions, showed that classical design solutions cannot create the necessary working conditions for maintenance personnel. For research, an instrument complex was developed using devices from the OVEN company, based on the methodology for assessing the microclimate parameters of the island. Fanger, heat engineering calculations were carried out. To optimize the microclimate parameters, a new type of air-thermal curtains was used, which redistributed air-heat flows throughout the room, sending warm air to serviced areas, and cold air to unserved ones. Field tests have shown that the use of new innovative solutions can optimize the microclimate parameters in frame rooms and create favorable climatic conditions in the workplace. Keywords: Tent building · Engineering system · Microclimate · Ventilation system · Energy saving · Thermal curtain

1 Introduction To solve operational production problems in various spheres of the national economy, buildings are required where it is necessary to organize technological process in the shortest possible time. Building a capital structure is long and expensive, so some enterprises prefer to use frame-tent type buildings for these purposes. Buildings of the frame-tent type do not belong to the category of capital buildings, therefore they do not require long bureaucratic coordination for their installation. The technology of frame-tent buildings can solve many technological problems quickly and efficiently, all preliminary work can be carried out in advance and only assembly work can be carried out at the construction site. This applies not only to the walls of the building, in advance, it is possible to design a system of power supply, heating, ventilation and other life support systems. It is also possible, in accordance with the technological process, to design the installation of technological equipment and create an automated control system for microclimate parameters at workplaces. According to the technology of frame-tent housing construction, it is possible to build and put into operation a room in a very short period [1]. The Polyus-Vertinskoye JSC enterprise is no exception, which, in order to solve technological problems at the mining and processing complex based on the Verninskoye gold © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_32

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deposit, in the Bodaibo district of the Irkutsk region, decided to build two frame-tent type buildings. The territory where the operation of these buildings will be carried out is characterized by a harsh climate, energy resources are limited. Therefore, it is necessary to carry out work to optimize energy costs while ensuring favorable conditions for equipment and workers. In frame-tent buildings, it is necessary to pay attention to the operation of the ventilation system and the movement of internal air flows created when doors or gates are opened. For this, we studied measures to optimize energy costs aimed at maintaining optimal microclimate parameters at workplaces in similar buildings [2] that carry out a similar type of work with similar lifting equipment. Many experts face similar problems and share them in their scientific articles. The author Butrina [3] in her article described how to optimize the costs of organizing a place for warm storage of materials and other resources in a temporary storage warehouse in the Far North, in which the lifting device was used. Makarova and Kulikova [4] approached this issue in more detail. In their article, they noted that the most important defining properties of a favorable environment are temperature, humidity and air composition, as well as the parameters of radioactive radiation. All these components affect the environment and affect the development, performance and well-being of a person. The problems in the operation of frame-tent buildings are very similar, regardless of the place of their use. The topic of using frame-tent structures for sporting events is interestingly disclosed [5]. Authors Zubareva and Mosunov showed that one of the main conditions for the formation of a strategic perspective for the development of rural sports infrastructure is innovative activity in this area, which guarantees the construction of modern sports facilities in the shortest possible time with the lowest cost. Promising for the authors is the construction of sports facilities with wooden arched structures. A separate scientific achievement is the domed frame structures, which are widely used, especially in countries where Islam is preached. The article [6] by Tikhonova and Myskova describes the formation and design of dome tent structures. The appearance of tent architecture has influenced the appearance of many large modern buildings. Awnings are used today for diverse, including large-span spatial structural structures of various curvilinear shapes. Awning architecture has a number of advantages: firstly, it is the lightness and mobility of structural systems, secondly, their flexibility and mobility, and, of course, the most important advantage is the short construction time. In the modern world, awning structures based on a dome-shaped form are especially popular. This uniqueness lies in the design of the form created by my own nature. The special appearance and natural geometry give the domed structure an excellent aesthetics. Another huge advantage of dome tent structures is the ability to create a light opening in any segment of the coverage, regardless of their shape and size. The article [7] raises the problem of creating effective insulation of external enclosing structures. Improving the quality of thermal insulation of external walls is one of the components of the task of energy efficient construction. This task is especially relevant in view of the ever-increasing cost of energy sources, which is observed throughout the world. On the example of dormitories, the technical and economic efficiency of insulation of external fences is explained.

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An important factor for the efficient use of thermal energy is the use of modern energy-efficient solutions. The article by Abdrakhimov discusses the use of recuperation units, he gives examples of the use of these units for heating and air purification, he describes the technology of recuperation devices for purifying and heating air to ensure microclimate conditions at the workplace [8]. Industrial ventilation is an integral part of the engineering process and complies with sanitary norms and rules that ensure controlled air exchange and the removal of polluted air from the premises and the supply of fresh air. Thanks to industrial ventilation systems, the air of industrial facilities is cleaned of explosive and harmful dust loads, maintaining the optimum temperature and humidity in the workplace, and has a beneficial effect on the human body [9]. One of the conditions for normal human life in production is the provision of favorable climatic conditions, which depends on the thermophysical characteristics of the process, climate, season, ventilation and heating conditions [10]. In some cases, it is possible to obtain optimal characteristics only by combined heating methods [11], since it is not possible to meet all the requirements of existing standards [12]. Production rooms should be dry with normal humidity, clean, well ventilated and free of unpleasant odors. Sudden changes in temperature and humidity, even within acceptable limits, are unacceptable. A special role in frame-tent type buildings is assigned to energy-efficient methods of designing interconnected engineering systems [13], which are usually based on the ventilation system. Ventilation systems are used to create and maintain favorable microclimate parameters in the premises for the well-being and health of people, as well as for the implementation of technical processes. The stability of the microclimate parameters is guaranteed by the most modern control systems for ventilation, heating and air conditioning.

2 Materials and Methods When carrying out work in the investigated industrial premises of a frame-tent type, it is clear that the comfortable state of the attendants will depend on many factors. Of the main factors affecting the general condition of the human body, three are usually distinguished: air temperature, humidity and the speed of air flow in the room. When designing heating systems, they often do not consider the fact that the radiation temperature plays an important role in the state of comfort. When determining the general state of comfort, the required amount of thermal energy is calculated according to aggregated indicators, temperature thresholds are determined and an appropriate control system is selected. In industrial premises, additional inputs are introduced that can have a negative impact on the parameters of the indoor microclimate, this is the number of harmful emissions in the room and the effect of opening and closing open openings in the form of doors and gates. An analysis of the engineering systems with which the frame-tent type building is equipped, shown in Fig. 1, showed that the current supply and exhaust ventilation system does not have an air exchange rate adjustment and is not related to the operation of the building’s heating systems and the protection of the building from the penetration of cold air flows. Serviced technological zones, where work is carried out, are fenced off from the walls for a long time. The gates in the building are located on both sides, next to the

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gates, on the right side there are ventilation ducts for supply and exhaust ventilation. A person feels comfortable with a certain combination of exposure to thermal radiation from enclosing structures and objects in the room, as well as from the air temperature in this room. Frame-tent buildings have cold walls and large masses of cold air enter the building when the gates are opened, so it is necessary to control the process of heating workplaces with temperature control of radiant heaters and air heaters.

Fig. 1. Frame-tent building chosen for research.

Let’s define the main parameters that need to be fixed to determine the comfortable state of a person in the workplace and those parameters that we can manage to change the state of comfort. First of all, we must record the temperature of the air and the speed of air movement. For this we will use the most common instrument called anemometer, testo 410-1 brand. The device simultaneously measures the speed of air flow and temperature. When opening the gate, we will be able to determine how the air-thermal curtain protects our premises from the penetration of cold air currents, how far from the gate they can penetrate and at what speed the temperature parameters in the room will be restored. To conduct more serious studies, it is necessary to evaluate the temperature parameters in a dynamic mode and measure not only the air temperature, but also the temperature of radiation exposure to a person. A stand was made to measure the convection temperature and radiation temperature over the area of the room. Tripods were also made, on which differential thermoelectric temperature sensors were installed in pairs. These thermoelectric sensors will be installed in the automated control system for microclimate parameters during the operation of air-thermal curtains. One temperature sensor measured the convection temperature, the second radiation temperature. The principle of temperature measurement is shown in Fig. 2. These tripods, which are shown in Fig. 2, were made 8 pieces, they are installed in the area where it is necessary to measure the parameters of heat sensation and are connected to measuring instruments. Moreover, the convective temperature is recorded by one device of the TPM138 brand, manufactured by the OWEN company, and the radiation

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Fig. 2. Combined sensor for measuring convective and radiation temperature.

temperature is recorded by another similar device. The signals from the sensors are processed by these devices and, using the standard software supplied with the devices (OWEN PROCESS MANAGER (OPM)), they are imported to a personal computer through the current loop interface into the excel program. Radiation temperature data is entered into a table that serves to enter readings into the temperature comfort assessment chart along the “X” axis, and convective temperature is entered into a table that serves to enter readings into the temperature comfort assessment chart along the “Y” axis. If the temperature value is in the comfort zone, then the resulting temperature gives the value “0”, which means that the overall temperature is in the “Comfortable” state. If the temperature value is at the edge of the zone, then the resulting temperature is “1” or “−1”, which means that the overall temperature is in the “Slightly warm” or “Slightly cool” state. If the temperature value is outside the edge of the zone, then the resulting temperature gives the value “2” or “−2”, which means that the overall temperature is in the “warm” or “cool” state. If the temperature value is at a distance from the zone, then the resulting temperature gives the value “3” or “−3”, which means that the overall temperature is in the “hot” or “cold” state [14]. The scheme of the measurement stand is shown in Fig. 3.

3 Research Results The analysis of design and technical solutions showed that the general parameters of the microclimate of the premises and directly at the workplace did not correspond. The parameters of heat sensation in terms of the area of the room were between the parameter “cool” and “cold”. Directly at the workplace, where the maintenance staff performs work on the repair of equipment, the parameters of heat sensations were in the “cool” parameter. This parameter was achieved since the category of work performed refers to heavy physical work. When the equipment is delivered, the operating personnel

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Fig. 3. Scheme of a stand for measuring comfort in a frame-tent room.

put on warm clothes and do not take them off for 2 h after they have been delivered. The microclimate parameters at the workplaces were not constant, during the period of supply of technological equipment for repair, the microclimate parameters decreased to the “cold” parameter. The supplied equipment was at negative temperatures, and this caused an additional uncomfortable state. Together with the equipment, outside air with a negative temperature penetrated the room, which also had a negative effect on the parameters of heat sensation. At an outside air temperature of −27 °C, when the gate is opened, two air-thermal curtains are switched on, the calculated parameters of which do not comply with existing norms and rules [15]. Figure 4 shows a graph of changes in temperature parameters directly at the grille of the thermal curtain. It can be seen from the graph that the stationary mode of the thermal curtain leaves only after 14 min, and the average time required to move the equipment through these gates was 21 min, while the temperature at the workplaces located in the immediate vicinity was within 5 min dropped to −4 °C and the operation of the air-thermal curtain has no effect on this parameter. If you install a design curtain at the gate, in accordance with the climatic factors that are present in the region, then its design and power would seriously differ from the design solution. The design decision was made considering the lack of the necessary energy resources, but the necessary measures were not taken to optimize the microclimate parameters directly at the workplace. Directly at the workplace, the period of recovery of temperature parameters was 94 min, in fact, 1.5 h, labor productivity at this workplace was minimal.

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Fig. 4. The temperature at the exit of the thermal curtain.

A serious drawback in the operation of air-thermal curtains is that the area where cold air flows cannot enter the room, there is no demand for this. Having protected the lower part of the gate from the active penetration of cold air currents, cold air currents penetrate from the middle of the gate and enter the service areas. In fact, when energy resources are spent on the operation of the air-thermal curtain, the microclimate parameters do not change. The essence of the air-thermal curtain is that it prevents the passage of any air through the gate, preventing the breakthrough of cold air into the production premises and preventing warm air from leaving the production premises without hindrance. Their goal is to maintain and maintain the required meteorological parameters in the production room and save thermal energy. In this case, if it is impossible to protect the entire premises, then it is necessary to develop measures to create favorable conditions for staying only in serviced areas. For such purposes, it is advisable to use distribution-type air-thermal curtains [16]. The air-heat flow from the curtain is added to the cold air flow and redirected to an unattended zone. The direction of the air flow is carried out by an automatic control system depending on the signals from differential thermoelectric temperature sensors, which control not only the temperature itself, but the temperature difference between the enclosing structures and the air temperature. Figures 5 and 6 shows graphs of the distribution of air flows: when working with a classic curtain; when working with a distribution type air curtain. A comparison of the two graphs shows that there have been changes in the immediate vicinity of the gate. With the same performance and power, the speed of air flow has decreased. Figure 7 shows the temperature distribution in the serviced area during the opening of the gate. It can be seen from the graph that the temperature remained not only positive, but also in accordance with the required standards. Mixing with the air stream leaving the air-thermal curtain, most of the incoming cold air is redirected to an unattended zone. Thanks to the installed differential thermoelectric temperature sensors, not only the air flows that enter the room from the outside are redistributed, but it is also heated to a

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Fig. 5. Graphs of the distribution of air flows when working with a classic air curtain.

Fig. 6. Graphs of the distribution of air flows when working with a distribution type curtain.

predetermined parameter. Depending on the temperature difference between the outside air and the indoor air, the air-thermal curtain generates the amount of energy that is necessary to ensure that the temperature in unattended areas does not drop to critical values. If the air temperature in the non-serviced areas drops to critical values, this will adversely affect the serviced areas, since under the influence of the internal ventilation system, the air environment of the serviced areas will be mixed with the non-serviced areas.

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Fig. 7. Temperature distribution in the served area during the opening of the gate.

4 Discussion and Conclusions The use of innovative solutions makes it possible to maintain the microclimate parameters in a normalized value at significantly lower energy costs, which could not be obtained with a classic design solution with limited energy resources. For the operation of airthermal curtains of this class, electrical energy is used, usually, in conditions of extremely low temperatures, this resource is limited, since it is used to solve the main technological problems. Reasonable use of energy resources should become the basis of industrial production and these measures should be carried out at the stage of the design decision, and not during the commissioning of the building, where the equipment has already been installed and repairs are starting to be carried out. Preliminary calculations and development of a design solution would avoid unnecessary financial costs. To do this, it is necessary to actively disseminate the positive experience of introducing new innovative developments. This work showed that it is necessary to change the attitude towards classical design solutions, since our production ranks first in the world in terms of energy intensity, which reduces its competitiveness. It is necessary to look for new constructive and technical solutions, as well as to apply new means of automatic control and management of technological parameters. When using a new type of differential thermoelectric temperature sensors [17], more favorable microclimate parameters are created with the lowest energy costs. These temperature sensor controls are not issued serially, as they need to be affected by special attention to considering the accumulation characteristics of the occurrence and use of technological equipment, as well as depending on the occurrence of system automation. It is possible to use classic temperature sensors that work on the basis of thermocouples. To do this, it will be necessary to connect two sensors in series and install them in those places where it is necessary to measure the temperature difference. But, these temperature sensors will have high inertia, which will adversely affect the operation of automation. Changing the way of classical thinking to innovative

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will help to make an economic breakthrough in various industries and optimize energy costs while creating favorable microclimate parameters in various types of buildings. Acknowledgements. The study was carried out with the financial support of the Russian Federal Property Fund and the Government of the Irkutsk Region as part of a scientific project No. 20-48-380002.

References 1. Guseva TP (2009) Innovative technologies for housing construction. Hous Constr 4:4–6 2. Stanke D (1998) Ventilation where it’s needed. ASHRAE J 39–47 3. Butrina AV (2016) Technologies for the use of load-lifting equipment in prefabricated structures. Reshetnev Read 2:411–413 4. Makarova TV, Kulikova OS (2016) Ecological heating as a fundamental factor in the creation of the natural environment of human life. Sci J Eng Syst Struct 1(22):65–67 5. Zubareva GI, Mosunov EE (2019) Arched frame-tent lightweight structures for prefabricated sports facilities. Nauk Among Us 8(24):50–54 6. Tikhonova DA, Myskova OV (2017) Dome tent structures: shaping and design. In: All-Russian scientific and practical conference “DISK-2017”: collection of materials, Moscow, November 20–24, A. N. Kosgin Russian State University (Tenology. Design. Art), pp 126–128 7. Shelekhov IYu, Polyanskaya MYu, Paranin VV (2022) Development of measures to optimize the microclimate parameters in a frame-tent building. Sci Cent “LJournal”. Trends Dev Sci Educ 84(1):117–120 8. Abdrakhimov YuR, Ivanov AN (2019) Methodology of a recuperator unit for air purification and space heating to ensure microclimate conditions at the workplace. Glob: Tech Sci 7(31):6– 7 9. SP 60.13330.2012 (2012) Heating, ventilation and air conditioning. Updated edition of SNiP 41-01-2003. Gosstroy of Russia. FGUP TsPP, Moscow 10. Ruslanov GV (2012) Heating and ventilation of residential and civil buildings. ASV, Moscow, p 345 11. Shelekhov IYu, Shishelova TI, Smirnov YuEI, Inozemtsev VP (2017) Combined system of electric heating of frame houses. Bull Mordovian Univ 2(27):198–214. https://doi.org/10. 15507/0236-2910.027.201702 12. GOST 30494–96 (1999) Buildings residential and public. Microclimate parameters in the premises. Gosstroy of Russia. FGUP TsPP, Moscow 13. Shelekhov IYu, Dorofeeva NL, Shelekhov MI (2018) Application of energy efficient methods in heating systems of industrial and public buildings. Collect Conf Pap: IOP Conf Ser: Mater Sci Eng 17:1–5 14. Fanger PO (1967) Calculation of thermal comfort: introduction of a basic comfort equation. ASHRAE Trans 73(2):II.4.1–III.4.20 15. Shelekhov IYu, Tolstykh YuA, Dmitriev IN (2019) Analysis of the application of various technical solutions to protect buildings from cold air flows. In the collection: NEW SCIENCE GENERATION collection of articles of the II international scientific and practical conference. Petrozavodsk, pp 314–317 16. Shelekhov IYu, Stepanov VS, Tyumentsev VA, Dinisikhina DM (2004) Air-thermal curtain Patent No. 38903 for utility model, priority dated 10.06.2004. Application: 2003137459/20, 12/25/2003. F24F 9/00 (2000.01), Bull. No. 19 17. Shelekhov IYu, Smirnov EI, Kashko KP, Shelekhova IV Patent for invention No. 2611562 dated 02.28.2017 Spatially oriented thermoelectric module and a method for its manufacture. Patentee: Thermostat + LLC. http://www1.fips.ru/fips_servl/fips_servlet

Method of Hydraulic Calculation of Gas Distribution Networks O. N. Medvedeva(B) and S. D. Perevalov Yuri Gagarin State Technical University of Saratov, 77 Politekhnicheskaya Street, Saratov 410054, Russia [email protected]

Abstract. The paper presents the results of a study of gas distribution systems. The purpose of the study is development a methodology and a program for calculating variable hydraulic modes of gas distribution networks. When choosing the optimal variant of the gas supply scheme, it is necessary to take into account the structure of the fuel and energy balance, the number of gas-supplied population and the distance from the gas supply source. A clarifying method of hydraulic calculation of gas pipelines is proposed, which allows reducing material and monetary resources for the construction and operation of gas distribution systems. When developing the mathematical model, the maximum number of influencing factors was taken into account. The results of the calculations showed that the proposed technique fully justifies itself and can be used in the design of gas distribution systems. As the analysis of the results shows, the use of the developed clarifying methodology for hydraulic calculation allows to reduce one-time costs for the construction and operation of gas distribution networks by 10% or more. Keywords: Natural gas pipeline · Optimization · Piping systems · Hydraulic networks · Gas distribution

1 Introduction One of the key problems of modern power supply systems is energy conservation. The lack of calculation methods that comprehensively take into account the variety of schemes of modern gas distribution networks and the emergence of new ways and means of regulating the parameters of energy carriers complicates long-term planning, forecasting of resources, reserves and precise regulation of the gas distribution system and the economy of gas fuel in general [1, 2]. The task of optimal design of gas distribution networks is still relevant today [3–6]. To solve it, there is a certain range of software products that partially solve the issues of route design, determination of diameter and pressures at nodal points and other parameters, but they have a number of disadvantages. In addition, at the moment there are no publicly available online services for completing the verification hydraulic calculation of gas distribution networks performed to analyze the operation of the existing gas distribution © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_33

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network according to such specified parameters as the actual pressures at the outlet of sources (gas distribution station or reduction point) and the actual estimated gas costs. The reliability of hydraulic calculations performed according to existing methods in the overwhelming majority does not cause contradictions and has been verified by many years of operational practice [1, 7–10]. At the same time, the reliability of the calculations of the pressure distribution over the sections of the gas distribution network requires a more detailed study due to the different approach to taking into account the factors determining the hydraulic mode of the gas pipeline. Justification of the calculated pressure drop in the gas supply system and its optimal distribution between the main sections—trunk sections Pts , branches Pbr and intra-house gas pipelines (including house inputs) Pinh , is an important optimization task [2]. In addition, the initial value for the hydraulic calculation of gas pipelines, as a rule, is the maximum hourly gas flow in accordance with the requirements of paragraphs 3.17–3.19 Code of Practice 62.13330.2011* Gas distribution systems. Estimated gas consumption according to consumption standards for the population, determined in accordance with the provisions of Code of Practice 62.13330.2011*, will be numerically greater than the actual one, since its component for heating from apartment heat generators is determined based on the estimated outdoor air temperatures for designing heating and ventilation in accordance with Code of Practice 131.13330.2020 Building climatology. It follows that the diameters of gas pipelines will be unreasonably overestimated. Actual consumers gas consumption data is determined by the indications of metering devices and is available from gas distribution organizations (GDO). Therefore, it is possible to determine the existing estimated gas consumption by industrial enterprises, heating boiler houses, household and other consumers with a greater degree of accuracy. Ionin [11] describes two methods for determining the maximum hourly expenses. The first is by using the coefficient of simultaneity of switching on gas appliances at the peak of K sim consumption, the second is by using the maximum coefficients of unevenness, representing the ratio of the maximum hourly gas consumption to the hourly average for the year. The calculation method with the simultaneous operation coefficient of the devices should be used for a group of similar gas-using devices, taking into account the fact that with an increase in the number of apartments connected to the gas pipeline, the load schedule is compacted and becomes more equable. For small promising areas of development of the same type of individual houses, the gas consumption of the heating device should be determined based on the heated area and climatic parameters of the construction area for the design of heating [1, 12–15]. Also, quite often, when checking the hydraulic calculation of the existing gas distribution network, the calculated gas pressures at the control points turn out to be less than those actually measured by the operating organization [1, 16–18]. In this regard, the purpose of the study is development a methodology and a program for calculating variable hydraulic modes of gas distribution networks for solving design, operational and training tasks.

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2 Materials and Methods The calculation of distribution gas pipelines is based on the method of hydraulic calculation for a minimum of metal investments [2]. In general, a gas distribution network consists of the following elements: individual elementary sections, nodes and elementary rings. All three elements take place in looped gas networks. There are no elementary rings in an uncirculated (dead-end) network [12, 19–23]. Gas networks have a graph structure and for its representation in mathematical form, Euler theorem is applied, according to which the number of elementary sections n can be determined from the following expression: n = k + y − 1, where k is the number of rings; y is the number of nodes. Each elementary section of the gas network is characterized by the following parameters: estimated flow rate, Qi , m3 /h; diameter, di , m; pressure loss, Pi , Pa; length, i , m. As a result of the calculation, it is required to determine the numerical values of the diameters of the elementary sections of the gas pipeline and the pressure losses on them. In general, pressure losses in an elementary section of the gas network must be determined using the Darcy-Weisbach equation: Pi = λ

ρ · ϑ 2 · i , 2di

(1)

where λ is the coefficient of friction resistance; ρ is the gas density, kg/m3 ; ϑ is the gas velocity, m/s; i is the length of the elementary section, m; di is the diameter of the elementary section, m. Three groups of equations are usually used to calculate the gas network. The first group includes dependencies for determining hydraulic losses:   Qi . (2) Pi = f di The total number of such equations is n. The second group includes the equilibrium equations of the nodes. According to Kirchhoff’s first law, the algebraic sum of expenses on all elementary sections that are adjacent to each node is zero. Expenses entering the node are assigned a plus sign, and those leaving are assigned a minus sign. The equilibrium equation of the node has the following form: y Qi = 0. The total number of such equations is equal to the number of nodes minus one, i.e. (y − 1). The third group includes the equilibrium equations of elementary rings. In accordance with Kirchhoff’s second law, the algebraic sum of the pressure losses on the elementary sections of each elementary ring is zero. Pressure losses in the semicircle, coinciding with the direction of clockwise movement, are assigned a plus sign, and counterclockwise movement—a  minus sign. The equilibrium equation of elementary rings has the following form: k Pi = 0. The total number of such equations is k, i.e. equal to the number of elementary rings. In the second case, when calculating a dead-end gas network, the directions of gas flows are known, and, therefore, it is possible to unambiguously calculate the estimated

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gas costs Qi for each elementary section of the gas network. In this case, only two parameters of the elementary section remain unknown: Pi and di . As an additional condition when calculating the looped gas network, it is assumed that the pressure drop in each direction from the supply point (at the outlet of the reduction point) to zero points (vanishing points), in which there is no gas flow, should not exceed the normalized available pressure drop Pav . Then for each direction of the gas network we get the following expression:  Pi ≤ Pav , (3) 

n

where n Pi is the total pressure loss on the elementary sections of the gas network included in the independent direction, Pa; Pav is the normalized available pressure drop in the independent direction, Pa. As one of the additional conditions, the requirement of constancy of the specific pressure drop on elementary sections of the gas network is often used: Pii = const, which does not give minimal material investment, and therefore, capital investment. In our case, investments in an equally reliable gas network (the same flow distribution) should be minimal: n 

Ci = min,

(4)

i=1

where Ci is the investment in one elementary section of the gas network. When laying gas networks from steel or polyethylene pipes, it should be assumed that the investment is directly proportional to the material investment in the pipes. Therefore, the economic conditions must be written in the following form: n 

Mi = min,

(5)

i=1

where Mi is the material investment in the elementary section. An additional requirement for the efficiency of distribution gas pipelines obtained from condition (5) with the same wall thickness of pipes for close diameters is determined by the expression n 

di · i = min,

(6)

i=1

where is the diameter of the elementary section, m; is the length of the elementary section, m.  The function ni=1 di · i is a target function and it contains n unknowns (diameters of elementary sections). In order to determine the conditions under which the objective function, Eq. 6, of many variables will reach a conditional minimum, we use the Lagrange method. The Lagrange function of many variables has the following form:  = ϕ(x, y, z...) + λ1 · ψ1 (x, y, z...) + λ2 · ψ2 (x, y, z...) + ...,

(7)

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where ψ1 (x, y, z...),ψ2 (x, y, z...) is the auxiliary equations; ϕ(x, y, z...) is the objective function; λ1 , λ2 —indefinite Lagrange constant coefficients. By equating to zero the partial derivatives of this function with respect to all variables, we obtain the conditional minimum of the Lagrange function: ∂ϕ ∂ ∂ ψ1 ∂ ψ2 = + λ1 + λ2 + ... = 0; ∂x ∂x ∂x ∂x ∂ ∂ ψ1 ∂ ψ2 ∂ϕ = + λ1 + λ2 + ... = 0. ∂y ∂y ∂y ∂y

(8)

The value of hydraulic pressure losses along the length of the gas pipeline is determined by the Darcy-Weisbach formula (1). Distribution gas pipelines (low, medium and high pressure) operate in turbulent mode. The turbulent flow mode is divided into three areas: the area of hydraulically smooth pipes; the transition area; the area of hydraulically rough pipes. The mode of hydraulically smooth pipes is characterized by the fact that the flow is turbulent in the center of the flow, and there is a laminar sublayer near the walls of the gas pipeline. The presence of a laminar sublayer leads to the fact that the influence of roughness in this flow regime is practically absent, because the protrusions of roughness are completely covered by this sublayer. The coefficient of friction resistance in Eq. 1 for this flow mode is determined by the Blasius formula: λ=

0.3164 Re

0.25

.

(9)

Hydraulic calculation of low-pressure distribution gas pipelines is performed according to the formula: 1.75

Pi = 45.67 ·

Qi

· i

4.75

di

ρ0 · ν

0.25

,

(10)

where Pi is the pressure losses on the elementary section of the distribution gas pipeline, Pa; Qi is the gas flow rate on the elementary section of the distribution gas pipeline, m3 /h; i is the length of the elementary section, m; di is the diameter of the elementary section of the gas pipeline, cm; ρ0 is the gas density under normal conditions, kg/m3 ; ν is the coefficient of kinematic viscosity of gas, m2 /s. When denoting constant values for a given gas composition with a letter a, Eq. 10 is written as: 1.75

 Pi = a ·

Qi

4.75

di

· i .

(11)

If we represent the average gas consumption on the main line of the distribution gas pipeline as a half-sum of gas consumption at the beginning and end of the main section of the gas pipeline, we get:

Method of Hydraulic Calculation of Gas Distribution Networks

• in the case of using gas for heating and cooking:   0.09 Qml + 0, 375gheat ; av = n · 0, 135gcook · n

345

(12)

• in the case of using gas for all needs—heating, hot water supply and cooking: 0.79 Qml + 0.375gheat · n, av = 0.237 · (gcook + ghws ) · n

(13)

where gcook is the gas consumption for the needs of cooking and heating, m3 /(h × apartment); n is the number of gas-supplied buildings; ghws gas consumption for hot water supply, m3 /(h × apartment). The average gas consumption for branches from the distribution gas pipeline, taking into account the coefficient of route flow, can be determined by the formulas: 1.58  0.45 0.5 ; (14) ) · 0.17g · n + 0.5n g cook heat n0.45 

 0.427gheat 0.244 0.5 0.4 · (gcook + ghws ) · n + 0.5 (gcook + ghws ) . = 0.289gheat · n + n0.4 n (15) Qbr av = (0.577 +

Qbr av

To determine the diameters of the sections of the design branch of the gas pipeline, the following equations can be used: • for the main trunk of the distribution gas pipeline:  ml 0.368 · dml = a0.21 0 (Qav )

ml Pml

0.21 ;

(16)

;

(17)

• for a branch from a distribution gas pipeline:  dbr =

br 0.368 a0.21 0 (Qav )

·

br Pbr

0.21

• for entry into a residential building (including yard and in-house wiring):  dinh =

inh 0.368 a0.21 0 (Qav )

·

inh Pav − (Pml + Pbr )

0.21 .

(18)

br inh where Qml av , Qav , Qav are the average gas consumption on the main line of the distribution gas pipeline, the branch from the distribution gas pipeline, the gas pipeline entering the building, respectively, m3 /h; ml , br , inh are the length of the main line of the distribution gas pipeline, the branch from the distribution gas pipeline and the entrance to the building, respectively, m; Pav is the calculated pressure drop in the distribution gas pipeline; Pml ,Pbr are the calculated pressure losses in the main line and branches, Pa; Pinh = Pav − (Pml + Pbr ) is the calculated pressure losses at the gas pipeline inlet into the gasified building [2].

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As a result, we have the following expression to determine the material characteristics of the design branch of the gas pipeline:     ml 0.21 br 0.21 0.21 ml 0.368 0.21 br 0.368 ml + a0 (Qav ) br M = a0 (Qav ) Pml Pbr  0.21 inh inh 0.368 + a0.21 (Q ) inh . (19) av 0 Pav − (Pml + Pbr ) To solve the problem of optimal distribution of pressure losses between the three main sections of the gas pipeline, we will use the Lagrange indefinite multipliers method. Then the optimal pressure drops in the sections of the distribution gas pipeline, Pa, can be determined by the following expressions: • for the main line of the distribution gas pipeline:

0.305 · ml Pav · Qml opt av Pml = ;

0.305 0.305 0.305 Qml · ml + Qbr · br + Qinh · inh av av av • for a branch from a distribution gas pipeline: 0.305 · br Pav Qbr opt av Pbr = ;

0.305 0.305 0.305 Qml · ml + Qbr · br + Qinh · inh av av br

(20)

(21)

• at the entrance of the gas pipeline into the building (including courtyard and house wiring):

0.305 · inh Pav Qinh opt av Pinh = ; (22)

0.305 0.305 0.305 Qml · ml + Qbr · br + Qinh · inh av av av opt

opt

opt

or Pinh = Pav − Pml − Pbr . The objective function of the problem has the following form: ⎛ ⎞ m t b · G0.368 · 1.21 s    j bk · G0.368 · 1.21 j j 0.21 ⎝ k k ⎠ Ci = α + , P0.21 P0.21 j k i=1 j=1 k=1

(23)

where b is the cost coefficient accepted according to the results of estimated financial calculations, rub/(meter × centimeter); α is the correction factor for the composition of gas; Gj is the gas consumption on the j-th section, m3 /h; j is the length of the j-th section of the gas pipeline, m; Pj is the pressure drops of the j-th section of the gas pipeline, Pa; m is the number of calculated sections of the gas distribution network. The limitation to the objective function of the problem is the following requirement: the calculated pressure drop is equal to the sum of the pressure drops across the sections of the gas network, starting from the gas supply source (reduction point) and ending  with the final gas consumer [1]. In general: kk=1 Pk,ml + Pk,br − Pav = 0.

Method of Hydraulic Calculation of Gas Distribution Networks

347

We use the iteration method to solve the problem. At the same time, the results of hydraulic calculation by the method of constant specific pressure loss performed according to the recommendations of Code of Practice 42-101-2003 are used as the initial pressure drop. According to the results of checking the balances at the nodal points of the gas network, the value of the discrepancy is determined. To reduce the pressure balance discrepancy to zero by increasing or decreasing the pressure at the nodal points, correction values of nodal pressures are introduced into the calculation: −1/1.21

δPk =

X0,k



−1/1.21

· P1,k − X1,k −1/1.21

2X1,k



· P1,k

−1/1.21

+ X0,k

.

(24)

Thus, with a known value of δPk , it is possible to determine the correction nodal pressures and optimal pressure drops for all nodal points of the design branch: optimal pressure drops for main sections:      opt opt opt opt P0,1 = P0,1 − δP1 ; P0,2 = P0,2 − δP2 ; P0,3 = P0,3 − δP3 ; ...P0,k = P0,k − δPk .

(25)

optimal pressure drops for branches: 

opt



opt



opt



opt



P1,1 = P1,1 − δP1 ; P1,2 = P1,2 − δP2 ; P1,3 = P1,3 − δP3 ; ...P1,k = P0,k − δPk . opt

(26) 

where Pi,k is the optimal pressure drops on the design section of the gas pipeline; P1,1 is the pressure drops on the design section of the gas pipeline obtained by the method presented in Code of Practice 42-101-2003; δP is the correction nodal pressures. The optimal diameters of the gas pipeline sections are determined by the values of the optimal pressure drops calculated according to the Eqs. 16–18.

3 Results and Discussion To find the optimal parameters of the gas network, a program was developed that allows adjusting the results of the hydraulic calculation of the gas supply system according to the regulatory methodology by optimally redistributing the pressure drops in the network and calculating the optimal diameters of the projected gas pipelines. The algorithm of the program is shown in Fig. 1. The calculation of optimal network parameters is carried out as follows. In the fields of the program request, the main initial parameters of the calculated gas supply system are set: the number of main sections of the gas network, the number of branches from the main sections, the initial gas pressure after the power source (reduction point), the kinematic viscosity of the gas, the cost coefficient for laying the gas pipeline, determined by the results of estimated calculations depending on the conditions gaskets, gas pipeline material. Depending on the type of gas-using equipment installed in apartments (gas stoves, flowing gas water heaters, heating boilers), the estimated hourly gas consumption and gas consumption in the main sections of the calculated branch of the distribution gas pipeline are determined, the pressure drop is determined for all sections of the gas

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Fig. 1. Block diagram. Program operation algorithm.

network, the diameters of the gas pipeline are calculated in all sections, taking into account the material gas pipeline. Based on the obtained diameter value, the program selects a value from the standard range of internal diameters of pipelines. According to formulas (25) and (26), optimal pressure drops are determined for the main sections and for branches from them and the optimal diameters of the sections of the design branch of the gas pipeline are recalculated, capital investments in construction and savings in capital investments are determined by comparison with the results obtained using the normative methodology of hydraulic calculation. For comparison, calculations of several gas supply systems were carried out using both polyethylene and steel gas pipelines and a different (specified) number of main sections of the distribution network and branches.

Method of Hydraulic Calculation of Gas Distribution Networks

349

The optimal distribution of calculated pressure drops across sections of the gas network, taking into account the probabilistically uncertain properties of the error of the initial information, is one of the ways to increase the efficiency, reliability and cost-effectiveness of supplying consumers with gas fuel. Acknowledgements. The work was carried out within the framework of the program for obtaining the Scholarship of the President of the Russian Federation for young scientists and postgraduates carrying out promising research and development in priority areas of modernization of the Russian economy (SP–4481.2021.1).

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17. Abdolahi F, Mesbah A, Boozarjomehry RB, Svrcek WY (2007) The effect of major parameters on simulation results of gas pipelines. Int J Mech Sci 49(8):989–1000. https://doi.org/10.1016/ j.ijmecsci.2006.12.001 18. Alamian R, Behbahani-Nejad M, Ghanbarzadeh A (2012) A state space model for transient flow simulation in natural gas pipelines. J Nat Gas Sci Eng 9:51–59. https://doi.org/10.1016/ j.jngse.2012.05.013 19. Demissie A, Zhu W, Belachew ChT (2017) A multi-objective optimization model for gas pipeline operations. Comput Chem Eng 100:94–103. https://doi.org/10.1016/j.compch emeng.2017.02.017 20. Fahmy Mohamed M, Nabih Hoda I, Nour Mohamed A (2019) Impact of thermal models on the performance of natural gas pipelines. J Pipeline Syst Eng Pract 10(3). https://doi.org/10. 1061/(ASCE)PS.1949-1204.0000389 21. Sundar K, Zlotnik A (2019) Dynamic state and parameter estimation for natural gas networks using real pipeline. CCTA 2019 – 3rd IEEE conference on control technology and applications. https://doi.org/10.1109/CCTA.2019.8920430 22. Sukharev MG, Kulalaeva MA (2021) Identification of model flow parameters and model coefficients with the help of integrated measurements of pipeline system operation parameters. Energy 21. https://doi.org/10.1016/j.energy.2021.120864 23. Jalving J, Zavala VM (2018) An optimization-based state estimation framework for largescale natural gas networks. Ind Eng Chem Res 57(17):5966–5979. https://doi.org/10.1021/ acs.iecr.7b04124

Urban Engineering and Planning

Industrial Renovation in Context Sustainable Urban Development N. M. Shabalina(B) South-Ural State University for the Humanities and Pedagogical, 69, Prospekt Lenina, Chelyabinsk 454080, Russia [email protected]

Abstract. The problem of renovation, the search for optimal solutions for the reconstruction of industrial complexes, the architecture of the infrastructure responsible for a comfortable urban environment still does not lose its relevance. In the modern world, the standards and construction and engineering norms associated with taking into account the needs of people have qualitatively changed. In different geographical regions have accumulated rich experience in the sphere of modernization of public urban spaces. In order to optimize the study, we have selected objects of industrial heritage that initially had the same structural and functional significance. Various models and methods of revitalizing depressed industrial zones have been analyzed, key vectors of urban planning renovation of industrial territories have been identified. The main directions of redevelopment in the regions of Russia are traced and the ways of further transformations of the open spatial environment are determined. In modern urban planning, a careful attitude to the historical architectural and construction heritage is noted. This attitude is manifested in the clear objectives of the urban planning concept. In the conclusion, a number of provisions are identified, such as the need to conduct a comprehensive analysis of the urban planning, ecological-economic and socio-cultural situation; provide for the multifunctionality of industrial complexes based on the flexibility and mobility of its volumetric-spatial structure, taking into account the intensive development of technological processes and systems. Sustainable design ensures renovations based on the principles of sustainable urban development. Keywords: Renovation · Industrial architecture · Industrial heritage · Redevelopment · Urban environment · Sustainable development

1 Introduction The modern global world embraces the ideas of sustainable development of the urban environment. Sustainability makes cities “Sustainable cities are resilient cities that are able to adapt to, mitigate, and promote economic, social, and environmental change. Sustainable development encompasses all aspects of a city’s healthy development and should address economic, financial, social, and environmental issues” [1]—written in

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_34

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the main provisions of the brief of the Sustainable Cities Initiative of the World Bank Group for Europe and Central Asia. In our time, cities are transforming into rational large agglomerations, where the authorities are concerned about reducing the cost of consumed electricity, reducing waste, creating a favorable urban environment with conditions for economic activity for the population. These objectives are set by the European Sustainable Cities Initiative (SCI), which consolidates communities of architects, builders and designers around the world. In the concept developed by this community, the module “Protection and revival of historic cities and districts” of interest to us is indicated. Over the past two or three decades, radical changes have taken place in socio-economic life. Some old industrial facilities that did not meet the needs of society were reconstructed and re-profiled to fit the new functionality. Others, taking into account the introduction of new principles and methods of production, intensively moving to the path of information technology and the digital industry, demanded appropriate organizational and substantive changes. In these conditions, the city as a unique integral system, the focus of the minds of various specialists, turned out to be optimal for the implementation of complex economic tasks [2]. A certain vector of global developments in Russia continues to be set by the Central Research and Development Institute of Industrial Buildings and Structures (founded in 1961, transformed into a joint stock company in 1994), which has stable contacts with foreign partners. From the field of scientific research, it is important to note the analytical analysis of the levels of sustainable urban renewal, carried out by a team of authors led by Zheng et al. [3]. Sustainable approaches and flexible methods in the development of industrial facilities are defined by the authoritative Russian scientist in this field Cherkasov [4–6]. The results of empirical generalizations, trends and prospects for the development of the program for the renovation of cities are given in scientific publications of the last decades [7–10].

2 Methods of Analysis of the Urban Environment The choice of research methods should take into account socio-political, culturalhistorical, economic and environmental aspects. From scientific methods of solving the problem of restoration and sustainable development of the urban environment, in our field of vision is the cultural and historical aspect of urban planning policy [4, 11]. Renovation of industrial facilities involves the universal application of various approaches and methods of their preservation, such as (1) restoration, (2) partial or point re-functionalization, and (3) full re-functionalization [12–15]. Based on the design methods, in our research we rely on the one hand on the structural and functional, on the other hand, on the style and system contextual analysis of the spatial environment.

3 Description of the Research According to the last researches the world experience in the development of the transformation of industrial territories, we note that with an integrated approach once depressed

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areas can become centers of attraction for local residents and the business community. In some cases, they even become a kind of visiting cards of the cities in which they are implemented. An example of a striking solution of office building renovation in the industrial zone is Umicore in Hoboken (Belgium) (Fig. 1a) which received a special prize in the Archizing Trophy 2010. The new architectural image contrasts with the environment, made the company’s image and sets the vector for the development of the rest of the territory, which preserves industrial zone status. The architecture of the building plays a dominant role. Such an approach to the use of ultramodern futuristic architecture in the context of historical industrial development solves, first of all, socio-cultural problems— increasing the attractiveness of territories for city residents, investors, tenants, etc. [16, 17]. The territory is endowed with features uncharacteristic of the former industrial function, “justifying” its location in urban development, often in the central locations of the city. The production sites of Rotterdam have gone through the path of complete refunctionalization. Modern architecture looks harmoniously against the background of cultural heritage sites. Several decades ago, this city was a continuous industrial zone. Its history is closely connected with the development of the port industry in the Netherlands, where a huge number of docks and infrastructure were located, which provided the enterprises of this industry. Conversion of former industrial sites into green areas, parks is one of the main and successful ideas of the local government and architects. For example, Dakpark, which is now popular with residents and guests of Rotterdam. It is located on the roof of a shopping mall. There is a huge greenhouse and space with fountains, benches, a barbecue area and an observation deck. The roof flows smoothly into the hillside. There is a playground and a vegetable garden for local residents, where they grow vegetables and fruits. The park, opened in 2013, was created to provide local residents with a recreational area within walking distance. A similar experience of the transformation of the city, and with it the urban industry— German Dortmund, British Liverpool, Madrid and Barcelona in Spain. All these cities not so long ago consisted of many production sites. Currently, they are examples of modern, well-maintained cities, comfortable to live in, attracting investment and tourists. The situation in another Spanish city, Bilbao, developed approximately according to the same scenario. In the post-industrial era, the city stagnated and could turn into a depressed area with dozens of abandoned factory sites. Now Bilbao is one of the centers of international architecture, during its transformation, the best proposals of city planners were used. The modern capital of the Basque Country is a synthesis of cultural, tourism institutions and related industries, as well as the IT industry and startups. On the territory of Russia, there are also more and more successful examples of rehabilitation of territories that have lost their relevance to their functional purpose. For example, the reconstruction of the mill built in 1894 by the merchant Zaryvny in Orenburg—a sample of the neo-Russian style (Orenburg), Architectural correspondents: T + T Architects (Trukhanov Sergey, Voevodina Polina, Moiseev Anton) in collaboration with Mealhouse Concept Design (Bocharov Vasily, Voronin Alexey, Polyakov Alexey) [18]. This is the city’s first experience of reconstruction in the direction of a loft turned out to be successful. The project won the International (Europe and Africa) Commercial

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Property Awards 2010 (London), the authors won in the category of the best architectural object “office building” (Fig. 1b). The former flour-grinding complex of Zaryvny was transformed using one of the widespread methods in modern architecture “Nova-inveteri” (from Latin nova in veteri—new in old). This technique of reconstruction makes it possible to recreate the spirit, atmosphere of time and actualize the context and semantic meaning of a historical monument. In such a solution, history meets modernity and will continue.

Fig. 1. a Office building of the industrial zone of the Umicore company in Hoboken (Belgium), 2005–2009. Conix Architects. URL https://ney.partners/material/concrete/ [17]; b reconstruction of the mill I. A. Zaryvnov for an office center, Orenburg, Russia. 2010–2014. T + T Architects, Mealhouse Concept Design. URL https://archi.ru/russia/57078/melnichnyi-loft-kupca-zaryvnogo [18].

During the period of intensive industrialization processes taking place in Soviet Russia, the tendency to create clusters of a socialist city received a purposeful development. Industrial facilities of large factory new buildings and the adjacent residential and public infrastructure were designed according to a single comprehensive plan. In the Ural-Siberian region in the first half of the twentieth century, a large number of such socially significant objects were concentrated, which today require reconstruction and renovation. In the post-Soviet space, the economic base of the city is diversifying, which leads to a correction of the city’s image [8]. In the modern urban planning policy, new principles and solutions for the harmonious presence of the enterprise within the city have been developed, including the Chelyabinsk pipe-rolling shop “Height 239” (2010, ecological production of white metallurgy), Pervouralsk new pipe plant/electric steel-smelting complex “Iron Ozone 32” (2011, Sverdlovsk region) and “Union Soyuzpishcheprom” (Chelyabinsk, 2016– present), which includes several holdings for the production of organic products of the South Ural region of Russia. These enterprises pursue a unified environmental policy and are in an open dialogue with the public, take an active part in the development of the cultural and social sphere and the urban environment. The enterprises are equipped with innovative gas cleaning units, low-power but efficient steam generator systems, which protect the air from negative emissions into the atmosphere. The focus of industrialists and urban planners, architects of Chelyabinsk turned out to be an operating industrial production—an agricultural production enterprise “Union Soyuzpischeprom”, located on an area of 4.5 ha in the central part of the city, and

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overlooking the river embankment, which contributes to the development of its infrastructure landscape. The territory of the enterprise is connected with city-wide transport routes, which will enhance its advantages in logistics. The industrial enterprise is also of additional interest as a production and tourist site. A cultural and historical object has been preserved on the territory—the mill of the Chelyabinsk businessman, merchant A. V. Kuznetsov (1905). This is one of the first objects of the flour-grinding industry in Chelyabinsk, built at the turn of the 19–20 centurie [19, 20]. The Kuznetsov dynasty owned several factories located in the southern Ural lands of the Chelyabinsk district. Kuznetsov built a whole complex of industrial, office and residential buildings on the western outskirts of Chelyabinsk. The flour mill supplied grain and cereals to the entire city and its surroundings (Fig. 2a, b). Within the boundaries of the enterprise there was a cart-stable, where freight and light equestrian transport were kept. Currently, the residential quarters located around the industrial zone and the territory of the complex itself fit into a single residential zone, and we are considering it in the general urban context. Electric and motor highways of city streets share the same roadway and optimally solve the transport mobility of movement across the territory. The developed transport infrastructure contributes to the organic connection of the industrial complex with the urban social and cultural development of the historical quarter.

Fig. 2. a Postcard “Mill Kuznetsova, Chelyabinsk” until 1917; b the building of the mill A. V. Kuznetsov. Photo Y. Latyshev, 2015. URL https://arhistrazh.livejournal.com/194566.html

Each generation of architects and urban planners faces the challenge of continuity. The first stage of modernization of the industrial complex included the reconstruction of the elevator building (the authors of the project are the architectural studio “YUKstudio” Natalya Kremyanskaya, Chelyabinsk). For the authors of the project, the reference method for renovating an industrial territory was the Signum method—in which, an industrial enterprise performs its direct function and at the same time is a sociocultural object (open to tourists) and a sign-symbol of the region. The renovated facade of the building is decorated with the emblem and laconic composition of golden wheat ears—the brand of the enterprise (Fig. 3a, b). The architectural shaping of the concrete elevator as the main structure for storing grain is distinguished by signs of ergonomics and functional validity. The traditional engineering construction of the silo is versatile and symbolic. Modern designers have enhanced the architecture of cylindrical tanks with

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decorative elements and made the image of the Soyuzpishcheprom enterprise easily recognizable and attractive. Strengthening the brand by means of design contributes to the development of the company’s competitive ability in the market for selling ecological products.

Fig. 3. a Elevator of the “Soyuzpishcheprom Association”, Chelyabinsk, Russia, 2016; b elevator building at night. https://www.redeveloper.ru/redeveloperskie-proekty/realise_actual/elevator-obe dineniya-soyuzpishcheprom-chelyabinsk-rossiya/

The next stage of the complex reconstruction involved the construction of a new workshop and the combination of the production site with the city infrastructure. The building of the new production hall is a volume of complex geometry with perforated facades and panoramic glazing, containing integrated advertising elements (imitation of spikelets, the name of the company’s trademark). The authors of the project used original aluminum structures, innovative technologies of nonlinear shaping, and successfully applied the possibilities of lighting design. The building looks most impressive in the evening, when the interaction of the spatial environment and artificial light transforms the architectural appearance of an industrial building, showing its aesthetic and artistic image and visual information envisaged by the project. Multi-level outdoor lighting enhances the emotional impact on citizens. Lighting transforms industrial buildings into a kind of art objects, setting different scenarios for their perception [21]. The mill buildings have once again acquired a dominant role in the coastal urban environment of the historic quarter (Fig. 4a, b).

Fig. 4. a Industrial Association “Soyuzpishcheprom”, Chelyabinsk, Russia; b fragment https:// www.redeveloper.ru/redeveloperskie-proekty/realise_actual/elevator-obedineniya-soyuzpishche prom-chelyabinsk-rossiya/

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In accordance with the planning project, the embankment must be landscaped. The industrial zone will organically include a landscape and park zone and a public and business part, the project of which is currently being developed. The historic building of the mill A. V. Kuznetsov is planned to be restored as a museum and exhibition complex of the enterprise, and it will be available for excursion visits. The same type of flour mills were erected almost simultaneously in a number of cities of the Russian Empire. Today Russian redevelopment projects are solved in different ways. In Yekaterinburg, the Borchaninov-Pervushin mill complex (1908) was reconstructed preserving its historical appearance, but the former administrative building was re-functionalized as a public and residential facility (architectural bureau “PM Vostokproekt”) [22] (Fig. 5a, b). The main mill building retains its historical appearance, but has other functionalities. The residential area with a covered courtyard and a threelevel parking lot under a common stylobate meets modern requirements for comfortable housing and forms a self-sufficient ecosystem for humans.

Fig. 5. a Industrial complex “Melnitsa”, Yekaterinburg, Russia; b fragment. https://www.redeve loper.ru/redeveloperskie-proekty/concept/melnitsa-borchaninova-pervushina-ekaterinburg-ros siya/

In Saratov, the historical hull flour industrialists brothers Schmidt (Big and Small, 1900) it was decided to transform into a powerful business quarter, “Schmidt Mill” [23] with a single concept and style solutions. The complex with a total area of 3.35 ha includes office buildings, apartments for living, a hotel for business partners, restaurants for business negotiations, shopping galleries, a yacht dock—multifunctional objects are concentrated in one area. In the renovation of this industrial area, the architects have successfully combined two design methods such as “Apertionem” (from the Latin apertionem—openness) and “Laborocentrum” (from the Latin laboro—to work, and centrum—the center, that is, the worker—the production center). The first one provided the visual openness of the urban area, the second one—the ability to locally concentrate all the necessary production and social infrastructure. In 2014, the project “Schmidt’s Mill” (design bureau “T + T Architects”) was awarded the prestigious international award “European Property Awards” (Fig. 6a, b). The originality of the Chelyabinsk renovation project lies not only in the preservation and restoration of cultural and historical objects of the past and their partial re-functionalization. The uniqueness lies in the systemic modernization of production,

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Fig. 6. a Business quarter “Schmidt’s Mill”, Saratov, Russia https://www.redeveloper.ru/red eveloperskie-proekty/concept/loft-kvartal-melnitsa-shmidta-saratov-rossiya/. b Architectural and urban planning reconstruction and renovation of the territory of the factory “Saratov Muk” https:// archi.ru/projects/russia/8677/rekonstrukciya-melnicy-i-a-zaryvnova-pod-ofisnyi-centr

preserving its original functions of a grain processing enterprise and multi-vector (taking into account economic needs and environmental necessity) expanding them. The consistent phased renovation of a large industrial cluster creates conditions for sustainable development of the urban environment in the present and in the future. Currently, the integrated development of territories, including industrial and production zones, is regulated by the Federal Law “On Amendments to the Urban Planning Code of the Russian Federation and Certain Legislative Acts of the Russian Federation in order to ensure the integrated development of territories” [24]. The aim of the integrated development of the territory is to ensure balanced and sustainable development of settlements, urban districts by improving the quality of the urban environment and improve the appearance, architectural, stylistic and other characteristics of objects of capital construction, as well as the promotion of urban development of depressed industrial and manufacturing zones. According to the Ministry of Construction and Housing and Communal Services of the Russian Federation for the last time 55 subjects of Russia have submitted lists of industrial areas, subject to the comprehensive development of the initiative of local authorities. It is about 974 plots of land with total area of 33 thousand hectares.

4 Conclusions The considered objects allow us to draw the following conclusions. (1) The need for a comprehensive analysis of the urban planning, economic and socio-cultural situation. (2) An immersive approach to the renovation of industrial zones in a modern urban environment is the involvement of townspeople in the life of the enterprise through the creation of tourist clusters. (3) The polyfunctionality of industrial complexes provides for the flexibility and mobility of their volume-spatial structure, taking into account the intensive development of technological processes and systems. (4) Renovation, based on the principles of sustainable urban development, creates conditions for the restoration and maintenance of the preservation of cultural and historical objects of industrial architecture. The concept of building the territory of the considered industrial flour-grinding facilities, on the one hand, contains projects for the construction of multifunctional complexes

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for public and residential purposes on the other hand it solves the pressing issues of reconstruction and renovation of historical, culturally significant architectural structures. The balance of tasks leads city planners and industrialists to optimal interaction, dialogic cultures of different historical periods, to the restoration and development of a sustainable object and the creation of a harmonious image of urban space. The process of re-profiling industrial buildings for new functions has a two-way exit to point or complex redevelopment. The choice of this or that option depends on the tasks set for the investors, which are designed to solve not only socio-economic, environmental, but cultural, aesthetic goals. Acknowledgements. The author of the article express their gratitude and appreciation for the help and support from colleagues to the Ministry of Construction and Infrastructure of the Chelyabinsk Region, the Committee of Architecture and Urban Planning of Chelyabinsk, RF.

References 1. Sustainable Cities Initiative (2021) Brief. https://www.vsemirnyjbank.org/ru/region/eca/ brief/sustainable-cities-initiative. Accessed 21 May 2021 2. Bessarabova YaI, Evtushenko-Mulukaeva NM (2019) Renovation and integration of industrial enterprises into the modern urban environment. Architecture 3(81). https://doi.org/10. 23670/IRJ.2019.81.3.035. https://research-journal.org/arch/renovaciya-i-integraciya-promys hlennyx-predpriyatij-v-sovremennuyu-gorodskuyu-sredu/. Accessed 2 May 2021 3. Zheng HW, Shen GQ, Wang H (2014) A review of recent studies on sustainable urban renewal. Habitat Int 41:272–279. https://doi.org/10.1016/j.habitatint.2013.08.006. Accessed 23 Apr 2021 4. Cherkasov GN, Kabaeva MM (2011) Socio-cultural aspects of the development of industrial architecture. Acad Arch Constr 4:18–30 5. Cherkasov GN, Kabaeva MM (2014) New trends in the development of industrial architecture: enterprise - people - city – society. Acad Arch Constr 4:34– 44. https://cyberleninka.ru/article/n/novye-tendentsii-v-razvitii-promyshlennoy-arhitekturypredpriyatie-chelovek-gorod-obschestvo/viewer 6. Cherkasov GN (2017) Some features of modern architecture. Acad Arch Constr 4:62–67 7. Balzannikova et al (2016) Sustainable development of the urban environment. Institute of Architecture and Construction, Samara State Technical University, Samara, p 237 8. Papenov KV (2019) Sustainable development of cities. Lomonosov Moscow State University, Moscow, p 288. https://www.econ.msu.ru/sys/raw.php?o=58030&p=attachment. Accessed 23 Apr 2021 9. Tolmachev VA (2020) Sustainable development of regions and cities of Russia. https://www. strategyjournal.ru/rossiya-i-mir/ustojchivoe-razvitie-regionov-i-gorodov-rossii/. Accessed 23 Apr 2021 10. Braila N, Iatsinevich P, Korenevskaya M, Erzakov S, Simankina T (2018) Reconstruction of industrial building with nonstandard spaceplanning decisions. IOP Conf Ser: Mater Sci Eng 365. https://doi.org/10.1088/1757-899X/365/2/022045 11. Tetior AN (2009) Social and environmental foundations of architectural design. Moscow 12. Golovanov EB, Kisileva EA (2013) Development of redevelopment as a direction for the transformation of urban areas. Bull South Ural State Univ Ser: Econ Manag 7(3):12–16

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13. Tsitman TO, Bogatyreva AV (2015) Renovation of industrial territory in the structure of the urban environment. Civ Eng Bull Casp Reg. Astrakhan Civ Eng Inst 4(14):29–35. https://agasu.rf/journal/files/documents/44-redaktor/isvp_4_14/isvp_2015_ 4_29-35.pdf. Accessed 23 Apr 2021 14. Klaus S (2017) The fourth industrial revolution. Crown Business 15. Bystrova TYu (2013) Rehabilitation of industrial territories of cities: theoretical premises, design directions. Acad Bull Ural NIIproekt RAASN 3:23–25 16. Dinnie K (2013) Territory branding. The world’s best practices. Moscow 17. Conix Architects. https://ney.partners/material/concrete/. Accessed 21 May 2021 18. Reconstruction of the mill I.A. Zaryvnov for an office center, Orenburg, Russia. https://archi. ru/russia/57078/melnichnyi-loft-kupca-zaryvnogo. Accessed 21 May 2021 19. Kuznetsova AV (2021) The complex of the former mill of the merchant. https://arhistrazh.liv ejournal.com/194566.html. Accessed 28 Apr 2021 20. Soyuzpishcheprom: architecture of the future (2019). https://uralpress.ru/news/ekonomika/ soyuzpishcheprom-arhitektura-budushchego#image-5. Accessed 28 Apr 2021 21. Shabalina NM, Glavinskaya EV (2019) The evolution of light design in industrial architecture. In: Lavrentiev AN (ed) Art of light: design, architecture, artistic and design work Art. International scientific-practical conference, Moscow, 18 Oct 2019, pp 169–178. https://www. elibrary.ru/download/elibrary_41438348_14716927.pdf 22. Mill Borchaninov-Pervushin, Yekaterinburg, Russia (2020). https://www.redeveloper.ru/ redeveloperskie-proekty/concept/melnitsa-borchaninova-pervushina-ekaterinburg-rossiya/. Accessed 28 Apr 2021 23. Loft-quarter “Schmidt’s Mill”, Saratov, Russia (2020). https://www.redeveloper.ru/redeve loperskie-proekty/concept/loft-kvartal-melnitsa-shmidta-saratov-rossiya/. Accessed 28 Apr 2021 24. Federal Law of 30.12.2020 N 494-FZ “On Amendments to the Urban Planning Code of the Russian Federation and Certain Legislative Acts of the Russian Federation in order to ensure the integrated development of territories”. http://www.consultant.ru/law/hotdocs/ 66918.html/. Accessed 30 Apr 2021

The Compositional Regulation of the Historic Environment and Urban Planning E. Prutskova(B) and O. Finaeva South Ural State University, Prospekt Lenina, 76, Chelyabinsk 454080, Russia [email protected]

Abstract. The paper provides a historical overview of issues concerning the refurbishment of old cities. It also presents summary information regarding current trends in urban reconstruction in Russian and oversea practice during the period from the end of WWII in the twentieth century to the beginning of the twentyfirst century. The main section considers the practical aspects of regulating the historical environment. Factors here include: the social and aesthetic functions of historic sites; the essence and dimensions of such historic sites; the psychological dimensions of environmental impact; the cultural potential of historic heritage; and the theoretical and practical importance of state protection for historic and cultural monuments. All these factors underpin the importance of a comprehensive approach to studies of monumental legacy and the current issues in this field. This paper will also consider the role of public interest in the design of historical and cultural monuments and heritage, as well as the potential for conservation, and current issues of urban planning and renovation. We will describe the issues and potential of modern practices in refurbishing the historic environment, while establishing the main principles of its renewal. The conclusions herein underpin the need to introduce a system of justifying urban planning when it comes to the renovation of buildings and the environment. This must be a mandatory stage in project design and permit issuing, aimed at competently resolving issues of urban renewal. Keywords: Refurbishment · Regulation of urban planning activities · Historical environment

1 Introduction With current and growing public interest in the conservation of cultural heritage, as well as professional research into the role of historic objects in the modern cultural environment, this paper will provide a review of the creative process and aim to establish a systematic approach towards resolving issues of modern urban renewal while conserving the historic factor. The concept of culture is considered from a semiological point of view, as socially-developed signs of human activities. Culture can be considered in three dimensions: ideal, material, and temporal. This approach reveals the monument through its connection with the objective world of culture, and by its connection with man, thus © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_35

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providing a better definition of its place in cultural heritage and its role in influencing modern reconstructions. This approach will also contribute to further research and historical analysis, which in turn will allow for the creation of a new and more advanced mechanism of state and public administration in culture regarding the place of historical heritage in the cultural policy of the state. A further aim is to resolve the issue of ideologically-driven schemes in the cultural sphere, and the prerogative of administrative activity. We also highlight the function of the researcher as a priority in the protection of historical and cultural heritage, a specific sub-culture per se. There is a growing and acute need to develop an independent academic discipline capable of defining the role of cultural heritage in modern culture and to integrate it into the modern cultural context based on research rather than socio-political motivation. 1.1 Historical Overview of the Reconstruction Problems of Old Cities Urban planners, architects, and restorers are primarily interested in the development and reconstruction of cities, but there is also a role for demographers, psychologists, sociologists, and specialists in the humanities and the history of architecture. Aspects of conservation and modernization are significant at all stages of urban development. We therefore need to study these concepts and evaluate the work already carried out in historic residential regions and their immediate surroundings. A wide range of original reports discussing restoration projects have been published on the development of work in urban territories. All of them emphasize the significance of urban complexes when it comes to the issues of renewal [1–3]. The key issues of the theory of reconstructions have been considered by both academics and research experts [4–6]. Their research is motivated by the desire to present issues of protecting historic urban areas both methodically and comprehensively [7–10]. This became particularly pressing after the Second World War, and the need to reconstruct cities and residential areas. Careful analysis of the key role played by medieval districts as part of the general urban environment evaluated their historic value [11, 12], as well as previous and potential drawbacks which could determine future urban development [13]. After the mass destruction of monuments during WWII and the subsequent changes in the social structure, ideas on restoration methods, albeit diverse, traditionally took into account the location of the renewal project. Although the holistic appearance of a monument remained uppermost in the minds of the people, they also perceived the ruins in the place of the former monument as something “normal”. As a result, a number of approaches emerged. Some believed that monuments should not be reconstructed, in order to avoid falsification. Others believed that the remains of the original be preserved with the minimum changes. Yet others considered that the loss of historical buildings be accepted and new structures be built in their place. The task was further complicated by the huge scope of destruction, and the moral component. Solutions depended on the proposed restoration documentation, the compositional role of the lost element within the urban environment, functional requirements, and other considerations. These principles guided archaeological restorations in the Soviet Union and European countries with varying types of motivation for restoration. Nevertheless, preference was generally given to urban planning based on historic considerations.

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2 Practical Aspects of Regulating the Historic Urban Environment 2.1 Modern Urban Planning Problems in the Renovation of the Urban Environment Planning issues of in the current urban environment (new buildings, regeneration) cannot be resolved without the close interaction between the new and the old. The multi-faceted nature of emergent objectives must be harmonized with compositional reorganization of the urban environment. The main issue here being the history of restoration, since urban developments undergo a period of formation before acquiring their current state. The compositional arrangements of three-dimensional urban structures are based on cultural, scientific progress, and the preferences of society as an indicator of human cultural advancement. 2.2 Social and Aesthetic Functions of Historical Objects The design of multidimensional spaces of human cultural life and activities is closely related to the social and aesthetic functions of objects which have survived from past eras of social development. They serve as an aesthetic representation of historical time and the cultural environment space of cities and settlements. The aesthetic functions of a historic object generally correspond to its social functions, and thus reveal the laws guiding the formation of the social content in the historic space–time continuum. The aesthetic meaning of spatio-temporal relations is expressed figuratively, while the diversity of the various aspects and links of spatiotemporal relations is denoted by the concept of style. A historic object is not just an objectification of history, its appearance imparts information, special expressiveness, visibility, and imagery achieved by a variety of means. Nevertheless, even given all the differences, the principle of style unites the variety of historical objects in terms of expressiveness. The aesthetic function of the object can suggest a different attitude to life (the set of the material conditions of social life), as well as the history of the development of aesthetic thought (principles of harmony) to the present day. The complex aims and objectives which require the study of historical and cultural heritage need to be based on the study of the socio-aesthetic and ethical functions of this heritage. Only this will permit the comprehensive formulation of the role of a historic object in the modern cultural environment. 2.3 Historic Objects, Their Value and Appreciation Whether an object is good or bad, active or passive, whether it possesses intense or weakly expressed qualities is not part of the primary question. The answers need to define and enumerate the specific features of objects, clarify and classify the object, and its value, thereby determining the place of the object in the overall picture of the world, the attitude towards it.

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2.4 Psychological Measurements of the Environmental Impact Ardent discussions are frequently heard about the need to preserve the historical and architectural environment. This appeals to the profound values of man and society to protect our roots and origin. However, it is important to recognize that the desire to preserve every object is absurd. We need to address the question about what can be lost relatively safely, and what should not be lost. The answers are to a certain extent determined by sociological surveys, art history, as well as ethical and pedagogical considerations. These approaches, however, are not sufficiently objective and are impractical in measuring the impact of change or preserving environments. We need to assess individual perception of objects and phenomena in the world. This is an approach of experimental psychology which allows us to compare the consequences of several competing projects involving environmental change when analyzing the risk of environmental destruction (the structure of this risk). 2.5 The Cultural Potential of Historical Heritage Modern society recognizes the role of cultural heritage, and indeed many generations have paid tribute to the monuments of the past. They are perceived as ancestral masterpieces which define the stages of the formation and development of human culture. This phenomenon, however, remains in the gap between the desire of society to preserve its heritage and the effective use of the historic urban legacy and monuments. 2.6 The Theoretical and Practical Significance of Legal Protection of Historic and Cultural Monuments State protection of historic and cultural monuments guarantees the legal protection of cultural heritage and offers practical opportunities its preservation and restoration. The need to preserve and use cultural heritage in the interests of the broadest masses of workers was first formulated in the Decree of the Council of People’s Commissars of the RSFSR dated October 5, 1918 “On the Registration, Accounting and Protection of Monuments of Art and Antiquity”. This decree was signed by V. I. Lenin and the main requirement was the state registration of movable and immovable property. The registers contained a careful record of historical heritage, but they were flawed. The lists of valuable objects included antiquities without any justification, scientific, or artistic assessment, without the date of their construction, the name of the project designer, or other important historical information. An integrated approach to research into monuments emerged in the late 1970s to the early 1980s. Of particular importance in this process were individual specialized disciplines studying material objects of the past, as well as interdisciplinary historical research. During this period, the issue of preserving not only individual monuments, but also their surrounding natural environment, also emerged. The objective was to preserve the integrated ensembles of streets, residential quarters, and even historic city centres. A new holistic approach to the study, use and preservation of monuments was developed. The achievements of various scientific branches were united and directed towards studying the preservation of the historical and cultural environment. It was also

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in this period that the concept of historical cultural monument was first defined. Such monuments were defined as a function of the objective world of culture, the role of which is bring socially significant cultural and technological traditions from the past into the future. The previous limited definition stated that a monument is an expression of the comprehensive activities of the peoples of Russia [14] or that a monument is “a combination of links, relations, and results of the spiritual production of past historical epochs”, or “a combination of cultural values inherited by humanity from past epochs, which are critically assimilated, developed, and used according to the objective criteria of social progress” [15]. Monuments were sometimes defined as “a combination of three categories of material objects: monuments themselves, ensembles, and places of interest” [16]. This definition of the concept of monument was in itself circular relationship: a monument is a part of cultural heritage, which per se is a collection of monuments… Some opinions state that a monument is not an object, but an attitude towards the time of which the object and its existence are a symbol. Thus the monument can only be recognized as a self-portrait of the time it symbolizes [17, 18]. Article 5 of the USSR Law “On the Protection and Use of Historical and Cultural Monuments”, which states: “other objects of historical, scientific, artistic, or any other cultural value may also be classified as historical and cultural monuments” gave new considerations to the essence of a historical and cultural monument [19]. In this article, it is man who turns a historic object into a monument. Man assigns merit due to the historical, cultural, scientific value of the object experienced and recognized by society as deserving perpetuation, protection, and care. Although the current legislation [20] of the Russian Federation has advanced the state protection of cultural heritage, even modern practice lags behind. To date, a huge number of cultural heritage objects have not been assigned the status of protection. The boundaries of the territory of these monuments is not established. The protection zones and development regulation zones remain undefined. Thus, there are no predefined planning regulations which prevent planning changes in urban areas at the present stage of urban development with the presence of historic districts, urban planning ensembles, complexes, and individual monuments. In modern conditions of regional development, given the functional involvement of cultural heritage and its environment, comprehensive measures have as yet not been established to regulate functional and compositional factors as part of the protection and reconstruction of urban areas of historical and cultural significance: • There are no defined boundaries of the territory of monuments, which would establish the degree of preservation and stages of regional development, and thus impose restrictions during urban planning works; • There are no defined protection zones or building development regulation zones for cultural heritage objects. This means that neither the best overview of monuments (protection zone) nor a visual overview within urban planning (building development regulation zones) is provided at the required level in the conditions of regional development.

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Approved and effective protection zones have a significant impact on urban planning processes. However, they have not been fully implemented in relation to cultural heritage as a whole. This has led to delays in the implementation of urban planning measures, since a great deal of time is spent on the drafting and approval of documents required to protect cultural heritage objects on construction sites. In the absence of protection documents for architectural and urban planning monuments, as well as lands of historical and cultural significance, the legal requirements are often neglected, and the valuable historical and architectural environment is irretrievably lost. The sole reason for this is that the requisite documents has not been obtained in due time. In other urban environments, a system of conservation conditions has been developed in compliance with applicable legislation on the protection of historical and cultural heritage. However, such legislation is not always fully implemented in practice. One key factor is the lack of competence amongst specialists in governmental bodies authorized to guarantee state protection of national cultural heritage, and whose role it is to prevent the bypassing of regulations and the silent demolition of monuments. Modern urban life is marked by natural rapid development and growth. The constant contradictions in attempts at regulation have significantly complicated urban planning due to the lack of implementation of the state protection of cultural heritage objects. The transformation of the city as a social category in response to modern objectives and the preferences of its residents is a component of capital work, architecture and general urban planning. Routine architectural practice needs to establish a valid framework for the use of composition in relation to the city and its parts, as well as the functioning patterns of a reasonable and holistic urban arrangement. Established urban planning environments contain capital construction objects from a range of time periods, some of which are classified as objects of cultural heritage. We therefore need to take into account the applicable urban planning restrictions, if we want to preserve cultural heritage and its historical and architectural environment. 2.7 The Role of Public Interest in the Design of Historical and Cultural Monuments An essential condition for the confirmation of an object as a monument is its public recognition as such, as our review also affirms. This requires a complex mechanism. We need to make a distinction between the impact of public interest in the formation of historical and cultural monuments, as well as in the further existence of monuments in society. Monuments play an important and decisive role in ensuring the transfer of material traditions from the past to the future. In the first case, the monument represents creativity, and in the second consumption. Therefore, when recognizing the cultural value of an object, assessment by the administrative authorities and group interests should be avoided. This can give rise to paradoxical situations when an object is recognized as a cultural monument, while officially it is not, and vice versa. Expert evaluation is crucial since the process of designing a monument needs to be regulated and managed. The positive effect of public interest in this process allows the systems of the objective world of culture to be imposed. This system characterizes the successive stages of cultural and technological development. This is inevitable and caused by the eternal human desire to find the divine principle, in which nature and society are commensurate, and to find

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a universal measure that would not violate the actual internal measure of each of the parties involved. The history of culture is not only the history of the continuous search for universal culture, but also the history of the human legacy of the most successful and perfect experiences. It is also the history of new violations of policy and new breaks in cultural tradition (transmitting images from one epoch to another). This is something which arises at a certain stage in the development of the material and spiritual culture of society (civilization). The primary objective of the preservation of cultural heritage, as can be seen from the above, is to serve as opposition to shallow practicality and the desire to derive direct material gain from everything, i.e. utilitarianism. The administrative (civilizing) approach to immovable heritage seeks to restrict the designation of construction objects as monuments, which can be explained by urgent social needs. The relationship between public and administrative interests follows the law of unity and conflict of opposites. The result of this conflict is social control used to resolve conflicts, depending on the requirements of the ecology of culture (the interaction of man, society, and the environment). It can, therefore, be concluded that social control is not only an important regulator of the construction of monuments, but also their preservation. This is social control adjusted according to historical and cultural traditions, as well as public and local priorities. It should also be recognized although that the significance of civic action is not fully understood, it can be truly effective. Only public interest and social control directly influence the understanding of a historical and cultural monument on a municipal, regional, and national scale. 2.8 Prospects for the Preservation of Historical and Cultural Heritage In modern times, human spiritual needs have grown immeasurably compared to previous periods of history. We live in a time when the entire objective wealth of the world falls under the spotlight. The individual acquires material evidence of their cultural and historical experience, and becomes aware of the value of historical and cultural objects. We must also note the criminal ignorance of public interest in recognized historical and cultural values. Such actions have led to a qualitative reduction in studying historical and cultural objects and an imperfect practical side of the matter. Many environmental impact assessments have been carried out on the perception of architectural objects, in the aims of seeking appropriate approaches to assessing the degree of recognition of architectural objects, their emotional impact, the experience of encountering the objects, and the impact on the perception of the objects when their environment changes. The most promising studies involve the construction of environmental impact models capable of systematizing situations, providing direct and quick assessments of the consequences of projected changes, while at the same time establishing approaches to solving environmental effects. Two such methods involve the construction of structural contour maps and carrying out analyses to justify reconstruction activities in historic districts. Structural contour maps are designed to understand the changes in the spatial structure of reconstruction works in historic districts. The aim is to prevent conflicts in scaling relations with the surrounding urban formations and the interconnection with the surrounding architectural landscape.

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Permissible methods of national architectural practice include: • The method of working in contrast, which should be strictly justified; • The method of fitting into the existing architectural environment (compositional techniques, stylistic features, forms); • The method of proportionality, comparability, visual conformity. • Analyses to justify reconstruction in historic districts are carried out on: • Spatial compositions in the city, in order to determine the degree of preservation and temporal changes of urban formations; • Existing planning structure of historic districts and their spatial structure; • The silhouette of historic districts and urban planning or architectural ensembles in the structure of the district, in order to preserve the principle of ensemble composition and maintain distant landmarks (dominants); • The ratios of building heights on historical streets in the district; contours of facades in the historical environment for new buildings, in order to preserve the principle of street facade composition (combination of dominants and ordinary buildings). The primary professional factors in historic environment renewal should regulate: • • • • • •

Historical and urban planning concepts (system of views); Architectural and aesthetic concepts; Artistic and emotional concepts; Functional concepts; Reconstruction concepts; General factors, such as vegetation; landscape; atmosphere and negative impacts on it; and acoustic impact.

3 The Modern Practice of Reconstructing Historical Environments Architectural practice has left many negative and positive examples: • Reconstruction necessitating the demolition of derelict buildings incompatible with modern engineering and technological requirements is justified from the moral, aesthetic (demolition of derelict low-value buildings), social, economic, and engineering standpoints, as well as from the standpoint of the hygienic efficiency of historical buildings. • Reconstruction of the urban development structure with a historic environment and monuments, involving the renewal of the environment, while incorporating old residential buildings of cultural value into the modern urban life. Having analyzed the practices of reconstruction in Russia and Europe, it can be concluded that simultaneous reconstruction is an effective solution for the renewal of the existing historical and architectural environment. Simultaneous reconstruction requires research and design work to be carried out in their entirety. This ensures comprehensive general planning which reproduces the future historical environment in full interaction with all existing buildings. Another key feature is the purposeful design of the

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entire system of spatial and engineering infrastructure, natural landscape, and urban land improvement, exposing the facade of historical buildings as a composite element of the architectural appearance of streets, squares, and embankments. Several objective compositional patterns need to be observed in the reconstruction of historic and architectural environments. The first of these patterns is volumetric-spatial relations with the historical environment. The construction of new buildings in the historic environment of the district needs to comply with the Law of Architecture, Key factors here are the proportionality of the ratio of volumes, the harmony of building heights, and the general nature of the silhouette. Harmonization of the architectural expressiveness of the facades requires: • Preservation of the harmony and integrity of the architectural environment (even if it was created over several eras); • Observation of the proportional ratios of volumes and heights of buildings, architectural expressiveness, consistent concepts of facades, and an acceptable choice of colors. New buildings ensure continuity with the neighboring buildings (including the use of techniques present in all style eras and times) Buildings which successfully harmonize with the environment lead to positive associations, while disharmonious buildings more often than not evoke condemnation. The second of these patterns is the silhouette and the relationship of the height of new and historic buildings, in compliance with the regulatory data on height restrictions of surrounding buildings. The appearance of a historic city, district, or architectural and urban ensemble can be preserved while maintaining the silhouette of the building. The geometric diversity of volumes and their combination is an important aspect of the appearance of a historic formation. A classic example of such compliance is the sensitive placement of belfries and bell towers in new developments. An example from Russian architectural practice is the high-rise building of Moscow State University on the Lenin Hills. The erection of modern buildings in the historical environment can be considered successful when the proportional ratios of the geometric dimensions of building heights conform to digital indicators and can be expressed by the ratios of 1:3; 1:4; 3:5; 5:8, etc. The use of decorative elements on new building facades which correspond to historic buildings helps to achieve spatial interconnection between old and new buildings of different volumes. Moreover, new objects are granted much more freedom in zones of strict urban development regulation. However, restrictions on the number of floors are applicable, in order to avoid distorting the silhouette of historic buildings. Soviet researchers developed a method of height restrictions which determined the location and dimensions of new buildings. This method can be practically applied for the following purposes: • The creative conceptualization of a specific urban space; • Establishing the permissible height of buildings to be constructed in environments with existing historical buildings;

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• Defining the optimal means of synthesizing the new and the old, which is the main artistic goal. The third of these patterns is the architecture of new buildings on historic streets. Unsuccessful construction projects in recent decades have lead to architects being forced into taking special responsibility. The construction of buildings with flat, monotonous facades is completely inappropriate in an organic environment and has caused damage to historic districts with architectural monuments. The recent work of designers is characterized by a rejection of the former practice of pre-fabricated panel buildings. Designers are searching for aesthetics in architectural solutions and mass-produced details. This is comparable to the era of the establishment of eclecticism and modernity—a reinterpretation of the architectural experience, a tentative interpretation of a new style and composition, revealing the aesthetic possibilities of architecture.

4 Conclusions The issues of modern urban planning, and in particular the construction of new buildings in the historic environment and its regeneration, cannot be resolved by ignoring the close interaction of the old with the new. The simultaneous reconstruction of districts, historical centers, and cities as a whole is made complicated by the existing opportunities available to urban development. Reconstruction work is performed in fragmented sections; something which can lead to revolutionary transformations of historic and urban heritage. This can lead to the loss of important factors in the development of volumetricspatial compositions as essential components during regeneration. It is also detrimental to architectural and aesthetic factors which can negatively affect the establishment of values in the stylistic solutions of modern development of a given district or historical centre. To this end, we suggest that urban planning justification in the renovation of buildings and the environment be introduced as an obligatory design stage, in order to resolve reconstruction problems in a competent manner during the application process for reconstruction permits.

References 1. Lysaya DA, Chzhan Ch (2021) Administrativno-pravovoy mekhanizm kompleksnoy rekonstruktsii zhilishchnogo fonda istoricheskikh tsentrov gorodov Rossi (Administrative and legal mechanism for the complex reconstruction of the housing stock of the historical centers of Russian cities). Vestn Inzhenernoy Shkoly Dal’nevost Fed Univ 1(46):136–148 2. Korshunova EM (2009) Problemy rekonstruktsii slozhivsheysya zastroyki tsentra SanktPeterburga (Problems of reconstruction of the existing development of the center of St. Petersburg). Ekon Vozrozhd Ross 4(22):67–70 3. Korneva EV (2014) Gradostroitel’nyye faktory obosnovaniya rekonstruktsii istoricheskikh kompleksov (Urban planning factors for the justification of the reconstruction of historical complexes). Arkh Sovrem Inf Tekhnol 3(28):119–125 4. Dayneko AI, Dayneko DV (2013) Normativno-pravovoye obespecheniye v sfere sokhraneniya ob”yektov nedvizhimosti kul’turnogo naslediya (Regulatory support in the sphere of preservation of real estate objects of cultural heritage). Vestn Irkutsk Gos Tekh Univ 9(80):140–148

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5. Lavrov LP (2014) Opyt sokhraneniya istoricheskogo tsentra v Myunkhene (Experience in preserving the historical center in Munich). Vestn St-Peterbg Univ. Iskusstv 1:239–252 6. Markin YuP (2006) Arkhitekturnyye metamorfozy Berlina (Architectural metamorphoses of Berlin). Sovrem Evr 4(28):130–144 7. Kozlova GS (2013) Kompromiss mezhdu sokhraneniyem i razvitiyem arkhitekturnoistoricheskikh ansambley (opyt Germanii) (Compromise between the preservation and development of architectural and historical ensembles (German experience)). Izv Vuzov. Invest. Stroit. Nedvizhimost’ 2(5):170–183 8. Potapova AV (2014) Nemetskiy opyt v zakonodatel’stve po sokhraneniyu istoricheskogo naslediya (na primere g. Drezdena) (German experience in legislation on the preservation of historical heritage (on the example of Dresden)). Izv Vuzov. Invest. Stroit. Nedvizhimost’ 6(11):122–132 9. Mitina ES Pervyye gradostroitel’nyye proyekty Kaliningrada (1946 - pervaya polovina 1950kh godov) (The first urban planning projects of Kaliningrad (1946 - the first half of the 1950s)). Retrospekt: Vsemirn Istor Glazami Molod Issled 8:51–58 10. Dagdanova IB (2013) Problema arkhitekturnogo ansamblya na primere gorodov sovremennoy Germanii (The problem of the architectural ensemble on the example of the cities of modern Germany). Izv Vuzov. Invest. Stroit. Nedvizhimost’ 2(5):131–144 11. Nekrasov AB (2019) Reconstruction of the lost historical building (on the example of the city of Kaliningrad). Acad Arch Constr 2:38–50 12. Nazarova AYu (2019) Teoreticheskiye aspekty izucheniya i sokhraneniya silueta istoricheskogo goroda (Theoretical aspects of studying and preserving the silhouette of a historical city). Vestn Tomsk Gos Arkh-Stroit Univ 21(3):77–85 13. Pasechnik IL, Marushina NV (2019) Kategoriya tsennosti v teorii i praktike sokhraneniya istoricheskoy gorodskoy sredy (v kontekste izucheniya ryadovoy istoricheskoy zastroyki) (Category of value in the theory and practice of preserving the historical urban environment (in the context of the study of ordinary historical buildings)). Vestn Tomsk Gos Arkh-Stroit Univ 21(3):9–19. https://doi.org/10.31675/1607-1859-2019-21-3-9-19 14. Beskrovnyy LG (1978) Okhrana pamyatnikov istorii i kul’tury v Rossii XVIII – nachala XX vv. Voprosy okhrany i ispol’zovaniya pamyatnikov istorii i kul’tury (Protection of historical and cultural monuments in Russia XVIII - early XX centuries. In: Issues of protection and use of historical and cultural monuments). Nauchno-Issledovatel’skiy Institut Kul’tury, Moskva, pp 3–18 15. Baller EA (1984) Preyemstvennost’v razvitii kul’tury (Continuity in the development of culture). Nauka, Moscow 16. Boguslavskiy MM (1979) Mezhdunarodnaya okhrana kul’turnykh tsennostey (International protection of cultural property). Mezhdunarodnyye Otnosheniya, Moscow 17. Glazychev V (1969) Srednerusskiy Disneylend (Central Russian Disneyland). Dekor Iskusstv SSSR 7:25–29 18. Glazychev V (1969) Pamyatnik vnutri nas (Monument inside us). Dekor Iskusstv SSSR 2:16–20 19. Prezidium Verkhovnogo Soveta SSSR (1976) Zakon SSSR ot 29.10.76 (red. ot 21.09.83) “Ob okhrane i ispol’zovanii pamyatnikov istorii i kul’tury” (Law of the USSR of 10/29/76 (as amended on 09/21/83) “On the protection and use of historical and cultural monuments”). Kreml’, Moscow 20. Gosudarstvennaya Duma Rossiyskoy Federatsii (2002) Federal’nyy zakon № 73 ot 25.06.2002g. “Ob ob”yektakh kul’turnogo naslediya (pamyatnikakh istorii i kul’tury) narodov Rossiyskoy Federatsii” (Federal Law No. 73 dated 25.06.2002 “On objects of cultural heritage (monuments of history and culture) of the peoples of the Russian Federation”). Kreml’, Moscow

Integrating Standard Residential Buildings with Architecture and Space of Historically Sensitive Environment N. V. Kuznetsova(B) and P. V. Monastyrev Tambov State Technical University, 106, Sovetskaya Street, Tambov 392000, Russia [email protected]

Abstract. Residentialareas with standard buildings of the 1960–1980s industrial construction period exist in many cities of Russia; they are located in remote areas and close to historical quarters in the city center. Sustainable and systematic development of such districts requires measures to improve the urban environment based on the principle of integrating standard development with the surrounding urban context. The problem of integrating mass produced residential buildings in the urban environment is considered from the point of view of the system-structural approach. For the “Historical Dominant Element-Standard Housing” (HDE-SH) system, the elements that make up this system are identified and interconnected, forming a structural unity. The concept of a ‘locum’ as a residential formation limited by a specific space is introduced. The historical dominant element in the architectural environment interacts with the environment, forming various types of dependencies—contact zones. To organize the integration processes, the characteristics of the system components are considered and the possible range of their transformations, the relationship between integration factors and characteristics of typical development are determined. The model of integration of typical building with the urban environment involves its transformation in two aspects: spatial and temporal. Architectural and spatial development must be carried out by compensating for the missing and increasing the existing value indicators of development. The temporal aspect of integration involves the organization of stages in the process of system transformation. As a result, a “multi-layered integrated system”, capable of quickly responding to the changing demands of society, is created. Keywords: Integration · Standard housing · Integration objects · Historical dominant element · Architectural and spatial characteristics

1 Introduction Many Russian cities inherited microdistricts built up with standard residential buildings known as the “Soviet heritage”. They occupy quite large areas and still play an important role as a place of residence for a significant number of people. Such areas are located in large numbers in the remote areas of cities, however, they can be found in the historical © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_36

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quarters of the city center, since such residential buildings were often built on the site of the demolished quarters. Microdistricts with mass standard housing look monotonous and homogeneous; they have high density and a large scale of spatial structures with a clear set of certain infrastructure facilities. These characteristic features of typical residential areas were due to the need to solve the problems of the country’s social development based on the principles of typification and industrialization of construction and are largely associated with the huge volumes of housing construction in the 1960–1980s in cities. Mass residential areas responded to the social demands of the time, creating comfortable living conditions for people who moved to cities. These residential blocks were equipped with central heating, hot water supply, sewerage, and light in apartments. Later on, in contrast to mass residential construction, understanding of the value of the historical urban environment was gained. The problem of the proximity of historical buildings and typical residential areas is not only a Russian phenomenon. The issues of chaotic construction near historical quarters and, in connection with this, disruption of the organic connection, the historical balance of the urban environment, and the loss of architectural and cultural identity are relevant for cities around the world. The main recommendations concerned mainly proposals on how to transform the historical environment with the inclusion of modern [1–3], the practical use of the principle of continuity, where “the new must find its way to the old”, rethinking the methods of traditional architecture [4, 5] and creation of a new urban identity through structural and temporal transformations of the historical environment [6–8]. The research is primarily at developing approaches for the preservation of architectural monuments and their adaptation for modern use in a diverse urban structure [9, 10], the use of multi-criteria analysis methods for the preservation of architectural historical as-sets [11]. To ensure the sustainable and systematic development of areas with standard housing (SH), measures are required to improve the urban environment. One of the methods for solving the problem is the principle of integration. According to Ikonnikov, by means of integration, the unity of the forms of functioning of and the spatial buildings shell can be achieved [12]. Glazychev, Gutnov, Regame et al. [13, 14] many researchers [15–18] focused on the development of methods for improving the designed standard development in order to make it humanistic. Integration of standard housing with historical urban environment comprised in the improvement of its artistic and aesthetic qualities, the emergence of integrated residential complexes, but this mainly concerned new standard series. The already erected typical buildings did not undergo any changes. The end of the period of mass standard housing construction interrupted scientific and practical developments in this direction. In early 2000s the issues of transforming standard housing in competitive projects, and later—in practical implementation, began to be raised again. To date, there are some results of transformations of standard housing. First of all, work is underway to eliminate the physical and moral depreciation of the building through major repairs, reconstruction with the addition of floors, increasing the degree of comfort of housing, insulating facades, and improving their visual characteristics [19, 20].

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The issues of attention to social problems during the reconstruction of typical buildings are perhaps no less important, therefore, the main means of transforming typical buildings, along with the reconstruction of the building itself, is the transformation of the public space adjacent to them and the renewal of social infrastructure (architect Stefan Forster) [21, 22]. Foreign practice in the reconstruction of standard houses shows ways to improve comfort, such as getting rid of monotony by using color accents, creating soft boundaries for private and semi-private spaces on the first floors, creating terraced silhouettes by lowering the number of storeys, etc. [23, 24]. As a result of taking into account social issues with the help of architectural techniques, individual, non-standard, urban spaces were formed (Fig. 1). Thus one can talk about the formed socio-spatial complexes, consisting of the most developed areas and sections of the city, which are characterized by the interconnection of certain types of activities of the population with the spatial organization of the environment [25]. However, this is far from the only expected result. There are town-planning situations that require taking into account a wide range of factors in the process of standard housing reconstruction.

Fig. 1. Examples of the reconstruction of residential buildings designed by the architect Stefan Forster, Germany.

The widespread use of the microdistrict model in Soviet urban planning led to the emergence of numerous areas with standard residential buildings in various parts of cities, including those in close proximity to the historical core. In the existing development of microdistricts at the time of construction, in most cases, the issue of combining mass standard housing construction with elements of attraction (architectural or natural dominants), such as lowrise buildings, historical ensembles or objects, recreational and park zones. The role of the context was not taken into account in the process of building typical microdistricts, and as a result, a differentiated environment arose, which today needs to be restored [4]. Modern approaches to the issues of urban planning and architecture include a transition from the process of summing volumes to integration, followed by the integrated development of the urban environment and its management. This is the core principle of the formation of urban structures [13]. Therefore, standard housing should receive a new development scenario: to make the transition from a “sum of single-valued structures” to

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a “multilayer integrated system”. This is possible due to the integration of standard residential buildings with the surrounding urban context. Transformations should be closely related to the strategies of social and economic development of the territory. Such an approach should take into account the opinions and interests of all users of typical urban development: developers, experts, and, of course, residents, which will ultimately allow us to formulate specific tasks and gradually solve them. Integration of standard housing with the adjacent historical environment is a process based on communication at all stages, leading to the creation and maintenance of the integrity of the urban environment [14, 18, 22]. Despite the above-mentioned shortcomings, standard housing has undoubted positive features, such as high adaptability, flexibility, “coziness”, low costs for housing and communal services, and green open spaces. Thus, the development of a methodology for integrating standard residential buildings with the surrounding historical context is of great interest. This makes it possible to develop the existing standard building with the adjustment of its main indicators to modern criteria for the quality of the urban environment. The purpose of the study is to identify the main criteria for the analysis of standards housing areas and develop a methodology for integrating standard residential buildings in the urban environment.

2 Materials and Methods In this paper, the problem of integrating standard residential buildings in an urban environment is considered from the point of view of a system-structural approach, which provides for a scientific description of the subject of research by identifying the system, the elements that make up the system and the relationships between its parts. Standard residential blocks and historical buildings are considered as a single system “Historical Dominant Element—Standard Housing” (HDE-SH). In the process of research, a multitude of elements that make up this system are interconnected and form a structural unity. To identify the main elements of the HDE-SH system, the concept of locum was introduced. It is understood as a formal unit correlated with the habitat shell—a specific space [26]. In this case, locum is a formal primary element of the model of the HDE-SH system. Locum is considered as a residential formation, in the volume of which the daily functions of residents (accommodation, rest, work) are realized and having a spatially limited material embodiment in the form of discrete components: volume (building), territory (yard), “communication”, places of application of labour (Fig. 2). A historical dominant element is a building, structure or complex that dominates the architectural environment and has the special qualities of a power center. One of the characteristic features of historical dominants is the formation of a contact zone between them and the environment. There are three types of contact zones: linear, infill, opposed (Fig. 3). Each locum in the general structure of connections occupies a certain place and plays a relevant communication role. Three types of dependences of elements-locums

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Fig. 2. Locum and its components: object “yard”—public space; object “yard”—private space; object “building”; object “point of connection”—communication; object “open door places”—a point of application of labor.

Fig. 3. Types of contact zone of standard housing and historical dominant: opposed, linear, infill.

and historical buildings, found in the structures of the spatial organization of architectural objects of the HDE-SH system are distinguished: • coordination (two spaces-locums, being part of the structure, due to their position can influence the properties of each other); • determination (one space changes the structural properties of the other, remaining unchanged); • constellation (spaces exist independently of each other, and changing them properties are not reflected on each other). The proposed methodology for integrating standard housing areas in the urban environment is inevitably associated with the development of the HDE-SH system over time. Changes are taking place both in the space of standard buildings and in the architectural and spatial design of historical buildings.

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3 Results and Discussion Generally, integration is the process of establishing optimal links between relatively independent objects and their further transformation into a single, integral environment in which all its parts are coordinated and interdependent. Standard housing components involved in the integration process are the following environmental objects: volume (buildings), territory (yards), communication (street). To organize the integration processes, it is necessary to consider the characteristics of the components of the new system and determine the possible range of their transformations. Volume (body) consists of buildings in such residential areas are mainly represented by typical multi-section, less often dotted residential buildings. Spatial shaping of residential buildings is subordinate to the system of unified standard sizes of premises. They can be classified according to the number of storeys, the material of the bearing walls, the constructive solution, and the location in the building. The objects of residential formations (the body—the term of Arakelyan—[27]) were formed at the same time in accordance with the principles of the public idea in force at that time. The expected potential for integration lies in the enlarged modularity of buildings, the universal base of standard series, the uniform standard sizes of residential buildings, and the cleanliness of the formative elements of buildings. The proposed method for transforming such objects is reconstruction. Reconstruction of buildings is carried out by adding, embedding, attaching additional architectural objects, changing the extended contour, and configuration. Territory (yard) covers the spaces between the objects of residential buildings. Spatial characteristics of such spaces are dictated by a combination of external and internal factors. External factors include political, technological, economic, and urban planning principles. Internal factors are the socio-psychological, aesthetic and value needs of the inhabitants of the environment [27]. The formation of yard spaces of typical residential areas took place under the influence of external factors. This territory was also created simultaneously in accordance with a single design concept, which determined the main functional processes and forms of behavior of residents. Such an approach in designing (of the total degree of readiness of the environment) launched the process of “settling in” huge spaces. The scale of this process had an impact on the psychology of user behavior, forming new social patterns of residents (disunity, isolation, individualization of lifestyle). Today, yard spaces are used inefficiently, but they have their own development potential: dimensions sufficient for transformation, general accessibility, and the presence of social infrastructure. Communication (street) is an element of residential space, the main functions of which are the formation of the boundaries of private and public, the organization of the main traffic flows and communication between a residential area and a city. The components of the street are extremely diverse and maximally saturated with information: public buildings, traffic flows, city paraphernalia, advertising, and people. In the process of “settling in”, the system of local service in cities has developed not within the micro-districts, as proposed by the designers of the standard housing projects, but along the line or in the nodes of the frame of city highways and streets. The main perception of the structure of a typical residential area occurs precisely in this spatial layer.

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The main factors for the integration of standard housing in the urban environment are: • nodes: the concentration of the functional processes of the urban area: public centers, intersections, interchanges, flat objects; • flows: linear prototypes of nodes: transport and human flows, linear public spaces formed in time with various functions; • verticals: objects with dominant height parameters relative to the adjacent buildings: such as “tower” and “plateau”; • recreation: planar static natural landscape elements of the urban environment; • historical dominant element. All these factors reflect the patterns of functioning of the urban space, form a complex system and affect the SH characteristics in the process of its integration (Fig. 4).

Fig. 4. Relationship between integration factors and characteristics of standard housing.

The study identified characteristic types of links through which SH can be integrated with the urban context: 1. Connection through the multi-layered space: • • • •

a clothing layer (facade); a screen layer (attachment-buffer); a mediator layer (new building); a mobile systems layer (transitional, collapsible, temporary, seasonal).

2. Communication through the cultivation of the signs of the times. 3. Communication through the enrichment of urban design.

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To assess the existing building parameters, the concept of value criteria of integration components (typical building and urban planning context) was introduced. The principles of integration within the HDE-SH system involve the identification of such indicators for each object of integration separately, their correction and further summation during the transition from a differentiated space to an integral concept. The main value criteria of standard housing are the following: functional (compliance with modern requirements in providing a function), social (a variety of social behavior patterns, organization of public spaces, etc.), environmental (stability, flexibility, adaptability of the environment) and phenomenological (“spirit places”, self-identification). Each component of the HDE-SH system corresponds to an individual scale of values. The concept of integration of typical building with the urban environment involves its transformation in two aspects: spatial and temporal. Architectural and spatial development must be carried out by compensating for the missing and increasing the existing value indicators. TK integration is solved within the framework of the chosen technology by means of reconstruction, modernization, sanitation, renovation of all integration components (SH buildings, territories, if necessary, HDE). The temporal aspect of integration involves the organization of stages in the process of transforming the HDE-SH system. The first phase of each stage is the selection of the main layers of integration. It is carried out on the basis of an analysis of the existing value indicators of the integration components. The second phase is the implementation of the adopted integration techniques and architectural and spatial solutions. The next step is the process of their “settlement”. “Settlement” becomes a natural selection criterion for the adopted technologies for transforming the environment. At this moment, the states of “engraftment” and “rejection” of the performed transformations of the SH environment should be fixed. The last phase is the fixation of the moments of bifurcation (readiness for new changes) of the general system. Their presence indicates the need for new transformations in the SH environment. The next stage-transformation is superimposed on the “settled” spatial structure, which will be a new starting point for subsequent changes (Fig. 5).

Fig. 5. Diagram of the spatial and temporal integration model.

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4 Conclusion Thus, in the ideal case, as a result of the development of the integration of standard residential buildings with the adjacent historical sensitive context, it is proposed to create a “multilayer integrated system”. Such an approach can be implemented by identifying transformation-priorities, consistency in implementation, launching the process of “settlement” and the infinity of the integration process. As a result, self-regulating metasystems of urban space will be formed, capable of quickly responding to the changing demands of society and the growth of technological progress.

References 1. Gambassi R (2016) Identity of modern architecture in historical city environments. Arch Eng 1(2):27–42 2. Day S (2011) Synergisms: building modern in the context of historic architecture 5:247–270 3. Dutsev MV (2012) Integral’naya kontseptsiya arkhitekturnoy sredy na primere gorodov Gollandi i iGermanii (Integral concept of the architectural environment on the example of the cities of Holland and Germany). ACADEMIA 4:12–20 4. Mazzetto S (2018) Heritage restoration as a tool to promote architectural identity in the Gulf regions. Sustainability 47(1):3–11. https://doi.org/10.1515/pdtc-2017-0015 5. Stureiko SA (2017) Bespokoynyye kamni. 9 esse dlya novogopo nimaniya arkhitekturnogo naslediya (Restless stones. 9 essays for a new understanding of the architectural heritage). YurSa-Print, Grodno, p 288 6. Boussaa D (2018) Urban regeneration and the search for identity in historic cities. Sustainability 10(1):48. https://doi.org/10.3390/su10010048 7. Monastyrev P, Kuznetsova N, Mischenko E (2018) Problems of integration of cultural heritage objects with architectural and historical environment of the city. IOP Conf Ser: Mater Sci Eng 463(2):1–7 8. Dembich AA, Orlova NG, Ulyanov DA (2020) Razvitiyeistorikokul’turnoyidentichnostikrupnykhindustrial’nykhgorodov (naprimere g. Naberezhnykh Chelnov) (The development of the historical and cultural identity of large industrial cities (on the example of Naberezhnye Chelny)). Izv KGASU 4(54):144–152 9. Mlinkauskien˙e A et al (2015) Transformations of cultural heritage objects in protected areas. J Sustain Arch Civ Eng 11(2). https://doi.org/10.5755/j01.sace.11.2.12521 10. Soliman OA, Aggour MM (2018) A framework for new architectural additions to heritage buildings. J Eng Appl Sci 65(6):423–445 11. Ferretti V, Bottero M, Mondini G (2014) Decision making and cultural heritage: an application of the multi-attribute value theory for the reuse of historical buildings. J Cult Herit 15(6):644– 655 12. Ikonnikov AV (2006) Space and form in architecture and urban planning. KomKniga, Moscow, p 352 13. Gutnov AE, Glazychev VL (1990) Mir arkhitektury: Litsogoroda (The world of architecture: the face of the city). Molodayagvardiya, Moscow, p 352 14. Regame SK, Bruns DV, Omelyanenko GB (1988) Sochetaniye novoy i slozhivsheysya zastroyki prirekonstruktsii gorodov (The combination of new and existing buildings in the reconstruction of cities). Stroyizdat, Moscow, p 143 15. Scuderi G (2019) Retrofit of residential buildings in Europe. Designs 3(1):8. https://doi.org/ 10.3390/designs3010008

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16. Gale J (2012) Cities for people (trans: Toktonov A). Alpina Publisher, Moscow, p 276 17. Bondarenko IA (2016) O reabilitatsiiistoriko-kul’turnykhtsennosteynaterritoriyakhnovostroyek (On the rehabilitation of historical and cultural values in the territories of new buildings). Acad Arch Constr 1:87–93 18. Norberg-Schulz K (1995) Zhizn’ imeyetmesto (Life has a place). Izv Vyss Uchebnykh Zaved. Arch (News High Educ Inst. Arch) 1–2:24–31 19. Kharicheva EY (2012) “Renovatsiya” massovogozhil’ya v pribaltiyskomregione (Germaniya, Pol’sha, Estoniya, Latviya, Litva, Rossiya) (“Renovation” of mass housing in the Baltic region (Germany, Poland, Estonia, Latvia, Lithuania, Russia)). Dom Burganova. Prostran (House Burganov. Space Cult) 3:17–30 20. Lupíšek A, Volf M, Hejtmánek P, Sojková K, Brandejs R (2017) Accelerating energy retrofitting of European residential buildings by prefabricated modular elements. In: Proceedings of the 7th international symposium on energy, 13–17 August 21. Koryakovskaya N Stefan Forster an expert on five-story buildings. http://archi.ru/russia/6176/ shtefan-forster-znatok-pyatietazhek. Accessed 23 Mar 2021 22. Engel B, Frantzseva I, Malko A, Rogge N (2019) Mass housing in the socialist city. Heritage, values, and perspectives. Case studies, in Germany, Russia and Ukraine). Dom Publishers, p 239 23. Melnikova M (2020) Ne prosto panel’ki. Nemetskiy opyt raboty s rayonami massovoy zhiloy zastroyki (Not just panel blocks.German experience of working with areas of mass housing development). Maria Melnikova, p 130. https://masshousing.ru/. Accessed 29 Mar 2022 24. Yakimenko A (2020) WBS 70: panel that changed the face of the GDR. https://technolirik. livejournal.com/154588.html 25. Krasheninnikov AV (2018) Sotsial’naya integratsiya v modelyakh gorodskoy sredy (Social integration in urban environment models). Arch Mod Inf Technol 4(45):329–338 26. Shubenkov MV (2006) Arkhitekturnyye svoystva pustoty (Architectural properties of the void). Arkhitekturnayanaukaiobrazovaniye (Architectural Science and Education), Moscow 27. Arakelyan RG (2011) Disclosure of the values of volumetric and spatial characteristics of traditional residential formations on the territory of the Armenian Highlands. Arch Mod Inf Technol 3(16):18

Relationship Between the Formation of Post-Covid Residential Complexes and the Architecture of Soviet Commune Houses I. N. Maltseva(B) and E. S. Zhilyakova Ural Federal University Named After the First President of Russia B. N. Yeltsin, 19, Mira Street, Yekaterinburg 620002, Russia [email protected]

Abstract. The article explores the connection between the principles shaping the architecture of contemporary Russian residential complexes and Soviet commune houses of the 1920s and 1930s. Today, the social picture has changed, society lives under the conditions of “new normality”. As a result of social upheaval, people develop new ideas about the world and their way of life is transformed. Modern residential complexes begin to be formed according to the principle of ‘self-sufficiency’, as a network of interconnected spaces which ensure the satisfaction of all the needs of the residents within the space of the residential complex. Soviet commune houses were formed on a similar principle, providing for the satisfaction of domestic needs within a residential unit. Considering the modern period and the period of Soviet history in the 1920s and 1930s, the author relates the ongoing global changes. Two factors, social and epidemiological, which had the strongest influence on the development of housing typologies of the two periods, are analyzed. By comparing the contents of the two typologies of housing in the considered periods, a direct analogy of functional spaces can be traced. The patterns which were laid down in the planning of residential space in commune houses are updated under the conditions of modernity and repeated in the solutions of new residential complexes. Modern architecture is revealed by the authors through a reinterpretation of the experience of past generations. Keywords: Architecture · Pandemic · Residential complexes · Commune house

1 Introduction During the pandemic, people’s lives have changed dramatically relative to “prepandemic” times. We can observe phenomena such as the acceleration of digitalization and the adoption of new technologies, and an increased awareness of health, environmental and sustainability issues. Today, society is in what has been called the ‘new normal’, a new state caused by societal upheaval that has resulted in people having new perceptions of the world [1, 2]. Following lifestyle changes, residential space is being transformed. For city dwellers, it is becoming important to have all the functions necessary for living close to home. As © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_37

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a result, a clear direction for the development of the city’s residential architecture can be traced: multifunctionality, sociality and pedestrian accessibility [3]. Today, the basic principle of the formation of a residential complex is ‘self-sufficiency’—a network of connected spaces contain all the residents’ needs. The new practice of urban planning implies the possibility of living, working and spending leisure time within a single accessible area. This is the principle behind the ‘post-covid’ residential project by the Spanish Guallart Architects bureau [4]. Analyzing contemporary residential complexes, an analogy to the Soviet residential architecture of the 1920s–1930s can be traced, when commune houses were developed. The commune house is a vivid architectural and social phenomenon which embodied the proletarian idea of “communalization of everyday life”, one of the manifestations of the Soviet avant-garde era. Architectural solutions of that time reflected the idea of Soviet life—along with residential units, the projects included a system of communal and domestic facilities: cultural, medical and pre-school institutions. In the new reality, the idea of creating a residential complex as a network of connected spaces that will serve the residents’ needs becomes a potential solution problem of comfortable living in isolation.

2 Research Methodology Changes in architecture are influenced by society changes. Canadian urbanist Gil Peñasola says that the crisis caused by the coronavirus pandemic has changed people’s perceptions. In the Russian-language media space, the impact of the pandemic on society and social change is told by the CoronaFOM sociological research project. The research is based on the method of sociological surveys as the primary source for collecting information about citizens’ lifestyles during the pandemic [5]. Under the influence of the pandemic, mixed-used development, where two 2 or more functions are integrated into a residential unit, is gaining the most intensive development. Most architects and urbanists agree that the number of public spaces and their functionality need to be increased several times over in order to cover the entire spectrum of services. In particular, this is written about by the Strelka Institute for Media, Architecture and Design [6]. All this leads to the need to combine infrastructure in the space of a residential complex, which will ensure that the needs of all the residents living in a residential unit are met [7]. Similarly, Soviet commune houses and housing cooperatives were formed as part of a new ideology and large-scale social transformations, such as the relieving women from the household in order to involve them in production and social life and the implementation of the cultural revolution [8]. All this was changing the way of life, social perception and was expressed in the architecture in the search for forms of interconnection of the residential house with the institutions of community services. For example, the “NKVD Housing Complex” or “Chekists’ Town” was designed as a system of communal and domestic facilities, cultural, medical and pre-school education institutions. By correlating the features of commune houses and modern mixed-use developments, it is possible to identify recurring patterns that form the typologies presented.

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3 The Impact of the Social Factor Changes in architecture always have certain prerequisites in the form of social changes associated with the transformation of the way of life. Looking at the modern period and the period of Soviet history in the 1920s and 1930s, we can see that global transformations are taking place working through different mechanisms. At the beginning of the twentieth century, changes in the living environment were dictated by the state. Architecture was a tool and new architectural solutions had to contribute to the creation of a new society and through the arrangement of a new way of life. Charles Fourier’s concept of the phalanster was taken as the basis. Phalanster was a new form of housing where people would live a collective life, freeing themselves from the burdens of domestic work, family ties and all the petty and private things [9]. Charles Fourier adhered to the idea of universal equality and created a “phalanster” following the conviction that “people are unhappy and wicked because they cannot satisfy all needs”. If conditions were created to satisfy needs, everything would be in harmony, destructive impulses would disappear and everyone would work for the common good. These ideas were in line with the ideology of the new state. Nadezhda Krupskaya, for example, said of the communes: “It is an organization of new social relations on the basis of communal life, new relationships between members of the commune, new… comradely relations between a man and a woman”. The introduction of elements of communal and cultural and leisure facilities into housing units solved important social and political problems. Firstly, as part of the ideology of universal equality, women should be freed from the household in order to maximize their involvement in production tasks and participation in public life, see Fig. 1. The same applied to men—life was to be simplified in order to free up energy for work. Kitchens were replaced by canteens, laundries, nurseries, crèches, baths, etc. were organized at the housing complex. Secondly, the worker had to be healthy and strong, which affected the organization of green spaces, sports halls and medical facilities. Thirdly, there was the need to improve the general cultural literacy of the population, which was achieved through the introduction of clubs, libraries, red corners, music rooms, etc. [8]. Following industrialization ideology, residential spaces were created and aimed at solving the problem of optimizing the satisfaction of domestic needs within the living unit in order to maximize the release of energy to solve production problems. Change was a top-down process 100 years ago, but today the revision of the filling of dwellings and complexes comes from the natural needs of society, shaped by the pandemic, from the bottom up. Above all, the coronavirus pandemic has demonstrated the value of socialization. Even after the end of quarantine, Russians continue avoiding social contacts and attendance at public and cultural institutions. According to the CoronaFOM research project, attendance of cultural institutions has fallen to 70%, regardless of the vaccination factor [5]. This has created a need for elements that provide communication and socialization, such as neighborhood and leisure centers. In isolation, the home becomes a place to work, but also a resource for productivity. Urban dwellers are looking for workspaces that satisfy the work environment, facilitate networking and save time. Apartment complexes including co-working spaces is becoming such a solution. In the case of families with children, kindergartens and children’s

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Fig. 1. Poster “Down with kitchen slavery—give us a new way of life!”. Shegal G., 1931.

leisure facilities are also included as part of the complex, so that a child is not a constraint for productive work or a trip to kindergarten is not time-consuming. At a time of increasing fear of illness, health care, which includes a healthy lifestyle, sport and regular visits to the doctor, becomes fundamental, which also imposes the need for appropriate structures. In general, there is a demand for the inclusion of all necessary social spaces within a residential development, such as retail, a co-working space, a daycare center and a health center, in order to live well in an isolated environment that limits mobility. The importance of mixing a large number of functions in a residential development is reaching its peak. Thus, different mechanisms at different points in time have led to a roughly similar result, the creation of a housing complex that provides: • • • •

Socialization Organizing as comfortable a working environment as possible Health care Diversity of public spaces within the complex.

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4 Impact of the Epidemiological Situation Separately, the influence of the epidemiological situation is worth considering. The extent to which architecture is linked to diseases can be traced back to the transformations that took place at the beginning of the twentieth century. In that period tuberculosis accounted for up to 25% of all causes of death, there were periodic outbreaks of cholera, and a flu epidemic paralyzed much of the world in the late 1910s. Fleming discovered the first antibiotic—penicillin—in 1928; before that, isolation, fresh air, sunshine, hearty meals and hygiene were the chief weapons against most diseases. Outbreaks of tuberculosis, cholera, Spanish flu at the beginning of the twentieth century caused architects and urban planners to rethink the treatment of sanitation, insolation, water and sewage systems, and the ventilation of living space. Many solutions were borrowed by avant-garde architects from sanatoriums and health resorts and integrated into residential complexes. Residential buildings are beginning to be positioned more freely and dispersed in space in order to achieve optimum insolation in the flats. A variety of balconies, loggias, terraces and solariums are appearing. Balconies are appearing in residential buildings even in the northern parts of the country, for the purpose of taking air and sunbathing [10]. Often in commune houses, constructivist architects arranged exploitable roofs with solariums and swimming pools, the houses became similar to health resorts, see Fig. 2. Sports fields, often also located on operable roofs, are organized to maintain health.

Fig. 2. A swimming pool on the roof of a commune house. Photo Alexander Rodchenko, 1932.

A great deal of attention was paid to the communal area, which was seen as having an impact on the health of the town’s inhabitants. The inhabitants of the commune, often united along professional lines, had to be strong and healthy in order to work for the benefit of the state. Planners created courtyards that were as protected as possible from wind and noise impacts, and landscaping standards were introduced. Medical facilities are provided at the commune houses. In general, a massive hygiene and health literacy campaign is being carried out and special sanitary committees are being set up.

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Many solutions are still relevant today. Whereas in the past most attention was paid to insolation of buildings, today residential insolation standards are compulsory and have existed in the Sanitary Regulations for a long time. More attention is paid to the ventilation system, which is due to the peculiarities of the spread of coronavirus infection. Equipping a flat with a supply and exhaust ventilation system and breezers is an obvious advantage, as this will reduce the concentration of harmful substances, viruses and bacteria in the air. At the same time, the level of insolation does not lose its relevance for fighting the spread of infection, as the virus is less active when exposed to sunlight. There is a need to include medical centers for first aid and diagnostics in the structure of the complex, or to take into account the possible location of a mobile hospital in the space of a neighbourhood area. For disease prevention and basic physical activity, the structure of the complex should include sports fields integrated into the courtyard spaces, spaces for fitness centers. Operable roofs are experiencing a new birth as a fifth façade, which, according to Le Corbusier’s precepts, should be utilized. It becomes a new green space for walks, sporting activities.

5 Patterns in a Multi-functional Dwelling The commune house can be called the first multifunctional complex in which previously incompatible functions were combined for the first time. The patterns laid down in the planning of the residential space of commune houses and residential complexes have survived transformations and have been updated to suit the conditions of modern times. Residents of these complexes received everything they needed within a single block. Serviced housing estates from the 1920s and 1930s generally included: • The canteen is a must, designed to free women from the obligation to cook • Pre-schools—crèches and kindergartens—also enable parents to free their time from childcare and direct them to work and social activities • Shops that provide essential food and household goods • Medical facilities • Houses of culture, reading rooms, clubs—were incorporated into the commune houses to provide cultural leisure activities to improve general literacy and cultural awareness of the population • Public baths • Green courtyard parks with sports and children’s playgrounds An example of such a commune house in Yekaterinburg is the «NKVD Housing Cooperative», or Chekist Town, which created a coherent living environment for a new social life, see Fig. 3. Chekist Town represents the unfolding implementation of the Soviet model of housing policy. The Chekist Town consisted of: a hotel-type house for small families and young people with a “Dinamo” sports shop on the ground floor; the building of the Dzerzhinsky Club with a canteen; “Voentorg” and “Grocery” shops; apartment houses; a clinic with a pharmacy; a kindergarten and a nursery. The building

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also housed a hairdresser’s and shoe repair shop. There was also a savings bank. There was a sports ground, which was used as an ice rink in winter, a children’s playground and a courtyard with a fountain for quiet recreation [11]. To get the services you needed, you just had to walk into the building next door. The buildings were connected to each other by a system of overground and underground passageways, so it was possible to access the infrastructure without having to leave the house.

Fig. 3. The NKVD Housing Cooperative. The “Dinamo” hotel-type house and the Dzerzhinsky House of Culture, connected by a ground passage. Arch. Ivan Antonov, Veniamin Sokolov, Arseny Tumbasov and Alexander Stelmashchuk, 1932.

Another example of a commune house in Yekaterinburg is the House of the Ural Regional Council of National Economy, designed under the direction of Moses Ginzburg, see Fig. 4. The house is one of the “transitional houses”, but it was also designed according to the principles of communal living with included service structures for the inhabitants of the house [12]. The complex consists of four residential blocks. A distinctive feature of the whole building is the removal of all public functions to the top floor and roof, such as the dining hall and the kindergarten. The design emphasised the health and hygiene of the dwellings, and a solarium terrace was built on the roof of one of the blocks. The buildings were connected across the roofs by bridges. The ability to access social spaces without leaving the boundaries of a residential complex is now an important trend in residential construction, which has been reinforced many times over by the coronavirus pandemic. When a person’s movement area is restricted to the boundaries of a residential complex, the possibility of having access to the desired functions comes to the fore. The first design proposals in residential construction predate the pandemic, but today this option is becoming not just a competitive advantage, but also a necessity for developers and developers to maintain the quality of their projects

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Fig. 4. House of the Ural Regional Council of National Economy in Yekaterinburg. Architect M. Y. Ginzburg, 1930s.

and maintain their profitability. Accordingly, we are beginning to see replications of the solution of linking the residential buildings of the complex with the retail and public areas through pedestrian galleries or enclosed stylobate areas [13]. In Yekaterinburg, solutions for combining the residential function and public structures can be seen in the example of the modern residential «Capitals’ Park» and «Forum City» complexes. These residential complexes are designed according to the “city within a city” or “mixed-use” concept, incorporating the social spaces necessary for high-quality and comfortable life of a modern person in the “new normal” reality. This concentration also solves the problem of pendular migration and reduces the spread of infection, as well as localizing its foci. The «Capitals’ Park» complex has a pedestrian gallery on the first two floors that connects the residential units to each other and gives residents access to all infrastructure, see Fig. 5. The project envisages a full range of social structures as part of its design: • Retail, including a hypermarket with food and household goods • Catering establishments—restaurants and cafés • Educational structures—municipal and commercial kindergarten, an innovative school • Structures for maintaining and taking care of health—family clinic, fitness and spa center • Office extension The residential blocks are also connected by a private, multifunctional courtyard park, the landscaping of which was created by the Polish architectural firm S&P Architecture Krajobrazu. The courtyard combines children’s playgrounds, sports areas—cycle and jogging paths, workout area and spaces for quiet rest. This multifunctionality allows residents to get everything they need without leaving the complex. The Forum City residential complex is also an example of an integrated approach to the project, where the residential complex does not just include retail on the 1st floor, but the infrastructure, the functional purpose of the premises, the tenants are thought through to meet the needs of future residents at the conception stage, see Fig. 6. The

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Fig. 5. The “Capitals Park” residential complex. Gallery and courtyard. Developer Atlas Development. 2021.

infrastructure of the residential complex includes medical care, retail, neighbourhood center, kindergarten and primary school, sports center, etc. Public spaces are not only located on the 1st floor, the roofs of the residential blocks are also used. The residential blocks are connected by an inner courtyard-park. There are solutions in the residential complex for sanitary-hygienic safety. The layout and form of the residential units increase the insolation duration of the flats, and air and water filtration systems are used in the flats of the residential complex. In this way, a space is created that is comfortable for residents with different interests, values and lifestyles. The commune house can be called the first multifunctional complex. The patterns laid down in the planning of the residential space of communal houses and housing estates have been transformed and updated for the conditions of the present. Each functional space is reborn in a new quality. Comparing the contents we can see direct analogies, see Table 1.

Fig. 6. Forum City residential complex.

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Table 1. Analogies between the functional content of communal houses and modern apartment blocks. Function

Communal houses

Modern multifunctional housing complexes

Nutrition

Canteens, canteen factories. The possibility of ordering food and groceries to your home

Restaurants, cafés, bistros, food shops. Food and meal delivery services at home

Children’s educational institutions

Kindergartens, crèches, schools

Municipal and commercial kindergartens, schools, children’s cultural institutions, children’s rooms

Products

Shops with food and household goods

Retail, hypermarkets

Leisure and culture

Houses of culture, clubs, reading Neighbourhood and community rooms, music areas centers—flexible spaces for work, socializing, sports and workshops, clubs, creative studios, restaurants and cafés

Work

Location of communal houses close to the immediate place of work (plant, factory), organization of creative workshops in communal houses for artists and writers

Co-working spaces, inclusion of office space as part of a residential complex

Health

Polyclinics, pharmacies, bath houses, sports grounds, solariums, landscaped yards

Municipal and commercial medical clinics, dentists, fitness centers, spa centers, jogging and cycling paths, courtyard parks

The coronavirus pandemic has increased the importance of social contact, which is reflected in the resurgence of a culture of neighbourliness [14, 15]. In a sense, there has been a rethinking of the experience of past generations, when people’s everyday lives were based on community. Houses of culture and hobby clubs have been transformed into community centers for communication with neighbours, workshops and cultural events. These elements carried the important function of building working relationships. At the beginning of the twentieth century, communal houses brought together residents who were connected in their professional lives; through communal leisure activities, relationships were formed, for example, between workers in a factory. A more comfortable and friendly atmosphere was created within the work community. Today, socializing in neighbourhood and co-working centers is a way of networking which is very important for professional development. Neighbourship centers can act as a co-working space and also contribute to productivity at work.

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6 Conclusion New life requires new forms of organization of life, and residential architecture is changing accordingly. Almost 100 years have passed and history has taken a turn, bringing back the format of commune houses in its new interpretation. The commune houses were an experiment that defined their time. While not widespread, they were engraved in the history of Soviet architecture. The main problem with the commune houses was that social functions were imposed on the inhabitants and drastically changed the way everyone was used to living. Today, the inclusion of a variety of social services is a consumer demand and has been shaped naturally. These solutions allow us to adjust to the modern specifics and provide a comfortable life for city dwellers in the context of the new reality.

References 1. Bushukhin I (2020) Nashi goroda rasschitany na sotsial’nuyu distantsiyu v 50 santimetrov (Our cities are designed for a social distance of 50 centimeters). Nedvizhimost’ (Real Estate) J. https://realty.rbc.ru/news/5f5766ac9a7947d421b41d52. Accessed 11 Mar 2022 2. Maltseva IN et al (2022) Impact of the pandemic on the sustainable development of metropolitan residential complexes. In: Radionov A, Ulrikh D, Gasiyarov V, Timofeeva S, Alekhin V (eds) ICCATS 2021: topics in civil engineering. 5th international conference on construction, architecture and technosphere safety, September 2021. 3. 3. 3. Lecture notes in civil engineering (Lecture notes in civil and structural engineering), vol 168. Springer, pp 365–374 3. Krits AM, Gazizov Kh (2021) Proyektirovaniye mul’tifunktsional’nogo zhilogo zdaniya v ramkakh komfortnoy sredy obitaniya v usloviyakh pandemii (Designing a multifunctional residential building within a comfortable living environment in a pandemic). J Innov Invest 2:163–166 4. Frolova N (2020) Gorod na samoobespechenii (Self-sustaining city). Archi.ru. https://archi. ru/world/87046/gorod-na-samoobespechenii. Accessed 04 Nov 2021 5. Project coronaFOM Ruk (2021) Oslon CAA (ed) Sociology of a pandemic. Institute of Public Opinion Foundation, Moscow, pp 235–267 6. Strelka KB (2020) Kakiye nedostatki zhil’ya vyyavila samoizolyatsiya i kak ikh ispravit (What shortcomings of housing revealed self-isolation and how to fix them). STRELKA MAG—Published by the Institute “Strelka”. https://strelkamag.com/ru/article/nedostatki-zhi lya-issledovanie-kb-strelka. Accessed 14 Nov 2021 7. Zhilyakova ES, Maltceva IN (2021) Formation of a sustainable architecture of a residential complex in Russia in the postpandemic period. Acad Her UralNIIproject RAASN 3(50):58–63 8. Truhacheva GA, Skobkitckaya YuA (2018) Arkhitektura mnogoetazhnykh zhilykh kompleksov. Organizatsiya obsluzhivaniya (Architecture of multi-storey residential complexes. Organization of service). Southern Federal University, Rostov-on-Don – Taganrog 9. Klenovyj I (2019) Doma-kommuny. Konstruktivizm (Houses-communes. Constructivism). Live J. https://klenovy.livejournal.com/17311.html. Accessed 08 Dec 2021 10. Budarin K (2020) Kak virusy i bakterii vliyayut na dizayn nashikh domov (How viruses and bacteria affect the design of our homes). Strelka Mag J. https://strelkamag.com/ru/article/ark hitektura-virusa-kak-medicina-vliyaet-na-dizain-nashikh-domov. Accessed 04 Nov 2021 11. Piskunova LP, Starostova LE (2015) “Gorodok chekistov” g. Yekaterinburga: voploshcheniye i transformatsiya utopii v povsednevnykh praktikakh sovet·skoy elity (The “Chekist Town” in Yekaterinburg: embodiment and transformation of utopia in everyday practices of the soviet elite). Izvestia of the Ural Federal University, ser. 3: Social Sciences, Yekaterinburg, pp 40–52

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12. Tokmeninova L (2017) Zhiloy kompleks “Dom Uraloblsoveta” (Residential complex “House of the Ural Regional Council of National Economy”). Tatlin J. https://tatlin.ru/articles/novye_ vremena-novaya_arxitektura. Accessed 04 Nov 2021 13. Fadeev B (2021) Real estate of the post-conventional era. Snob J. https://snob.ru/profile/ 32336/blog/1000945. Accessed 14 Nov 2021 14. Stsenariy budushchego: postkovidnyye trendy ot gollandskikh arkhitektorov (Scenario of the future: postcovid trends from Dutch architects). Repa J. https://repa-pr.ru/scenarij-budush chego-post-kovidnyetrendy-ot-gollandskih-arhitektorov. Accessed 04 Nov 2021 15. Cohen A (2020) Gorod i virus (City and virus). Constr Ind J 5:44–45. http://ancb.ru/files/pdf/ pc/Otraslevoy_zhurnal_Stroitelstvo_-_2020_god_05_2020_pc.pdf. Accessed 18 Apr 2021

Improving the Efficiency of Urban Wastewater Treatment Plants Based on Information Modeling A. Antonets1 , N. Buzalo2 , M. Trubchaninov3(B) , and S. Scherbakov3 1 Rostov State Medical University, 29, Nakhichevanskiy Pereulok, Rostov-on-Don 344022,

Russia 2 Platov South-Russian State Polytechnic University (NPI), 132, Prosveshcheniya, Rostov

Region, Novocherkassk 346428, Russia 3 First Project Company, 72 Office 307-308, Sokolova, Rostov-on-Don 344000, Russia

[email protected]

Abstract. The process of forming an information model of an object taking into account the green building standard is considered. The basis of such a model is a system of biological phyto-purification of air, composed of typical photobioreactors. The presence of standard modules makes it possible to integrate air purification complexes with sewage treatment plants, agricultural complexes, large closed condominiums, industrial enterprises. Purification and absorption of carbon dioxide occurs due to the growth of unicellular chlorella algae, which are a separate product and can serve as raw materials for the production of medicines and agricultural products. Based on the created model, the issues of efficient use of water, reduction of the carbon footprint, favorable transformation of the landscape due to restoration of the natural environment and purification of reservoirs are solved. The modular structure of biological phyto-purification of air allows you to create three options for using the system—basic, local and hybrid. Keywords: Green building standard · Energy efficiency · Numerical information model · Life cycle · Capital construction object · Phyto-purification of air · Chlorella

1 Introduction The state of the environment is one of the most acute economic, scientific, technical and social problems that directly or indirectly affect the interests of every person. In recent decades, the state of the environment has begun to really reduce the quality of life of the population, limit the possibilities for economic and social development of large industrial regions and cities. Humanity’s hope for a better life lies in the future of large cities. Therefore, many environmental, economic, social problems will arise and be solved in large cities [1, 2]. The excessive concentration of the population in large cities makes it necessary to move from the category of “environment” to the category of © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_38

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“environment of human survival”, that is, human well-being becomes the main criterion for making decisions in the field of environmental protection and its interests are put at the forefront in the development of basic concepts for national security [3, 4]. Since 1993, in many countries, the LEED (Leadership in Energy and Environmental Design) has been introduced into project practice. It is a green building standard for measuring energy efficiency, environmental friendliness and sustainability of projects and constructed buildings for the implementation of the transition construction industry to the design, construction and operation of “green” buildings. A 2011 US Department of Energy study found that LEED-certified buildings use 25% less energy and have 19% lower operating costs than the average US building. At the same time, buildings certified to the “Gold” level stand out significantly in terms of energy efficiency [5, 6]. Also, studies have shown that productivity in green buildings is 16% higher, also due to a reduction in the incidence of sickness among employees. The project’s LEED boundary must include all contiguous parcels of land that are associated with the project and support its normal operation. The project’s LEED boundary also includes land that has been affected by the construction processes and installation of items that are used by people in the project building, such as pavement (parking and sidewalks), septic tank or stormwater treatment equipment, and landscaping. When establishing a LEED, boundaries must not unreasonably exclude parts of a building, space, or site in order to give the project an advantage in meeting the criteria. A LEED project must accurately reflect the scope of the project’s certification in all narrative and submission materials, and distinguish it from non-certifiable sites. Twelve mandatory requirements must be met during the design and construction phases to achieve LEED certification. At the design stage: 1. Reducing water consumption in the surrounding area—it is required to reduce water consumption in the area by eliminating irrigation or minimizing the amount of water for irrigation. 2. Reducing water use within the building—choose plumbing that uses 20% less water than a baseline calculation that must be done in accordance with EPA 1992 requirements. Procedures within the scope of the project that meet the requirements given in the tables in the Reference Guide for Building Design and Construction. 3. Accounting for water consumption inside the building—install permanent meters that measure the total use of drinking water for the building and the sources of this water. 4. Minimization of energy consumption—demonstrate a reduction in energy consumption of 5% for new construction (3% for major repairs) from the base value. The base value must be calculated in accordance with ANSI/ASHRAE/IESNA Standard 90.1-2010 using the computer information model of the system. 5. Building energy metering—install new or use existing energy meters that can be combined to provide data on the overall level of energy consumption in the building. 6. Use of refrigerants—do not use chlorofluorocarbon (CFC) refrigerants in new heating, plumbing, plumbing or cooling systems.

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7. Collection and storage of materials for recycling—provide sufficient space dedicated to the collection and storage of paper, cardboard, glass, plastics and metals for further processing, in addition to mercury lamps, batteries, electronics. 8. Minimum Indoor Air Quality—Design ventilation systems using the Air Change Determination Procedures to meet the minimum ventilation requirements of ASHRAE Standard 62.1-2010. Monitor the flow of outside air consumed. 9. Tobacco Smoke Control—No smoking inside the building and within 25 ft (8 m) of all building entrances, outside air intakes, opening windows. Prohibit smoking outside the site in areas designated for commercial purposes. Post a no-smoking sign within 10 ft of all building entrances. At the construction stage: 1. Pollution Prevention from Construction Works—Establish and implement an erosion and sedimentation control plan that lists all activities implemented. To fulfill the mandatory requirement, it is also necessary to prepare and provide a description, photographs, inspection reports of the contractor. 2. Basic building acceptance—complete the commissioning process steps for mechanical, electrical, plumbing, renewable energy systems, and equipment in accordance with ASHRAE Guideline 0-2005 and ASHRAE 1.1-2007 for heating, plumbing, sewerage and refrigeration supply, if they relate to energy and water consumption, internal environmental quality, building reliability. 3. Construction and demolition waste planning and management—develop and implement a construction and demolition waste management plan. Submit a final report detailing the main waste streams, the percentage of waste collected and recycled. For the standards assessment of conformity, the criteria for assessing the evaluating of the project have been introduced: • • • •

Reducing the level of consumption of energy and material resources by the building; Reducing the adverse impact on natural ecosystems; Ensuring a guaranteed level of comfort in the human environment; Creation of new energy-efficient and energy-saving products, new jobs in the manufacturing and operating sectors; • Formation of public demand for new knowledge and technologies in the field of renewable energy. The requirements of the LEED standard include, among other things, the requirements for the efficient use of water and the provision of favorable climatic conditions inside the building: • • • •

Innovative wastewater treatment technologies; Reduction of water consumption volumes; Monitoring the supply of fresh air into the room; Efficient ventilation;

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• Establishment of a system for monitoring the maintenance of indoor air quality (during construction and after commissioning); • Use of materials that affect the reduction of CO2 emissions (materials for sealing, floor coverings, insulation, paints and fillers, composite wood, etc.); • Control over the content of sources of chemical and pollutants in the air.

2 Methods and Materials With extensive experience in wastewater treatment projects, including technically complex ones, the project team aims to create a model and implement technologies that ensure the formation of a sustainable environment, guided by the principles and requirements of LEED standards for efficient use of water, reduced carbon footprint, favorable transformation landscape through the restoration of the natural environment. Government Decree of 5 March 2021 establishes the mandatory use of information modeling (BIM) technologies in the design, construction and operation of buildings and structures, funded from the Russian budget. According to [7], a digital information model should contain interconnected graphic and attribute data representing the results of the design of an object, that is, its architectural, technical and technological design solutions. Taking into account the requirement of the Decree of the Government of the Russian Federation on the transition to BIM technologies, having the necessary resources and qualified personnel, realizing the need and advantages of such a transition, a BIM model of a modular wastewater treatment installation was created (Fig. 1) for its further design development and implementation in practice [8, 9]. The digital representation of the physical and functional characteristics of module wastewater treatment—three-dimensional building model associated with a database, in which each element of the model assigned all the necessary attributes [10]. The peculiarity of this approach lies in the fact that the module wastewater treatment is actually designed as a single whole: changing any of its parameters entails automatic changes in the parameters and objects associated with it, up to drawings, visualizations, specifications and schedules [11]. Thus, the BIM model is resource for obtaining information about an object, forming a reliable basis for decision-making throughout its life cycle—from the concept of a project to the demolition of a building [12].

3 Results The basis of such a model is a system of biological phyto-purification of air, composed of typical photo bioreactors with a volume of 150–200 dm3 with a chlorella concentration of more than 10 g/L. With low energy consumption (about 10 kW per installation) and scalability, a standard air filter can recover more than 3.0 kg of CO2 per day. During cleaning process generates about 1.5–2 kg of chlorella biomass in each installation per day. The installation simulation was performed in the ArchiCAD 25 software environment, taking into account additional software modules written in Python (Fig. 2). The presence of standard modules allows integrating air purification complexes with sewage treatment plants, agricultural complexes, large closed condominiums, and industrial enterprises (Fig. 3). Cleaning and absorption of carbon dioxide occurs due to the growth of unicellular algae, which are a separate product [12].

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Fig. 1. General view of the experimental modular installation of phyto-bio-purification in the industrial version (BIM model).

Fig. 2. General view of the experimental modular plant for phyto-biopurification (BIM model).

The resulting raw materials can serve as a link between the ecological cycle city-cleaning-environment-city [13, 14]. In particular, the following options for using chlorella formed during air purification due to biomass growth are possible: • chlorella is rich in useful substances, which are the basis of many medicines, as well as agricultural amino acid fertilizers, which is widely introduced for the production of various medical and agricultural products abroad (Table 1);

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Fig. 3. Cultivating chlorella to purify and absorb carbon dioxide.

• due to the peculiarities of growth in open reservoirs, chlorella naturally displaces blue-green algae, healing the reservoir; • it is possible to use chlorella directly as a fertilizer for plant nutrition. Thus, the use of this unit allows you to get the following advantages: • • • •

reduction of energy consumption by reducing air exchange; CO2 consumption and utilization; production of useful raw materials; landscape transformation (direct application of chlorella as fertilizer, restoration of reservoirs).

Given the modular structure of biological phyto-purification of air, there are several options for using the system. Let’s show the main ones. The advantage of the basic option (Fig. 4) is the scale effect—large consumers already have a built-in delivery logistics. The integration of installations at the treatment facilities of large facilities makes it possible to use energy efficiently and obtain large volumes of chlorella, localization in the industrial zone helps to deploy auxiliary production for the processing of raw

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A. Antonets et al. Table 1. The list of products for which microalgae are the raw material.

Number

Product

Price, $ per gram

Name of corporation

Producing country

1

Immunoglobulin

165,000

Biochemie

Austria

2

Streptavidin

145,000

Martek

USA

3

13 C-docosahexaenoic acid

38,000

Spectra stable

USA

4

Allophycocyanin

11,500

Forelight

USA

5

R-Phycoerythrin

8,625

Cyanotech

USA

6

13 C-arginine

5,900

Isotopes

USA

7

15N4-arginine

260

8

Polyunsaturated fatty acids

Isotopes

USA

60

Biochemie

Austria

9

Astaxanthin

7

Cyanotech

USA

10

ω 3,6-docosahexaenoic acid

6

Biochemie

Austria

11

β-carotene

2

Cognis

Australia

Fig. 4. Basic option of biological phyto-purification of air.

materials, and achieve a lower unit cost. Comprehensive air purification allows reducing the sanitary protection zone of treatment facilities, the presence of a water body makes it possible to build a project to improve the aquatic environment through the settlement of unicellular algae. The disadvantage of this option is the higher cost of implementation as the focus shifts away from local CO2 producers (factories and condominiums).

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The advantages of the local option (Fig. 5) are the high speed of implementation, due to lower capital costs, the absence of the necessity for extended communications, the possibility of using the obtained chlorella on the spot for watering the adjacent territory or restoration of reservoirs.

Fig. 5. Local option of biological phyto-purification of air.

The disadvantages of this option are a higher unit price, a focus on air, and the need to take into account the use of produced chlorella on site in the project (vertical gardens, aquaculture cultivation, etc.). It is also necessary to take into account the imperfection of the regulatory framework and gaps in the requirements for certification of products obtained during cleaning for their use in the production cycle. The hybrid variant is a consequence of the wide combination of the first two variants. It requires the preliminary implementation of one of the above options, the improvement of the regulatory framework, the resolution of issues with the processing of chlorella formed in the process of air cleaning.

4 Conclusion The created BIM model of the complex of treatment facilities with the integration of an air purification unit with unicellular plants is a common knowledge resource for obtaining information about the facility, forming the basis for implementing decisions throughout its life cycle—from project research to demolition, waste collection and use (Fig. 6). The most important advantage of this model is the complete interdependence of all types of information, each of which is updated automatically when any changes are made once. The information model can be a computer model of a real-life building, embedded technologies throughout its life cycle and reflects all the changes, additions to the current and future conditions in close connection with the chlorella production system that provides increased environmental sustainability through energy efficiency and reduction of the carbon footprint of the building. The use of digital models allows the creation of green buildings that consume significantly less water than conventional structures, using natural landscapes that eliminate the need for irrigation, installing water-saving equipment and reusing wastewater. Based on such models, it is possible to move forward on many points: saving energy, rational use of resources, including water, reducing CO2 emissions, improving the quality of the environment and the indoor environment.

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Fig. 6. Integrated treatment facilities with the integration of an air purification unit with unicellular plants (BIM model)

The problem of environmental regulation of the quality of the environment in megacities using modern technologies and procedures for choosing management decisions based on digital models in order to ensure an environmentally sustainable and balanced development of the city is of particular socio-economic importance and requires its prompt.

References 1. HQE system of environmental certification of buildings. Notes of the designer GREEN BIM, CFD. http://bim-proektstroy.ru/?p=1721 2. Rogacheva Ya, Kovalev S, Smorodina E, Vasilyeva O (2017) “Green building” as a driver of sustainable innovative development of the industry. In: MATEC web of conferences. “International science conference SPbWOSCE-2016 “SMART City””, p 08038 3. Davis RD (1989) Agricultural utilization of sewage sludge: a review. J Inst Water Environ Manag 3(4):351–355 4. Guidi G, Hall J (1984) Effects of sewage sludge on the physical and chemical properties of soils. In: Processing and use of sewage sludge, pp 295–305 5. Cinti Luciani, Garagnani S, Mingucci R (2012) BIM tools and design intent. Limitations and opportunities. In: Peng J (ed) Practical BIM 2012 - management, implementation, coordination and evaluation, Los Angeles 6. Green Building Construction - ecological construction. https://www.icsgroup.ru/engineer/tec hnology/green/ 7. SP 333.1325800 (2020) Building information modeling. Modeling guidelines for various project life cycle stages 8. Oti AH, Tizani W (2015) BIM extension for the sustainability appraisal of conceptual steel design. Adv Eng Inform 29:28–46

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9. Forbes LH, Ahmed SM (2010) Modern construction: lean project delivery and integrated practices. CRC Press 10. Bukunov AS (2020) Information processing for decision-making in information modeling. In: BIM-modeling in problems of construction and architecture. SPbGASU, St. Petersburg, pp 386–392. https://doi.org/10.23968/BIMAC.2020.050 11. Zgoda YuN, Semenov AA (2020) Prospects for the development of software and hardware for BIM modeling. In: New information technologies in architecture and construction: materials of a scientific and practical conference with international participation. Urgakhu, Yekaterinburg, p 43. https://www.elibrary.ru/item.asp?id=44224199, http://www.usaaa.ru/news/2020/ nitac-sbornik-2020.pdf 12. Petrov DS, Salnikov AYu (2020) BIM technologies in the construction industry and the relevance of their implementation. In: Actual problems of construction, housing and communal services and technosphere safety: materials of the VII All-Russian (with international participation) scientific and technical conference of young researchers. VolGTU, Volgograd, pp 68–70. https://www.elibrary.ru/item.asp?id=44381468 13. Kosheleva E, Elliot J (2006) Ecological construction in the Russian context: a study of the LEED-type rating system of ecological construction in the Russian Federation. J Green Build 1(3):5–10 14. Diaz LF, de Bertoldi M, Bidlingmaier W, Stentiford E (2007) Compost science and technology. Waste management series, no 8. Elsevier, Amsterdam 15. Thomson A, Pricea GW, Dixonc M, Arnold P, Graham T (2021) Review of the potential for recycling CO2 from organic waste composting into plant production under controlled environment agriculture. J Clean Prod. https://doi.org/10.1016/j.jclepro.2021.130051

Comprehensive Analysis of Pedestrian and Walking Spaces of Cities (Including Coastal Areas) N. Burilo(B) , A. Kruglikova, A. Tsyba, I. Makarikhina, and A. Volikova Novosibirsk State University of Architecture and Civil Engineering (Sibstrin), 113, Leningradskaya Street, Novosibirsk 630008, Russia [email protected]

Abstract. As recreational spaces for the megacities’ population spear time, walking and pedestrian spaces are considered by scientists from various sides, both from the architectural side and from the side of psychological aspects affecting people’s lives. Heavy transport, which number is growing in all major cities and makes people to find psychological safeness and relaxation in quiet spaces, in green areas of the city (such as parks, river embankments and reservoirs, and so on). The authors of the article analyze large cities development in Armenia, Azerbaijan, Turkmenistan, Russia, Ukraine and also identifies factors affecting the pedestrian and transport network of large cities. The systematization of the data obtained was carried out and therefore, the possible development of the city’s pedestrian network was proposed. Keywords: Recreational spaces · Pedestrian spaces · Walking spaces · Urban planning · Coastal territories · Riverine territories · Layout of territories · Comprehensive analysis · SWOT analysis

1 Introduction There is a concept of “Common Use Territories”, the possibility for an unlimited number of people to freely use them is emphasized. The incomplete list of such territories includes squares, streets, driveways, embankments, squares, boulevards. At the same time, the term “Common Use” in such a regulatory context reveals an aspect of the legal regime for the use of land plots, where citizens have the right to be there and to use the natural objects available on these plots within the limits permitted by law and other legal acts, freely and without any permits. If we consider pedestrian spaces in the aspect of the legal regime for the use of territories, so most of them relate specifically to public areas, but a certain part of pedestrian spaces may be privately owned, remaining open to visitors. The system of public spaces for pedestrian traffic is equivalent to the transport network in its importance in the organization of the city’s planning framework. The organization of open urban pedestrian spaces is one of the priority areas of modern urban © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_39

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planning and urban reconstruction, which can help solving the transport and environmental problems of the city centers, contributing to the preservation and restoration of the urban fabric integrity, existing buildings adaptation to modern functions, uniting the social and commercial efficiency of the urban environment. Currently, control over the distribution and consumption of urban resources is fully provided by the city authorities. In this regard, a new methodological and regulatory framework is needed for a system formation of open urban pedestrian spaces in cities in general and in the historical center in particular. The main design requirements should be developed for roadways and sidewalks, pedestrian and bicycle paths (taking into account bus shelters and car parks); landscaping, lighting, drainage (storm sewer); measures for traffic management and environmental protection (bins, garbage sorting, and so on) [1].

2 Materials and Methods In order to conduct this study, the following methods were used: domestic and foreign references of on the research subject were studied, comparative and graphical analysis of data was carried out as part of the study. The study of cartographic and historical design data was carried out including normative ones. The architectural and planning organization of the large cities’ plans was studied, as well as the quality analysis of pedestrian spaces environment in the center and coastal territories of domestic and foreign large megacities was carried out. A criteria analysis was done, as well systematization of the studied research materials obtained from archival sources. Field surveys of a number of Siberian cities were conducted as well as several large cities in Ukraine: Moscow, St. Petersburg, Kiev, Kharkiv, the results of the research were presented in articles of various levels. The most significant are: Ketova and Burilo “Influence of environmental factors on the formation of coastal zones in Siberian urbanized territories” [2], Burilo “Analysis of landscape and urban planning of the coastal areas” [3]. It should be noted that the issues of formation and development within their reconstruction are considered in details in the following works: dissertations for the degree of Candidate of Architecture: Zakirova “Urban planning reconstruction of the system of pedestrian walking spaces in the central historical part of the city” [1], Wagner “Principles of the formation of the architectural environment of public pedestrian spaces in the context of the current urban buildings” [4], Shesterneva “Architectural typology and principles of development of existing pedestrian communications of the largest city: on the example of St. Petersburg” [5].

3 Results and Discussion In large cities, the possibility of successful operation of pedestrian streets becomes available only at high costs for changes in the transport structure of citywide transport, as well as the allocation of parking spaces and the urban areas improvement. The analysis was carried out on a number of large cities of Russia, Ukraine, Azerbaijan, Armenia and Turkmenistan: Moscow, Kiev, Kharkiv, Baku, Yerevan and Ashgabat.

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Kiev has a unique landscape and it is widely known for its architectural ensembles, tactfully inscribed in it. Despite significant losses, they create a holistic image of the historical city located along the water area of the ancient Dnieper-Slavutich. The city is characterized by a complex territorial structure. The modern planning structure of the city, as in a mirror one, reflects all the historical milestones of the city territory development, and at the same time a wide range of functions performed by the capital of Ukraine at the present time. In the public center, all institutions of comprehensive services for the residential area’s population are concentrated in accordance with building codes. Parking of personal vehicles was partially solved in a public center using an underground level. The recreation area for the first stage of construction is formed between the approaches to the southern bridge crossing and the border of collective gardens on an area of 47.5 ha. Architectural monuments are organically included in the new development and are partially used for cultural and tourist institutions, exhibition halls and museums. The general plan of Kiev provides for the continuous development of the historically established planning structure, taking into account its improvement in order to ensure the normal functional organization and interconnection of residential and industrial zones, a citywide center and recreation areas. The latter are close to new residential formations. The functional and planning structure of Kharkiv was formed under the influence of the external trade and military movement associated with the landscape of the area. Kharkiv landscape is a central plateau, elongated in the form of a wedge from north to south. With a narrow cape, it goes to the confluence of the Lopani and Kharkiv rivers. Their wide valleys cover the central plateau from the west, the south and the southeast. The slopes of the Bald and Cold Mountains in the west, the Saltovsky plateaus in the east and the gentle plateau in the southeast descend into these valleys in amphitheaters. The outer paths respectively descended from these natural amphitheaters or ascended to the watershed of the central plateau from the north [6]. The conditional borders of the central part of the city from the east and south are the Kharkiv River, from the west—the Lopan River, from the north—Bursatsky Descent, Sovetskaya Ukraine Square and Korolenko Street. The elevated part of the cape formed at the confluence of the Kharkov River with Lopan, called University Hill, is surrounded on three sides by squares—Soviet Ukraine, Rosa Luxemburg and Proletarian. From the University Hill to the riverbeds there is a decrease in the relief. It is the most pronounced on the western side, where the Lopan River comes close to the foot of the hill. As in many other cities, the urgent problem of the planning of Kharkiv is the conflict “man-car”. Here is an example of how motorists park in the center of Kharkiv. For pedestrians, the space between the hoods of cars and the wall of the building is less than a meter. Maybe it is necessary to restrict the entry of private vehicles into the city center. At the same time, the modern core of Kharkiv has largely preserved the features of a three-hundred-year-old planning structure. Interesting creations of the architectural biography of the city have been preserved here. The old and the new merged into an original mosaic, giving a unique historical center [7]. Considering Baku (Azerbaijan), it should be noted that its central street—pedestrian Nizami, crosses the central part of the city from west to east. It starts from Abdullah Shaiga Street, in the mountainous part of the city, and ends at the railway track on Sabit

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Orujev Street, at the monument to Shah Ismail Khatai in the “Black City”. The total length of the street is 3,538 km. The architecture of the street was various styles and trends synthesis, which was due to the fact that intensive construction and development was carried out in three main stages: the end of the XIX—beginning of the XX century, the 1950–1970s of the XX century and the modern period. Most of the first stage buildings, as well as other buildings of that period, were built in the style of “Neo-Renaissance”, “Neo-Gothic”, “Baroque”, “neoclassicism”. The “neo-Moorish” style also prevails, where architects attempt to use elements of national architecture in the construction. The houses are lined with natural limestone stone breeds—aglaem. The first stage, in its turn, can be divided into three building sites: the first—between Vorontsovskaya Street (now Islam Safarli Street) and Persian (now M. Mukhtarov Street), where the oldest buildings were built according to the project of architects N. A. von der Nonne and M. Kafar Izmailov, the second—from the site adjacent to to the Tezepir Mosque to the west, which was a complex of one—and two—storey buildings, and the third towards the railway station, and it was in this third zone, at the turn of the XIX—beginning of the XX century, that the most significant three- and four-storey buildings began to be built according to the designs of architects Jozef Ploshko and I. V. Goslavsky. The next stage of the street’s architectural development is associated with the introduction into the buildings’ architectural layout of the middle of the XX century, made in the style of “Empire”, or the so-called “Stalin Empire”. Later, at the end of the 50th, residential buildings were erected, most of which were designed and built in a new architectural and artistic style, known as “constructivism”, which was widespread in many countries of the world at that time. According to art critic G. F. Mammadov, the architectural style of constructivism was hardly anywhere else in the USSR as fully and variously represented as in Baku, where it was used to give the city a new look. The fascination with constructivism in Baku led to the creation of its local variety—“Baku constructivism”. As it was in earlier buildings, the architects significantly introduced oriental and national flavor, which was especially felt in the execution of arches and monograms of buildings, significantly changed the overall stylistic appearance of these buildings, the facade of the buildings was finished with aglay. Modern buildings, mostly high-rise, were built in the “neo-modern” style, lined with aluminum composite panels, fiber concrete, marble and granite. According to experts, two buildings located on this street fall out of the general architectural complex of both the street and nearby houses. This is the Young Spectator Theater building, which is too massive for the architectural ensemble of this street’s section, does not harmonize with the classical style of architecture; it represents nearby houses and violating the general geometry of the site, excessively cuts into the pedestrian lane. The architectural solution of State Securities Committee building is made in the style of “constructivism” and spoils the “classical” monumentality of the street’s perimeter. The central square of Yerevan (Armenia) is the Republic Square (Napgareyuap Bgaragak). The central part of the city is closed by an almost regular ring of Karmir

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Banaki, Saryan, Moskovyan, Khanjyan streets. This ring is crossed by the main highways—Lenin Avenue, Teryan, Abovyan, Nalbandyan, Tumanyan, Amiryan Streets and Sayat-Nova Avenue. Until the beginning of the XX century, the planning structure of Ashgabat was represented by a rectangular grid in combination with a radial layout. In 1948, the city had been completely destroyed by an earthquake, after which it was rebuilt taking into account the preservation of the historically established layout. Modern Ashgabat is a city that has preserved the basic principles of urban planning decisions of the Soviet period—a regular layout with wide streets, squares, and extensive parks. The rejection of the traditional carpet building for eastern cities is explained by the desire to give it the scale of the capital city. It was in the architectural environment of Ashgabat that the trend of self-expression of a politically significant person was most clearly manifested due to the return of the traditional oriental architectural principles adapted to modern conditions. A characteristic feature of the modern development of oriental architecture has become the active use of classical forms. The pompous forms of the Empire emphasize the grandiose scope and significance of the new time buildings. The defining role of the personality of the first president of Turkmenistan Saparmurat Niyazov became the most important factor that influenced the nature of the capital’s architectural image. The most important buildings of the capital, forming the administrative part of Ashgabat, erected taking into account the wishes of the president, were grandiose structures with a dome system traditional for Islamic architecture in combination with a classical plan scheme and an order system. Rich decor, the use of gold, mirrors and mosaics in decoration are combined with modern building materials. The modern layout of Moscow belongs to the radial-branching—the streets radiate from the historically formed center of the metropolis. The system of transport highways, main streets, squares, urban planning nodes and main territories of the citywide centers’ system forms an urbanized planning and architectural framework of the city. The master plan provides for the development and improvement of the historically established radial-ring structure of the urbanized planning framework by: • strengthening the social, cultural and leisure structure-forming role of the historical center core in Moscow; • accentuation of the main radial and ring highways by the system of large social and business centers on the periphery of the historical center and in the “middle belt” of the city, as well as multifunctional primary territories; • formation of new radial and ring elements of the urbanized planning framework: the third ring, the understudies of the main radial highways; • formation of “contact zones” of natural landscape and urban planning frameworks that form the basis for the development of urban recreational complexes. • the zones of the current concentration and prospective development of the planning framework’s elements—as the planning cores of the territory, the Moscow River bed and the massif of the national reserve “Losiny Ostrov”, as the main spatial divided, as well as the pronounced environmental specifics of the historically formed part of the

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city determine the planning structure of Moscow, including the central planning zone and three planning sectors located in the middle and peripheral belt of the city [8]. In the area of the historical center of Moscow, the master plan provides for the preservation and development of the historically established planning structure: • • • •

functional and architectural-spatial completion of the main streets and squares system; preservation and restoration of historical morphotypes of planning and development; development of pedestrian zones, streets, routes system; reconstruction of the lost elements of the historical landscape.

The architectural and planning organization of the pedestrian space in a large city depends entirely on the current urban planning situation, the reception of the transport and pedestrian flow separation, the location of objects that are the foci of the population gravity and other factors. The following types of pedestrian spaces are the most typical for urban recreational coastal areas: • • • • • • •

streets isolated from transport; streets with limited traffic; single-level pedestrian squares; two-level streets (with vertical separation of pedestrians and transport); "suspended” areas above transport hubs; covered galleries and in complexes of commercial and public buildings; underground pedestrian communications [9].

There is foreign and domestic experience in determining the principles of architectural and planning formation of pedestrian spaces, but it is not generalized and requires detailed study, study and systematization. According to the classification adopted by the Federal State Budgetary Institution “Central Research and Design Institute of the Ministry of Construction and Housing and Community Services of the Russian Federation”, open spaces in cities include “undeveloped territories in general, including water-green systems, main avenues, embankments, esplanades, pedestrian zones, squares, boulevards and other elements of the city’s planning structure that make up the system of open spaces.” Being in such spaces, a person is less protected from the effects of the elements, but the main thing for him is the ability to maneuver and quickly reach the desired point, in which landmarks help, which overview is often limited. In order to clarify the patterns and the relationship between the type of space and the form of behavior, Nikolsky and Knyazkova in their article “Spiritual and moral aspects of color architectural space” compiled a table, were the main aspects of the architectural environment that affected human behavior were identified (Table 1) [10]. Also, these issues were considered in his dissertation Titov “Organization of the architectural environment and human behavior” [11, 12]. After analyzing the Table 1, one can conclude that a pedestrian in the city needs a sufficient number of open spaces, but the existing density and height of the building is

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dictated by high business and creative activity, requiring constant contacts and interactions. In such a space, the inverse relationship is also visible, when behavior literally dictates the principles of spatial organization. Table 1. The type of space is a form of behavior. Type of space

Characteristics of space

Main aspects Prevailing affecting behavior emotional state

Characteristic features of behavior

Open

The presence of Extent, reach of long undeveloped landmarks and areas, good destinations visibility of adjacent territories

Natural

Natural pace of movement, absence of tension and stress reactions

Semi-open

Alternation of densely built-up areas and open areas, periodic restriction of the view

The rhythm of changing the environment (the frequency of changing spaces), the visibility of landmarks

Wary

“Ragged” pace of movement (frequent alternation of accelerations and stops), alertness

Closed

Densely built-up areas, lack of large open spaces, viewing opportunities are constantly limited

Distances to traffic restriction elements, visibility of landmarks

Active

The fast pace of movement, the absence of stops and reflections, the desire to get to a comfortable site

Pedestrian space should harmoniously combine the properties of open and closed type, as an example of natural formations: valleys with trees, gorges and caves, on the other hand, meadows, deserts, plains, lakes. It is no coincidence that landscaping elements are so often used in urban development—trees and lawns, as well as fountains and pools, and pedestrian space should contain these elements in order to include natural scenarios based on environmental archetypes.

4 Conclusion The method of obtaining high-quality pedestrian spaces is cyclical and consists of three successive stages, which were deduced by Shesterneva in her PhD thesis “Architectural typology and development principles of existing pedestrian communications in the largest city: on the example of St. Petersburg” [5]: At this stage, a group of surveys is conducted and the parameters and characteristics of all components of the environment are determined, among the identified parameters, “conflict points of pedestrian spaces” are determined.

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At the second stage, the methods and direction of project activities are determined. In accordance with the architectural and planning principles of designing pedestrian spaces, a complex transformation of the network’s specific element is carried out. The third stage—in accordance with the identified principles, after the implementation of the main measures for the pedestrian spaces transformation, the analysis’ mandatory stage of this element operation by residents follows, on the basis of which new “conflict points of pedestrian spaces are determined and the design cycle is repeated” [5, 13, 14]. Spatial development of cities will help solve the problem in favor of a polycentric model, namely the intentional transfer of a “point” in areas far from the center. The role of the “point” can be objects of shopping and entertainment infrastructure, business and community centers, embankments and pedestrian streets, which serve as the basis for creating an autonomous territory with its own infrastructure for recreation and work directly to the place of residence. In particular, the positive features of the new reanimated city will manifest themselves in other areas. For example, in a comfortable city there is no acute issue of street crime, problems associated with the migration of the educated population. Hence the lack of personnel also do not arise acutely in well-maintained cities, as well as an increase in the number of comfortable cities indicates the rise of state prestige, since it directly affects its cultural, economic, and political state [15, 16]. It is impossible not to say that the renovation of disadvantaged areas and the control of excessive growth of the cities’ territory and especially two conditions in tandem have a particularly favorable effect on the environment. Urban areas do not serve for the benefit of ecological harmony, but especially abandoned territories that are uncontrollably increasing and flooding ecologically healthy spaces do not cope with this task [17, 18]. All the facts mentioned above confirms the need for the most thorough study of pedestrian spaces in large cities and their problems, reassessment of their importance taking into account domestic and foreign experience, which shows that the potential of pedestrian spaces can be used many times more effectively, simultaneously solving transport and environmental problems of the city [19, 20].

References 1. Zakirova YuA (2009) Urban planning reconstruction of the system of pedestrian walking spaces in the central historical part of the city: specialty 18.00.04. Dissertation for the degree of Candidate of Architecture, Moscow, p 186 2. Ketova EV, Burilo NA (2018) Influence of environmental factors on the formation of coastal zones in Siberian urbanized territories. In: MaTEC web of conferences. International scientific conference SPbWOSCE2017 “business technologies for sustainable urban development”, vol 170, p 6. https://doi.org/10.1051/matecconf/201817004010 3. Burilo N (2022) Analysis of landscape and urban planning of the coastal areas. Lect Notes Civ Eng 168:287–298. https://doi.org/10.1007/978-3-030-91145-4_28 4. Wagner EA (2018) Principles of the formation of the architectural environment of public pedestrian spaces in the context of the current urban buildings: specialty 05.23.20 “Theory and history of architecture, restoration and reconstruction of historical and architectural heritage”. Dissertation for the degree of Candidate of Architecture, Nizhny Novgorod, p 301

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5. Shesterneva NN (2007) Architectural typology and principles of development of existing pedestrian communications of the largest city: on the example of St. Petersburg. Dissertation 18.00.04, St. Petersburg, p 220 6. Historical continuity of the composition of the kharkov center. http://dalizovut.narod.ru/ist orii/ist_arh.htm. Accessed 13 July 2021 7. Leibfreid A, Reusov V, Titz A Architecture, monuments, new building. Guide, Kharkiv. https://www.alyoshin.ru/Files/publika/leibfreid/leibfreid_harkov_02.html. Accessed 07 2021 8. The draft general plan for the development of the city of Moscow for the period up to 2020. The main directions of urban development of the city of Moscow. The main directions of development of the planning and architectural-spatial structure. http://www.mskvd.ru/gen plan/structure/index.htm. Accessed 13 July 2021 9. Moiseyev YuM, Bikinyayeva AA, Stepanova DA (2016) Strategy and tactics of managing the image of the city. Arch Constr Russ 2:80–85 10. Nikolsky MV, Knyazkova LA (2007) Spiritual and moral aspects of color architectural space. Issues of modern science and practice. V.I. Vernadsky Univ 1(7):177–187 11. Titov AL (2018) Pedestrian environment of a shopping and entertainment center as a factor shaping urban space. Sociol City 2:32–45 12. Titov AL (2004) Organization of the architectural environment and human behavior: specialty 18.00.01. Abstract of the dissertation for the degree of Candidate of Architecture, Yekaterinburg, p 22 13. Zvyagintseva EM (2017) The structure of the modern architectural environment. In: International student construction forum-2017, Belgorod State Technological University named after V.G. Shukhov, Belgorod, pp 318–322 14. Yarmosh TS, Ivanova SI (2016) The influence of the architectural environment on human behavior. In: High-tech technologies and innovations: collection of reports of the international scientific and practical conference, Belgorod, 6–7 Oct 2016. Belgorod State Technological University named after V.G. Shukhov, Belgorod, pp 261–266 15. Maleeva TV (2005) Formation of factors and conditions for the sustainable development of a large city based on the effective use of land resources: specialty 08.00.05 “Economics and management of the national economy (by branches and spheres of activity, including: economics, organization and management of enterprises, industries, complexes; innovation management; regional economics; logistics; labor economics; population economics and demography; environmental economics; entrepreneurship economics; marketing; management; pricing; economic security; standardization and product quality management; land management; recreation and tourism)”. Dissertation, St. Petersburg, p 332 16. Ketova EV (2012) Mechanisms, patterns and principles of evolution of historical cities of Siberia (late XVI - early XX centuries): specialty 05.23.20 “Theory and history of architecture, restoration and reconstruction of historical and architectural heritage”. Dissertation, Novosibirsk, p 192 17. Burilo NA, Logachev YeS, Kalpakova YuA (2021) Aesthetic and psychological environment for people with disabilities. In: Culture, science, education: problems and prospects: materials of the IX international scientific and practical conference, Nizhnevartovsk State University, Nizhnevartovsk, pp 591–596. https://doi.org/10.36906/KSP-2021/85 18. Kruglikova A (2022) Change of liquid waste temperature in open wastewater treatment plants. Lect Notes Civ Eng 168:493–503. https://doi.org/10.1007/978-3-030-91145-4_47 19. Shulgina VS (2019) Architectural and spatial structure of the lawyer of the territory of the city of Tomsk. Bull Tomsk State Univ Arch Civ Eng 21(5):74–84. https://doi.org/10.31675/ 1607-1859-2019-21-5-74-84 20. Karelin DV, Shulgina VS (2018) Functional organization of the coastal territory of West Siberian cities. Historical aspect. Bull Tomsk State Univ Arch Civ Eng 20(1):74–81

The Influence of the Building Configuration on the Occurrence of Increased Wind Speeds V. D. Olenkov(B) , A. V. Alemanov, A. O. Kolmogorova, A. E. Sarayeva, and E. S. Sozikina South Ural State University, 76, Lenin Avenue, Chelyabinsk 454080, Russia [email protected]

Abstract. Urban planning is closely related to the design of residential development that could provide comfortable living conditions for the people. Aeration mode is one of the most important factors. It must be taken into account when designing buildings. If its characteristics are set, it is possible to create wind protection of the territory, its ventilation and ensure the safety of the people. The article presents the main types of residential development according to F. L. Serebrovsky. The article considers the transformation of the air flow at the entrance to the building, which has gaps on both sides (street). There is a description of the methodology and an example of setting up a design case for numerical simulation of wind effects on a residential development model in the article. The hydrodynamic problem was solved using the ANSYS CFX software package based on finite element analysis. The existing information on the influence of the roughness of the underlying surface in the building has been supplemented. The transformation of the wind flow is investigated when the distance between two buildings changes. There are two types of building configuration: in the presence of a highrise building on the symmetry axis of the building and in its absence. The analysis of the effect that a high-rise building has in residential development is carried out. Keywords: Residential development · Building configuration · Wind comfort · High-rise buildings

1 Introduction A residential building has unequal distribution in large and old cities. A significant quantity of cars and high-rise buildings were just left out during the urban planning and construction [1–4]. That is why there are narrow streets, modern planning far from the center in old cities. Perhaps some years later our modern planning rules become irrelevant because the humanity is always in development. So an opinion and requirement to the world around us have to be changed too [5–8]. The main aim of engineers is to envisage all the possible scenarios. There should be a calculation of airflow for a separate building and for building plan during it development [9, 10]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_40

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For example, in article “Design, construction and operation of high-rise buildings, taking into account the aerodynamic aspects” by Mikhaylova et al. [11] presented an investigation of basic aspects of building’s aerodynamics. The aim of the research was an identification of aerodynamic building characteristics, a complex of buildings aerodynamic analysis, an Identification of key indicators influenced on forming and changing aerodynamic environment. Also an attention was given to wind-shields on the pedestrian level. The study found that the most effective method of airflow distribution identification is blowing through a building model in a wind tunnel. In article “Experimental study of wind loads on a multifunctional high-rise residential complex” by Buslaeva et al. [12] there is a description of the experimental results in a small wind tunnel. According to it the pressure coefficients of wind loads depending on force angle were determined. In order to simplification and expedition of the calculation the neighborhood plan is seeking to typification [13, 14]. It is necessary to develop new more efficient buildings from the point of view of the aeration regime [15, 16]. The objective of this study is to approach this goal.

2 Systematization of Residential Development Nowadays there are the following base types of residential development: quarterly buildings, line buildings ribbon development, bedroom communities, point construction, mixed districts, microdistrict development, dense buildings, blocked buildings, single-storey building. All the development can be divided in to parts. Its main fragments were classified by Serebrovsky F. L. [13]: 1—rectangular, 2—diamond-shaped, 3—trapezoidal, 4— pentagonal, 5—hexagonal, 6—heptagonal, 7—octagonal (Fig. 1). Also it is possible to show the classification of main building forms: linear, flat, tower rectangular, round (Fig. 2a). In addition to simple forms, there are also complex building forms: the variable cross-section can be in height, in width on racks, etc. (Fig. 2b).

Fig. 1. The main forms of building fragments.

One of the key problem of building is a removal of accumulated exhaust gases from cars and plants, settled dust and the need to saturate it with fresh air. There must be gaps

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Fig. 2. a Classification of simple forms of buildings: I and III—linear, II—flat, IV—rectangular towers, V—round; b complex forms of buildings.

in building gaps between buildings that would provide aeration regime. Serebrovsky F. L. identifies the main combinations of breaks: 1, 2—fragment with one break on the windward side, 3—fragment with two breaks on the windward side, 4—the open fragment from the windward side, 5, 6—fragment with one break on the windward side and one break on the windward side opposite each other, 7—fragment with two breaks on the windward side and one break on the windward side, 8—fragment with two breaks on the windward and windward sides, 9—fragment with one break on the windward side and one on the windward side opposite each other, 10—an open fragment on the windward side and with a break on the windward side (Fig. 3).

Fig. 3. The combination of breaks: I—fragment with a combination of breaks (9); II—fragment with a combination of breaks (3).

3 Wind Transformation in a Residential Development Gaps between buildings have different effects depending on their configuration. F. L. Serebrovsky, based on the research of N. N. Serebrennikov, considers that breaks from the sides have insignificant effect on the direction and speed of air flows inside the building when the wind direction is along the building. But it must also be taken into

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account that this applies to breaks of a certain length. If the wind is directed at any angle to the building the direction and speed of wind flows are changed. Therefore, the street can be considered as a fragment of a building, open from two sides (Fig. 4a, b). What happens to the transformation of the airflow? The coefficient of transformation of the air flow is the ratio of the wind speed at a certain height in the building to the value of the wind speed above the building there is no influence of building at this height. Serebrovsky tested a model of building open from two sides (streets) and established the following patterns (Fig. 4c): • The wind angle is α = 0°. If the axis of the fragment coincides with the direction of the air flow, the flow is transformed slightly. The angle of transformation is zero. The transformation coefficient t3 = 0.8…1. The inhibiting influence of building as well as the Earth’s surface affects only the layers surrounding to them. • The wind angle is α = 45°. When the air flow is transformed at such an angle to the axis of the open fragment from both sides, the direction of the transformed flow coincides with the axis of the fragment.

Fig. 4. A street as a fragment of a building: a—a general plan; b—a diagram of a fragment opens from two opposite sides; c—air flow around a fragment open on both sides (street).

In the real model, the wind does not move in a laminar flow, but has some turbulence [17]. This is due to the roughness of the underlying surface of the earth and buildings [18], green spaces, fences and other elements of landscaping—micro-roughness. Eurocode for wind loads [19] gives the turbulence characteristics. It is expressed by the intensity of turbulence (1) and the length of the vortex (2). The intensity of turbulence increases as it approaches the earth’s surface (Fig. 5a). This is due to micro-roughness. For the same reason, the length of the vortices decreases as they approach the earth’s surface (Fig. 5b). Moreover, under the influence of intensity, there is a gradual increase in wind speed when its particles pass a certain distance in the horizontal plane (Fig. 6). As the

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graph shows, the speed changes according to the logarithmic law. Lv (z) =

ki σv  = for zmin ≤ z ≤ zmax vm (z) c0 (z) × ln(z z0 )  α z L(z) = Lt × for z ≥ zmin zt

(1) (2)

There ki —turbulence coefficient. The ki value can be specified in the national annex. The recommended value ki = 1, 0; c0 —topography parameter (orographic coefficient); z0 —roughness parameter; zt —base height, zt = 200 m; Lt —the basic scale of the vortex length, Lt = 300 m; α—a degree indicator.

Fig. 5. a A change in the intensity of turbulence in height; b a change in the length of the vortex in height.

Fig. 6. Wind speed depending on the path traveled by particles at a height of 5 m.

4 Numerical Modeling of Building Configurations The object of the study was the wind flow around the architectural and planning composition of residential buildings. In this paper, two building configurations were considered: without a building between the houses of the building and with its presence. The research was carried out by numerical simulation in the ANSYS CFX software package used to solve computational problems of hydrodynamics. The Navier–Stokes

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equations for laminar flow regimes and the Reynolds equations for turbulent regimes are solved in the FLOTRAN hydrodynamic module. Similar studies can be carried out with the use of other software systems [20–22]. As initial data, the wind profile was set for the type of terrain C [5] at a wind speed at an altitude of 60 m equal to 30 m/s. The intensity of turbulence and the length of vortices were set for terrain type IV [3]. 4.1 Stage 1. Parallel Arrangement of Buildings in the Development (Building Model, Open on Both Sides) Based on the information that the gaps located along the wind direction practically do not affect the wind flow in the building, two elongated buildings were built (length 600 m, width 15 m, height 60 m) (Fig. 7).

Fig. 7. Building configuration № 1.

The dependence of the distribution of wind speeds depending on the distance between buildings was investigated. The following distances between buildings are accepted: 100, 150, 200 m. The results obtained are presented below. The figures (Fig. 8) show the wind velocity fields and a graph of the velocity distribution in the middle of the building for a height of 5 m. After analyzing the data obtained, the following conclusions were made: • As the distance between buildings increases, an area of increased wind speeds is formed and increases in size at the end of the development. • When the wind flow explodes into the building at its beginning, a sharp increase in wind speed occurs, flow breaks are formed. • A zone of elevated (in the center) and lowered (near buildings) is formed in the building speeds. • As the distance between buildings increases, the wind speed increases. The excess of the average wind speed at an altitude of 5 m is 6–9 m/s. 4.2 Stage 2. The Influence of a High-Rise Building in the Center of a Development with Parallel Buildings The influence of a free-standing square-section building, whose height is twice the height of the building, has been studied. The building is located between the other two

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Fig. 8. Wind speed contours and wind speed distribution curves over the building width for configuration № 1. The distance between buildings is: a 100 m; b 150 m; c 200 m.

Fig. 9. Building configuration № 2.

at a distance of 85 m, the distance between the entrance line of the building and the building being entered is 0, 300, and 600 m (Fig. 9). The following results were obtained (Fig. 10). After analyzing the data obtained, the following conclusions were made:

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Fig. 10. Configuration test results № 2. The distance between a feed building line: a 0 m; b 300 m; c 600 m; d graphs of wind speed distribution, general view.

When a high-rise building is located at the beginning of the development, the wind speed slows down before the construction. The separation of the wind flow at a high-rise building affects the separation of the wind flow of buildings, thereby reducing the zone of increased speeds. On the windward side of the high-rise building, a zone of increased wind speeds is formed, but it has a value less than the wind speed obtained in the first stage of research with the same building parameters, by about 4 m/s. In addition, there is a track of reduced wind speeds. At the buildings of the development, as well as at the first stage of the study, zones of reduced speeds are observed along the buildings. When a high-rise building is located in the middle of a building, the wind speed slows down already in the building itself, and not in front of it. The wind speed in the building remains in the same ranges as for the configuration with the location of the building at the beginning of the development. At the same time, the separation zones of the wind flow of elongated buildings are smaller than in the first stage of the study. But a high-rise building has more pronounced separation zones. When a high-rise building is located at the end of the development, there is a slight increase in the field of increased speeds at the entrance to the building, while the field of separation of wind flow from buildings is practically absent. There is a decrease in wind speed in front of the high-rise building. The wind speed differs from the first stage of research by about 5 m/s. Wind flow reviews from a high-rise building do not affect wind speeds in the building.

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5 Conclusion A building with gaps on both sides (street) was tested. Two configurations were considered in the calculation: without a high-rise building on the axis of symmetry of the building and with it. It was found for configuration 1 that as the distance between buildings increases, the maximum wind speeds increase, and an area of increased speeds is formed at the end of the development. For the 2nd configuration, it was found that a high-rise building reduces the wind speed in the building, but in local places contributes to the formation of high wind speeds. If we evaluate the aeration regime and pedestrian comfort in the complex, it is best suited from configuration 1 building with a distance between buildings of 150 m, and for configuration № 2 building with the location of the building at the end.

References 1. Retter EI (1984) Arhitekturno-stroitel’naya aerodinamika (Architectural and construction aerodynamics). Stroyizdat, Moscow 2. Dunichkin IV (2005) Features of the aeration regime of residential development during development and reconstruction: on the example of a five–storey building in Moscow in the 1950s-60s, not subject to demolition. Dissertation, Moscow State University 3. Lozinskaya VA (2020) Assessment of the wind comfort of the territory during the densification of residential development by a high-rise building. Bull Donbass Natl Acad Constr Arch Ser “Probl Arch Urban Plan” 2(142):159–164 4. Mironova YuV, Gabdrakhmanova LM (2019) Wind impacts on existing low-rise buildings when placing high-rise and multi-storey buildings in the current development. Izv KGFSU 1:147–154 5. Set of rules 20.13330-2016 (2016) Loads and impacts (with Amendments N 1, 2). Moscow 6. NEN 8100 (2006) Wind comfort and wind danger in the built environment. Dutch Standard, Netherlands 7. Grimmond CSB (2006) Progress in measuring and observing the urban atmosphere. Theor Appl Climatol 84(1–3):3–22 8. Set of rules 42.13330.2011 (2010) Urban planning. Planning and construction of urban and rural Ministry of Regional Development of Russia 9. Simiu E, Scanlan R (1984) The impact of wind on buildings and structures. Stroyizdat, Moscow 10. Janssen WD (2013) Pedestrian wind comfort around buildings: comparison of wind comfort criteria based on whole flow field data for a complex case study. Build Environ 59:547–562 11. Mikhaylova MK, Dalinchuk VS, Bushmanova AV, Dobrogorskaya LV (2016) Design, construction and operation of high-rise buildings taking into account aerodynamic aspects. Constr Unique Build Struct 10:59–74 12. Buslaeva YuS, Gribach DS, Poddaeva OI (2014) Experimental study of wind loads on a multifunctional high-rise residential complex. Bull Belgorod State Technol Univ Named After VG Shukhov 6:58–62 13. Serebrovsky FL (1985) Aeration of populated places. Stroyizdat, Moscow 14. Myagkov MS, Alekseeva LI (2014) Wind pattern features in typical city models. AMIT 1(26) 15. Olenkov VD, Kolmogorova AO, Sapogova AE (2021) Computer modeling of the aeration regime of residential buildings for the purpose of ventilation and wind protection. Bull SUSU, “Constr Arch” 21(1):5–12

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16. Gnyrya AI, Korobkov SV, Koshin AA, Terekhov VI (2018) Modeling of wind loads during airflow of a system of building models with variations in their location. Bull Tomsk State Univ Arch Civ Eng 20(4):65–73 17. Rusakova TI (2014) Investigation of the structure of the wind flow on the streets of the city. Natl Min Univ Collect Sci Pap 44:146–152 18. Gagarin VG, Guvernyuk SV, Ledenev PV (2010) Aerodynamic characteristics of a building for calculating wind impact on enclosing structures. Hous Constr 1:7–10 19. Eurocode 1 (2010) Impacts on structures. Part 1–4. General impacts. Wind impacts (EN 1991-1-4:2005, IDT) 20. SimScale Blog CFD (2022) Assessing wind comfort in urban areas with CFD. https://www. simscale.com. Accessed 14 July 2022 21. Fadl MS, Karadelis J (2013) CFD Simulation for wind comfort and safety in urban area: a case study of Coventry University Central Campus. Int J Arch, Eng Constr 2(2):131–143. https://doi.org/10.7492/IJAEC.2013.013 22. Konovalova KV, Potekhin IA (2019) The possibilities of the simscale computer program for assessing the wind comfort of urban development. Vestn VSTU, Ser “Constr Real Estate” 1(4):63–66

Engineering Structure Safety, Environmental Engineering and Environmental Protection

Irregular Process Type Effect on Fatigue Crack Propagation Rate I. Gadolina1(B) , N. Dinyaeva2 , and M. Bubnov1 1 Mechanical Engineering Research Institute of the Russian Academy of Sciences (IMASH

RAN), Maly Kharitonievsky Pereulok, Moscow 101000, Russia [email protected] 2 Moscow Aviation Institute (National Research University), 4, Volokolamskoe Shosse, Moscow 125993, Russia

Abstract. Building and engineering structures experience variable loads. Exploitation by damage tolerance method is a common practice nowadays. To build the plan for inspection of the current state of construction it is important to have a tool for longevity scatter. For the analysis, the experimental and imitation modelling scheme was used. To judge the longevity the coefficient of spectra fullness of irregular loading is proved to be helpful. The experimental results showed that this coefficient might be helpful in the task of fatigue crack propagation. The developed imitation method allows estimating the possible scatter of steel specimens’ longevities at the crack propagation stage. Due to the specific experimental data presented in the reference paper, it was a need to recalculate the data concerning the loading parameters. For this purpose, the numerical investigation of the stress–strain stale of the construction was performed. Application of finite element design provides an opportunity to utilize our previously written program in the scatter analysis task. Keywords: Finite elements · Crack propagation · Metal fatigue · Irregular loading

1 Introduction It is hard to underestimate the importance of fatigue for the safety and reliability of machines and constructions. Natural cracks can appear in building structures [1] without special violations of manufacturing technologies and operating rules due to the following reasons: material wear, erosion, weathering, temperature and humidity fluctuations. Becoming more and more actual especially in aviation, the exploitation based on damage tolerance method, additionally, bring extra interest to the fatigue crack propagation stage. In the first place, that method had been developing in aviation since [2]. In fatigue the scatter matters because it influences reliability and should be considered. Since about 1990 more and more attention is devoted to the investigation of the crack propagation speed with the emphasis on variability of characteristics [3, 4]. A very © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_41

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prominent approach was developed by Prof Sunder [5], who proposed an original approach to consider the peculiarities of the material investigated and the random character of the environmental impact (including the atmosphere impact). The theme of crack growth under fatigue is presented in international standards, look for example the paper [6]. The frequency-domain in fatigue studies suits well in the case of vibration studies. While considering the finite element decision in multiply noodles of construction a lot of computations are required. In this case, the frequency approach is preferable due to computation time decreasing [7, 8]. On the other hand, the classical studies of fatigue, in particular the studies of crack growth, give a close representation of the nature of the phenomena. It is very important to know the exact values of overloads. Usually, in the time domain researchers analyze the extremum sequence, that is the local peaks in their proper order: MIN1 − MAX1 − MIN2 − MAX2 .... . . . . . . . . . . . . . . . ..MINn − MAXn

(1)

After obtaining the list (1) all information concerning the loading cycle shape and frequencies is discharged according to the time domain method.

2 Numerical Investigation of Stress–Strain State As many important issues stay unsolved there is a need to consider all available in literature experimental information concerning crack propagation. To reuse the previously published by other authors results [9] with the aim of our investigation we faced the problem of recalculating the forces into stresses. For this purpose, a numerical model was developed. Using three-dimensional numerical simulation in a static formulation using the ANSYS Mechanical software version 2021R2, a picture of the stress–strain state in the vicinity of the incision vertex in the part corresponding in shape and size to the previously tested one was obtained. The characteristic type of displacement distribution is shown in Fig. 1, stresses—in Fig. 2a, b. To find the correct stress field and search for the true maximum in the vicinity of the incision vertex, grid convergence was investigated (Table 1). In Fig. 3 we show the process of grid convergence of element size for the numeric estimation using the data from Table 1. The direction of the search is shown in the figure with an arrow. It might be seen from the table and the picture that the element size of 35 mkm appears to be sufficient for this task. Following this analysis, we could find the coefficient K in Eq. (1) which allows us to obtain σ based on information from [9] concerning the load F. σ =KF

(2)

Following the computational analysis, the estimated value of K = 558 MPa/kips for estimation of maximum stress. The obtained value of K was used in the further analysis.

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Fig. 1. Distribution of displacements in the Finite Element model with a superimposed grid.

Fig. 2. Stress field with simplified (a) and accurate (b) sampling of the model.

Table 1. Grid convergence investigation Characteristic element size of the element, mkm,

500

50

25

10

Maximum stress, [MPa]

74

454

876

882

3 Crack Propagation Models To perform the analysis, we should choose among the various crack propagation models. There is no consensus so far among the authors concerning which model of fatigue crack growth under random loading is the best. Since appearing the Paris model in 1963 many attempts have been done to consider various aspects of the phenomena. One of the

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Fig. 3 Optimization of element size to find a proper decision (an arrow shows a direction of optimization)

important topics is the influence of cycle mean stress (σm ) on fatigue crack propagation. As one of the authors of [5] said, this question leads us to the unravelling field where there are more questions than answers. Anyway, a bunch of models to consider σm exist [2, 3]. Most of the models consider the crack retardation due to the appearance of the plastic zone after overloading. Some of the models give similar results. In [9] the results showed the vicinity among the calculated results using Wheller’s [10] and Willinborg’s [11] models. Also, they both coincided well with the experimental results. Further, we employ Willenborg’s model, as one of the best among the others. To estimate the crack growth under irregular loading the geometric parameters of the element and the characteristics of the particular material are necessary. The initial data for the calculation according to [11] are: the dimensions of the specimen, material characteristics (yield strength, kinetic diagram of fatigue fracture), and the loading history. To study the possible variability a set of loading histories were investigated. The material characteristics for steel 4340 have been taken from [9] and the reference book [12]. Steel 4340 usually are employed in general engineering and defense industry. The Willenborg’s algorithm [11] was earlier described also in [13]. Here it is: 1. Set a sequence of turning points of each modelled trial to calculate the stress intensity factor (SIF) values at each step of the algorithm. For this purpose, the initial sequence of loading history or the sequence of rain-flow cycles obtained by one of the generally accepted procedures can be used; 2. It is Necessary to Obtain the Values of SIF at the Minimum and Maximum Points of Each Cycle of the Sequence Obtained in Step 1. For the Specimen with a Hole the Equation Will Be  √  πa  brutto √ π a sec( ) MPa m (3) K =σ W

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here: σbrutto [MPa] is the stress value in the specimen far enough from the crack with length a [mm]; W [mm]—is the finite width of the band; 3. Calculate the Radius of Plastic Deformation Zone at the End of the Crack:   K 2 1 ru = (4) [mm] 2π σ02 4. Next, the location of the crack end and the maximum distance from the crack boundary of the current plastic deformation zone should be obtained, following the geometry of the positions of previous and current plastic zones (see Fig. 4).

Fig. 4 Model of crack retardation because of the load’s interaction (overloading effect). In Fig. 2: a0 —is the crack length at the overloading, ai—is the current crack length, rp OL —the dimension of the plastic zone under overloading, ri OL —plastic zone under current cycle.

5. The extreme position of the current plastic deformation zone and plastic deformation zone obtained at previous iterations is compared (if this is not the first iteration of the considered algorithm). If the current plastic deformation zone is in the field of the plasticity of earlier cycles, the formula (3) is used:  (5) K ∗ = σ02 2π(rPOL + a0 − ai) 6. Calculate the difference between the SIF (K) at the minimum and maximum point of the cycle and determine the increment of the crack and the new crack length by the kinetic fatigue fracture diagram by Forman’s equation: K n da =C dN (1 − R)Kc − K

(6)

where C, n—are the constants of the material; R—asymmetry factor; K C —the critical value of fracture, that is the viscosity of fracture; 7. The algorithm is repeated from step 2 until the failure criterion is met (either the critical crack length or critical SIF = Kc are achieved).

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4 Random Sequency Imitation In [9] the longevity at crack propagation stage of steel specimens under block loading was experimentally investigated. Due to the fact, that the loading in service is often of random nature (not just blocks) it was interesting to estimate the longevities under modelled random sequencies. We could not carry the testing under random loading, so we decided to perform the imitation experiment. To build the random sequence similar to (1) a special algorithm was developed. The initial block (blue) is shown in the Fig. 4, left side. its cycles distribution is presented in Table 2. Table 2. Loading block for experiment on crack growth in steel specimens [9]. Loading index

Cycles maximums

n, repetition number

1

1

3

2

0.6

6

3

0.45

12

4

0.33

24

To create the multiple random replicas on the base of distribution shown in Table 2, the analysis (Fig. 5a) and synthesis (Fig. 5b) of the random sequence were performed.

Fig. 5. An analysis stage Markov’s matrix modelling. a division the process by levels; b filling the target matrix.

The random process is divided by the horizontal levels by classes. The recommended classes number is 32. A short sequence of the random process is shown in Fig. 5a, in the left: In Fig. 5b the process of filling the matrix is shown. In cells the repetition of ascending (right up triangle) and descending (left down triangle) ranges are shown. The filled in

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this way matrix is further used for the syntheses of the random replicas. Due to the fact, that not only the information from the matrix 5b) is used, but also the random number generator is employed, the replicas are similar only in average and are different concerning the peaks order in them. Due to peculiarities of the loading in study [9] all the minimums are equal to zero. So, the special algorithm for the sequence’s generation was developed. The algorithm was as follows: • Allow MIN 1 = 0. • To select MAX k the function SAMPLE in R [14] was used. The function SAMPLE selects the entry randomly from the pool, which contain all maximums of the cycles (Table 2). • MIN 2 and all other minimums are equal to zero [9]. Following this algorithm, we can generate the necessary number of replicas. In Fig. 4a as the example three of the possible replicas are shown graphically. To characterize the degree of irregularity of random loading two parameters are used. They are: I—the irregularity coefficient, which show the ratio of the number of the processes mean level crossing to the extremum number and the fullness ratio of the loading spectra V [15]:   σai m m 1 hi (7) V = n σˆ a The value V is non-dimensional and lay in interval (1 …. 0.1). In (7) m—is the fatigue exponent, for metals it might be taken as m = 6; n—is the sum of cycles in block; hi —is the cycle number at the step i; σai —is the stress value; σˆ a is the maximum amplitude in block. The dependence (7) indicates, that V depends not only on the shape of the loading block, but also on m. It goes out that this parameter is material dependent. Factor V proved to work well at the crack initiation stage [15] to compare the deteriorating degree of spectra. Surprisingly, after studying the results of [9], we found a distinct correlation between V and crack propagation longevity L. The authors of [9] carried out the experiments under two different block shape. The block shape might be characterized by V. Except for one result shown in the study [9] all data shows the good agreement with the reverse dependence L A /L B ~ V B /V A [16]. To study longevity variability due to uncertainty of the loading the target Markov’s matrixes modelling method was employed. The idea of the method to create the random sequence similar to (1) is described in [17]. According to [17] the probability of each succeeding extremum depends only on current extremum values (that explains the name of the method: the Markow’s matrix method). The probabilities are specific for each type of random process. In [17] three types of processes were presented covering the wide range of processes’ irregularities. The next step had been done in [18] introducing the so-called ‘target Markow’s matrixes. Those last ones consider the service processes peculiarities, which might influence the machine parts resistance against fatigue. The target matrixes might be employed in testing and in calculations. Due to this modelling method instead of a unique sequence (1) we obtain the numerous modelled sequences,

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which are built on the base of the initial sequence (1) and might serve as a source for variability assessment. The details of the algorithm are described in [18]. In Fig. 6a the initial loading block (top, blue) and three sample random sequence are shown. In Fig. 6b the calculated by Willenborg method [11], (2–6 equations) curves of crack propagation are shown. Table 3 presents the estimated cycles number N until the moment when the crack reaches L = 10 mm and fullness ratio factor V (7). The noticeable pair correlation (R2 = 0.806) between V and lg(N) was estimated based on the data in Table 3.

Fig. 6 Loading sample realizations and their crack growth rate (estimated by Willenborg [11]). The lines colors in 4 (a) correspond to ones in 4 (b). Table 3. Estimated cycles number N until the crack reaches L = 10 mm. Loading sequence

N

V

Block loading

1,400,000

0.64

Random sequence “ex1”

2,100,000

0.67

Random sequence “ex2”

800,000

0.55

Random sequence “ex3”

1,200,000

0.65

5 Conclusions The data from the literary source were employed to study the peculiarities of irregular (block and random) loading. The original method of constructing the random sequence was applied to analyze the scatter. During the modelling experiment, the longevities, calculated by Willenborg’s approach with our previously developed program were used. Based on the results of the experiment [9] the important conclusion has been done: the fulness ratio V influences longevity at the crack propagation stage. The developed method might be useful in comparing numerically the block and random loading.

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Acknowledgements. The authors express gratitude to our colleagues PhD S. Lebedinsky (IMASH RAN) and engineer A. Bautin (TZAGI) for their valuable ideas and assistance.

References 1. Ushakov AE et al (2021) Testing results of bridge fiberglass elements after 12 years of exploitation. Compos Nanostructures 13:29–36 2. Paris PC, Erdogan FA (1963) Transactions of the American society of mechanical engineers. J Basic Eng D 85:528–534 3. Romanov AN, Nesterenko GI, Filimonova NI (2018) Damage accumulation under variable loading of cyclically hardening material at the stages of formation and development of cracks. J Mach Manuf Reliab 47–5:414–419. https://doi.org/10.3103/S1052618818050102 4. Lebedinskii SG (2018) Design modeling of propagation of the fatigue cracks in the steel of molded parts of the railway structures. J Mach Manuf Reliab 47–1:62–66 5. Sunder R (2012) Unraveling the science of variable amplitude fatigue. J ASTM Int 9(1):20, Paper ID JAI103940 6. Elber W (1971) The significance of fatigue crack closure. In: Smith CW (ed). Damage tolerance in aircraft structures, vol 486. ASTM STP, pp 230–242 (1971) 7. Susmel L, Taylor D (2011) The theory of critical distances to estimate lifetime of notched components subjected to variable amplitude uniaxial fatigue loading. Int J Fatigue 33(7):900– 911. https://doi.org/10.1016/j.ijfatigue.2011.01.012 8. Braccesi C, Cianetti F, Tomassini L (2015) Random fatigue. A new frequency domain criterion for the damage evaluation of mechanical components. Int J Fatigue 70:417–427. https://doi. org/10.1016/j.ijfatigue.2014.07.005A 9. Kathleen RD (1986) Fatigue crack growth of gun tube steel under spectrum loading. Dissertation, Virginia polytechnic institute and state university 10. Wheeler OE (1972) Spectrum loading and crack growth. Trans ASME J Basic Eng 94:181–186 11. Willenborg J, Engle RH, Wood HA (1971) A crack growth retardation model using an effective stress concept. AFFDL-TM-71–1 FBR, WPAFB (1971) 12. Brown BB, Reiner AN, Davidson TE (1972) The fatigue life characteristics of the 105 mm M137A1 Howitzer Barrel. Watervliet Arsenal Rep 7202:6 13. Gadolina IV, Plotnikov EV, Bautin AA (2020) Studying the crack growth rate variability by applying the Willenborg’s model to the Markov’s simulated trials. In: Advances in intelligent systems and computing AISC, vol 1127, pp 175–184 14. R Core Team (2020) A language and environment for statistical computing. In: R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/ 15. Savkin N et al (2018) Express analysis of fatigue crack growth life under constant and variable amplitude loading. Mechanics, resource and diagnostics of materials and structures (MRDMS-2018). AIP Conf Proc 2053:030059-1–030059-5. https://doi.org/10.1063/1.508 4420 16. Gadolina IV, Voronkov RV (2021) Numerical study of the crack growth variability under irregular loading. Ind Laboratopy Mater Diagn 87–5:56–60. https://doi.org/10.26896/10286861-2021-87-5-56-60 17. Fisher R, Haibach E (1983) Modeling functions loading in experiments on the evaluation of materials. In: Dahl V (ed) Behavior of steel under cyclic loads, pp 368–405 (1983) 18. Makhutov NA et al (2020) Imitation of random sequences of extremums in fatigue tests with irregular loading. Russ Eng Res 8:614–621. https://doi.org/10.3103/S1068798X2008016X

Ensuring the Safety of a Quarry Distribution Network with a Voltage of 6–35 kV Kh. D. Boboev1,2(B) , R. T. Abdullozoda3 , O. S. Sayfiddinzoda3 , I. T. Abdullozoda2 , and K. V. Ivshina1 1 South Ural State University (National Research University), 76, Lenin Prospect,

Chelyabinsk 454080, Russia [email protected] 2 Tajikistan Power Energy Institute, 73, Street Nosiri Khusrav, Kushonien District 733036, Republic of Tajikistan 3 Tajik Technical University Named After Academician M. Osimi, 10, Prospect Akademikov Radzhabov, Dushanbe 734042, Republic of Tajikistan

Abstract. A rational solution to issues related to the prevention of electrical injuries, as well as to the safety of operation and reliability of electricity supply to consumers at mining enterprises, is impossible without knowledge of the insulation parameters of electrical installations, primarily the magnitude of the total insulation resistance relative to the ground. The control of these parameters during the operation of electrical equipment makes it possible to increase the efficiency and reliability of electrical equipment. The current problem of choosing methods for monitoring the isolation parameters of the network phases relative to the ground of distribution electric networks with an isolated neutral is highlighted. If, during the operation of electrical equipment, to identify areas in which there is a persistent decrease in the level of insulation and to take them out for repair in advance, it is possible to significantly increase the reliability of power supply and operational safety. To solve this problem, the article proposes an isolation control system developed by us. The operability of the proposed insulation control system has been tested on a computer model. The results obtained showed that at rated load in the network or close to it, the error in determining the insulation resistance does not exceed 20%. Thus, the introduction into practice of the developed insulation monitoring system will improve the reliability and safety of power supply systems, and also provides a minimum possibility of false triggering of the monitoring device and a minimum time of interruption in power supply. Keywords: Quarry network · Isolation level · Control system · Isolation parameters

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_42

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1 Introduction Electrical safety is ensured by the design of electrical installations, technical means and methods of protection, organizational and technical measures [1–5]. The tasks of ensuring electrical safety during the operation of electrical installations with a voltage above 1000 V in quarries are solved both by improving the protective characteristics of existing protective equipment and by developing new methods and devices [2, 6–10]. In accordance with [11, 12], the following main technical methods and means are used at mining enterprises to ensure electrical safety in quarry distribution networks (QDN) with a voltage above 1000 V: protective grounding, protection against singlephase earth faults, isolation of current-carrying parts and its control, etc. Electrical protective properties of a set of safety means used in It is convenient to describe electrical networks with special indicators that characterize the safety of the system as a whole [13–17]. It was noted above that ensuring electrical safety in open-pit mining depends on solving a number of issues, among which one of the main ones is the control of the insulation resistance of the network phases relative to the ground. In the operating mode, the insulation of electrical equipment is affected by electrical, thermal, mechanical and other loads. They cause complex processes in isolation, the consequence of which is a constant deterioration of properties, called aging [1, 2, 10, 18–23]. Timely detection of network sections with reduced insulation resistance is one of the main measures to prevent electric shock and maintain uninterrupted power supply. In addition, the reliability of electrical equipment and the safety of its operation are directly related to the insulation parameters of electrical equipment and, above all, the amount of capacitance and active insulation resistance relative to the ground. The control of these parameters during the operation of electrical equipment makes it possible to increase the efficiency of electrical equipment, the quality of the technological process. When operating electrical distribution networks, the main requirements for electrical installations are the reliability of the supply of electrical energy to consumers and the safety of operation of electrical equipment. The safety of operation of electrical equipment is largely determined by the state of insulation of electrical networks and installations [10, 24–27]. Damage to the electrical insulation between the wire and the ground or the housing of an electrical installation can cause electric shock to a person when touching the metal parts of electrical receivers that are energized as a result of insulation damage or as a result of exposure to step voltage. Damage to the electrical insulation between the wire and the ground can cause leakage currents to the ground. These currents, under certain conditions, can cause ignition of electrical equipment or an explosion in an explosive environment. Thus, in order to ensure fire safety, explosion safety and electrical safety, it is necessary to maintain the insulation of the network at a high level. This requirement can be met by the use of effective measurement methods and isolation monitoring devices.

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2 Relevance and Problem Statement There are two types of insulation monitoring during the operation of electrical equipment: periodic and continuous. The classification of existing methods of periodic insulation monitoring without removing the operating voltage with an assessment of the advantages and disadvantages was considered in [22, 28, 29]. The conducted studies have shown that of the known methods, taking into account the metrological requirements and the need to create safe conditions for those involved in measurements, the most suitable will be an indirect method that provides obtaining the necessary information parameters due to artificial displacement of the neutral [2, 10, 22, 23]. Of these, the most acceptable from the point of view of safety and accuracy of measurements, as well as reliability of power supply, is an indirect method based on connecting an additional capacity to one of the phases [22, 30]. In order to assess the influence of various factors on the results of measuring the insulation parameters by the indirect method, we developed a computer model of a quarry distribution network [8, 15, 18], which allowed us to obtain data for various methods of the indirect method of measuring the insulation parameters of the network phases relative to the ground. In [10, 28], a method for measuring the active and capacitive components of the insulation resistance of the phases of the network relative to the ground is considered when connecting an additional capacity to one of the phases of the network and measuring voltages in this network. The conducted studies have shown that with asymmetry in the network, as well as with changes in the magnitude and nature of the load, the error in determining the insulation parameters does not exceed 8%. Periodic inspections of the insulation condition and high-voltage tests do not exclude the possibility of emergency damage, and therefore electric shock. In order to reduce the likelihood of emergencies, it is necessary to organize continuous isolation monitoring in existing installations, which is especially important in networks with isolated neutral. Over time, during the operation of electrical installations of quarries of mining enterprises, significant changes in the network scheme are observed in terms of length, number of lines, composition of consumers and the quality of insulation of working electrical installations. These changes are caused by the action of operational personnel, the impact of protective devices on individual elements of the electrical installation, aging insulation and other factors. With such changes in the length of the network and the composition of working consumers, the parameters of the insulation resistance of the network also change, i.e. the total insulation resistance relative to the ground and its active and capacitive components. In addition, it is known that the insulation parameters of electrical installations are not stable over time. The decrease in insulation properties due to the aging of materials under operating conditions occurs not only under the influence of environmental factors, but also as a result of electrical processes occurring in electrical networks. Therefore, even today, the task of ensuring control over the state of insulation and timely detection and elimination of insulation defects before they develop into phaseto-phase and multi-site earth faults is urgent. The fulfillment of this task will prevent the occurrence of dangerous situations and ensure proper electrical safety conditions during mining operations.

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The state of insulation of electrical installations with an isolated neutral is a determining factor in their reliable operation. This issue is of particular relevance for special electrical networks (mining enterprises, oil and gas enterprises, etc.) with severe operating conditions of electrical equipment. The organization of technically competent operation of such networks requires the determination of three parameters of network isolation relative to the ground (full, active and capacitive). Thus, one of the promising tasks associated with increasing the efficiency and reliability of power supply is to control the insulation parameters of electrical installations. In addition, to ensure the reliability of electrical installations and uninterrupted power supply, it is necessary to maintain the insulation of the network at the proper level.

3 Research Methods and Isolation Control System Continuous monitoring of insulation resistance in QDN with insulated neutral contributes to an increase in the level of electrical safety of electrical installations and the reliability of power supply to consumers, since it allows timely detection of a decrease in insulation resistance and thereby prevent accidents in electrical installations [2, 4, 7, 31]. Figure 1 shows the classification of known continuous insulation monitoring schemes based on the analysis of literary sources. Note that the most common currently in 6– 35 kV networks is the scheme of 3 voltmeters connected to the network via a voltage transformer of the VTOM-6 type. The advantages and disadvantages of this scheme are well known. Therefore, it can be argued that with the help of such a scheme, only cases of insulation breakdown are detected, i.e. an accomplished event. The latter does not allow timely detection of the beginning of the process of reducing the level of isolation, and consequently, to manage the state of isolation in QDN.

Fig. 1. Classification of known continuous insulation monitoring systems.

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The existing systems for determining the insulation resistance of the network phases relative to the ground have significant disadvantages. Most of them (fixing the reduction, rather than determining the value of the insulation resistance, do not have a selective effect, additional high-voltage equipment needs to be installed, can affect the quality of electricity) can be eliminated using a method for determining the insulation resistance of the phases of the network relative to the ground, based on measuring the operating parameters in the network. The analysis performed in [2, 7, 10, 31] showed that the most promising systems for monitoring the isolation parameters of the network phases relative to the ground are those based on measuring the operating parameters in an electrical network with an isolated neutral. For distribution networks of industrial enterprises, we propose an isolation control system, the theoretical foundations of which are described in [2]. An insulation monitoring system containing two measuring units, the first of which, installed at the beginning of the line (MU1), is connected to a three-phase voltage transformer, for example, of the NTMI type (TV1), and the second, installed at the end of the line (MU2), is also connected to a similar voltage transformer (TV2) and, in addition, to the current transformers installed in each phase (TA), the first output of the first measuring unit is connected to the first input of the computing unit (CU), and the first and second outputs of the second measuring unit, respectively, to the second and third inputs of the computing unit (CU), the output of which is connected to the information unit (IU), the current value of the insulation parameters is displayed (Fig. 2). When single-phase earth faults occur, the operation of the insulation monitoring system is blocked [31].

Fig. 2. Operation of the insulation control system.

For a practical study of the developed insulation control system, as well as checking its operability and obtaining additional information about the operation of the insulation control system, we considered the scheme of one of the lines with a load, the schematic diagram of which is shown in Fig. 3. It should be noted that the basis is a computer model developed at the SUSU Department of “Life Safety” [22, 28].

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Fig. 3. Checking the operability of the developed insulation control system.

The model contains the following elements: 35 kV three-phase source; Three-phase two-winding transformer; Switch installed at the main step-down substation (ThreePhase Breaker); Overhead and cable lines extending from the bus section with connected load (BL-1, KL-1, Three-Phase Series RLC Load); Active and capacitive insulation resistance of the network phases relative to the ground (RC1-RC6); The purpose of blocks 1 and 2 will be viewed below. The model also uses the Scope blocks (a virtual oscilloscope displaying graphical dependencies of the studied quantities in a function of time in a form resembling the waveforms of a modern digital oscilloscope), Display (designed to represent the numerical values of the measured quantities on the screen) and RMS (used to measure the effective value of the input signal), (Fig. 3). The insulation control system includes the following main blocks: block 1, which determines the complex values necessary for calculating the voltages and currents at the beginning and end of each line (Fig. 4); block 2, in which the total insulation resistance of the phases of the network relative to the ground, as well as each phase, is calculated. The values are displayed (Fig. 5). The study of the errors of the proposed insulation control system consists in revealing the dependences of the values of the installed total insulation resistance of the network relative to the ground on the asymmetry in it, as well as the magnitude and type of load. A person, as an element of an automated control system, perceives the displayed information and decides whether to continue the operation of the network section or turn it off. Based on the information received about the state of isolation of the network section, the dispatcher decides to continue its operation.

4 Research Results and Discussions The test results are shown in Table 1. The load in the network varied from 10 to 140%, the influence of active, reactive and full load in the network was studied. It follows from this table that with a decrease in the load in the network, the error in determining the total insulation resistance of the phases of the network relative to the ground increases. At low load, the voltages U1 and U2 are close to each other and

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Fig. 4. a The scheme of measuring units 1; b the scheme of the computing unit 2.

Fig. 5. The scheme of the computing unit 2.

the small value of the load current results in a measurement error. At rated load in the network (from 90 to 110%), the error in determining the total insulation resistance does not exceed 20%. It should be noted that with a minimum load, the relative error can reach 90%. It should be particularly noted that the presence of asymmetry in the network practically does not affect the measurement results. The research data on the computer model of the network section showed the operability of the developed system for monitoring the isolation of the phases of the network relative to the ground. The proposed system for monitoring the insulation resistance of the network relative to the ground, consisting of an isolation monitoring device and an

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Table 1. Results of the study of the insulation control system operation on a computer model of a quarry distribution network (in the model Z = 39.548 kOhm). Network Active load in the network Reactive load in the load % network

Full load on the network

Obtained Inaccuracy Obtained Inaccuracy Obtained Inaccuracy during during during measurements measurements measurements Z, kOhm

δ, %

Z, kOhm

δ, %

Z, kOhm

δ, %

10

511

−92,2

854,2

−95,4

438,625

−91

20

268

−85,2

422,33

−90,6

220,39

−82

30

172,842

−77,12

280,62

−86

147,177

−73,13

40

129,918

−69,55

210,15

−81,2

110,546

−64,2

50

104

−62

167,9

−76,44

88,522

−55,3

60

86,84

−54,4

139,82

−71,7

73,84

−46,4

70

74,5

−47

119,79

−67

63,337

−37,5

80

65,26

−39,4

104,77

−62,2

55,452

−28,7

90

58,06

−33

93,08

−57,5

49,328

−20

100

52,29

−24,3

83,75

−52,77

44,427

−11

110

47,54

−16,8

76,12

−48

40,41

−2,13

120

43,64

−9,3

69,76

−43,3

37,065

7

130

40,3

−1,8

64,34

−38,5

34,236

15,5

140

37,45

5,6

59,78

−33,8

31,81

24,3

automatic disconnection device of the outgoing line with reduced phase isolation, provides a minimum possibility of false triggering of the monitoring device and a minimum time of interruption in power supply.

5 Conclusion 1. To improve the safety and reliability of power supply to mining enterprises with a complex technological process, increased danger to fires and explosions, it is necessary to continuously monitor insulation resistances in networks with a voltage of 6–35 kV. 2. The data of the study on the computer model of the network section showed the operability of the developed system for monitoring the isolation of the phases of the network relative to the ground. The use of an insulation monitoring system will allow timely identification of a network section where there is a tendency to reduce the insulation resistance and disconnect this section from the power source before an emergency occurs, which makes it possible to exclude the impact on the insulation of the entire electrically connected network of overvoltage’s arising from single-phase

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earth faults. This ensures the elimination of the previously mentioned reasons for reducing the level of isolation. 3. The isolation monitoring system allows you to selectively monitor the isolation of network sections. Polling of sections is carried out cyclically and when a decrease in the insulation resistance of any section is detected below the set level, the corresponding information appears on the display unit, with a further decrease, the system disables the emergency section [29].

References 1. Gladilin LV, Shchutsky VI, Batsezhev YG, Chebotaev NI (1977) Electrical safety in the mining industry. Moscow 2. Sidorov AI (1994) Theory and practice of a systematic approach to ensuring electrical safety in open pit mining. Dissertation, South Ural State University 3. Sidorov AI, Petrov OA, Ushakov IM (1990) The error of the indirect method of measuring the capacitive conductance relative to the ground in electrical networks with a voltage of 6–10 kV. In: Electrical, pp 33–36 4. Shchutsky VI, Sidorov AI, Sitchikhin YV, Bendyak NA (1996) Electrical safety in open pit mining. Moscow 5. Shchutsky VI, Mavritsyn AM, Sidorov AI, Sitchikhin YV (1983) Electrical safety in open pit mining. Moscow 6. Volotkovsky SA, Shchutsky VI, Chebotaev NI (1987) Electrification of surface mining: a university textbook. Moscow 7. Lapchenkov KV (1998) Management of the state of insulation in electrical distribution networks. Dissertation, South Ural State University 8. Bariev NV (1977) Maintenance of grounding devices at mining and coal enterprises. Moscow 9. Abdulloev RT, Tryapitsyn AB, Khanzhina OA (2016) The electrochimical corrosion processes simulating of grounding devices. In: 2nd international conference on industrial engineering, applications and manufacturing. https://doi.org/10.1109/ICIEAM.2016.7911694 10. Boboev KD, Bogdanov AV (2021) Isolation parameters relative to the ground in the quarry distribution networks of mining enterprises of the Republic of Tajikistan. Bulletin of South Ural State University Ser. Energy, pp 29–37. https://doi.org/10.14529/power210103 11. GOST 12.1.019-79 (1979) Electrical safety. General requirements. Publishing House of Standards 12. GOST 12.1.019-2009 (2011) Electrical safety. General requirements and nomenclature of types of protection. Publishing House of Standards 13. Bukhtoyarov VF (1983) Protection against earth faults. In: Occupational Safety in Industry, pp 55–56 14. Burgsdorf VV, Jacobs AI (1987) Grounding devices of electrical installations. Moscow 15. Sidorov AI, Abdulloev RT (2016) Development of a screening experiment plan to study the influence of various factors on the corrosion process of grounding devices. In: Bulletin of the South Ural State University Series: Energy, pp 52–58. https://doi.org/10.14529/power160207 16. Perera N, Rajapakse AD, Buchholzer TE (2016) Isolation of faults in distribution networks with distributed generators. IEEE Trans Power Deliv 2347–2355. https://doi.org/10.1109/ TPWRD.2008.2002867 17. Mousse KB, Shuletskaya SP (1982) Devices of preventive directional control of insulation in 6 kV distribution networks with isolated neutral. Ind. Energy 35–38

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18. Sidorov AI, Petrov VI, Pichuev AV, Suvorov IF (2009) Ensuring electrical safety in power supply systems. Chita 19. Peturov GM (2004) Control of insulation parameters of electrical networks of industrial enterprises with severe operating conditions. Min Inf Anal Bull (Scientific and Technical Journal) 270–271 20. Pichuev AV (2011) Parameters of electrical network insulation taking into account active and capacitive resistances to absorption current. Electr Saf 22–28 21. Uakhitova AB (2012) Methods of monitoring the state of insulation in an asymmetric network with an isolated neutral voltage of 6–10 kV. News of higher educational institutions. Energy Probl 102–106 22. Sidorov AI, Boboev KD (2020) Investigation of the errors of the indirect method of measuring the parameters of the isolation of the phases of the network relative to the ground on a simulation model. In: Occupational safety in industry, pp 24–29 23. Utegulov BB (2016) The method of determining the insulation parameters in three-phase electrical networks with isolated neutral with voltages up to and above 1000 V. In: IOP conference series: earth and environmental science, Beijing, p 012024. https://doi.org/10. 1088/1755-1315/40/1/012024 24. Boboev K, Sidorov A, Davlatov A (2020) Evaluation of indirect methods for determining the isolation parameters of the network phases relative to the ground on a computer model. In: International Ural conference on electrical power engineering (UralCon), pp 556–560. https://doi.org/10.1109/UralCon52005.2021.9559538 25. Sidorov AI (2001) Fundamentals of electrical safety. Chelyabinsk 26. Utegulov BB (2018) Analysis of the error of the developed method of determination the active conductivity reducing the insulation level between one phase of the network and ground, and insulation parameters in a non-symmetric network with isolated neutral with voltage above 1000 V. In: International Conference “Actual Problem of Electromechanics and Electrotechnology” Institute of Physics Publishing, pp 012–015. https://doi.org/10.1088/1757-899X/313/ 1/012015 27. Shchutsky VI, Sidorov AI (2001) Safety in the operation of electrical systems. Chelyabinsk 28. Sidorov AI, Boboev KD, Medvedeva YV, Sadullozoda SS (2021) Investigation of indirect methods for determining the insulation parameters on a computer model. Bull East Sci Res Inst Sci Cent Ind Environ Saf 47–54 (2021). https://doi.org/10.25558/VOSTNII.2021.32.20.005 29. Boboev KD, Averyanov YI, Bogdanov AV, Kravchuk IL (2022) Error analysis of the indirect method for monitoring network isolation parameters relative to the ground in the MATLAB/Simulink software environment. In: Bulletin of the South Ural State University. Series: energy, pp 106–116. https://doi.org/10.14529/power220112 30. Boboev K, Sidorov A, Khanzhina O (2020) Determining ground insulation parameters in quarry distribution networks of mining companies in Tajikistan. In: International Ural conference on electrical power engineering (UralCon), pp 344–348. https://doi.org/10.1109/Ura lCon49858.2020.9216311 31. Boboev KD, Averyanov YI, Bogdanov AV, Kravchuk IL (2022) Organization of isolation control in the distribution network of the “Terror” quarry. In: Bulletin of the South Ural State university. Series: energy, pp 57–65. https://doi.org/10.14529/power210407

Analysis of Recreational Zones Negative Impact on Water Area of Lake Baikal O. Grebneva1,2 , O. Lavygina1(B) , and O. Vanteeva2 1 Ikutsk National Research Technical University, 83, Lermontov Street, Irkutsk 664074, Russia

[email protected] 2 Melentiev Energy Systems Institute of SB RAS, 130 Lermontov Street, Irkutsk 664033, Russia

Abstract. The relevance of scientific research in the field of assessing of anthropogenic impact on water resources, in particular, on the water area of Lake Baikal, is confirmed by many studies in this direction. One of the priority sources of water area pollution is surface effluent, which is generated from highways located on the coast. The results of numerical studies (on the example of the urban-type settlement Listvyanka) are showed that during the operation of the road 12 tons of suspended solids, 1.6 tons of mineral salts and 0.16 tons of oil products enter the water area of Lake Baikal annually. To minimize the flow of pollution with surface effluent, it is advisable to carry out timely assessment of the harmful effects of poor-quality road surfaces for the organization of regular cleaning and their timely repair. These measures will significantly reduce the negative impact on the water area of the investigated object. Keywords: Surface effluent · Water area · Lake Baikal · Sources of pollution · Recreational areas

1 Introduction The pollution of Lake Baikal is regarded as one of the global environmental problems. At the same time, special attention is paid to atmospheric air pollution [1–4], wastewater discharge into a water area, and waste generation as a result of recreational activities. When studying the pollution of a water area, the problems of the formation and disposal of household wastewater coming from the exploitation of recreational areas and from settlements located on the coast of the lake are most often considered. However, in addition to household and industrial effluents, surface waters generated in the adjacent territory enter the water area. When studying the ecological problems of Lake Baikal, special attention is paid to industrial and recreational activities. Many authors [5–10] study the consequences of the activities of the Baikal Pulp and Paper Mill (BPPM), various tourist complexes on the state of the water area. However, the problem of the state of the road infrastructure, which should provide not only the possibility of comfortable movement and stay on the territory, but also environmental safety, has not been sufficiently studied. The task of © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_43

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improving residential areas is not only to transform the environment in order to increase comfort and visual perception, but also to protect its components from negative impacts during exploitation. The protection of Lake Baikal is regulated by international, federal and regional legislation [11, 12]. Modifications in modern environmental legislation require a more thorough approach to environmental protection in general, and, in particular, to the protection of the water area of Lake Baikal [13]. According to some authors [14], the East Siberian Railway makes a significant contribution to the pollution of the snow cover and surface waters of the tributaries of Lake Baikal. Typical types of such contaminants are oil products, ferrous and non-ferrous metals. Considering the transport infrastructure located along the coast of Lake Baikal, It should be noted the location of the highway in close proximity to the water area. Similar sites are noted on the territory of the urban-type settlement Listvyanka, Kultuk and others. As a result of the intensive operation of the highway, suspended solids and oil products enter the water area of Lake Baikal. Surface effluent, formed as a result of rainfall and the formation of melt water, carries out products of destruction of road pavements, residues of oily products, elements of anti-ice mixtures, etc. On the whole, the ecosystem of the southern part of Baikal and its coast continues to be strongly influenced by emissions into the atmosphere from the enterprises of Baikalsk, Listvyanka, Slyudyanka and the transport highway running along the coast [14].

2 Research Methods The research method is based on the methodology developed by the Research Institute VODGEO and recommended for determining the volume of surface effluent and the concentration of pollution in storm wastewater. The average annual volume of surface effluent from residential areas is determined in accordance with the Recommendations for the Calculation of Systems for Collection, Drainage and Treatment of Surface Effluent in Residential Areas [15]. The average annual volume of surface effluent generated in residential areas and sites of enterprises during the period of rainfall and snow melting is determined by the formula: Wse = Wr + W

(1)

In Eq. 1: Wr , W —the average annual volume of rain and melt water, respectively, m3 . The average annual volume of rain and melt water, flowing down from residential areas and industrial sites, is determined by the formulas: Wr = 10 · hr · ψr · F

(2)

W = 10 · h · ψ · F

(3)

In Eqs. 2–3: hr —precipitation layer, mm, for the warm period of the year, determined by [16]; ψr i ψ—total effluent coefficient of rain and melt water, respectively; F— drainage area, ha; h—precipitation layer, mm, for the cold period of the year (determines

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the total annual amount of melt water), or the water reserve in the snow cover by the beginning of snow melting, determined by [16]. The volume of pollution in the form of suspended solids, mineral salts and oil products is determined by the formula: M =c·F

(4)

In Eq. 4: c—specific removal of pollutants from residential areas, kg/ (ha per year). For small and medium-sized cities with old low-rise buildings and an insufficient level of improvement, the specific removal of suspended solids should be taken 20% more in comparison with the data given in Table 1. Table 1. Specific removal of pollutants. Polluting component

Specific removal of pollutants, kg/(ha per year)

Suspended solids

2500 (adjusted for the low level of improvement 3000)

Oil products

40

Mineral salts

400

Table 1 shows averaged data for determining the mass of pollutants discharge with surface effluent for suspended solids, oil products and mineral salts. In the absence of the analysis results for the concentration of pollutants in the surface effluent diverted for treatment, it is allowed to take it by analogs [15]. The approximate composition of surface effluent for various sections of the catchment surfaces of residential areas is given in Table 2. The most polluted by all indicators is the melt effluent, which by the value of the BPK20 indicator is close to untreated domestic wastewater. Using specific concentrations, the calculation of pollutants coming with melt and rain effluent was made based on the volume of the generated effluent. For this, the formula was used: M = k · Wse

(5)

Table 2. Results of determining the specific removal pollutants mass. Polluting component

Specific removal of pollutants, kg/(ha per year)

Suspended solids

2500 (adjusted for the low level of improvement 3000)

Oil products

40

Mineral salts

400

In Eq. 5: k—specific concentrations of pollutants (main streets with heavy traffic); Wse —the average annual volume of rain and melt water, m3 .

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3 Object of Study When calculating of pollutants, a road, which includes a section of the Baikalsky tract route and a road along the street Gorky on the territory of Listvyanka settlement of Irkutsk region, was taken as the object of study. This settlement is located along the coastline of Lake Baikal and is a recreational center on the northern coast. The choice of this site of road as an object of research is due to the high traffic intensity of vehicles, as well as the proximity of the highway to the water area of Lake Baikal. Figure 1 shows the location of the analyzed section of the road.

Fig. 1. Schematic map of the location of the highway along the water area of Lake Baikal (highlighted in red).

There are no industrial enterprises with significant emissions in the urban-type settlement Listvyanka. The influence on air pollution is exerted by the shipyard, small boiler houses, stove heating of the residential sector and vehicles [14]. The study area is marked in Fig. 1, originates from the Baikalsky tract and turns into street Gorky on the territory of Listvyanka settlement. The total length of the road along the coastline is 6.8 km. The total area of the surface road was approximately 8.4 hectares. Figure 2 shows a section of the road passing along the coastline of the lake Baikal on the territory of the Listvyanka urban-type settlement. This territory is characterized by a high recreational load, which manifests itself in an increase in traffic flow, mainly on weekends and holidays. The Fig. 2 shows that the road is located along the coastline of Lake Baikal. The state of the road pavement and the pedestrian zone has a high degree of destruction; there are no drainage devices for storm sewers. All of these factors lead to the massive removal of suspended solids and oil products into the water area of Lake Baikal. In the spring–summer periods, when the snow cover melts and precipitation falls in the form of rain, these processes manifest themselves most intensively. The features of the sharply

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Fig. 2. A fragment of the road and the water area of Lake Baikal: a in summer (Photo by authors); b in winter (Photo by Alexey Krivelya [17]).

continental climate on the territory of Eastern Siberia, which consist in the frequent change of positive and negative air temperatures, lead to increased wear and tear of road pavements and their accelerated destruction.

4 The Discussion of the Results The calculation carried out according to the enlarged indicators of the pollutants concentrations in residential areas showed that the priority pollutant entering the water area of Lake Baikal is suspended solid. When analyze the quantitative ratio of pollutants in the winter and summer periods, it can be seen that in the warm period of the year, the mass of pollutants is significantly higher. This is primarily due to the quantitative ratio of precipitation. In accordance with [16], for the calculations, a precipitation layer of 401 and 69 mm was taken in summer and winter, respectively. It should be noted that climatic data for the city of Irkutsk were taken for calculations. Tables 2, 3 show the results of pollutants calculations coming with surface effluent from the investigated section of the road. Table 3. Results of determining the total pollutants mass per year. Polluting component

Total per year Kg

Ton

Suspended solids

12,240

12.24

Oil products

163.2

0.1632

Mineral salts

1632

1.632

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Based on the obtained data, a diagram was drawing. It shows the ratio of gross discharges of pollutants from the territory of the highway to Lake Baikal, which is shown in Fig. 3.

Fig. 3. Diagram of the ratio of gross discharges of pollutants from the territory of the highway to Lake Baikal (blue—Suspended solids, brown—Oil products, green—Mineral salts).

The predominance of suspended solids in the surface effluent is primarily connected with the destruction of road surface during intensive operation of the road. The danger of the enters of a large amount of suspended solids leads to a change in the structure and properties of bottom sediments, an increase in water turbidity, a decrease in the concentration of dissolved oxygen, etc. To a lesser extent, mineral salts, which are formed as a result of work on the maintenance of the road, with the destruction of road pavements, enter with the removal of surface effluent. Mineral salts (in the form of chlorides and sulphates) entering in excess quantities into the water area of Lake Baikal. This leads to a change in the hydrochemical composition of water, a modification of the species composition of aquatic organisms, etc. The relatively small share of oil products entering the water area is due to the relatively low specific indicator. However, the entry of oil products into water resources is connected with the formation of carcinogenic and mutagenic substances that can accumulate in the food chain. Also, the flow of oily surface water can lead to a change in the oxygen regime, violations of the reproductive functions of aquatic organisms, etc. Comparison of the calculated data with studies that show an increase in the concentration of oil products noted in samples taken near the road and boiler houses [18] indicate the importance of the contribution of road transport to the total pollution of surface effluent. Tables 4, 5 show the results of calculations of the pollutants mass, determined by specific concentration indicators. Based on the results of the calculated study, a comparison was made of the amount of discharged pollutants with rain and melt effluent. The histograms are shown in Figs. 4, 5 and 6. The obtained data can be used in the development of criteria for the application of standards for permissible impact on the ecosystem of Lake Baikal [19], as well as in ranking according to the intensity of the total anthropogenic load, which allows

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Table 4. The results of calculating the pollutants mass coming with rain effluent, tons per year. Polluting component

The value of indicators of rainwater pollution, mg/dm3

Rain effluent Suspended solids, mg/dm3

BPK (20), mg/dm3

Oil products, mg/dm3

1000

80

20

0.3926592

0.0981648

Surface effluent volume, 4908.24 m3 Total

4.90824

Table 5. The results of calculating the pollutants mass coming with melt effluent, tons per year Polluting component

The value of indicators of rainwater pollution, mg/dm3

Melt water effluent Suspended solids, mg/dm3

BPK (20), mg/dm3

Oil products, mg/dm3

3000

120

25

0.1013472

0.021114

Surface effluent volume, 844.56 m3 Total

2.53368

Fig. 4. Comparison of discharged suspended solids amount with rain and melt effluent (blue—rain effluent, brown—melt water effluent).

using a universal methodology for a comprehensive assessment of the region’s water management based on geoinformation technologies [20].

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Fig. 5. Comparison of BPK20 amount with rain and melt effluent (blue—rain effluent, brown— melt water effluent).

Fig. 6. Comparison of discharged oil products amount with rain and melt runoff effluent (blue— rain effluent, brown—melt water effluent).

5 Conclusions The analysis showed that annually 12.24 tons of suspended solids; 0.16 tons of petroleum products; 1.6 tons of mineral salts come from the territory of the road with surface effluent. Reducing the mass of pollutants can be achieved by increasing the level of landscaping of the coastal area, regular cleaning of the area, and timely repair of road surfaces. Thus, when studying the environmental problems of the Baikal region, one should not be limited to research exclusively on industrial and recreational activities. The calculation method proved that the main mass of the pollutants in the surface effluent is contained in the summer period. Analyzing the degree of coastal improvement on the territory of settlements, as well as the state of road surfaces, it can be concluded that infrastructure facilities not only do not provide environmental safety, but are also sources of adverse impact on the water area of Lake Baikal and the ecosystem as a whole.

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The data obtained as a result of the study allows concluding that it is necessary to increase the degree of improvement of residential areas located in close proximity to the water area of Lake Baikal and intensively exploited for recreational purposes. Climatic factors and the special value of the protected object presuppose the use of advanced technologies in the improvement and drainage systems of surface runoff. One of the main and modern areas of improvement is the installation of systems for drainage of surface runoff using not only equipment for its picking, but also cleaning. Such measures will reduce the anthropogenic load on the water area of Lake Baikal. Acknowledgements. The work was carried out within the framework of the scientific project of the ESI SB RAS “Theoretical foundations, models and methods for control of the development and functioning of intelligent pipeline systems in the energy sector. Topic number: FWEU-2021-0002. Registration number: AAAA-A21-121012090012-1.

References 1. Lavygina OL, Grebneva OA, Korabenkova ON, Smolyar AV (2020) An assessment of prevented ecological deprivation during the implementation of innovative technologies in the systems of housing and utility infrastructure. J. Izvestiya vuzov. Investitsii. Stroitel’stvo. Nedvizhimost (Proceedings of Universities. Investment. Construction. Real estate) 10(2):234–241. https://doi.org/10.21285/2227-2917-2020-2-234-241 2. Lavygina O, Grebneva O, Maizel I (2019) Environmental aspects for the reconstruction of housing and communal services in the village Listvyanka of Irkutsk region. In: IOP conference on series: materials science and engineering, vol 667, p 012056. https://doi.org/10.1088/1757899X/667/1/012056 3. Lavygina O, Grebneva O (2020) Study of changes in emissions into the atmosphere with the reconstruction of heat supply systems. IOP Conf Ser: Mater Sci Eng 880(1):012048. https:// doi.org/10.1088/1757-899X/880/1/012048 4. Grebneva O, Lavygina O (2021) Study of ecological and economic efficiency for resource supplying organizations in the transition to alternative sources. IOP Conf Ser: Earth Environ Sci 751:012007. https://doi.org/10.1088/1755-1315/751/1/012007 5. Korytny LM (2012) Baikal Pulp and Paper Mill (BPPM): ecological serial (Beginning). J ECO (All-Russian economic journal) 2:22–38 6. Kuzmin MI (2012)) Scientists about Baikal. J ECO (All-Russian economic journal) 2:39–57 7. Korytny LM (2012) Baikal Pulp and Paper Mill (BPPM): ecological serial (The end). J ECO (All-Russian economic journal) 3:105–122 8. Zilov EA (2013) Current state of anthropogenic impact on Lake Baikal. J Siberian Federal Univ Biol 4(6):388–404 9. Afonina TE, Kolomina TM, Ponomarenko EA, Slauta AA (2015) Assessment of the quality of water resources in the coastal part of the lake Baikal and the sources of their pollution. J Bull Irkutsk State Tech Univ 6(101):37–43 10. Lavygina O, Grebneva O (2021) Analysis of emission estimates using the Atmospheric Pollution Index in the Baikal Natural Territory. IOP Conf Ser: Earth Environ Sci 751:012015. https://doi.org/10.1088/1755-1315/751/1/012015 11. Water Code of the Russian Federation N 74-FZ by 03.06.2006 (edition by 08.12.2020) 12. Federal Law “On Environmental Protection” N 7-FZ by 10.01.2002

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13. Gladun E, Zakharova O (2017) State environmental ideology: from tsarist Empire to sustainable Russia. J BRICS Law J 4(4):39–64. https://doi.org/10.21684/2412-2343-2017-4-439-64 14. Belozertseva IA, Vorobyeva IB, Vlasova NV et al (2017) Chemical composition of snow in the water area of lake baikal and on the adjacent territory. J Geogr Nat Resour 38(1):68–77 15. Recommendations for calculating systems for collecting, diverting and treating surface effluent in residential areas, sites of enterprises and determining the conditions for its release into water bodies. Moscow (2015) 16. SR 131.13330.2020 (2020) Set of rules. Building climatology 17. IA Irkutsk today (2021) https://irk.today/ez5. Accessed 15 May 2021 18. Yanchuk MS et al (2019) Petroleum products in the surface and snow waters of the southwestern coast of lake Baikal. J News from the irkutsk state university. Ser: Earth Sci 18:140–149 19. Ulzetueva I, Gomboev B, Zhamyanov D et al (2019) Advantages and disadvantages of the state system for regulating the water area quality in the Baikal natural territory. In: Conference proceedings 19th international multidisciplinary scientific geoconference (SGEM 2019), p 17 20. Beshentsev AN, Tsibudeeva DT (2018) Geoinformation monitoring of water use in Lake Baikal basin. Geoinf Mapp Nat Prot Secur Environ Saf 24(1):341. https://doi.org/10.24057/ 2414-9179-2018-1-24-341-347

Basic Procedure to Estimate the Accumulated Environmental Damage Caused by Mining Facilities as Exemplified by the Kachkanar Tailing Dump in the Middle Urals V. A. Pochechun1(B) , V. E. Konovalov2 , and A. I. Semyachkov1 1 Ural Branch of RAS, 29, Moskovskaya Street, Yekaterinburg 620014, Russia

[email protected] 2 Ural State Mining University, 30, Kuibysheva Street, Yekaterinburg 620144, Russia

Abstract. Quantifying the accumulated environmental damage caused by economic activity facilities, including those of the mining complex, entailing further selection or development of the environmental measures to restore disturbed natural systems is an urgent problem. There are known techniques to estimate environmental and economic damage, but they are not perfect enough and require significant improvement. The problem is the lack of unified methodological approaches to such estimations, e.g., the already accumulated damage from facilities with exhausted ecological capacity or decommissioned ones. Estimating harm or damage should start with a field survey of the facility causing it, followed by a study of the affected environment with further analysis of field and laboratory data. The study comprises a full-scale survey of a complex hydraulic structure—a tailing dump located in the area of the Kachkanar industrial hub in the Middle Urals and posing a potential technospheric hazard. Some components of this tailing dump have exhausted their ecological capacity, i.e., ceased waste storage activity, and therefore, they cause accumulated environmental damage. The paper proposes an approach and gives some recommendations to develop a procedure for estimating the accumulated environmental damage from mining facilities. Keywords: Assessment of accumulated harm · Environment · Tailings storage · Ecological capacity

1 Introduction The Federal Targeted Program Elimination of Accumulated Environmental Damage for 2014–2025 (hereinafter—the Program) is aimed at restoring disturbed natural systems exposed to negative anthropogenic and technogenic impacts as a result of past economic activity. Herewith, the Program’s priority task is the ecological rehabilitation of territories adversely affected by the accumulated environmental damage resulting from the past mining and ore-dressing facilities activity, which features eliminating environmental © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_44

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hotspots that significantly affect the population and the environment and pose the risk of polluting the environment or emergencies. To achieve this goal, it is proposed to combine the following aspects: • a new pollution object—groundwater, • a new pollution source—industrial water, • a new negative impact object—deformation of the ground surface under the impact of mining operations, • migration of harmful substances through air (dust from dumps), water, and soil. 1.1 Relevance and Scientific Significance of the Issue In the Ural mining region, mineral deposits are developed by open-cast, underground, and subsea mining (at alluvial mines and sand deposits). This results in the formation of recesses (quarries, cuts, pits, etc.), piles (rock dumps, liquid and solid waste landfills—tailing and sludge dumps, settling ponds, etc.), and areas of contaminated soil and deformed ground surface. The soil pollution sources are quarries, dumps, landfills, and primary mineral processing facilities. Hence, the material indicator of the negative environmental impact is the accumulation of harmful substances in soil or water bodies resulting in the risk of pollutants release into the environment. Also, the active impact on the lithosphere during the mining facilities construction and minerals extraction changes the natural stress–strain state of the geological environment both on the ground surface and in the bowels. It is physical (energy) in nature and is expressed in the deconsolidation of rocks, i.e., causes the release of a part of the internal bond energy, the breach of bonds between minerals in rocks, and the rock mass cracking [1, 2]. This leads to an unstable equilibrium of the exposed edges and deformation of the mountain range and, consequently, the deformation of the ground surface, i.e., the risk of emergencies. These phenomena are mechanical in nature and are accompanied by the movement of rocks and mucks. Thus, a change in the natural stress–strain state of the geological environment under open-cast mining conditions causes screes, collapses, landslides, and caving of openpit (quarry) sides, and under the underground mining conditions– rock mass deformation over underground workings (plump holes, cracks, and subsidence) [2–4]. This is most actively expressed during mining, but secondary processes of the ground surface deformation occur in abandoned fields as well. Geomechanical phenomena occurring during the formation and development of accumulated environmental damage objects are not limited to the subsoil. Signs of such phenomena are observed in the interaction of the embankment and its base, i.e. base soils, e.g., dumps, liquid waste dams, etc. [5]. The weak embankment base with the bearing capacity below the design value is deformed, causing the embankment mass destruction, which in turn leads to the base uplift, collapse, or slump. The probability (risk) of the aforementioned earth surface failures occurs when the physicomechanical properties of rocks or mucks mismatch the stresses arising in the rock mass due to technological errors or failure to consider its properties and structure [6]. The probability of such event is usually evaluated based on a geomechanical prognostic model of the rock mass in the possible rock deformation area.

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1.2 Formulation of the Problem The paper aims at studying a complex and potentially dangerous hydraulic structure— a tailing dump as an accumulated environmental damage object and develop recommendations for estimating the environmental damage caused by the objects of the type.

2 Theoretical Introducing an energy indicator characterizing the mechanical change in the ground surface into the concept of accumulated environmental damage along with a material indicator characterizing the accumulation of harmful substances necessitates including areas with the surface ground deformations and objects located in the bowels and causing the manifestation of such deformations, i.e., the complex of underground workings on the territory of accumulated environmental damage, in the list of accumulated environmental damage objects. In this case, according to the Federal Law On Environmental Protection [7], when estimating an accumulated environmental damage object, the area where the accumulated environmental damage object is located, the degree and volume of the negative environmental impact, including the occurrence of emergency risks in the form of the ground deformation, and the population living in the impacted territory or the threat of negative impact from the accumulated environmental damage object should be considered.

3 Practical Significance, Suggestions, and Implementation Results Let us consider the accumulated environmental damage object in detail. The Sverdlovsk region hists the Gusevogorsk titanium-magnetite iron deposit, where a mining enterprise operates. This enterprise is engaged in mining and enrichment of ore, resulting in the formation of refinement tailings. These tailings are stored in a tailing dump, which is an accumulated environmental damage object and, simultaneously, a complex hydraulic structure. This is an alluvial, hill-type tailing dump located in the Vyya River and its right-bank tributary—the Rogalevka River valley, within the enterprise’s land allotment boundaries. The tailing dump consists of three compartments: Rogalevsky, Intermediate, and Vyisky with individual ponds and drainage facilities (Figs. 1, 2). The total area of all the tailing dump compartments is 19.75 km2 [8] including: • Rogalevsky—6.90 km2 , • Intermediate—10.05 km2 , • Vyisky—2.80 km2 ,

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Fig. 1. Intermediate Compartment of the Tailing Dump, Distant View—Rogalevsky.

Fig. 2. Vyisky Compartment of the Tailing Dump.

Including the area of the dump compartment ponds: • Rogalevsky—1.50 km2 , • Intermediate—2.30 km2 , • Vyisky—2.07 km2 . The tailing dump belongs to the primary importance category [9]. The compartments are located in a cascade: Rogalevsky, Intermediate, and Vyisky, with a settling pond water table height difference of 2.77 and 50.8 m from south to north. The Rogalevsky and Intermediate compartment reservoirs are formed by alluvial embankment dams and partially, from the northeast, east, and southeast, by hillsides. The

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Vyya compartment reservoir is formed by blocking the Vyya river valley with a rock-fill dam. Along the Vyya River channel, the compartment is bounded by the downstream retaining dam of the Nizhnevysky reservoir, located in a cascade to the Vyysky recycle water compartment. Rogalevsky and Intermediate compartments are designed to store refinement tailings and clarify the liquid slurry. The Vyisky compartment is mainly intended to receive clarified water from the Rogalevsky and Intermediate settling ponds. Waste stored in the tailing dump amounts to 700.6 mln. m3 , including, by compartments [10]: • Rogalevsky—328.4 mln. m3 , • Intermediate—368.9 mln. m3 , • Vyisky—3.3 mln. m3 . The residual (free) tailing capacity of the Rogalevsky and Intermediate compartments up to the elevation of 331.0 m is 161.5 mln. m3 [11]. The tailing dump annually receives about 19.470 mln. m3 (36.994 mln. tons)1 of wet magnetic separation tailings. When filling the tailing dump to the elevation of 331 m, the embankment dam height ranges from 40 to 111 m; the length is 11.29 km [12]. The capacity of the Rogalevsky compartment is 318.1 mln. m3 , it contains 5 embankment dams and 1 settling pond. The water volume in the settling pond is 3.2 mln. m3 , the water horizon elevation is 300.37 m. Clarified water from the Rogalevsky settling pond is fed to the Intermediate compartment through a flooded channel. The Intermediate compartment capacity is 340.3 mln. m3 , it contains 5 embankment dams and 1 settling pond. The water volume in the settling pond is 3.8 mln. m3 , the water horizon elevation is 297.6 m. Clarified water from the settling pond is discharged by siphon spillways into the Vyisky compartment. The Vyisky compartment is designed to finally clarify water coming from the Intermediate compartment. Additionally, the Vyisky compartment receives the Rogalevka River flow, quarry waters are pumped in during the warm period, the Nizhnevysky reservoir waters inflow through the bottom outlet, the slurry is pumped from the emergency pond of slurry pumping damming I, II, and III, drainage waters of the Rogalevsky and Intermediate compartments are collected through the Riverside, South, and Dividing dams. The settling pond capacity is 44.4 mln. m3 , the pond area is 2070 thousand m2 ; the water volume in the pond is 28.7 mln. m3 . The water horizon elevation in the settling pond is 246.5 m. The water depth in the pond ranges from 14.7 to 23 m. Clarified water from the settling pond is supplied as process water by two pumping stations to the processing plant. In the case of the settling pond overflow, part of the clarified water may be released into the Vyya River. The intermediate and Vyisky compartments are separated from each other by the Dividing Dam, the crest length of which is 2,840 m, the crest width is 10 m, the maximum

1 The tailing density is taken equal to 1.9 t/m3 according to the Hydraulic Structure Datasheet

of the Processing Plant Tailing Facility Workshop Tailing Dump [10].

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crest elevation is 331.0 m, and the maximum dam height is 108 m. This is an alluvial dam of tailing deposits. The Rogalevsky compartment includes the Riverside, South, No. 3, No. 4, and Dividing dams. The Riverside Dam is an alluvial dam of tailings. The crest length is 10 m. The maximum height is 91 m; the maximum crest elevation is 331 m. The South Dam is alluvial. The crest length is 1250 m; the crest width is 10 m. The maximum crest elevation is 309.0 m; the maximum height is 56 m. Dam No. 3 is alluvial. The crest length is 820 m. The crest width is 10 m. The maximum crest elevation is 304.0 m; the maximum height is 21 m. Dam No. 4 is alluvial. The crest length is 780 m. The crest width is 10 m. The maximum crest elevation is 331.0 m; the maximum height is 50 m. The Dividing Dam is alluvial. The crest length is 1,800 m. The crest width is 10 m. The maximum crest elevation is 331.0 m; the maximum height is 40 m. The Intermediate compartment includes dams No. 1, No. 2, No. 5, and the East Dam. Dam No. 1 is rock-fill up to the elevation of 250.0 m and alluvial above. The crest length is 1,400 m; the crest width is 10 m. The maximum crest elevation is 302.5 m; the maximum height is 82.5 m. Dam No. 2 is rock-fill up to the elevation of 250.0 m and alluvial above. The crest length is 1,320 m; the crest width is 10 m. The maximum crest elevation is 303.5 m; the maximum height is 61.5 m. Dam No. 5 is alluvial. The crest length is 780 m; the crest width is 10 m. The maximum crest elevation is 331.0 m; the maximum height is 31 m. The East Dam is alluvial. The crest length is 1,100 m; the crest width is 10 m. The maximum crest elevation is 331.0 m; the maximum height is 79 m. The Vyisky compartment dam is earth-and-rockfill with a loamy core. The maximum crest elevation is 250 m; the crest width is 6 m; the maximum height is 40 m; the crest length is 1.9 km. The tailing dump has drainage facilities to receive and discharge drainage (filtered) water from the settling ponds of the compartments, ensure the deepening of the drawdown curve below the soil freezing zone, minimize the filtration flow area, and prevent destructive water filtration through the dam body. Drainage facilities are placed in the dam body and at the base. Drainages comprise a filter, a transition zone, and a catch drain. To improve the tailing dump safety, ensure the deepening of the drawdown curve in the embankment dam body, and prevent the development of suffusion in the downstream slope and the dam bottom, a complex of operations is planned to reconstruct the existing and build new drainage. To bring the existing drainage systems into a serviceable condition corresponding to the safe state of the tailing dump, when it is filled up to the elevation of 331.0 m, it is planned to backfill the batter drainage with rocky soil 3.0 m thick to the design elevation of the seepage water outlet to the downstream slope surface for the dams Riverside, Dividing, East, South, No. 2, No. 3, and No. 4. To receive slurry overflows from the slurry pumping tailing stations, empty the slurry pipes, and receive the processing plant wastewater, the tailing dump contains an

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emergency pond (Fig. 3). The emergency pond filling way is alluvial. The pond was dug at the tailing dump downstream slope in natural soil. The total volume of the pond is 0.367 mln. m3 ; the useful capacity is 0.280 mln. m3 . The pond is bounded by a 5 m high embankment dam. When the emergency pond is fully filled, it is emptied by a ZGM 350/50 L dredger. The slurry is pumped into the Vyisky compartment of the tailing dump.

Fig. 3. Emergency pond of the tailing dump.

The tailing dump is operated by the tailing facility workshop, which is an independent structural unit of the enterprise, developing the Gusevogorsk field. As a process chain link, the workshop performs the following functions: • hydro transportation of tailing slurry from the 1st damming of the slurry pumping station receiving chambers to the tailing dump, • storage of tailings in a tailing dump, • discharge of clarified water from the Rogalevsky compartment to the Intermediate one and from the latter to the Vyisky compartment,2 2 The settling pond of the Vyisky compartment is the source of the enterprise’s recycle water. The

recycle water process flowsheet comprises recycle water pumping stations NOV-1 and NOV-2, five steel recycle water pipelines 1,400 mm in diameter with switching units, shut-off valves, and storage tanks. Recycle water is supplied to the processing plant, the pelletizing plant, the power shop, and to the slurry pumping stations for hydraulic sealing of the pumps. In the event of a shortage of water in the Vyisky compartment, pit waters from the Northern and Western quarries can be supplied to the Vyisky compartment in summer to feed the recycle water supply system.

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• increasing the height of embankment dams, • backfilling of drains. The tailing workshop comprises five slurry pumping stations (SPS) with slurry pipelines to pump the sludge (slurry) and two pumping stations to supply clarified water to the plant’s units. By structure, slurry pumping stations are divided into the first, second, and third damming. The first damming comprises three slurry pumping stations (Nos. 1, 2, 3) and 13 slurry pipelines transporting slurry from these stations to the second damming. The second damming comprises one station and 13 slurry pipelines transporting slurry from the intermediate tank of the second damming SPS to the sludge storage and the third damming SPS. The third damming comprises one slurry pumping station and 3 slurry pipelines transporting slurry from the intermediate tank of the third damming SPS to the sludge storage. The tailing slurry is pumped through the main slurry pipelines by sand pumps 2GRT4000/71 and 2GRT-8000/71 from the first damming slurry pumping station (SPS-1) to the second damming slurry pumping station (SPS-2), to the sumps or directly the suction of soil pumps. From SPS-2, the slurry is fed by soil pumps through distribution slurry lines to the tailing dump, where relatively large particles settle on the alluvial beach, and the liquid slurry phase—water containing finer particles or sludge—flows to the Rogalevsky or Intermediate settling pond. To the distant survey stakes of the Rogalevsky and Intermediate compartments, the slurry is fed by the third damming soil pumps without the jet break. In total, four pumps of the third damming are installed at the tailing dump. The alluvium and filling of the Intermediate and Rogalevsky compartments are performed by discharging slurry from the end of the distribution slurry pipeline laid parallel to the embankment dam axis at a distance of 25–30 m. Secondary embankment dams are created on the alluvial beach surface using bulldozers and an excavator. In summer, tailings are discharged dispersedly onto alluvial beaches from slurry lines laid parallel to the embankment dam, forming a beach slope of 1:40 to 1:60. In winter, tailings are stored by dumping the slurry onto alluvial beaches at a distance of at least 200 m from the embankment dam axis. 3–4 slurry outlets operate simultaneously. The common storage process is controlled from the tailing facility control room. Thus, the tailing dump survey results allow concluding that the technical condition and reliability of the tailing dump hydraulic structures and their components meet the requirements of the regulatory documents in force in the RF to ensure the safe operation of tailing facilities. This tailing dump stores production and consumption waste; therefore, this waste disposal facility is a potential accumulated environmental damage object. The tailings of wet magnetic separation stored in the tailing dump are similar in mineral composition to the overburden rocks of the Gusevogorsk titonomagnetite deposit mined by the enterprise and are represented by diallag pyroxenites, olivine pyroxenites, amphibolized pyroxenites, plagioclase-containing pyroxenites, gabbro. Ore beneficiation technology, which includes crushing, dry and wet magnetic separation, is carried out without the use of chemical reagents. The solid phase of the tailings is medium-grained

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sand. Sand porosity—46%, filtration coefficient—12 m/day. The bulk density of the tailings is 1790 kg/m3 , the density of the mineral part is 3270 kg/m3 . According to the mineral composition, the sands are mainly represented by pyroxenes, olivines, amphiboles, plagioclases interspersed with magnetite, iron oxides and hydroxides. According to the chemical composition, the sands are represented by oxides of iron (9.81%), titanium (0.85%), vanadium (0.044%), calcium (19.22%), silicon (47.2%), magnesium (13.94%), aluminum (7.23%). The toxicity assessment of wet magnetic separation tailings was carried out taking into account long-term effects and their impact on the environment. In the study of tailings of wet magnetic separation, the migration properties of pollutants were studied, the amounts of potentially mobile forms of constituent elements were established, an experimental study of the complex toxicological characteristics of waste was carried out by assessing the general toxic, mutagenic, embryotoxic and sensitizing effects of waste on the organisms of experimental animals. The results of the studies have shown that wet magnetic separation tails do not cause either general toxic or specific long-term consequences: mutagenic, embryotoxic and allergic effects. From a toxicological point of view, tailings are reasonably classified as non-toxic, environmentally safe. Determination of the hazard class for the environment of enrichment waste—“Waste from the extraction of ore minerals (tailings of enrichment of ore minerals by wet magnetic separation)”, was carried out in accordance with the “Criteria for classifying hazardous waste as a hazard class for the environment” by calculation the basis of chemical analysis and experimental method—by their biotesting. The calculation method in accordance with the “Criteria for Classifying Hazardous Waste as a Hazard Class for the Environment” has established the 5th hazard class of “Waste from the extraction of ore minerals (tailings of ore minerals by wet magnetic separation)” for the environment. In order to clarify the calculated hazard class for the environment “Waste during the extraction of ore minerals (tailings of the enrichment of ore minerals using the wet magnetic separation method), biotesting of the water extract of the waste was carried out. Biotesting of the waste was performed on two test objects. The algae Scenedesmus quadricauda (Turp). Breb were used as test objects for biotesting. and Daphnia magna Straus. Biotesting was carried out in accordance with the methods of FR.1.39.2001.00284 “Method for determining the toxicity of water and water extracts from soils, sewage sludge, waste by changing the level of chlorophyll fluorescence and the number of algae cells”, FR.1.39.2001.00283 “Method for determining the toxicity of water and water extracts from soils, sewage sludge, waste on mortality and fertility of daphnia. According to the results of biotesting, the assignment of “Waste from the extraction of ore minerals (tailings of enrichment of ore minerals by wet magnetic separation)” to the 5th class of hazard for the natural environment was confirmed.

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4 Conclusion Given the aforementioned, the following actions are required when inventorying and surveying an accumulated environmental damage object [13] to prepare data and materials: • identifying territories with signs of the ground surface deformation, defining its type, manifestation area, and state—during the ‘collection and study of archive materials containing data on the environmental conditions in the accumulated environmental damage object location area’ [14], • drawing up a consolidated plan of underground workings and the ground surface if underground workings are found in the surveyed area, creating a geomechanical predictive model of the rock mass in the zone of possible rock deformations to calculate the risk of the ground surface deformations, and performing hyper- and multispectral surveys in the course of remote sensing—during the ‘performance of engineering surveys and other types of work to clarify data on the land plot where accumulated environmental damage object is located and/or accumulated environmental damage is identified’ [15–19]. In conclusion, note that introducing an energy indicator—the ground surface deformation—into the concept of accumulated environmental damage will allow generating data and materials on the condition of the territory of the past environmental damage accumulated during mining [20, 21]. This would be important when performing the inventory and inspection of such territories to estimate the accumulated environmental damage objects considered for inclusion in the state register of accumulated environmental damage objects with the required completeness and objectivity.

References 1. Latyshev OG, Kornilkov MV, Osipov IS, Synbulatov VV (2007) Theoretical basis for forecasting and managing the geological environment properties under underground man-made impacts. Publishing House of USGU, Ekaterinburg, p 216 2. Turintsev YI, Samarin VP (2001) Mining geomechanics. Part 1. Movement of rocks and the ground surface under the impact of underground mining: textbook. USMGA Publishing House, Ekaterinburg, 150 p 3. Landslide at a Coal Mine in Kuzbass (Kemerovo Region). https://Opolzni.ru 4. Konovalov VE, Murasheva AA (2021) General principles of arranging a database for subsoil use objects. Min Inf Anal Bull 11–1:5–14. https://doi.org/10.25018/0236_1493_2021_1 11_0_5 5. Riaza A, Buzzi J, Garcia-Melendez E, Vazquez I, Bellido E et al (2011) Pirite mine waste and water mapping using Hymap and Hiperion hyperspectral data. In: Environmental earth sciences. Springer (2011). https://doi.org/10.1007/s12665-011-1422-0 6. Rybnikov PA, Buzina DA (2021) Using aviation and spacecraft multi- and hyperspectral data to study mining areas. Min Inf Anal Bull 11–1:55–70. https://doi.org/10.25018/0236_1493_ 2021_111_0_55/ 7. Nikishin YuA (2013) Prospects for the development of a space-based hyperspectral imaging system. News High Educ Inst Geod Aer Photogr 3:35–41

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8. Veretenova TA, Vokin VN, Zhukova VV et al (2019) Ore quarries of non-ferrous metallurgy in Russia from space. Siberian Federal University, Krasnoyarsk, Mining and ecology of disturbed lands, p 604 9. Semyachkov AI, Pochechun VA, Konovalov VE, Ganin EV (2020) Ecological concept of mining landscape rehabilitation. Institute of economics of the Ural branch of the RAS, Yekaterinburg, 190 p. 10. Konovalov VE (2013) Forecasting the ground surface disturbances in the mine working and dump impact areas. In: Design, construction and operation of underground complexes: proceedings of the 4th international conference, Yekaterinburg. Publishing House of USGU, pp. 144–147 11. Fisenko GL (1965) Stability of quarry walls and dumps. Nedra, Moscow, p 378 12. Kuznetsov MA, Akimov AG, Kuzmin VI, Panteleev MG, Chernyshev MF (1971) Rock movements in ore deposits. Nedra Publishing House, Moscow, p 224 13. Nekrasov SM, Gracheva EM (2009) Report ‘monitoring of the geological environment at the gusevogorsk titanium-magnetite ore deposit’ (Information Report for 2008) 14. On Environmental Protection: Federal Law No. 7-FZ dated January 10, 2002 (as amended on March 26, 2022). Access from the reference-legal system ConsultantPlus. http://www.consul tant.ru/document/cons_doc_LAW_409623/. Accessed 11 Aug 2022 15. Information on The Tailing Compartment Areas: Mekhanobr engineering CJSC (2008) 16. Letter of The Ministry of Natural Resources of Russia No. 05-12-53/35728 dated December 31, 2020, On providing recommendations (together with recommendations for the preparation of applications for the inclusion of an accumulated environmental damage object in the state registry of accumulated environmental damage objects. Access from the referencelegal system ConsultantPlus (2022). http://www.consultant.ru/document/cons_doc_LAW_ 409623/. Accessed 10 Aug 2022 17. The Law of the Russian Federation N 2395-1 dated 02/21/1992 (as amended on July 14, 2022. On Subsoil. Article 24. Basic requirements for the safe conduct of work related to the use of mineral resources. In: The reference-legal system ConsultantPlus (2022). http://www.consultant.ru/document/cons_doc_LAW_343/5172a7490cf21c0be01d9 2ef4321df6e0efab84e/. Accessed 11 Aug 2022 18. Tailing Dump Operation Project for 2006–2010 (2006) Mekhanobr Engineering CJSC 19. Information on the Basic Tailing Specifications (2008) Mekhanobr Engineering CJSC 20. Annual Report on The State of The Tailings Dump Hydraulic Structures (2008) Promgidrotekhnika LLC, Belgorod 21. Conclusion on the Tailing Dump Safety (2009) Promgidrotekhnika LLC, Belgorod

Technosphere Safety in Russia by Ensuring Carbon Neutrality in the Face of Climate Change N. Umnyakova1,2(B) and I. Shubin1,3 1 Research Institute of Building Physics of the Russian Academy of Architecture and Building

Sciences, Lokomotivniy pr., 21, Moscow 127238, Russia [email protected] 2 Moscow State University of Civil Engineering (National Research University), 26, Yaroslavskoye Shosse, Moscow 129337, Russia 3 Russian University of Transport, 9, B.9, Obraztsova Street, Moscow 127994, Russia

Abstract. The ongoing global warming has also affected Russian Federation territory. In 2021, in Russia, the anomaly of the mean annual air temperature was +1.35 °C, with the growth rate of the average annual temperature equal to + 0.49 °C/10 years. The reason for this warming is an increase in the concentration of greenhouse gases in the atmosphere. Therefore, in a changing climate, it is necessary to reduce greenhouse gas emissions and reduce their concentration in the atmosphere. To solve this problem in Europe, it is planned to introduce a carbon tax. For this purpose, methods for assessing the carbon footprint are being developed. This problem is relevant for Russia, which supplies Europe with a significant number of energy-intensive products. They consider all stages of the life cycle of products when assessing the carbon footprint, but the absorption capacity of Russian forests, which occupy about 20% of the forest area in the world, is not adequately assessed. In this regard, it becomes necessary to correctly estimate the absorption of carbon dioxide by Russian forests in order to bring industrial production closer to carbon neutral and reduce the carbon tax. Keywords: Temperature · Climate · Carbon neutrality · Safety · Global warming · Absorption capacity · Greenhouse gases

1 Introduction On the base various climatic parameters analysis and their dynamics, it can be noted that the trends in temperature change and global warming [1–3], occurring in all regions of the globe, have strongly affected the Russian Federation [4–6]. Thus, 2021 largely retained the existing trends in climate change towards warming observed in all seasons. In 2021, in Russia, the anomaly of the average annual air temperature, i.e., deviation from the average value for 1961–1990 was +1.35 °C. Temperatures above the climatic norm were observed mainly throughout the country, with the exception of Chukotka. The © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_45

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growth rate of the average annual temperature was +0.49 °C/10 years (Fig. 1), which is slightly less than in 2020 (+0.51 °C/10 years), and the fastest temperature increase occurred in the spring period—(+0.66 °C /10 years), as in 2020 [4–6].

Fig. 1. Average annual (top) and seasonal anomalies of surface air temperature (°C) averaged over the territory of Russia for the period 1936–2021.

The highest growth rate of the average annual temperature was observed on the coast of the Arctic Ocean, which in the Asian part was +0.8 °C/10 years, on the Taimyr Peninsula on the coast of the East Siberian Sea +1.1 °C/10 years [6]. In summer, the fastest warming occurred in the European part of Russia south of 55°n.l. The maximum summer warming was observed in the south of the European part of Russia and in the Southern Federal District, where the temperature growth rate was +0.74 °C/10 years. In the Central Federal District this value was +0.59 °C/10 years and in the North Caucasian Federal District +0.63 °C/10 years. In addition, in spring intensive warming was observed in Western (+0.78 °C/10 years), Central Siberia

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(+0.85 °C/10 years); in Eastern Siberia in spring (+0.76 °C/10 years) and in autumn +0.82 °C/10 years [6]. However, a warm summer with an average temperature anomaly across Russia of + 2 °C was partially compensated by a relatively cold winter with an anomaly of average temperature across the Russian Federation (−0.46) °C. It was colder than the norm in the center and east of the European part of Russia, in the central regions of the Asian part of Russia, and the coldest conditions were in Western Siberia, where the anomaly averaged over the region was (−2.38) °C. Averaged for Russia as a whole, the temperature anomaly in January was (−1.28) °C, which indicates that this January was the coldest over the past 10 years. In most of the Asian part of Russia, except for Taimyr, Sayan and Transbaikalia, and in the north-east of the European part of Russia, temperatures below the climatic norm were observed (anomalies up to −7–8 °C) (Fig. 2). The annual average warming minimum was noted in the south of Siberia, where in winter there is an area of decrease in temperature, although in a much smaller area and much weaker than in the period 1976–2014.

Fig. 2. Surface air temperature anomalies in Russia in January, February, May and August 2021.

In the conditions of climate warming in Russia, it is not surprising that the average duration of snow cover in Russia turned out to be much less than the climatic norm. First snow in winter 2020–2021 in most of the European territory of Russia, it fell 5–10 days later than the average climatic dates, with the exception of part of the Southern and North Caucasian Federal Districts. On the Asian territory, 5–15 days earlier than the climatic dates, snow cover appeared in the south of Siberia and in Transbaikalia. It is important to note that much of the country experienced earlier snowmelt (Fig. 3) due to

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unusually warm weather that prevailed in March and April, resulting in rapid snowmelt. Despite the warm weather, the snow cover lingered longer than the climatic periods in the Lower Volga region, Transbaikalia, in the south of the Khabarovsk Territory, and in certain areas of Yakutia and Chukotka. This is due to heavy snowfalls that took place in these areas in February–March.

Fig. 3. The state of snow cover on the territory of Russia in the winter period 2020–2021; a— dates of the appearance of the first snow; b—anomalies in the dates of the appearance of the first snow from the norms of 1971–2000; c—anomalies in the dates of snow melting from the norms of 1971–2000.

At the same time, the winter period of 2020–2021. was one of the “snowiest”, the maximum height of snow cover on average in Russia turned out to be significantly higher than the climatic norm. The maximum height of snow cover exceeded the norm in the center of the European part of Russia, on the Arctic coast and Chukotka, in the central regions of Yakutia, in the south of Western Siberia and the Krasnoyarsk Region. So, the climatic changes in Russia were serious and affected some changes in the atmosphere.

2 Problem Formulation It is generally accepted that an increase in the concentration of greenhouse gases is the cause of global warming occurring on the globe and, in particular, on the territory of the Russian Federation [6, 7]. Therefore, in a changing climate, almost everyone considers it necessary to reduce greenhouse gas emissions and reduce their concentration in the atmosphere. And in recent years, the fight against the “greenhouse effect” has taken quite

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active forms [8]. Thus, the European Union plans to reduce carbon dioxide emissions by 55% by 2030 compared to 1990. To achieve this goal, it is planned to reduce the consumption of hard coal by 70%, oil by 30%, and gas by 25% compared to 2015. It is planned to spend about 1 trillion euro on the implementation of the “Green Energy Transition”. During the next 10 years in order to achieve in 2050 in the EU countries the so-called climate neutrality—the amount of carbon dioxide emissions produced by mankind should be equal to the amount of CO2 absorbed [9, 10]. To achieve this goal, the EU Parliament adopted a resolution on the introduction of a carbon tax, or a carbon border adjustment mechanism (CBAM). The leadership of European countries believes that tax regulation will be an excellent tool in order to make the necessary changes and “green” the economy. In Europe, they plan to solve the climate problem by introducing a carbon tax, which will be gradually raised [11, 12]. According to the Europeans, this will make it possible to make all sources of greenhouse gases economically ruinous, so that non-greenhouse gases can replace them.

3 Analysis of Calculation Methods When calculating the carbon footprint, the entire life cycle of an item or object is considered—from obtaining the necessary ingredients or components for production, their transportation, production, and operation (maintenance). To assess the carbon footprint in Russia, the national standard GOST R ISO 14067– 2021 (ISO 14067:2018, IDT) “Greenhouse gases. Carbon footprint of products. Requirements and guidelines for quantification and provision of information”, developed on the basis of the translation into Russian of the English version of the international standard ISO 14067:2018 “Greenhouse gases. Carbon footprint of products. Requirements and guidelines for quantification” (ISO 14067:2018 “Greenhouse gases—Carbon footprint of products—Requirements and guidelines for quantification”. IDT), which retains the principles of carbon footprint assessment, like to the European standard [13]. This standard has been developed to define the formal requirements for estimating greenhouse gas emissions. The process of assessing the carbon footprint is based on the analysis of the life cycle of products, in accordance with the international standards of the ISO14040 series, includes four stages: Stage 1—quantitative determination of the impact that this or that product (good, service, activity) has on global warming by taking into account the number of significant emissions of all greenhouse gases throughout the life cycle of the product. Stage 2—inventory analysis of the life cycle. It identifies processes at each stage of the life cycle that generate significant greenhouse gas emissions. Stage 3—quantification of the carbon footprint throughout the entire life cycle. Greenhouse gas emissions data are expressed in common units, which are traditionally tons of CO2 e, and are adjusted to the functional unit of the product system. Stage 4—interpretation of the results is the final stage of the quantitative assessment of the carbon footprint. In accordance with the goals and objectives of the study, conclusions are formulated. In particular, conclusions can be drawn regarding: • compliance of the carbon footprint with industry standards, benchmarks and/or certain environmental categories.

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• the effectiveness of the fulfillment of quantitative obligations in the field of reducing greenhouse gas emissions. • compliance with the expectations of interested parties [14].

4 Discussion It is known that the total concentration of greenhouse gases in the atmosphere depends on the ratio of the amount of emitted and absorbed greenhouse gases. Therefore, the carbon footprint can be assessed both with and without absorption. Now many states declare that they will reach carbon neutrality by 2050 or 2060. To achieve carbon neutrality, many countries are actively engaged in forest management to increase the absorptive capacity of greenhouse gases. The historical role of deforestation in increasing the concentration of CO2 in the atmosphere has been assessed in many studies, in particular, in 2013, the compilation of this information at the global level was carried out by the IPCC. From the beginning of the industrial era to 2011, the flow amounted to 660 ± 300 billion tons of CO2 [15]. Thus, Russia’s contribution to the CO2 flux into the atmosphere associated with terrestrial ecosystems can be estimated at about 5%. In 1850–2014, CO2 emissions from the combustion of fossil fuels in the world as a whole amounted to1 1400 ± 100 billion tons of CO2 , and Russia’s share was 105 billion tons of CO2 . Accordingly, the contribution of our country to the flow of CO2 into the atmosphere associated with energy is about 7%. In Europe, the area of green forests remained virtually unchanged between 1850 and 1980 and spreads to about 1.6 million km2 , with a total area of 4.7 million km2 . But before the seventh century, 70–80% of the area of the modern European Union, was covered with forests, and cut down before the industrial age. Therefore, now in the EU countries it is impossible to ensure greater absorption of CO2 than it is. Russia is actively engaged in energy conservation and reduction of emissions into the atmosphere, due to which the carbon intensity of GDP in the Russian Federation is better than that of China, but worse than that of Europe or the United States. Russia has enough measures to significantly reduce the carbon intensity of electricity generation and maintain “carbon neutrality” by 2050 [16]. At the same time, it should be taken into account that 20% of all forests of the world grow in Russia, which occupy an area of 815 million hectares (for comparison: China has 216 million hectares of forests), a significant part of which are undisturbed (Fig. 4) [17–19]. Also in Russia, 25% of forest land is occupied by reserve forests—forests in which it is not planned to harvest timber in 20 years, with the exception of timber harvesting by citizens for their own needs [20]. But these areas are not taken into account in the methodology for calculating the carbon footprint of products. That is, Russia has the potential to increase the absorption capacity of forests by 50–100%, which will radically change the national balance between emissions and absorption of greenhouse gases. “In order to absorb 1 ton of carbon, 2.5 hectares of forest are needed,” Roslesinform said. Considering the cost of renting a site and caring for it, the cost of absorbing 1 ton of carbon is 207 rubles. “Studies on carbon landfills, which include not only forest lands,

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Fig. 4. Five countries in the world with the largest forest area (according to data for 2020).

but also meadows, swamps and other types of relief, gave more optimistic data. There scientists have discovered absorption of up to 7 tons of carbon per hectare of surface. Experiments are ongoing and, perhaps, it will still be possible to prove the notorious carbon neutrality of Russia [21]. According to Roslesinform, deciduous forests have the best absorbing properties: 1 hectare of aspens can rid the atmosphere of 3.6 tons of carbon dioxide, birches—from 3.3 tons, oaks—from 3.2 tons. These trees account for about 30% of Russia’s forest fund. Coniferous trees are noticeably inferior to deciduous trees in terms of emissions capture. A hectare of pines is able to absorb 2.4 tons of CO2 per year, and the same number of firs and cedars—2 and 1.8 tons of CO2 , respectively [22]. Roslesinform believes that in order to increase the ability of forests to neutralize emissions, it is necessary to plant trees of fast-growing species, most of which should be deciduous, such as birch and poplar. One hectare of these trees in the first year can rid the atmosphere of 2.6 tons of carbon dioxide per year [23, 24]. It is possible to increase the intensity of carbon dioxide absorption by replacing mature forests with young trees and plantations that absorb CO2 from the atmosphere well, such as oak, larch, pine and spruce. It is these forests that ensure Russia’s carbon neutrality, which may allow avoiding a cross-border tax in the framework of carbon regulation by the European Union. Specialists from Roslesinform have calculated especially for Rossiyskaya Gazeta the possibility of absorption of CO2 by Russian forests and the cost of this process. According to them, the absorption of our forests is approximately equal to the emission of CO2 per year, and the cost of “natural utilization” of one ton of carbon is a little more than 200 rubles. According to the analytical center under the Government of Russia, our country emits more than 1.5 billion tons of carbon dioxide per year. During the same time, Russian forests absorb 395 million tons of carbon, that is, 1.5 billion tons of CO2 , experts from Roslesinform calculated [25]. That is, as much as the country has allocated, so much has been processed. Moreover, the absorptive capacity of Russian forests will increase by the end of the twenty-first century [26]. But according to the now used methodology for calculating absorption, approved by the international community, Russia is far from the first place. As an example, we can cite the differences in the absorption capacity of the forest on the border of the Pskov region and Estonia, which differs by almost a factor of two. Although the forest is the same. Also, the methodology for calculating the carbon footprint does not take into

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account the presence of agricultural land overgrown with forests, which, according to expert estimates, amount to about %. According to many experts, the data of the National Greenhouse Gas Inventory do not fully take into account the absorption of carbon by Russian forests and overestimate its losses [27]. Carbon-dioxide absorption by forests can be estimated using different time ranges of absorption averaging. Absorption capacity of Russian forests according to different assessment methods under different scenarios of forest use is shown on the Fig. 5. According to the Russian method, following the recommendations of the UNFCCC, the absorption is averaged over one year [28], while in another method, where the absorption is averaged over the entire period of the stand life, a significantly greater absorption is obtained. In addition, according to the rules stipulated by the UNFCCC, countries report only on managed forests, i.e. on those forest areas on which economic activities are carried out. An analysis of methodologies that take into account all forests or only managed forests shows some discrepancies [22].

Fig. 5. Anthropogenic net—absorption of greenhouse gases by Russian forests according to different assessment methods under different scenarios of forest use, mln t CO2 eq/year: 1—on forest lands in managed forests in 1990–2015; 2 and 3—predictive calculations of dynamics for 2010–2050 (smoothed curves), respectively, for the minimum and maximum felling scenarios (according to the State Report of 2017, calculations are made for a specific year according to [29]); 4—according to the method of VNIILM with averaging of net ecosystem production over the lifetime of a forest stand [30, 31].

The method of calculating emissions and removals of greenhouse gases is determined by the UNFCCC Guidelines. It is they, and not the set of rules of the Paris Agreement, that will determine the suitability of a particular methodology for a country’s reporting under the UNFCCC [22]. And European countries have less forests, so they focus on reducing emissions through energy efficiency, the use of renewable energy sources and hydrogen energy. At the same time, Europeans seek to level the issue of the absorbing capacity of forests. But according to the now used methodology for calculating absorption, approved by the international community, Russia is far from the first place. As an example, we

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can cite the differences in the absorption capacity of the forest on the border of the Pskov region and Estonia, which differs by almost a factor of two. Although the forest is the same. Also, the methodology for calculating the carbon footprint does not take into account the presence of agricultural land overgrown with forests, which, according to expert estimates, is about 40%. The European Union plans to impose a special payment on imports of products that produce a carbon footprint from 2023. The EU carbon tax could cost Russia at least e1.1 billion a year when the tax is levied at 100% [32]. This follows from the calculations of RBC, certified by the Ministry of Economic Development. Particular attention should be paid to the fact that Russia exports a significant part of the products, the production of which requires large energy consumption and the consumption of natural resources—these are metals (steel, nickel, lithium), chemical products, including a significant number of mineral fertilizers, cement, agricultural products, energy resources. The government has been tasked with minimizing the country’s losses from carbon regulation. One of the areas of such work is to convince the West that Russian forests absorb much more carbon dioxide than it is produced in the course of industry, transport. housing and communal services. Therefore, we need not just an objective accounting of all forests, including reserve forests and those growing on agricultural land, but a significant refinement of the methodology. A project has been launched through the Ministry of Science to create experimental “carbon polygons”, where they consider the absorbing capacity of forests, grasses, and even swamps. It turns out that the older the forest, the less it absorbs carbon dioxide. Therefore, it is necessary to engage in effective forest management—sanitary felling, reforestation and reforestation. This is a colossal work in our territories, and huge amounts of money are required. Plus, the problem of fires, which produce about 250–300 million tons of emissions per year, is more than twice as much as emissions from all agriculture. There is also huge potential for reducing emissions. All this in general will allow us to more than double the current values to increase the absorption capacity. But the main condition for this is the verification of the assessment methodology. Of course, we will calculate everything, but the correctness of our calculations will need to be proved to our European colleagues. And their main goal is to neutralize our energy advantages. To do this, they are trying to transfer their economy to renewable energy sources. But renewable energy is much more expensive than ours, so European products are not cost competitive. They want to level this difference through a carbon tax so that the cost of production of their metallurgists and our metallurgists becomes the same. That is, they are trying to nullify our advantages and increase their own.

5 Conclusions Based on the study and analysis of climate change in the Russian Federation, the following conclusions can be formulated: 1. Methods for assessing the carbon footprint of products based on European methods have been developed in Russia.

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2. Existing methods do not fully take into account the absorption capacity of Russian forests, the area of which is 815 hectares, which is about 5 times less than the area of forests in the European Union. 3. An analysis of the absorption capacity of Russian forests has shown that they can ensure Russia’s carbon neutrality. 4. It is necessary to verify the methods for assessing the carbon footprint of products and the recognition of the Russian methodology by the EU countries to ensure the competitiveness of domestic products.

References 1. Arrhenius S (1896) On the influence of carbonic acid in the air upon the temperature of the ground. Philos Mag J Sci 5(41):237–276 2. Hansen J, Lebedeff S (1987) Global trends of measured surface air temperature. J Geophys Res 13345–13372 3. Petit JR, Jouzel J, Raynaud D et al (1999) Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399(6735):429–436 4. Umnyakova NP, Shubin IL (2021) On the problem of revising SP 131.13330 “Construction climatology” in a changing climate. Zhilishchnoe Stroitel’stvo (Hous Construction) 6:3–10 5. Report on climate features in the territory of the Russian Federation for 2020 (2021) Roshydromet, Moscow, p 104 6. Report on climate features in the territory of the Russian Federation for 2021 (2022) Roshydromet, Moscow, p 110 7. Jacobson MZ (2019) The health and climate impacts of carbon capture and direct air capture. Energy Environ Sci 12:3567–3574. https://doi.org/10.1039/c9ee02709b 8. Greenhouse effect: what it is for and how it affects climate change (2021). https://trends.rbc. ru/trends/green/603766c39a794772017c8a13 9. Mitrova T (2021) The fourth energy transition: risks and challenges for Russia. Vedomosti 10. Wan B, Tian L, Fu M, Zhang G (2021) Green development growth momentum under carbon neutrality scenario. J Clean Prod 316. https://doi.org/10.1016/j.jclepro.2021.128327 11. Tikhonov, RS (2021) We need to update the data on the absorption of CO2 by our forests. Rossiyskaya Gazeta. https://rg.ru/2021/04/26/reshetnikov-nuzhna-aktualizaciia-dannyh-opo gloshchenii-co2-nashimi-lesami.html 12. Safi A, Chen Y, Wahab S, Zheng L, Rjoub H (2021) Does environmental taxes achieve the carbon neutrality target of G7 economies? Evaluating the importance of environmental R&D. J Environ Manag 293. https://doi.org/10.1016/j.jenvman.2021.112908 13. ISO 14067:2018 (2018) Greenhouse gases—Carbon footprint of products—Requirements and guidelines for quantification 14. Usov A (2017) Carbon footprint. Oil Russia 4:18–21 15. Stocker TF, Qin D, Plattner GK et al (2013) Information on greenhouse gas emissions and national INDCs in the data. In: Climate change 2013: the physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change. Cambridge, United Kingdom and New York, Cambridge University Press, USA, p 1535 16. Filipchuk A (2016) How Roshydromet “Defended” Russia’s forests in the Paris climate agreement. Information agency Regnum. https://regnum-ru.turbopages.org/regnum.ru/s/news/220 3928.html

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17. Terekhin EA (2019) Recognition of disturbed forest ecosystems of the forest-steppe on the basis of spectral-reflective characteristics. Comput Opt 43(3):412–418. https://doi.org/10. 18287/0134-2452-2019-43-3-412-418 18. Pakhuchy VV, Pakhuchaya LM (2014) Virgin forests of the Komi Republic: current state and prospects for use and development. Actual Probl For Complex 38:44–47 19. FAO (2020) Global forest resources assessment 2020. Main conclusions, Rome. https://doi. org/10.4060/ca8753ru 20. Forest Code of the Russian Federation (2006) N. 200-FZ ed 21. Duel A (2021) The carbon footprint is growing. Rossiyskaya Gazeta, no. 93 22. Kokorin A, Lugovaya D (2018) CO2 uptake by Russian forests in the context of the Paris agreement. Sustain For Manag 2(54):13–18 23. https://rg.ru/2021/04/27/eksperty-podschitali-sebestoimost-pogloshcheniia-lesom-ugleroda. html 24. https://m.lenta.ru/news/2021/12/16/forest_power/amp/ 25. Lyubimova NG (2022) Ways to achieve “carbon neutrality” in the Russian power industry. Bull Univ 1:63–69 26. Potaeva K, Katkov M (2021) The global tariff on CO2 emissions will hit Russia’s key primary sectors the hardest. Vedomosti. September 09, 2021 27. Filipchuk AN, Malysheva NV, Moiseev BN, Strakhov VV (2016) Analytical review of methods for accounting for emissions of greenhouse gas absorption by forests from the atmosphere. For Inf 3:36–85 28. Romanovskaya AA, Federici S (2015) Emission quota and the role of the forest sector in the national obligations of the Russian Federation in the new climate agreement. In: Proceedings of the St. Petersburg research institute of forestry, vol 1, pp 20–38 29. Seventh National Communication of the Russian Federation submitted in accordance with Articles 4 and 12 of the United Nations Framework Convention on Climate Change (UNFCCC) (2017) Ministry of natural resources and ecology of the Russian Federation. Federal Service for Hydrometeorology and Environmental Monitoring, Moscow, p 348 30. Forecast for the development of the forest sector of the Russian Federation until 2030 (2012) Food and agriculture organization of the United Nations, Rome, p 96 31. Fedorov BG (2017) Russian carbon balance. Moscow, p 82 32. Russia will pay the EU 1.1 billion euros a year in carbon tax. https://www.rbc.ru/economics/ 26/07/2021/60, fac8469a7947d1f4871b47. Accessed 26 July 2021

Drilling Waste as a Promising Man-Made Material for the Synthesis of Aluminosilicate Proppant A. A. Tretyak, A. A. Chumakov(B) , V. A. Smoliy, D. A. Golovko, and N. S. Goltsman Platov South-Russian State Polytechnic University (NPI), 132, St. Enlightenment, Novocherkassk 346428, Russia [email protected]

Abstract. The problem of the need to increase the development of wells with shallow oil depths is described. The essence of the hydraulic fracturing method is described and the chemical composition of the drilling fluid is given. The definition of drilling waste and its characteristics are given. The average chemical composition of the proppant and the requirements that are imposed in accordance with regulatory documents are revealed. Studies of the chemical and phase composition of the selected drilling waste from the Vostochno-Chumakovskoye field were carried out, during which it was established that it is promising for use in the synthesis of high-quality aluminosilicate proppants. On the basis of theoretical data, studies of the radiological safety of drilling waste were carried out, which showed that it can be used in the developed resource-saving technology of proppants. Based on analytical and physico-chemical studies, modifying additives were selected and raw mixtures were compiled for the synthesis of model samples in order to determine their characteristics (density and strength). The optimal composition of the raw mixture and the temperature regime of firing samples were determined. It was found that in order to obtain a strong proppant (strength above 68.9 MPa), it is necessary to introduce the following modifying additives into the composition of the raw mixture with specified amounts, wt. %: aluminum oxide powder (over 100)—5, sodium fluoride powder (over 100)—4, BT-1 cullet—20. Keywords: Drilling waste · Recycling · Hydraulic fracturing · Aluminosilicate proppant

1 Introduction To date, the main regions for oil production in the Russian Federation are Western and Eastern Siberia. The depth of occurrence of oil reservoirs in these fields is from 4500 m, thus the main drilling method here is the traditional vertical one. However, these deposits are being depleted every day, which leads to the development of new deposits and the improvement of oil production methods [1–3]. In this regard, today there is an active development of oil fields in the territory of the Southern Federal District of the Russian Federation. The depth of oil reservoirs in this © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_46

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region is 2500 m, which makes it impossible to use vertical drilling here. Therefore, in the territory of the Southern Federal District, it is recommended to use the method of horizontal well drilling using hydraulic fracturing (HF). The essence of the hydraulic fracturing method is the gradual injection of fluid pressure on the formation until a crack appears in it, the fixation of which will further increase the oil recovery of the formation, thereby increasing the well flow rate [4–7]. To form fractures in the formation, polymer-bentonite drilling fluids based on lignosulfates are used, having the following composition, kg/m3 : bentonite—30–40, Na2 CO3 —1.0–2.0, NaOH—1.0, KSSB—10–20, CMC 500—1–3, drilling detergent— 1, GPAA—1–2, defoamer—0.3, lubricant additive—3–6. These solutions can significantly increase not only the oil recovery of the well, but also improve the penetration of the drill into the oil reservoir [8–11]. However, when using the hydraulic fracturing method in the process of oil production, a large amount of drilling waste is generated (up to 2500 thousand tons per year), which has a negative impact on the environment. In addition, to increase the well flow rate and hold the reservoirs after hydraulic fracturing, a large amount of proppant is required. In this regard, it would be extremely expedient to conduct a study on the possibility of using drilling waste from the fields of the Southern Federal District in the synthesis of aluminosilicate proppant [12].

2 Main Part Drilling waste is typically generated during the drilling or testing of a well by companies seeking or obtaining hydrocarbon feedstock. They are formed as a result of the separation of solid rock from the so-called drilling fluid in devices such as centrifuges, desalters, vibrating screens and sediments. Another way to generate production waste is to change the drilling parameters, when the drilling fluid is replaced with a different type. In its composition, drilling waste usually contains: cement paste residues, crude oil, barite and chlorides; oily waters; rock remains, etc. In this regard, drilling waste is classified as IV hazard class waste, because due to the presence of harmful substances in its composition, they can have a negative impact on the environment. The authors of the article previously conducted research on the development of drilling waste recycling technology. Due to the fact that drilling waste contains up to 80% of clay minerals in its composition, it is extremely expedient to process them into raw materials for the synthesis, for example, aluminosilicate proppants [8, 9]. Aluminosilicate proppant is a granular material (granule diameter 0.5–1.2 mm) obtained by high-temperature firing. Traditionally, proppant has been formulated with natural raw materials such as alumina and silica. The main raw materials and types of proppants were previously studied by the authors of the article [14]. Table 1 below shows the average chemical composition of the traditional proppant, obtained in the course of analytical studies [13–18]. However, due to the high consumption of proppants by oil companies, there is a reduction in the stocks of raw materials. In this regard, technologies for producing proppants using technogenic raw materials (fly ash from thermal power plants, drilling waste, etc.) are being developed in the world as modifying additives, which are introduced

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A. A. Tretyak et al. Table 1. Average chemical composition of aluminosilicate proppant.

Average content of oxides in proppants, wt. % Al2 O3

SiO2

Fe2 O3

TiO2

15.0–45.0

50.0–65.0

4.5–5.0

4.5–5.0

in amounts up to 20 wt. %. In connection with the use of drilling waste as the main raw material is extremely appropriate [19, 20].

3 Materials and Methods The drilling waste of the Vostochno-Chumakovskoye field, located on the territory of the Southern Federal District of the Russian Federation in the Krasnodar Territory, near the city of Temryuk, was chosen as the object of research. Study of the chemical composition of drilling waste The determination of the concentration of rock-forming oxides and some trace elements in the samples was carried out by X-ray spectral fluorescence analysis (XRF) on a sequential vacuum spectrometer (with wavelength dispersion) model PW2400 manufactured by Philips Analytical (Netherlands). The spectrometer is equipped with a 3 kW X-ray tube with an Rh anode. The maximum voltage on the tube is 60 kV, the maximum anode current is 125 mA. When calibrating the spectrometer, industrial and state standard samples of the chemical composition of rocks, soils and bottom sediments were used. The studies were carried out at the Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry of the Russian Academy of Sciences (IGEM RAS) located in Moscow. Radiological safety studies of drilling waste Radiological studies of drill cuttings from the Morozovskoye field were carried out using the MULTIRAD spectrometric complex with the PROGRESS software. The operating principle of the “MULTIRAD” complex with the “PROGRESS” software is based on obtaining a hardware spectrum of pulses from a detector that registers the radiation of a counting sample exposed under fixed measurement conditions. The activity of the radionuclide in the test sample is determined by processing the obtained spectrogram on a PC using a special software package “Progress-3.0”. Classification based on the results of radiological tests of drill cuttings was carried out in accordance with SP 2.6.1.758-99 “Radiation safety standards (NRB-99)” and GOST 30,108–94 “Construction materials and products. Determination of specific effective activity of natural radionuclides”. Study of the phase composition of drilling waste To determine the phase composition, a sample of drill cuttings from the Morozovskoye field was subjected to grinding and examination of the resulting powder using an X-ray

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powder diffractometer ARL X’TRA (Thermo Fisher Scientific), which is part of the Central Collective Use Center “Nanotechnologies” of the Platov South-Russian State Polytechnic University (NPI). The obtained data were interpreted using the ICDD database (The International Center for Diffraction Data). Derivatographic studies of drilling waste Derivatographic studies were carried out at the Scientific Research Institute “Nanotechnologies and New Materials”, located in the Platov South-Russian State Polytechnic University (NPI), using a synchronous thermal analysis device STA 449 F5 Jupiter (Netzsch, Germany). Derivatographic studies of drill cuttings were carried out in a helium medium at a heating rate of 50 °C/min to a temperature of 1000 °C. Preparation of laboratory model samples All raw materials used have undergone preliminary preparation, which consists in drying at 100–105 °C and grinding to particles no larger than 250 microns. From the prepared raw mix with the addition of 5 wt. % water, model laboratory samples were molded in the amount of three pieces in the form of cubes with a face length of 20 mm and a mass of 10 g by uniaxial pressing with a maximum load of 5 MPa. The obtained samples were placed on a mesh substrate and loaded into a cold muffle furnace for firing in an air atmosphere at a temperature of 1100 °C for 70 min without exposure at a heating rate of 6 °C/min. After sintering, the samples were kept in the furnace until they cooled completely, then they were removed and tested. The arithmetic mean of three parallel measurements is taken as the final result.

4 Results and Discussions The results of the chemical analysis study are presented in Table 2. Table 2. Chemical composition of drilling waste. Oxide Na2 O

Content, wt. %

Oxide

Content, wt. %

1.36

P2 O5

0.17

MgO

1.43

BaO

15.53

Al2 O3

11.01

Cl−

0.06

SiO2

35.14

CuO

0.03

K2 O

1.64

PbO

0.12

CaO

9.25

Rb2 O

0.01

TiO2

0.45

SO3

MnO

0.14

SrO

0.28

Fe2 O3

5.07

LOI (1000 °C)

6.36

11.89

From Table 2 it can be seen that the drilling waste of the Vostochno-Chumakovskoye field has a small amount of Al2 O3 (11.01 wt.%) and SiO2 (35.14 wt.%). Therefore,

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based on the data in Table 1, when developing raw mixes, it is necessary to use various modifying additives. It was described above that drilling wastes are classified as hazard class IV wastes. In this regard, a radiological safety study was carried out, the results of which are shown in Table 3. Table 3. Results of radiological studies. Drilling waste

Defined indicators

Research results; units; confidence level

The value of the allowable level; units

ND for the research method

Vostochno-Chumakovskoye field

Effective specific activity of radionuclides Ra-226, Th-232, K-40

(108 ± 14) Bq/kg; P = 0,95

Not more than 370 Bq/kg (1 class)

GOST 30,108–94 MI CMII GNMC “VNIIFTRI” from 22.12.2003

According to Table 3, it can be seen that the studied drilling wastes belong to the 1st class of building materials, since their effective specific activity is (108 ± 14) Bq/kg, with a normal value of not more than 370 Bq/kg. Therefore, they can be freely used in the synthesis of aluminosilicate proppants. The results of the phase analysis are shown below in Fig. 1.

Fig. 1. X-ray of the drilling waste of the Vostochno-Chumakovskoye field: —calcite, — quartz.

From Fig. 1 shows that the predominant phase of the Vostochno-Chumakovskoye sludge is quartz (SiO2 ), which is present in two modifications α-SiO2 and β-SiO2 , present in amounts of 11 and 28%, respectively. The second phase is calcite (CaCO3 ) and the third, subtle phase is barite (BaSO4). Of all the phases, the most significant for the synthesis of aluminosilicate proppants is the presence of α- and β-modifications of quartz.

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Below in Fig. 2 shows a derivatogram of drilling waste from the VostochnoChumakovskoye field.

Fig. 2. Derivatogram of drilling waste from the Vostochno-Chumakovskoye field.

As can be seen from Fig. 2 on the derivatogram of the drill cuttings of the VostochnoChumakovskoye field there are two noticeable peaks: 1. At 487.83 °C, bound water is removed in the kaolinite lattice in the form of hydroxides. As a result, metakaolinite -3Al2 O3 -2SiO2 is formed. This process is completely completed at 550 °C; 2. at 715.80 °C, the beginning of decomposition of calcite into CaO with the release of CO2 is observed. The process is completed completely at 800 °C. The derivatogram of the drilling waste from the Vostochno-Chumakovskoye field fully confirms the XRD results. According to the technology described above, the following raw mixtures were prepared, the compositions of which are presented below in Table 4. According to the results of the chemical analysis of the drilling waste from the Vostochno-Chumakovskoye field (Table 2) and the average chemical composition of the traditional proppant (Table 1), it can be seen that the missing amount of aluminum oxide and silicon is present in the drilling waste. However, at the initial stage of research, it is necessary to check the assumption of a reduced content of silicon oxide in the composition of not only drilling waste, but also the final material. In this regard, the following were chosen as modifying additives: aluminum oxide powder (commercial alumina), which is added in excess of the main raw material mass and will contribute to the introduction of the proper amount of Al2O3; BT-1 cullet was chosen as the main melting point, since aluminum oxide powder increases the firing temperature to

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A. A. Tretyak et al. Table 4. Component compositions of raw mixes.

Composition number

Content, wt. % Drilling waste from the Vostochno-Chumakovskoye field

Cullet brand BT-1

Al2 O3 powder (over 100)

NaF powder (over 100)

1

80

20

5

3

2

80

20

5

3.5

3

80

20

5

4

4

80

20

5

4.5

1500 °C, which is unacceptable when developing resource-saving technology, and since cullet has a melting point of 850 °C, it will reduce the firing temperature of the mixture approximately 100 °C; sodium fluoride powder was used as an additional flux, which was introduced in excess of the main mass, since an increase in the content of cullet will lead to complete melting of the samples, which is unacceptable, which is why NaF was introduced in small quantities [21]. According to the technology described above, model samples were made and fired, the appearance of which is shown in Fig. 3.

Fig. 3. Appearance of fired model samples.

As can be seen from Fig. 3, all samples did not lose their geometric shape after firing. However, on the surface of each sample there is a vitreous film, which is formed during firing due to the fusion of drilling waste particles with particles of the introduced floodplains. The higher the content of NaF in the composition, the greater this reflow. The results of the physical and mechanical tests carried out are presented below in Table 5. Below in Fig. 4 shows the dependence of density and strength on the amount of sodium fluoride introduced. As can be seen from Table 5 and Fig. 4, with an increase in the content of sodium fluoride from 3.0 to 4.0 wt. %, there is an increase not only in density from 1940.21 to 2029.82 kg/m3 , but also in strength from 60.11 to 70.35 MPa. Such a sharp jump indicates the completeness of sintering of the particles of drilling waste and the hardening additive between themselves. In addition, during the firing process, only when the content of NaF

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Table 5. Results of physical and mechanical tests of model samples. Sample number

Characteristic Volume before firing, V1 , cm3

Density before firing, ρ1 , kg/m3

Volume after firing, V2 , cm3

Density after firing, ρ2 , kg/m3

Sintering coefficient, K

Strength, R, MPa

1

4.58

2089.25

4.25

1940.21

1.07

60.11

2

4.69

2110.33

4.34

2001.13

1.08

63.89

3

4.61

2197.08

4.05

2029.82

1.14

70.35

4

4.52

2099.66

4.35

1890.23

1.04

57.12

Fig. 4. Dependence of density and strength on the amount of NaF.

in the amount of 4.0 wt. %, a sufficient amount of the liquid phase is formed, which contributes to a better flow of solid- and liquid-phase sintering reactions, as well as the formation of a strong silicate framework during cooling, which subsequently has a direct effect on the strength characteristics of the samples. However, with an increase in the NaF content to 4.5 wt. %, there is a sharp decrease in density to 1890.23 kg/m3 and strength to 57.12 MPa. This can be explained as follows. With small amounts of sodium fluoride introduced into the raw mixture during its dissociation in the temperature range of 600–650 °C, the formation of a glassy film is not observed on the surface of the samples, and the resulting hydrogen fluoride (HF) is removed through micropores on the surface. But with an increase in the content of NaF to 4.5 wt. % in a given interval, a vitreous film begins to form due to the large amount of the liquid phase, thereby blocking the removal of HF from the sample structure. Thus, the internal filling of various shapes and sizes occurs, which leads to foaming and subsequent loss of strength characteristics.

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5 Conclusion Based on the research, the following conclusions can be drawn: 1. Based on the results of physical and chemical tests of drilling waste from the Vostochno-Chumakovskoye field and analytical studies, it was found that the selected waste belongs to hazard I class ((108 ± 14) Bq/kg), which allows it to be used in the development of resource-saving technology for aluminosilicate proppants. In addition, it was found that drilling waste contains a small amount of silicon and aluminum oxides that are important for proppants, therefore, to improve the quality of the synthesized material, it is necessary to introduce high-aluminate raw materials into the composition of the raw mixture, for which aluminum oxide powder (commercial alumina) was chosen, in the amount 5.0 wt. %. According to the results of derivatographic and X-ray studies, the presence of calcite (CaCO3 ) and quartz (SiO2 ) in the waste, which play an important role in the technology of aluminosilicate materials, was determined. 2. In the course of research, the following composition would be determined for the synthesis of high-quality proppants, wt. %: drilling waste—80, cullet grade BT1—20, aluminum oxide powder (over 100)—5, sodium fluoride powder—4. The samples were fired at a temperature of 1100° C for 70 min without holding at a heating rate of 6 °C/min The ultimate compressive strength of samples of optimal composition was determined, which is 70.35 MPa, which meets the requirements of GOST R 51,761–2013 “Aluminosilicate proppants. Specifications”. 3. The optimal content of each additive and its effect on the sintering processes and the strength of the fired samples were established. It has been determined that in order to obtain a proppant of increased strength (over 68.9 MPa), the content of aluminum oxide powder in the raw mixture should be 5.0 wt. %. However, to reduce the sintering temperature of the samples and increase the completeness of the sintering reactions, it is necessary to introduce modifying additives-fluxes in the following amounts, wt. %: cullet brand BT-1—20, NaF powder (over 100)—4.

Acknowledgements. The work was performed in SRSPU (NPI) with the financial support of the Russian Science Foundation under agreement No. 20-79-10142 "Development of an effective technology for the synthesis of aluminosilicate propants using oil and gas drilling waste from the Southern Federal District" (supervisor—A.A. Tretyak).

References 1. Vorobyov ES (2020) Hydraulic fracturing is a method of enhanced oil recovery (GRP – metod povysheniya nefteotdachi). Tribune scientist (Tribuna uchenogo) 11:25–31 2. Kurenkov VV (2016) Application of hydraulic fracturing technique with production geophysical methods for tight reservoirs (Primeneniye metodiki gidravlicheskogo razryva plasta s promyslovo-geofizicheskimi metodami dlya nizkopronitsayemykh plastov). Scientific research; from theory to practice (Nauchnyye issledovaniya; ot teorii k praktike) 4–1(10):94–97. https://doi.org/10.21661/r-113712

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3. Meng T, Lifeng M, Fengbiao W, Gan F, Yongbin X (2021) Experimental study on permeability evolution and nonlinear seepage characteristics of fractured rock in coupled thermo-hydraulicmechanical environment: a case study of the sedimentary rock in Xishan area. Eng Geol 294:106339. https://doi.org/10.1016/j.enggeo.2021.106339 4. Yatsenko EA, Goltsman BM, Chumakov AA, Smoliy VA (2022) Investigation of the properties of aluminosilicate material for the production of proppants based on drill cuttings using modifying additives. J Min Inst 5. Kurazov MA, Gazabieva ZH, Mollaev RH, Khaladov AS (2020) Methods for improving the efficiency of hydraulic fracturing in oil production processes (Sposoby povysheniya effektivnosti gidravlicheskogo razryva plasta v protsessakh dobychi nefti). GGNTU Bulletin. Technical science (Vestnik GGNTU. Tekhnicheskiye nauki) 16:32–38 6. Serebryannikov AA (2020) Efficiency of hydraulic fracturing in the joint development of oil reservoirs of different permeability (Effektivnost’ gidravlicheskogo razryva plasta pri sovmestnoy razrabotke neftyanykh plastov razlichnoy pronitsayemosti). Probl Dev Depos Hydrocarb Ore Miner (Problemy razrabotki mestorozhdeniy uglevodorodnykh i rudnykh poleznykh iskopayemykh) 2:358–364 7. Suleimanov SSM (2020) Problems arising during hydraulic fracturing and the possibilities of their solutions (Problemy, voznikayushchiye pri GRP i vozmozhnosti ikh resheniy). Alley Sci (Alleya nauki) 12(51):210–215 8. Tretyak AA, Yatsenko EA, Onofrienko SA, Karel’skaya EV (2021) Identification of drilling waste and their use. Bulletin of the Tomsk Polytechnic University. Georesour Eng 332(2):36– 43. https://doi.org/10.18799/24131830/2021/2/3041 9. Tretyak AA, Yatsenko EA, Borisov KA, Karel’skaya EV (2022) Drilling fluid cleaning and recycling technology. Bulletin of the Tomsk Polytechnic University. Georesour Eng 333(2):62–70. https://doi.org/10.18799/24131830/2022/2/3560 10. Bello A, Ozoani J, Kuriashov D (2022) Proppant transport in hydraulic fractures by creating a capillary suspension. J Petrol Sci Eng 208:109508. https://doi.org/10.1016/j.petrol.2021. 109508 11. Hari S, Krishna S, Gurrala LN, Singh S, Ranjan N, Vij RK, Shah SN (2021) Impact of reservoir, fracturing fluid and proppant characteristics on proppant crushing and embedment in sandstone formations. J Nat Gas Sci Eng 95:104187. https://doi.org/10.1016/j.jngse.2021. 104187 12. Yatsenko EA, Goltsman BM, Chumakov AA, Vilbitskaya NA, Li W (2021) Research on the synthensis of propants applied for oil production by the method of hydraulic facing. Mater Sci Forum 1037:181–188. https://doi.org/10.4028/www.scientific.net/MSF.1037.181 13. Yatsenko EA, Goltsman BM, Tretyak AA (2021) Chumakov AA (2021) Influence of metallurgical slag additives on proppants synthesis processes based on drilling muds. Chernye Met 8:49–53. https://doi.org/10.17580/chm.2021.08.09 14. Yatsenko EA, Tretyak AA, Chumakov AA, Smoliy Vs A (2022) Research of the possibility of using glass and sodium hydroxide for synthesis of aluminum silicate propants based on drill sludges. Key Eng Mater 910:678–683. https://doi.org/10.4028/p-mmf175 15. Yatsenko EA, Goltsman BM, Ryabova AV (2018) Complex protection of pipelines using silicate materials based on local raw materials of the far east. Mater Sci Forum 46–52. https:// doi.org/10.4028/www.scientific.net/MSF.945.46 16. Abd El-Kader M, Abdou MI, Fadl AM, Abd Rabou A, Desouky OA, El-Shahat MF (2020) Novel light-weight glass-ceramic proppants based on frits for hydraulic fracturing process. Ceramics International 46:1947–1953. https://doi.org/10.1016/j.ceramint.2019.09.173 17. Alexander S, CharlesW D, AndrewR B (2016) Assembly of porous hierarchical copolymers/resin proppants: new approaches to smart proppant immobilization via molecular anchors. J Colloid Interface Sci 466:275–283. https://doi.org/10.1016/j.jcis.2015.12.038

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Application of Kaniadakis κ-Statistics to Load and Impact Distributions A. Bushinskaya1,2(B) and S. Timashev1,2 1 Science and Engineering Center «Reliability and Safety of Large Systems and Machines», Ural

Branch, Russian Academy of Sciences, 54-A, Studencheskaya, Yekaterinburg 620002, Russia [email protected] 2 Ural Federal University, 19, Mira, Yekaterinburg 620002, Russia

Abstract. The article considers application of the Kaniadakis’ κ-statistics (nonextensive statistical mechanics introduced by C. Tsallis in 1988, is presented in relation with the q-triplet estimation concerning experimental time series from climate, seismogenesis, and space plasmas systems), which appeared in 2001 in the framework of Einstein’s special theory of relativity, to description of loads and impacts on buildings and structures. The κ-deformed Kaniadakis exponential function is used, with the help of which new classes of κ-deformed statistical versions of already known distributions are introduced. These distributions coincide with the original ones with the exception that their κ-deformed tail follows the Pareto power law. This allows converting the original distributions into heavy-tailed distributions that more closely match the experimental data of mixed systems and systems operating under conditions of increased uncertainty. This allows, within the framework of the already known distributions of loads and impacts, to model above-standard stressors and analyze the near impossible to predict “Black Swan” ultra rare type of events with humongous consequences. Keywords: Kaniadakis · κ-statistics · Heavy-tailed distributions · Black swan · Uncertainty · Load · Impact

1 Introduction During the operation of a complex technical system, no matter how carefully the calculations are carried out during its design, due to its complexity, there will always be unforeseen impacts due to beyond- design (extreme) loads, which will eventually lead, at best, to its local damage. In this case, it is very important to know whether these damages will cause catastrophic destruction of the system as a whole or to its unsuitability for further operation. Such out-of-design or extreme loads and impacts fall on the tails of the so-called fat-tailed distributions. An example of such a distribution is shown in Fig. 1.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_47

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Fig. 1. Example of distribution of an impact, load or damage.

The distribution shown in Fig. 1 is divided into two parts: central (solid thick line) and caudal (dashed thick line). Separation boundary K represents a threshold value determined by specifics of the task. The central part represents the values at design loading (normal operation), the tail represents the beyond design values. The central part is usually described by standard distributions (exponential, Weibull, Rayleigh, lognormal, etc.), the caudal (tail) part is described by power-law or heavy-tailed distributions. Below, we consider the application of Kaniadakis κ-statistics [1–3] to known distributions of loads and impacts, which makes it possible to model excess stressors in the tails of these distributions and analyze the consequences of beyond-design situations (including black swan type disasters). The use of κ -statistics makes it possible to obtain simple analytical closed-form expressions for all major statistical functions such as the probability density function, distribution function, survival function, quantile function, risk function, and cumulative risk function. Let’s consider this approach in more detail.

2 Mathematical Description of κ-statistics Consider a random value (RV) X with probability density function (PDF) f (x). In statistical mechanics, the general equation for the rate of change of f (t) is a first-order linear ordinary differential equation (ODE): df (x) = −r(x)f (x), dx where the function r(x) is the decay rate. The solution to this ODE is exponential. ⎛ f (t) = c exp⎝−

x

(1)

⎞ r(t)dt ⎠,

(2)

x0

with the standard normalization condition defining the constant c: x f (t)dt = 1 x0

As an exponential solution, consider three simple cases.

(3)

Application of Kaniadakis κ-Statistics to Load and Impact Distributions

491

1. Exponential model for constant decay rate, i.e.: r(x) = λ,

(4)

which from Eq. 1 leads to the exponential PDF. f (x) = λe−λt .

(5)

2. Pareto distribution type I. The PDF of the pareto distribution is obtained from Eq. 1 with a decay rate function equal to p , p > 1, x

(6)

p − 1  x0 p , p > 1, x ∈ (x0 , +∞), x0 > 0. x0 x

(7)

r(x) = those PDF in this case: f (x) =

3. The κ-exponential model [1–3] has proved useful in many applications. According to [1–3], experimental data indicate that the PDFs should resemble an exponential function for x → 0. However, as x → 0, the Pareto PDF diverges. On the other hand, for high values of x, many experimental results show a Pareto—like PDF with power-law tails instead of tails with exponential decay. Therefore, as x → 0 it follows that r (x) ∼ λ, and as x → + ∞ it follows that r(x) ∼ p/x. Thus, the actual decay rate function r(x) should smoothly interpolate between these two modes. A good suggestion for r(x) was introduced in the context of special relativity where the function r(x) is given via the Lorentz factor. (8) γκ (q) = 1 + κ 2 q2 . This expression includes the dimensionless momentum q, where the parameter κ is the reciprocal of the dimensionless speed of light c, i.e. κ ∝ 1/c. Then, taking r(x) =

β 1 + κ 2 β 2 x2

,

(9)

we get for x → 0, the decay rate r(x) corresponds to an exponential distribution, i.e. r (x) ∼ λ, and as x → + ∞ corresponds to the Pareto distribution, i.e. r(x) ∼ 1/κx. The solution of ODE (1) leads to the following PDF:   f (x) = β 1 − κ 2 expκ (−βx), (10) where κ is the deformed exponential function given by. expκ (x) = for 0 < κ < 1.



1 + κ 2 x2 + κx

1/

κ

.

(11)

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It is important to note that as k → 0 and as x → 0, the function expκ (x) tends to the usual exponent, i.e. expκ (x) ∼ exp(x), κ→0

expκ (x) ∼ exp(x).

(12)

x→0

On the other hand, the function expκ (− x) as x → + ∞ is a power tail, i.e. expκ (−x)

∼

t→+∞

(2κx)−1/κ .

(13)

In addition, the κ—exponential satisfies the following identity expκ (x) expκ (−x) = 1.

(14)

by analogy with the standard, undeformed exponential. The κ-exponent is a very powerful tool that can be used to formulate a generalized statistical theory capable of considering systems described by distribution functions that have power tails. Consider the application of the Kaniadakis κ-statistic to the Weibull distribution. According to [4], the κ-deformed Weibull cumulative distribution function is:  (15) F(x) = 1 − expκ −(x/τ )α , x ≥ 0, α, τ, κ > 0, where α is the shape parameter, τ is the scale parameter. Let’s make a replacement β = τ −α . It is easy to obtain the κ-deformed Weibull PDF:

 αβ 2 κ 2 x2α−1 eκ (−βxα ) αβκ xα−1 − √ 1+κ 2 β 2 x2α dFκ (x)  

= fκ (x) = dx κ 1 + κ 2 β 2 x2α − βκ xα

 α eκ (−βxα )αβκ xα−1 1 − √ βκ2x 2 2α 1+κ β x

√  = . (16) 2 2 2α 1+κ β x κβκ xα − 1 βκ xα αβ Introducing a substitution y = √

2 κ 2 x 2α−1

1+κ 2 β 2 x2α

fκ (x) =

yields

eκ (−βxα )αβκ xα−1 (1 − y) eκ (−βxα )αβκ xα−1 y   = = κβκ xα κβκ xα 1−y y

eκ (−βxα )αβ xα−1 α (x/τ )α−1 eκ (−(x/τ )α ) =

= . τ 1 + κ 2 β 2 x2α 1 + κ 2 (x/τ )2α

(17)

The shape parameter (index of power) α quantitatively characterizes the shape of the distribution, which is less (more) pronounced at smaller (larger) values of the parameter.

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The parameter τ is a scale parameter: if τ small, then the distribution will be more concentrated around the mode; if τ is large, the distribution will be less concentrated and more scattered. Finally, the parameter κ characterizes and measures the heaviness of the right tail: the larger (smaller) its value, the thicker (thinner) the tail. As κ → 0, the distribution tends to the standard Weibull distribution. It can be easily verified that  α  x α−1 exp −(x/τ )α , κ→0 τ τ  lim Fκ (x, α, τ, κ) = 1 − exp −(x/τ )α . lim fκ (x, α, τ, κ) =

(18)

κ→0

Since the exponential distribution is a special case of Weibull with a shape parameter equal to 1, then as κ → 0 and α = 1, the κ-deformed functions tend to the exponential law. For x → 0 + , the distribution behaves similarly to the standard Weibull model, while for large values of x it approaches a Pareto distribution with a scale parameter 1 τ (2κ)− α and a shape parameter ακ , i.e. α κ

 α 1 κ τ (2κ)− α

, α x κ +1   ακ 1 τ (2κ)− α lim Fκ (x, α, τ, κ) = 1 − . x→+∞ x lim fκ (x, α, τ, κ) =

x→+∞

(19)

From Eq. 15 one can find the quantile function (inverse distribution function) and the survival (reliability) function: 1/α

1 , 0 < u < 1, Fκ−1 (u, α, τ, κ) = τ lnκ 1−u  S(u, α, τ, κ) = expκ −(x/τ )α ,

(20)

where the κ-logarithm of lnκ (u) is the inverse of expκ (u), i.e. lnκ (expκ (u)) = expκ (lnκ (u)) = u,

(21)

and is determined by the formula lnκ (u) =

uκ − u−κ . 2κ

(22)

The Median of κ-deformed Weibull distribution xmed



2κ − 2−κ = τ [lnκ (2)] = τ 2κ 1 α

 α1

.

(23)

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Mode xM can be obtained analytically as a function of the parameters α, β and κ. So xM is the point of maximum PDF, then by equating the derivative of the PDF to zero, we can find tM :   βκ xα

βκ xα 1 −

1

(1+κ 2 β 2 x2α ) 2 dfκ (x) (α − 1) −  = 0. = − 1  dx α 1 + κ 2 β 2 x2α κ 1 + κ 2 β 2 x2α 2 − βκ xα β 2 κ 2 x2α

(24)

α , then Let’s make the replacement XM = β xM



 κ XM

1−  1 1+κ 2 XM2 2 κ 2 XM2 dfκ (x) (α − 1)   = 0. = − −  1 dx α 1 + κ 2 XM2 1+κ 2 XM2 2 κ −1 κ XM Denote y =

κ XM



1+κ 2 XM2

1

(25)

, then

2

 1 (α − 1) (1 − y) (α − 1) − y2 − κ −y y+ =0 = α α κ y (1 − y)

(26)

We got a quadratic equation for the unknown y: y2 +

y (α − 1) − = 0. κ α

(27)

Solving this equation, we get D=

1 (α − 1) , +4 κ2 α

y1,2 =

− κ1 ±

1 κ2

+ 4 (α−1) α

2

(28) .

Since y ≥ 0, then y=

− κ1 +



1 κ2

+ 4 (α−1) α

2

.

(29)

Substituting the expression for y, we finally get ⎛

⎞2 1 1 (α − 1) ⎝ + ⎠ = 2 +4 . 1  κ κ α 1 + κ 2 XM2 2 2κ XM

(30)

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After a series of identical transformations κ 2 XM2 XM (α − 1)  + . = 1 2 2 α 1 + κ XM 1 + κ 2 XM2 2   Multiply both sides of this equation by 1 + κ 2 XM2 1 + κ 2 XM2   1 (α − 1) 1 + κ 2 XM2 2 2 2 2 2 . κ XM + XM 1 + κ XM = α From this expression it follows that  2    (α − 1) 1 + κ 2 XM2 2 2 2 1 + κ XM = − κ XM . αXM

(31)

(32)

(33)

Squaring and bringing like components, we get  2 (α − 1)2 1 + κ 2 XM2 α 2 XM2

 2(α − 1) 1 + κ 2 XM2 κ 2 XM − + κ 4 XM2 − 1 − κ 2 XM2 = 0. αXM (34)

Multiply both sides of this equation by α 2 XM2 α 2 XM2  2   (α − 1)2 1 + κ 2 XM2 − 2(α − 1) 1 + κ 2 XM2 κ 2 αXM2 − α 2 XM2 −

(35)

−κ 2 α 2 XM4 + κ 4 α 2 XM4 = 0. Open the brackets and bringing like components:     (α − 1)2 1 + 2κ 2 XM2 + κ 4 XM4 − 2(α − 1) 1 + κ 2 XM2 κ 2 αXM2 − −α 2 XM2 − κ 2 α 2 XM4 + κ 4 α 2 XM4 = 0, (α − 1)2 + 2(α − 1)2 κ 2 XM2 + (α − 1)2 κ 4 XM4 − 2(α − 1)κ 2 αXM2 −

(36)

−2(α − 1)κ 4 αXM4 − α 2 XM2 − κ 2 α 2 XM4 + κ 4 α 2 XM4 = 0. In the last expression   (α − 1)2 − 2(α − 1)α + α 2 κ 4 XM4 − κ 2 α 2 XM4 = κ 4 XM4 − κ 2 α 2 XM4 .

(37)

Then κ 4 XM4 − κ 2 α 2 XM4 + (α − 1)2 + 2(α − 1)2 κ 2 XM2 − 2(α − 1)κ 2 αXM2 − α 2 XM2 = 0. (38) Grouping the components with respect to κ, we get   κ 4 XM4 − κ 2 α 2 XM4 − 2(α − 1)2 XM2 + 2(α − 1)αXM2 + (α − 1)2 − α 2 XM2 = 0. (39)

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In the last expression −2(α − 1)2 XM2 + 2(α − 1)αXM2   = −2 α 2 − 2α + 1 XM2 + 2α 2 XM2 − 2αXM2 = −2α 2 XM2 + 4αXM2 − 2XM2 + 2α 2 XM2 − 2αXM2 = 2αXM2 − 2XM2

(40)

= 2XM2 (α − 1). Then we get a biquadratic equation for an unknown parameter κ:     κ 4 XM4 − κ 2 α 2 XM4 + 2XM2 (α − 1) + (α − 1)2 − α 2 XM2 = 0

(41)

Solving this equation, we get that    2 D = α 2 XM4 + 2XM2 (α − 1) − 4XM4 (α − 1)2 − α 2 XM2 = α 4 XM8 + 4α 2 XM6 α,  √ α 2 XM2 + α, D = 2αXM3 4  2 4 α 2 XM2 2 3 α XM + 2XM (α − 1) ± 2αXM 4 +α 2 κ1,2 = . 4 2XM (42) Since κ 2 ≥ 0, then finally we get.     α 2 XM2 α 2 XM2 1  + αXM + α, κ= (α − 1) + XM 2 4

(43)

α . where XM = β xM Equation 20 is very useful for analyzing empirical data. For example, using a data sample, it is possible to estimate the parameters of the usual Weibull distribution by solving a system of following equations: 

⎧ 1 ⎪ ⎪ , M = τ ·  1 + ⎪ ⎨ α   2  (44) ⎪ M 2 ⎪ 2 ⎪D = τ  1 + − , ⎩ α τ

where M is the sample mean, D is the sample variance. Then the shape parameter α can be found from the equation:   1 + α2 D  = 1+ 2. 1 2 M  1+ α

(45)

Application of Kaniadakis κ-Statistics to Load and Impact Distributions

Next, it is needed to evaluate the mode: ⎧

1 ⎪ ⎪ α − 1 /α ⎨ , α > 1, xM = τ α ⎪ ⎪ ⎩ 0, α ≤ 1.

497

(46)

α and substituting them Finally, having found the parameters β = τ −α ,XM = β xM into (43), the parameter κ is determined.

3 An Example of Applying κ-Statistics to Wind Speed Distribution As an example, let us consider the results of the analysis [5] of the wind speed in the high-mountain area Chopok located in the Low Tatras, a mountain range in the central part of Slovakia. The analyzed wind speed data were collected over an 11-year period (2005–2015) and measured at a height of 10 m above the ground using calibrated anemometers. It was found in [5] that PDF of annual wind speeds is well approximated by the Weibull distribution with the following parameters:

α  t , (47) S(t) = exp − τ where the shape α = 1.63 parameter is the scale parameter τ = 9.26. For the worldwide distribution of wind speed the Weibull shape parameter α usually ranges from 1.5 to 3 [5]. The value of the shape parameter α can be considered as an indicator of the stability of the wind speed. A high value α(2.5–4) indicates a more stable wind speed, while a lower value α(1.5–2) indicates a high wind speed variability (e.g., gusty wind locations). Using (46) we find the mode xM : xM = 5.16 m/s.

(48)

In our case β = τ −α = 0.0265. By formula (43) we find that the parameter κ = 3.33. PDF of the annual wind speed for the usual and κ-deformed Weibull distribution is shown in Fig. 2. As expected, the κ-deformed PDF has a heavy tail. Let’s find the probability that the annual wind speed V will exceed the given value v, that is P(V > v) = 1 − F(v).

(49)

 P(V > v) = exp −βxα ,  Pκ (V > v) = expκ −βxα .

(50)

For our example, we have:

Function graphs P(V > v), Pκ (V > v) are shown in Fig. 3, from which it can be seen that the exceedance probabilities coincide up to about 4 m/s. Above this value,

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Fig. 2. PDF of the annual wind speed for the conventional and κ-deformed Weibull distribution.

the exceedance probability with a κ-deformed distribution is greater than that with a regular Weibull distribution. For example, the probability that the annual wind speed V will exceed 10 m/s is 0.322 with the usual Weibull distribution, and 0.542 with the κ-deformed Weibull distribution.

Fig. 3. The Probability of exceedance for annual wind speed v.

4 Conclusion The use of κ-statistics makes it possible to transform the original distributions into heavy-tailed distributions that more closely match the systems experimental data of mixed distribution, operating under conditions of increased uncertainty. This allows, within the framework of already known and well established distributions of loads and impacts, to model excess stressors in the tails of these distributions and analyze the consequences of beyond-design situations, including black Swan type disasters (ultra rare type of events with humongous consequences that are near impossible to predict).

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References 1. Kaniadakis G (2002) Statistical mechanics in the context of special relativity. Phys Rev E 66:17 2. Kaniadakis G (2009) Maximum entropy principle and power-law tailed distributions. Eur Phys J B70:3–13 3. Kaniadakis G, Scarfone AM et al (2017) Composition law of kappa-entropy for statistically independent systems. Phys Rev E 95:052112 4. Clementi F, Gallegati M, Kaniadakis G (2011) A model of personal income distribution with application to Italian data. Empir Econ 39:559–591 5. Poboˇcíková I, Sedliaˇcková Z et al (2020) Statistical analysis of the wind speed at mountain site Chopok, Slovakia, using Weibull distribution. IOP Conf Ser: Mater Sci Eng 776(1)

Specifics of Applying the Fragility Theory to Technical Systems and Structures S. Timashev1,2(B) and A. Bushinskaya1,2 1 Science and Engineering Center “Reliability and Safety of Large Systems and Machines”, Ural

Branch, Russian Academy of Sciences, 54-A, Studencheskaya, Yekaterinburg 620002, Russia [email protected] 2 Ural Federal University, 19, Mira, Yekaterinburg 620002, Russia

Abstract. The paper presents the features of applying the Nassim Taleb’s fragility theory to technical systems and structures. This theory allows analyzing stability and survivability of an object subjected to exceptionally large shock whose likelihood is close to impossible. For example, when an existing integral system (or a set of such systems), designed according to current standards, starts experiencing the impact of loads that have qualitatively changed their nature (for example, due to global climate change). The nature of catastrophes is associated with a strong interdependence of ongoing events. The concept of fragility can be used in risk analysis of technical systems for which loss distribution curves are considered, where losses are described by positive numbers and the right tail of the distribution is considered. Fragility, in the context of the problem under consideration, lies in the incorrect calculation of the risk from large-scale negative events. This is the so-called “simulation fragility”. That is, the systems are “fragile” to inaccuracies in estimating the distribution of stressors, and, consequently, to modeling errors, since this inaccuracy increases the likelihood of loads and impacts exceeding the design limits, leading to a greater likelihood of system failure. Fragility can be used to measure the non-linear response to a change in a model parameter by correlating fragility with model error. Keywords: Fragility · Heavy-tailed distributions · Black swan · Uncertainty · Catastrophe · Loss

1 Introduction Most scientists and researchers believe that the tails of the distributions of random variables (RVs) involved in probabilistic analysis of physical infrastructures (loads and impacts, manufacture errors of components and structures, the properties of the product materials, etc.) are insignificant and can be neglected in normal practice, since they contain a negligibly small part of the statistical sample. Therefore, the traditionally probabilistic analysis of various infrastructures is carried out using the probability density function (PDF) with the so-called “thin tails” (Gaussian, exponential, etc.), in which large deviations from the average values are very rare. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_48

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However, in recent years, accidents and catastrophes of physical infrastructures, caused by realizations of random loads and impacts whose values are at significant distances from their average values, have become more and more frequent. In these cases, the actual probabilities of their manifestation turn out to be one or several orders of magnitude greater than the values predicted by PDFs with thin tails. Probability density functions whose tails decay much slower than in the case of a normal or exponential distribution are called fat-tailed distributions. They allow taking into account events of (vanishingly) low probability with disproportionately significant (catastrophic) consequences. These kind of events are found in hydrology, geology, electrical engineering, informatics, physics, and insurance; they describe well the behavior of financial markets [1–4]. The statistics described by such distributions is different in that the rare events that fall on the tail of the distribution do not occur so rarely that they can be ignored [5]. In terms of safety and risk assessment, the tail of the distribution corresponds to crisis phenomena and catastrophic situations (Black Swan events [6]). Fat-tailed PDFs are fundamental concepts of risk theory, since they adequately describe the absolute majority of the processes of development of natural disasters with great damage, crisis phenomena and catastrophic situations [7]. In terms of safety and risk theory, the tail of such a distribution robustly describes the so -called hypothetical accidents [5]. Probability of catastrophic consequences calculated using thick-tailed PDFs can be an order of magnitude or more higher than the probabilities calculated from thin- tailed PDFs, because tails that slowly decrease with increasing values of variables contain a significant part of the sample, which is automatically discarded in the second case, which leads to significant errors. Often ideas about reliability and risk are based on the assumption that serious events occur solely as a result of an unfavorable combination of a number of circumstances (the so-called “perfect storm” type disaster), i.e. that any large event arises as the sum of a large number of small independent events, which, by virtue of the central limit theorem, is normally distributed [7]. However, as practice shows, this is far from the case. The nature of catastrophes actually is associated with a strong interdependence of ongoing events. A “chain reaction” leads to the appearance of fat-tailed PDFs, i.e. an avalanche-like increase of the catastrophe with the involvement of an increasing number of objects in the event (the so-called “domino effect”) [7]. The reliability of technical systems is analyzed using probabilistic methods based on collected statistics. The application of Gaussian statistics is based on the belief that the results obtained do not depend on the sample size, changing randomly from sample to sample. When working with fat-tailed distributions, this approach leads to serious errors, because for non-Gaussian populations, the PDF moments increase with sample size. Therefore, when choosing an appropriate empirical distribution, one should take into account not only the degree of closeness of the selected PDF to the histogram of a particular sample, but also the specifics of the entire population. The theory of catastrophes (a catastrophe is a sudden, unexpected abrupt change in the state (response) of a real complex system with external conditions changing smoothly) considers the limit states of the system in the aspect of its stability-instability. The origins of catastrophe theory are Whitney’s theory of singularities and the theory of bifurcations

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of dynamical systems by Poincaré and Andronov. V.I. Arnold, considering in his work on the theory of catastrophes the problem of stability of two-parameter systems [8] formulated the so-called “principle of the fragility of the good”: “For a system belonging to a special part of the stability boundary, with a small change in parameters, it is more likely to fall into the region of instability than into the region of stability. This is a manifestation of the general principle that all good things (such as sustainability) are more fragile than bad things. Apparently, all good objects satisfy several requirements at the same time, while an object is considered bad if it has at least one of a number of shortcomings”. With an increase in the number of parameters that determine the dynamics of the system, new possibilities for the loss of stability appear, and the probability of this loss rapidly increases. The more complex the dynamic system, and the weaker the mechanisms of its self-regulation, the more fragile its state is. With approaching the boundary of the stability region, even small smooth changes in parameters can lead to a very fast, abrupt loss of stability—a catastrophe [8]. In other words, stability is provided by a whole range of features, and the loss of stability can be provoked by a violation of any one of them [9]. All modern mechanical systems and objects are designed on the basis of existing standards (created by summarizing many years of experimental and theoretical studies of materials, loads, impacts, structures) and the cumulative accumulated experience of their operation. Thus, existing regulations concentrate on what is already known about the system and its operating environment. The question arises: “What will happen when the existing integral system, created according to the current norms (or many such systems), begins to experience the impact of loads that have qualitatively changed their nature, for example, from global warming?”. If a technical system (for example, a bridge, an aircraft, an oil or gas pipeline) is subjected to stress exceeding its design (normative) values, then the probability of its failure increases sharply. Then the system either fails (its further operation is inexpedient), or is physically destroyed. Thus, to increase system survivability, it is necessary to include in its design and diagnostics, monitoring and control subsystems the appropriate functions that allow it to continue its useful activity in a certain range of loads and impacts that exceed the design values. In other words, adapt the functionality and performance of the system to the uncertainty. Below the Nassim Taleb’s fragility theory is considered [1–3]. Taleb, being a financier and trader, in the mathematical description of fragility (and antifragility) uses concepts of the stock market theory and transfers them (at times, inconsiderately) on any random variables and their distribution functions.

2 Graphical Representation of Fragility and Antifragility The fragility and antifragility concept was originally created to consider losses in the financial system (stock exchange) when a random event x occurs, causing real, momentary tangible losses. Usually, possible losses and profits are presented in the form of the so-called profit-loss distribution (profit-and-loss distribution) for the considered time range (year, month, day, etc.). This distribution is generally a skewed distribution where

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the origin separates profits and losses. Thus, the right side relative to the origin represents positive values of possible profit, and the left side represents negative values of possible losses. Taleb considered the function g (x) as a risk associated with the variable x. One can also call g (x) “the return on x”, “the impact of x”, even the “utility of the return on x “if g (x) is a utility function. The variable x is a random variable; therefore, g (x) is a function of a random variable and is itself a RV. Consider the PDF of a random variable g (x) [1–3], where the return of (values of) g (x) is displayed on the horizontal axis, and the PDF value for this return is displayed on the vertical axis. We consider that the values of g (x) located to the left of the distribution center (mean, mode or median) are losses (negative returns), and those located to the right are gains (positive returns). Thus, distributions of the “profit-loss” type are considered. The possible states of a system depending on the PDF of g(x) are presented in Fig. 1. The Invulnerable (robust) state is characterized by both mall positive and negative return. The Fragile (Type 1, very rare state) is characterized by both large positive and large negative. Such symmetry is very rare in practice, but statistical distributions usually simplify reality to just such a graph. Fragile (type 2) state is characterized by incredibly large losses (often hidden and ignored), small gains. A catastrophic bad outcome (left) is much more likely than a good one (right) because the left side of the distribution is thicker than the right. Antifragile state is characterized by big gains, small losses. A favorable outcome is much more likely than an unfavorable one (the latter may be impossible at all). The right side of the distribution, corresponding to a favorable outcome, is thicker than the left side.

Fig. 1. Dependence of states on the type of distribution.

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3 A Measure of the Distribution Tails’ Sensitivity to Uncertainty Consider the left tail of the distribution (fragility). Sensitivity to the uncertainty of the left tail of the distribution is based on such concepts as the absolute semi-deviation. Consider such concepts as semi-variance and semi-deviation. Variance and standard deviation are used as a measure of RV dispersion and represent the uncertainty. A certain disadvantage of the variance is that it equally takes into account the deviations of the RV from its average in both directions of the distribution. Since we are considering only the left tail of the distribution, we will use the indicator of the left semi-dispersion (left semi - variance): D (D − x)2 f (x)dx,

(1)

−∞

where f (x) is the probability density of the RV distribution X; D is the target level of return. If D is the expected value, then (1) is called the below-average semi-variance. The semi-variance differs from the dispersion index only in that only such values of a random variable that are less than the distribution center or a certain target value are taken into account when calculating the indicator. Similar to the standard deviation, the square root of the semi- variance is called the semi-deviation. By analogy, one can determine the right half-dispersion index (right semi-variance), i.e. such values of a random variable that turn out to be greater than the distribution center or a certain target value +∞ (D − x)2 f (x)dx.

(2)

D

Note that in the case of a symmetrical distribution (for example, normal), the right and left semi-variances will be equal. However, in the case of non- symmetric distributions, the value of these semi-dispersions will be different (Fig. 2).

Fig. 2. Examples of skewed distributions.

Consider now the absolute semi-deviation. As this measure, we use half of the mean absolute deviation (MAD), that is, only the part that is to the left of the center of the

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distribution (in other words, loss, to determine fragility). To ensure consistency, we treat losses as negative numbers, even though they are physically positive. In statistics, the absolute deviation of elements in a data set is the absolute difference between an element and a selected point from which the deviation is measured. The MAD of a data set is the average of the absolute deviations from the center point. This value is one measure of the scatter or variability of the data. In general, the center point can be the mean, median, mode, or any other arbitrary data point. If we take the median or the average value of the data set under consideration as the reference point of the absolute deviation μ, then the average absolute deviation will be: 1 |xi − μ|, n n

MAD =

(3)

i=1

where xi is an element of the data set. Using this expression in relation to formula (1), we obtain the left absolute semideviation s

(−)

D =

(D − x)f (x)dx.

(4)

−∞

It should be noted that the variance (standard deviation) requires the existence of a second moment of the distribution, so using the absolute semi-deviation solves this problem. Determine the measure of the sensitivity of the distribution tails to uncertainty, which depends on the semi-deviation s(−) from the distribution center . Let X be a random variable whose distribution belongs to the family of one-parameter distributions. Denote the PDF as f (λ, x), where λ is the distribution parameter. Then the left absolute semideviation is: s

(−)

 (λ) =

( − x)f (λ, x)dx.

(5)

−∞

Under the parameter λ(s) ∈ I ⊂ R+ , we consider the distribution scale parameter, which depends on the half- deviation values s(−) ∈ R+ = [0; +∞]. As the uncertainty (scatter of the data) increases, the scale parameter will strictly increase. Since λ(s) and s(−) (λ) are linked by functional dependence (3), the function s(λ) : R+ → I can be considered as a function inverse to the function λ(s) : I → R+ , that is, by definition of the inverse function s(−) (λ(s)) = s. Thus, in order to define function λ(s), it is necessary to find the function inverse to s(−) (λ).

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4 Mathematical Definition of Fragility Formally, we consider a system in which events cause losses X. Losses can be anything that can be quantified. The random variable x can be an economic variable (losses, unemployment, GDP of a country, value of company assets) or epidemiological (number of victims of a pandemic), environmental (deforestation, loss of biodiversity), or any other loss, consisting of a single measure large values of which correspond to a highly undesirable result. In this case, define the value of K as a threshold that separates critical loss levels from non- critical. For a fixed value K <  and s(−) ∈ R+ consider the following function: K       (−) = ξ K, s ( − x)f λ s(−) , x dx,

(6)

−∞

This value is the value of the semi- deviation in the  from −∞ to K, where K  interval is a threshold (some level of stress). The function ξ K, s(−) is a measure of sensitivity (measure of risk).   It is assumed that the function is ξ K, s(−) differentiable on the segment [−∞; ]× R+ . Then the K-sensitivity of the left tail of PDF f (λ, x) at stress level K <  and semideviation level s(−) > 0 will be: ⎛ K ⎞          dλ ∂ξ ∂f λ s(−) , x dx⎠ (−) . (7) V K, s(−) = (−) K, s(−) = ⎝ ( − x) ∂λ ∂s ds −∞

  K -sensitivity determines the change rate of semi-deviations ξ K, s(−) between _ −∞ and K when changing the value s(−) .   Increase the semi- deviation s(−) by increment s. The difference ξ K, s(−) + s −   ξ K, s(−) is then the sensitivity of the left tail to the increase in uncertainty, where: K       (−) ξ K, s + s = ( − x)f λ s(−) + s , x dx.

(8)

−∞

There are two types of fragility: local, i.e. own or built-in, and inherited. In this paper, only local fragility is considered. Local (intrinsic) fragility of a random variable X with PDF f (λ, x), depending on (−) is the Kparameter λ, at the level of K and the level of semi- deviation s  stress (−) . sensitivity of the left tail V K, s Local finite-difference fragility of a random variable X with PDF f (λ, x), depending on the parameter λ,  at the stress level K is the finite-difference K-sensitivity of the left tail V K, s(−) , s . Antifragility, in contrast to fragility, is defined only for functional non-linear relationships Y = ϕ(X )(inherited antifragility), and the PDF of the RV X must be unimodal and differentiable. Antifragility applies only to (profit–losses) type distributions because

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its definition considers the sensitivity of both tails of the distribution. Hence, the concept of antifragility can be applied to manage the operation of a technical object that generates profit/loss, provided that it is possible to build the PDF of the “profit-loss” type. Fragility, on the contrary, is an independent concept and can be used for any unimodal distributions and any type of its tail, representing damages/losses or other critical values of any parameters of the object under consideration. For example, when analyzing the risk of technical systems, loss (damage) distribution curves are mainly used, where losses are described by positive numbers and the right tail of the distribution is considered.

5 Application Features of the Fragility Theory Modern technical systems are inevitably designed to be more or less fragile [10]. Fragility, in the context of the problem under consideration, lies in the incorrect calculation of the risk from large-scale negative events. This is the so-called “simulation fragility”. That is, the systems are “fragile” to inaccuracies in estimating the distribution of stressors, and, consequently, to modeling errors, since this inaccuracy increases the likelihood of loads and impacts exceeding the design limits, leading to a greater likelihood of system failure. Fragility can be used to measure the non-linear response to a change in a model parameter by correlating fragility with model error. For example, a small perturbation of the PDF parameters provokes a significant increase in the probability of a negative event (a convex response). This can be illustrated as follows: if a system is more damaged by a stressor with intensity n ·Z than by a stressor with intensity Z applied n times—up to destruction (i.e., the system’s response to stress is nonlinear), then such a system is especially vulnerable to extreme events and to forecasting their errors. The issue of constructing the loss PDF for a specific scenario of an event development is quite complex. To do this, it is necessary to consider the risk R (possible loss) as the probability Pf of occurrence of an event of failure, accident or catastrophe multiplied by the consequences of these events (damage C): R = Pf C,

(9)

When analyzing the structural risk, the probability of an event Pf and damage C can be considered as RVs with their own distribution densities fPf (p), fC (c). The probability of an event Pf can be considered a random variable, because it is estimated with a certain degree of reliability on a limited sample size (for example, according to accident statistics). Then we have a system of two random variables with given distributions, and we can find a joint distribution fPf C (p, c). If RVs Pf and C are independent, then the distribution function and the risk PDF R have the form ¨ FR (r) = P(R < r) =

r/ 1  p fPf C (p, c)dcdp = fPf (p)fC (c)dcdp,



1 fR (r) = 0

r dp. fPf (p)fC p

0

0

(10)

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Thus, knowing the PDFs of the probability of an accident and the damage due to this event, one can find the risk PDF. If the probability of failure Pf , accident or catastrophe is not a RV then the risk can be calculated using the formula.  R = Pf cfC (c)dc, (11) 

where the integration is performed over the entire damage area . Using fragility, it is possible to analyze sensitivity of the model to errors (or changes) in the original data, as well as compare two models according to the fragility criterion. As an example, consider the annual losses from storms and fires in a small seaside town, which are independent exponentially distributed random variables with average values of 1.5 and 2.4 million rubles, respectively. Let us find the probability that the maximum damage from storms and fires will be more than 3 million rubles. For an exponential distribution, the PDF and the distribution function have the form. f (x) = λe−λx , F(x) = 1 − e−λx , x ≥ 0,

(12)

where λ is the distribution parameter (intensity). Let RVs X,Y be annual losses from storms and fires, respectively, U = max (X,Y). Then P(U > c) = 1 − P(U ≤ c) = 1 − P(X ≤ c, Y ≤ c) = = 1 − P(X ≤ c)P(Y ≤ c) = 1 − F1 (c)F2 (c).

(13)

where F1 (x), F2 (x) are the distribution functions of RV X and Y respectively: F1 (x) = 1 − e−λ1 x , F2 (x) = 1 − e−λ2 x ,

(14)

1 1 = 0.667, λ2 = 2.4 = 0.417. where λ1 = 1.5 Suppose we are not sure about the correct estimate of the parameters λ1 , λ2 , as they are not clearly defined. Then consider the parameters λ1 , λ2 as RVs. In this case, we get a compound probability i.e.,a probability distribution that arises as a result of the assumption that the RV X with PDF fX (x, θ ), where parameter θ is a random variable with PDF gθ (x). As a result of the connection f with g, a new distribution h arises, which is called the unconditional or composite distribution. The distribution of a parameter gθ (x) is called a mixing or latent distribution. Formally, the unconditional distribution h results from marginalization over g, i.e. from combining the original distribution with the distribution of the parameter θ . The original distribution fX (x, θ ) is called the conditional distribution. The composite distribution h is much like the original distribution f that created it, but tends to have larger variance and often heavy tails. Unconditional distribution of RV X is the weighted mean of the PDF f (x, θ ), where the weight is the PDF of the random parameter θ (mixing weight):

+∞ fX (x, θ )gθ (θ )d θ . hX (x) = −∞

(15)

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Unconditional distribution function of the parameter θ will be a function of the form: +∞ HX (x) = FX (x, θ )gθ (θ )d θ ,

(16)

−∞

where FX (x, θ ) is the conditional distribution function of RV x. Let’s assume that RV λ1 , λ2 have the Gamma distribution with PDF g1 (x), g2 (x) respectively: β1α1 xα1 −1 e−β1 x , (α1 ) β α2 xα2 −1 e−β2 x , g2 (x) = 2 (α2 )

g1 (x) =

(17)

where α1 , β1 are the parameters of the RV distribution λ1 ; α2 , β2 are distribution parameters of RV λ2 . Then PDF and FDF (distribution function) of the unconditional distribution of RV X: +∞ +∞ α1 α1 −1 e−β1 λ β1α1 −λ1 x β λ hX (x) = d λ1 = λ1 e e−(x+β1 )λ1 λα1 1 d λ1 = (α1 ) (α1 ) 0

=

0

β1α1 (α1 + 1) (α1 )(x + β1 )

+∞

α1 +1

β1α1 (α1 + 1)

0

1 (x + β1 )α1 +1 e−(t+β1 )λ λα1 1 d λ1 = (α1 + 1)

(18)

α1 β1α1

= , (α1 )(x + β1 )α1 +1 (x + β1 )α1 +1 x α1 β1α1 β1α1 HX (x) = dt = 1 − . (x + β1 )α1 (t + β1 )α1 +1 =

0

Thus, the unconditional distribution of RVX is a heavy-tailed Lomax distribution for type I Pareto distribution. Similar to the PDF and the distribution function of the unconditional distribution of the RV Y α2 β2α2

, (y + β2 )α2 +1 β2α2 . HY (y) = 1 − (y + β2 )α2

hY (y) =

(19)

Assume that the mean M and standard deviation S of RVs λ1 , λ2 : M (λ1 ) = λ1 , M (λ2 ) = λ2 , S(λ1 ) = 0.5 · λ1 , S(λ2 ) = 0.7 · λ2 .

(20)

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Gamma distribution parameters by solving the system of equations: ⎧ α ⎪ ⎨M = , β α ⎪ ⎩ S2 = . β2

(21)

Then α1 = 3.99, β1 = 5.99; α2 = 2.04, β2 = 4.89. Charts for the PDF of RV X (storm damage losses) and RV Y (fire damage losses) with their exponential distribution and the Lomax distribution are shown in Figs. 3 and 4. It can be seen that the Lomax distribution associates smaller values of damage with lower probabilities, and larger values of damage with higher probabilities, which makes it heavy-tailed.

Fig. 3. PDF of storm damage losses (exponential and Lomax distribution).

Then, according to (13), the probability that the maximum of these damages will be more than 3 million rubles: without taking into account the uncertainty in estimating the distribution parameters λ1 , λ2 :    (22) P(U > 3) = 1 − 1 − e−0.667·3 1 − e−0.417·3 ≈ 0.383, taking into account the uncertainty in estimating the distribution parameters λ1 , λ2 :



β2α2 β1α1 1 − ≈ 0.5, (23) P ∗ (U > 3) = 1 − 1 − (3 + β1 )α1 (3 + β2 )α2 Charts of functions P(U > c), P ∗ (U > c) depending on the value of c are presented in Fig. 5.

Specifics of Applying the Fragility Theory to Technical Systems

511

Fig. 4. PDF of fire damage losses (exponential and Lomax distribution).

Fig. 5. The probability that the maximum of the damages will exceed one million rubles.

Figure 5 shows that the probabilities approximately coincide only for 0 ≤ c ≤ 1 million rubles. As the value of c increases, the Lomax distribution gives a greater probability of exceedance than the exponential distribution. Thus, as uncertainty increases, the distribution of damages becomes more fragile, i.e., large damages become more likely.

6 Conclusion Probability of catastrophic consequences calculated using thin-tailed PDFs can be an order of magnitude or more higher than the probabilities calculated from thin-tailed PDFs, because tails that slowly decrease with increasing values of variables contain a

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significant part of the sample, which is automatically discarded in the second case, which leads to significant errors. Often ideas about reliability and risk are based on the assumption that serious events occur solely as a result of an unfavorable combination of a number of circumstances (the so-called “perfect storm” type disaster)”, i.e. that any large event arises as the sum of a large number of small independent events, which, by virtue of the central limit theorem, is normally distributed [7]. However, as practice shows, this is far from the case. The nature of catastrophes is associated with a strong interdependence of ongoing events. The concept of fragility can be used in risk analysis of technical systems for which loss distribution curves are considered, where losses are described by positive numbers and the right tail of the distribution is considered. Fragility, in the context of the problem under consideration, lies in the incorrect calculation of the risk from large-scale negative events. This is the so-called “simulation fragility”. That is, the systems are “fragile” to inaccuracies in estimating the distribution of stressors, and, consequently, to modeling errors, since this inaccuracy increases the likelihood of loads and impacts exceeding the design limits, leading to a greater likelihood of system failure. Fragility can be used to measure the non-linear response to a change in a model parameter by correlating fragility with model error.

References 1. Taleb NN (2015) Antifragility. How to capitalize on chaos. LLC “Publishing Group “AzbukaAtticus”, Moscow 2. Taleb NN (2014) Silent risk: lectures on fat tails, (Anti) fragility, and asymmetric exposures. SSRN Electron J 3. Taleb NN, Douady R (2013) Mathematical definition, mapping, and detection of (anti) fragility. Quant Financ 13(11):1677–1689 4. Bevrani H, Anichkin K (2005) Estimation of the parameters of distributions with heavy tails using empirical distribution. In: Riznichenko GY (ed) Proc of the XII international conference of “mathematics. a computer. education”, vol 2. Scientific Publishing Center “Regular and Chaotic Dynamics”, Izhevsk 5. Papkov BV, Kulikov AL, Osokin VL (2018) Estimation of probabilities and risk of rare events in the electric power industry. In: Proceedings of the 90th meeting of the international scientific “methodological issues of researching the reliability of large power systems” 6. Timashev SA (2020) Black-Swan type catastrophes and antifragility/supra-resilience of urban socio-technical infrastructures. IOP Conf Ser: Mater Sci Eng 972:012001 7. Vladimirov VA, Vorobyov YL et al (2000) Risk management: risk. sustainable development. synergetics. Nauka, Moscow 8. Arnold VI (1990) Theory of catastrophes. Nauka, Moscow 9. Alekseev YuK (1990) Introduction to the theory of catastrophes. Finance and statistics, Moscow 10. Kennie HJ (2014) Engineering antifragile systems: a change in design philosophy. Proc Comp Sci 32:870–875

Suspended Ceiling Safety for Firefighters in Case of Fire in the Attic S. V. Fedosov1,2(B) , A. A. Lazarev3 , V. G. Kotlov2 , V. G. Malichenko4 , and D. E. Tsvetkov2 1 Moscow State University of Civil Engineering (National Research University), 26,

Yaroslavskoe Shosse, Moscow 129337, Russia [email protected] 2 Volga State University of Technology, 3, Lenin Square, Yoshkar-Ola 424000, Russia 3 Ivanovo Fire and Rescue Academy of the State Fire Service of the Ministry of the Russian Federation for Civil Defense, Emergencies and Elimination of Consequences of Natural Disasters, 33, Stroiteley Avenue, Ivanovo 153040, Russia 4 Ivanovo State Politechnical University, 21, Sheremetyevo Avenue, Ivanovo 153000, Russia

Abstract. An analysis of the literature indicates a significant number of solutions to ensure the fire safety of residential buildings, the operational characteristics of attic rooms and the operation of nagel joints of wooden structures. At the same time, there are practically no studies of various aspects of the safety of a suspended ceiling for firefighters when extinguishing a fire while they are in the attic. The main purpose of the study is to determine the dynamics of changes in the resistance to pulling out of a non-smooth nail depending on its characteristics under normal conditions. These experiments are necessary to develop the concept of a method of non-destructive testing of the overhead joints of suspended ceiling elements to assess the load-bearing capacity and determine the possibility of firefighters being in the attic when extinguishing a fire. A stand has been created for conducting research. The specified stand allows you to determine the resistance to pulling out a non-smooth nagel from a bar (bars). With the help of this stand, the regularities of the change in the resistance to pulling out the notched and screw nagel, depending on their characteristics, have been established. The results obtained will allow improving approaches to drawing up fire extinguishing plans in buildings with suspended ceilings, determining the locations of firefighters in the attic, developing recommendations for the use of nails with notches and screw nails for the installation of suspended ceilings. Keywords: Suspended ceiling · Firefighters · Fire · Attic · Fire safety

1 Introduction Fire safety of buildings is very often considered from the point of view of fire prevention, installation of fire detection systems, development of organizational and technical solutions. At the same time, the technosphere safety aspects of suspended ceilings were © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_49

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not properly considered. There are known solutions for the creation of fire-resistant suspended ceilings with high fire resistance limits. These solutions were proposed by [1]. However, the technosphere safety of a suspended ceiling for firefighters is not only in its fire resistance. It is important to evaluate the possibility of using this ceiling when extinguishing a fire while firefighters are in the attic. The nature of the control of the nagel joints of the elements of wooden structures is also of significant importance. Nondestructive testing methods are known for steel [2–9] and wood [10–12]. Studies of aspects of the operation of attic rooms were also studied. Saha and Khan considered natural convection and heat transfer in the attic space [13]. Miler and Gosar assessed heavy metal contamination of attic and household dust [14]. Heat resistance in attic rooms was studied by [15]. The temperature and humidity state of the attic covered with an awning was studied by [16]. Dolnikova et al. studied the effect of changes in the area of dormer windows on the microclimate in the classroom in the attic room [17]. Stejskalova and Bujdos compared various measures to reduce the temperature in the attic room in summer [18]. Aleixo and Curado evaluated the tightness in the attic [19]. The study of thermal insulation boards based on flax fiber on the attic floor was carried out by Romanovskiy and Bakatovich [20]. Methods of local automatic regulation of the thermophysical parameters of the external walls of buildings in the places of condensate occurrence were also studied [21]. At the same time, the possibility of using a suspended ceiling when extinguishing a fire while firefighters were in the attic was not investigated. At the same time, it is important to take into account the characteristics of the building materials used. Natural stone materials are widely used for the construction of low-rise buildings. These materials are obtained from rocks as a result of using only mechanical processing (splitting, crushing, sawing, grinding, etc.). These materials are used for the construction of walls, the arrangement of floors, stairs and building foundations, facade cladding, etc. Rocks are also used in the production of artificial stone materials (glass, thermal insulation and composite materials, ceramics, etc.), as well as as raw materials for the production of binders (cements, gypsum, lime). Various processes occur in the stone materials of low-rise buildings under the influence of high temperatures. These processes lead to a decrease in strength and destruction. The properties of fire hazard of building materials are determined by their flammability, flammability, the ability of flame propagation over the surface, smoke-forming ability, toxicity [1, 21–28]. Building materials are usually divided into combustible and non-combustible. An example of non-combustible building materials can be ceramic products. These products are obtained mainly from clay. According to their intended purpose, these materials and products for low-rise buildings can be divided into the following types: wall products (bricks, hollow stones, wall panels); roofing products (tiles); products for facade cladding (small-sized tiles, face bricks, set panels, architectural and artistic details); products for interior wall cladding (glazed tiles and shaped products to them); fillers for light concrete (expanded clay, sinterite); thermal insulation products (perlite ceramics, cellular ceramics, etc.); sanitary products (washbasins, bathtubs, toilets); floor tiles; refractories; products for underground utilities. Metals are also widely used in the construction of low-rise residential buildings. They are used for the construction of frames in the form of steel rolling profiles. A significant amount of steel is used to create reinforcement for the manufacture of reinforced

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concrete. In low-rise buildings, steel and cast iron pipes are used, as well as roofing steel. Lightweight building structures made of aluminum alloys in recent years have become more widely used for the construction of low-rise buildings. Building materials and products based on mineral melts are widely used in the construction of low-rise buildings. These include glass materials, products made of slag and stone casting, sitals and slag metals. Consider another material for the construction of low-rise buildings. This material is one of the most common. However, it is a combustible building material. This material is wood. It has such qualities as relatively high strength, low density, sufficient elasticity, low thermal conductivity, ease of machining, durability. Wood is used for the manufacture of load-bearing structures of buildings: trusses, arches, beams, girders, rafters, frames, enclosing elements: wall panels, partitions. Wood is also used in the manufacture of joinery for low-rise residential buildings: windows, doors, floors, baseboards, platbands. In construction, wood is used in the form of round timber or lumber. Wood-fiber, chipboard, fibrolite, arbolite contain wood waste in their composition. Glued structures and wood parts are also widely used [1, 21–28]. The relevance of this study is due to two circumstances. The first circumstance for a low-rise building arises in the case of installation of a suspended ceiling when nailing boards from the side of the room under the attic (Fig. 1a). The danger for a firefighter arises when he is dislocated from the back of such a ceiling when extinguishing a fire in an attic room. In this case, the ceiling may not support the weight of a firefighter (Fig. 1b). A person may fall to the underlying floor. The second circumstance arises when there is a threat of collapse of the suspended ceiling from above. In this case, the firefighter may also be injured. The second circumstance must be connected with the dynamics of the heat and humidity state of the environment in the attic. This condition leads to the appearance of temperature and humidity gradients in the plane of contact of the nagel and the plane of the ceiling (rafters). The result of this impact may be the development of critical stresses leading to destruction. The object of the study is a non-smooth and smooth nagel inside the bar (test block). The subject of the study was to establish the dynamics of changes in the resistance to pulling out of a non-smooth and smooth nail depending on its characteristics under normal conditions. Research objectives: 1. Create a stand to determine the resistance to pulling the nagel out of the bar (bars). 2. To establish the regularity of the change in the resistance to pulling out the nagel with notches [29] depending on its characteristics. 3. To establish the regularity of the change in the resistance to pulling out the screw nagel [30] depending on its characteristics. 4. To develop a concept of a method of non-destructive testing of nagel joints of suspended ceiling elements to assess the load-bearing capacity and determine the possibility of firefighters being in the attic when extinguishing a fire.

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Fig. 1. Design scheme: a when a firefighter is on a beam: 1—a wooden board; 2—a wooden beam of the attic floor; 3—the place of impact of the load on the beam; 4—wall; b when a firefighter is on the boards: 1—a wooden board; 2—the place of the load on the wooden board; 3—the place of attachment of the wooden board with a nagel to a wooden beam; 4—the wooden beam of the attic floor; 5—wall.

2 Methods A stand was assembled for testing (Fig. 2). This stand assumed carrying out tests on pulling out the nagel from wooden bars (pine, humidity 12%) on a testing machine. To capture the nagel, a device is used to connect the test unit (a sample with a nagel) to the test machine (Fig. 3). The test machine has a load measurement error of no more than 1%. During the tests, notched nails [29] with dimensions of 2.8 × 60 mm, 2.8 × 70 mm, 3.4 × 80 mm and screw nails [30] with dimensions of 3.0 × 40 mm, 3.0 × 50 mm, 3.0 × 60 mm, 3.0 × 70 mm, 3.0 × 80 mm, 3.0 × 90 mm (Figs. 4 and 5). Nails with a clean, fat-free surface and indented notches (if any) were used for testing. Four samples were cut from each wooden bar selected for testing. These samples had the shape of a parallelepiped with three sizes: 1) 50 ± 1 mm long and 50 ± 1 mm wide; 2) 40 ± 1 mm long and 40 ± 1 mm wide; 3) 20 ± 1 mm long and 40 ± 1 mm wide. Before the test, the samples were conditioned to a constant mass at a temperature of (20 ± 2) °C and a relative humidity of (65 ± 5)%. The mass of the sample was recognized as constant if the results of two consecutive weighings with an interval of 24 h differed from each other by no more than 0.1%. The test unit is assembled separately for each test. To determine the specific resistance to pulling out nails, they were hammered into the edge in the center of the selected face of the sample. This is done for the entire length of the nail until it stops in the metal retainer of the nail head (the width of the metal retainer of the nail head is 3 mm). The test unit is installed in the grips of the device on the testing machine (Fig. 5). In this case, the axis of the nail coincides with the axis of the device. The nails are pulled out in the direction of their axis with the speed of movement of the movable gripper of the testing machine 10 ± 1 mm/min. The highest load is recorded on the electronic scoreboard of the test machine.

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Fig. 2. Scheme of the test stand: 1—a base for fixing a wooden bar; 2—a steel non-smooth nagel; 3—a device for connecting the test unit to the test machine; 4—a measuring device; 5—a ceiling; 6—a metal ring; 7—a metal cable; 8—an electric test machine.

3 Results and Discussion With the help of the stand, a series of tests was carried out on pulling out three types of steel nagels from three types of wooden bars by a testing machine. The results are presented in Tables 1 and 2. The analysis of the results of the data in Tables 1 and 2 indicates that there is a tendency to increase the difference in the pulling resistance of screw [30] and smooth nails compared to nails with notches [29] with an increase in the thickness of the connected elements of wooden structures. The results of the experiment are presented in tables. Under the given conditions, there is an increase in the resistance to pulling out with an increase in the length of contact between the nail and wood. These data are adequate, do not contradict the calculation results in accordance with Eurocode 5 [31] and can be used to develop a concept of a method of non-destructive testing of the overhead joints of suspended ceiling elements to assess the load-bearing capacity and determine the possibility of firefighters being in the attic when extinguishing a fire. The study of the operational properties of the nagel joints of the elements of wooden structures and the features of their behavior under cyclic temperature and humidity changes in the operating environment continues.

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Fig. 3. Device for connecting the test unit to the test machine: 1—a base for fixing a wooden bar; 2—a wooden bar; 3—a metal nail head lock; 4—a steel nail.

Fig. 4. The type of notched nails used in the experiment [22].

4 Conclusions In the work on the study of aspects of ensuring the technosphere safety of firefighters during a fire in an attic room, a number of experiments were conducted under various conditions of destruction of joints of elements of wooden structures with non-smooth nagels. The results obtained allow us to draw the following conclusions: 1. With an increase in the thickness of the connected elements of wooden structures, the difference in the resistance to pulling out of screw [30] and smooth nails increases compared to nails with notches [29].

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Fig. 5. Type of screw nails used in the experiment [23].

Table 1. Resistance to pulling out the nagel from wooden bars, N. Bar, pine tree 50 × 50 mm

Bar, pine tree 40 × 40 mm

Bar, pine tree 40 × 20 mm

2.5 × 60

196

333.2

127.4

3.0 × 70

225.4

303.8

147

3.0 × 80

284.2

372.4

176.4

4.0 × 100

421.4

490

284.2

Nagel size, mm Smooth steel nail

Steel nail with notches 2.8 × 60

166.6

539

215.6

2.8 × 70

372.4

578.2

313.6

3.4 × 80

441

637

470.4

3.0 × 40

137.2

264.6

137.2

3.0 × 50

225.4

235.2

137.2

3.0 × 60

274.4

294

117.6

3.0 × 70

421.4

372.4

127.4

3.0 × 80

441

411.6

176.4

3.0 × 90

568.4

568.4

284.2

Steel screw nail

2. The experimental results are adequate, do not contradict the calculation results in accordance with Eurocode 5 [31] and can be used for further research. 3. When developing the concept of the method of non-destructive testing of nagel joints of suspended ceiling elements to assess the load-bearing capacity and determine the

520

S. V. Fedosov et al. Table 2. Resistance to pulling out the nagel from two wooden bars, N. Bars, pine wood 50 × 50 mm /50 × 50 mm

Bars, pine tree 40 × 40 mm/40 × 40 mm

Bars, pine tree 40 × 20 mm/40 × 20 mm

3.0 × 70

245

499.8

294

3.0 × 80

274.4

568.4

294

4.0 × 100

548.8

597.8

421,4

Nagel size, mm Smooth steel nail

Steel nail with notches 2.8 × 70

343

1107.4

588

3.4 × 80

1048.6

1450.4

686

3.0 × 70

392

441

294

3.0 × 80

421.4

529.2

343

3.0 × 90

1068.2

1283.8

539

Steel screw nail

possibility of firefighters being in the attic when extinguishing a fire, it is necessary to take into account: • expanding the possibility of carrying out computational calculations to determine the load-bearing capacity of a suspended ceiling when using various types of; • improving approaches to drawing up fire extinguishing plans in buildings with suspended ceilings, determining the locations of firemen (firefighters) in the attic; • determination of the dependence of the bearing capacity of the nagel joints of wooden building structures under cyclic changes in the operating environment; • for production facilities, the possibility of exposure to aggressive environments on wooden structures; • development of recommendations on the use of notched nails and screw nails [29, 30] for the installation of suspended ceilings; • study of the influence of fire hazards on the load-bearing capacity of a suspended ceiling.

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Biocidal Corrosion-Resistant Composite Coatings from Industrial Waste Yu. E. Tokach(B) , A. A. Balakhonov, V. Yu. Zhilenko, V. A. Doroganov, and M. M. Flores Arias Belgorod State Technological University Named After V.G. Shukhov, 46, Kostyukov Str, Belgorod 308012, Russia [email protected]

Abstract. The opportunity of using the electroplating industry metal-containing waste for creating a biocidal building material has been researched. The research of chemical composition of the waste has evidenced the presence of salts of heavy metals, such as zinc, copper, nickel, chrome, lead and others. By means of biotesting methods the toxicity of not only pure salts of these metals, but wastes, containing these metal compounds in various amounts, to microfungi, bacteria and algae, was confirmed. In order to concentrate the active component in the designed product the waste was modified by chemical activation methods based on transforming this or that component into soluble or insoluble fraction. It was noted that the acetic acid treatment of waste results in various alterations in its composition, which allows doubling, at an average, the biocidal activity of materials, which can be evaluated by the size of fungicidity area when using microfungi as test objects, and by the quantity of the killed organisms when testing the materials on bacteria and algae. Keywords: Metal-containing waste · Chemical action · Acetic acid · Biotesting · Microfungi · Bacteria · Algae · Biocidal activity

1 Introduction The aggressive impact of the environment on structural materials depends on the operating conditions, occurs constantly and manifests itself in the form of various types of corrosion. Corrosion is the process of destruction of materials under the influence of the environment. There are three main types of corrosion—chemical, electrochemical and biological. According to the nature of the impact of an aggressive environment, corrosion can be atmospheric, soil and water. In this case, various types of corrosion damage occur such as uniform, uneven, focal corrosion, subsurface, pitting, intergranular corrosion, etc. The most common types of corrosion are atmospheric and soil, which cause a huge harm to the national economy [1–3]. The most destructive is soil corrosion, because soil, as an aggressive environment, contains various chemical compounds that accelerate the corrosion process. In the presence of moisture, the chemical elements of the soil form an electrolytic environment, and therefore soil corrosion proceeds © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_50

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according to the electrochemical mechanism. In addition, due to the presence of a large number of microorganisms in the soil, soil corrosion includes biological corrosion. Biological corrosion is the destruction of structural materials as a result of the impact of associations of microorganisms, the product of which can be the structural elements of structural materials. The term “biological corrosion” is usually attributed to metals and metal products. At the same time, the external manifestations of biological corrosion almost do not differ from ordinary atmospheric corrosion with the appearance of rust. In this regard, microbiologists are often involved to determine the type of corrosion. So, for example, when thionic (sulphur-oxidizing bacteria) bacteria are contained in the soil under anaerobic conditions, they do not affect underground metal structures. But when aeration occurs and oxygen appears, the rapid growth of thionic bacteria begins with the appearance of sulfuric acid, which causes intense corrosion. The exclusion of aeration, on the recommendation of microbiologists, stops this type of corrosion. Biological corrosion of metals can be caused by various lithotrophic bacteria. Most often, corrosion of metals is associated with the activity of: sulfate-reducing bacteria (SRB) of the genera Desulfovibrio and Desulfotomaculum, iron bacteria, genera Callionella and Sperotilus, which oxidize ferrous iron to oxide. Biological corrosion under the action of SRB proceeds under anaerobic conditions, the main pathogens are two genera of SRB—Desulfovibrio and Desulfotomaculum [4]. Non-ferrous metals, in particular aluminum alloys, can also be subject to biological corrosion. Such corrosion is caused by microorganisms of the genus Pseudomonas aerugenosa, which can develop in the presence of water and hydrocarbons, for example, in aviation fuel tanks. There are various methods to protect materials and products from microbiological destruction: mechanical, physical, chemical. The most effective is the chemical method, which uses chemicals that have a biocidal effect on microorganisms. At the same time, these substances must meet such important requirements as environmental safety, harmlessness to humans and living organisms. A large number of different types of biodamage, which is constantly increasing, is associated with the saturation of the biosphere with new materials created in the process of human production activities. Among polymer composite materials for protective coatings, materials based on epoxy and vinyl chloride copolymers are widely used. In the total volume of such materials produced in Russia and abroad, they account for more than 80%. The main disadvantage of these materials is a short service life, no more than 3–5 years, depending on the operating conditions. Therefore, due to the high costs of obtaining coatings, which sometimes exceed the cost of materials, the problem of the service life of coatings of at least 15–20 years is of great scientific and practical importance. The main requirements for protective coatings include: • adhesive strength of biocidal coatings under the influence of various aggressive media; • exclusion of migration of biocides from coatings into the environment and ensuring the environmental safety of biochemically resistant materials. The most rational and economically justified approach to the creation of protective, biochemically resistant coatings consists in modifying composite compositions with multifunctional additives capable of providing adhesive and cohesive strength of coatings, inhibiting the development of corrosion processes, and ensuring physical-mechanical and biocidal properties and their stability during operation.

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The main methods for protecting metal structures from soil corrosion are the application of protective insulating coatings and the provision of electrochemical protection. To protect underground pipelines, cathodic protection is used, which significantly reduces the rate of soil corrosion. To do this, a metal pipeline is connected to the cathode potential of an external current source, and failed steel pipes or rails are used as the anode, which are placed in the ground next to the main pipeline. To protect various surfaces (wood, concrete, brick, etc.) from microbial contamination, paint and varnish coatings are used based on a binder in the form of drying oil, pigment, filler, polyhexamethylene guanidine phosphate or acetate, an organic solvent or water, and a preparation of nanostructured silver particles in combination with sodium dioctylsulfosuccinate. The coatings obtained on the basis of this paint and varnish material have good physical, mechanical and protective properties and a high degree of inactivation of microorganisms on the surface of the material [5]. A method for obtaining biochemically resistant coatings from production waste has been developed. The raw materials used are sludge from pickling brass with hydrochloric acid and dolomite fly dust, which is formed during calcination of dolomite at a temperature of 900 °C. The technology includes the production of zinc oxide and crystalline hydrates of magnesium and calcium chlorides by adding to the filtrate, after separation from the pickling solution of copper oxide, dolomite suspension and sequential processing of the separated filtrates. Moreover, zinc oxide can be used for the production of car enamels, as well as at the first stage of the proposed method for obtaining copper oxide from a solution, and high-quality and heat-resistant building materials are obtained from magnesium and calcium crystalline hydrates [6]. To protect marine vessels from biofouling, a paint containing a biocide containing a mixture of pyritic zinc salt and monovalent copper oxide is used in an amount of up to 75% of the total mass of the paint. The results of the operation of ships using this paint and varnish coating provide high biocidal effectiveness against a wide range of marine organisms. To obtain bactericidal paints, a biocidal component is used that contains nanostructured particles of copper and silver ranging in size from 2 to 200 nm. Protective coatings with paints containing nanostructured particles of copper and silver provide a suppressive effect on the painted surface of various types of pathogenic bacteria of a wide range of infections and can be used in children’s and medical institutions, at home, as well as to create impregnations, protective antifungal and antifouling coatings [7]. The papers [8–10] present the results of a study of the toxicity of nanostructured particles of copper and zinc oxide used to obtain biocides. The strain of photobacteria E-Coli M-17 was used as test objects. The criterion of toxicity was the change in the intensity of the bioluminescence of the test object in the test sample compared to the control. From the obtained results, it follows that cuprous nanoparticles in fresh suspensions showed abnormal toxicity. In the medium of physiological saline, the maximum antibacterial effect was observed at medium (0.1 mg/l) and maximum (10 mg/l) concentrations. Bivalent copper nanoparticles did not show a biocidal effect in aqueous suspensions, however, in a physiological saline medium, an average degree of toxicity was observed at the maximum of the studied concentrations.

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The results of the study of the toxicity of zinc oxide showed that the highest degree of toxicity is observed in the ZnO sample. In physiological saline, on the contrary, ZnO2 showed the highest toxicity. Thus, suspensions of zinc oxide nanoparticles have the highest antibacterial ability. At the same time, for aqueous solutions, ZnO nanoparticles with a size of 20 nm have a greater degree of toxicity, and for physiological solutions, ZnO nanoparticles with a size of 100 nm. Therefore, due to their high biological activity, relatively low cost, and environmental safety, copper and zinc nanoparticles are very promising for the development of antibacterial agents. One of the promising areas of application of metal and oxide nanoparticles is the creation of a new class of alternative antimicrobial drugs. The need to search for such biocidal agents is dictated by the rapid formation of resistance of microorganisms to the effects of biocides. Currently, there are a large number of works aimed at studying the antibacterial properties of metal nanoparticles and their oxides, which have a wide spectrum of antibacterial action and do not cause the development of resistance in microorganisms [11–13]. 1.1 Steel Oxidation Oxide films on iron and its alloys can be obtained by thermal, chemical and electrochemical methods. The thermal method consists of heating parts in air or in an environment of water vapor. In this case, a film up to 3 µm (microns) thick is formed on the metal surface, which, depending on the composition of the metal and the oxidation mode, has a different color. To obtain protective and decorative black films on carbon steel, the parts heated to 450–470 °C are immersed in linseed oil, repeating this operation several times. Black films are obtained by processing parts in a mixture (melt, without adding water) consisting of 4 parts of caustic soda and 1 part of sodium nitrite at a temperature of 250–350 °C. The blue color of the films is obtained by oxidation in a mixture containing 55% of nitrite sodium and 45% of sodium nitrate. The thermal method is used to oxidize the tool and some small parts. To obtain protective and decorative films, the most widely used chemical method is oxidation in alkaline and alkali-free solutions. In the first case, steel is processed in a hot concentrated alkali solution containing oxidizers. The resulting film consists mainly of magnetic iron oxide Fe3 04 . The non-alkaline working solution contains phosphoric acid and oxidizing agents— nitrate salts of calcium, barium. The phosphate-oxide film formed in it consists of phosphates, iron oxide and metal, the nitrate salt of which is added to the solution. Its thickness reaches 3–4 microns. Such films are distinguished by the greater mechanical resistance and better protective ability than oxide layers obtained in alkaline solutions. Alkali-free oxidation is carried out at a lower temperature, which makes it possible to simplify the design of the baths. The duration of the process compared with the alkaline method is reduced by 2–3 times. The oxide-phosphate layer can serve as a good primer for paintwork. It is also used for decorative finishing and corrosion protection of products made of carbon and alloy steels, as well as zinc and its alloys.

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Electrochemical oxidation is carried out by processing products on the anode in an alkaline solution. The process takes place at a lower temperature and requires less chemicals than chemical oxidation. The films are black with a blue tint, more resistant to corrosion. To implement the method, additional costs are required for supplying baths with direct current and special suspension devices for loading workpieces into the bath. 1.2 Oxidation of Aluminum and Its Alloys The simplest and most reliable way to protect aluminum and its alloys from corrosion is oxidation—the process of obtaining oxide films on the metal surface as a result of chemical or electrochemical treatment. Chemical oxidation is used to protect products from corrosion and to obtain a primer for paintwork. The thickness of oxide films obtained by chemical means is 0.5–3 µm. Films are characterized by low mechanical strength and, therefore, are not applicable in cases where increased hardness or wear resistance is required. Chemical methods include processing aluminum in a slightly alkaline solution of chromates or in a solution containing, along with chromates, phosphoric acid and fluorine compounds, but they are easily abraded and destroyed by the action of hot water and hot air. Films obtained in a phosphate solution are characterized by the greater mechanical strength. Their thickness reaches 3–4 microns. They are painted light green. Oxide-phosphate films are a good primer for paint coatings, but even in their absence they protect aluminum from corrosion. Thin but dense films with low electrical resistance are obtained by treating aluminum in a solution containing chromates and fluorides in low concentrations. The advantage of chemical methods of aluminum oxidation is the short duration of the process, the simplicity of its implementation, the simplicity of the equipment, which has a positive effect on economic indicators. Electrochemical oxidation of aluminum requires the use of current sources to power the bath, but it gives exceptionally high quality of the obtained oxide films, therefore, it is most common in production. Phosphating of steel and non-ferrous metals. The process of phosphating consists in the formation of a film of water-insoluble phosphate salts of manganese and iron or zinc and iron on the surface of the metal. The dimensions of the parts during phosphating change insignificantly, since along with the growth of the phosphate layer, the thickness of the metal decreases due to its etching. The phosphate layer has a number of valuable properties that determine the scope of phosphating. It is stable in atmospheric conditions, lubricating oils and organic solvents; breaks down in acids and alkalis. Phosphate film is characterized by high adhesion and high electrical resistance. Its disadvantage is low mechanical strength and elasticity and low resistance to mechanical abrasion. Phosphating is most widely used to protect products from corrosion. The protective properties of phosphate films on steel are higher than those of films obtained by chemical oxidation in alkaline solutions. Impregnation with oils, greases or varnishes significantly improves corrosion resistance. Phosphating can be applied to carbon and low-alloy steels, cast iron, some nonferrous and light metals: aluminum, magnesium, zinc, cadmium. High alloy steels

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are difficult to phosphate and produce lower quality films. Phosphate films on aluminum and magnesium are less reliable protection of these metals against corrosion than films obtained by anodic oxidation. The industry uses chemical and electrochemical phosphating of steel and non-ferrous metals. 1.3 Metal Passivation One of the effective methods of protecting the metal surface from the effects of corrosion is surface treatment using special chemical solutions. When they interact with the metal, a chemical reaction occurs, as a result of which a neutral (passive) compound is formed on the surface, capable of resisting the course of corrosion processes. This treatment is called metal passivation. After completion of this process, an oxide film forms on the surface. It has chemical properties not to enter into an oxidation reaction and, thus, prevents the destruction of not only the surface layer, but the entire part. This type of processing is most common for steel, aluminum, nickel, copper and their alloys. Various acids are used for passivation. Most often, a solution based on nitric acid is created. It is the created salts based on this acid that create a protective film with high protective characteristics on the steel surface. The technology of passivation of nonferrous metals practically does not differ from the technology of steel processing. The main difference is the composition of the solutions used. For example, for the processing of aluminum, copper, nickel, potassium and sodium chromates or chromic anhydride are used. Acceleration of the processing process is carried out by adding various salts and acids to the composition of the solution. Passivation of copper is carried out in solutions of sulfuric acid, surface treatment of copper is carried out in a solution of phosphoric acid, zinc and cadmium in solutions of hydrochloric and nitric acid. The removal of the passive film occurs when the plate is immersed in dilute acid or when a salt solution of a less electronegative metal (copper, zinc, tin, bismuth, lead) comes into contact with it. An important point for obtaining a high-quality film during passivation is finishing. In all cases, it is necessary to thoroughly rinse the part after removing the part from the bath with the solution. This is necessary in order to stop the passivation process. After thorough washing, it is recommended to dry the finished part. Due to their high biological activity, relatively low cost, and environmental safety, calcium and magnesium oxide nanoparticles are very promising for the development of antibacterial agents [14–17].

2 The Main Part The aim of the work was to study the antibacterial properties of oxide coatings obtained on the basis of industrial waste. To achieve this goal, a method for obtaining a bactericidal coating was developed, including the preparation of a film-forming solution by acid treatment of industrial waste containing compounds of calcium, magnesium, zinc, copper, applying a film to the surface of a solid inorganic material, drying the coated material and subsequent heat treatment at temperatures above temperature of decomposition of metal salts [18–21] vanic coating shops of machine-building parts of the Starooskol Automotive Equipment

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Plant (SOATE), Stary Oskol, Belgorod Region, with the chemical composition shown in Table 1. Table 1. Chemical composition of galvanic sludge. Na2 O

CaO

MgO

ZnO

TiO2

P2 O5

Fe2 O3

Al2 O3

Cl

CuO

SO3

29.6

23.2

5.5

7.3

6.1

18.9

6.6

0.4

0.9

0.8

0.7

The proposed method consists of the following steps. First, a film-forming solution was prepared by treating production waste in the form of galvanic sludge with a solution of nitric acid [22–27]. For the experiment, 20 g of nitric acid was loaded into a laboratory reactor and 40 g of galvanic sludge was added, with constant stirring. In this case, the following chemical reactions of the interaction of nitric acid with the components of the galvanic sludge in the form of hydroxides, carbonates, or oxides took place. Me(OH)2 + 2HNO3 = Me(NO3 )2 + 2H2 O. MeCO3 + 2HNO3 = Me(NO3 )2 + H2 O + CO2 . MeO + 2HNO3 = Me(NO3 )2 + H2 O. The use of nitric acid for the treatment of galvanic sludge is due to the formation of metal nitrates, the decomposition temperature of which is lower than, for example, sulfates. For example, the temperature of thermal decomposition of calcium sulfate is 1400 °C, and that of calcium nitrate is 600 °C. After cooling to room temperature, the suspension was neutralized with an ammonium solution to pH = 5–6 and then settled. After settling, the solution was separated from the precipitate and used for coating steel parts by spraying. Coated products were dried at a temperature of 20–30 °C for 1 h. After drying, the products were subjected to heat treatment at a temperature of 650–700 °C to form metal oxides on the surface of the product. During heat treatment, as a result of the decomposition of metal nitrates on the surface of the product, a coating of metal oxides with biocidal properties was obtained. 2Me(NO3 )2 = 2MeO + 4NO2 + O2 . On Fig. 1 shows a micrograph of the resulting coating. The chemical composition of the coating was determined using an X-ray fluorescence spectrometer ARL 9900. The results obtained are presented in Table 2. The biocide of the resulting coating was tested in the following way. Samples of products were placed in Petri dishes with Czapek’s nutrient medium and fungi of the genus Aspergilius niger (producer of citric acid) were sown. Fungal growth was observed for 10 days. The results on the biocidal properties of the resulting coating are shown in Fig. 2. The fungicide zone for coated products is 100%. Determination of the corrosion resistance of the samples was carried out in accordance with GOST 9. 913–90. by the method of artificially created conditions simulating the impact of climatic factors in the atmosphere [28].

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Fig. 1. Micrograph of a coating on a steel plate.

Table 2. Chemical composition of galvanic sludge. Oxides, mass, % CaO

MgO

ZnO

TiO2

Fe2 O3

Al2 O3

SiO2

CuO

MnO

Cr2 O3

26.0

6.3

8.3

0.3

6.7

0.4

0.1

1.1

0.1

0.4

Fig. 2. Impact of microscopic fungi Aspergilius niger on coated parts—(a) and uncoated—(b).

The tests were carried out in a salt spray chamber (SST) for 48 h at a temperature of 25 °C and a humidity of 85% by spraying a 3% NaCl solution every 20 min according to the VDA 621–415 method. The results are shown in Fig. 3. The hardness of the resulting coatings was tested by determining the microhardness of materials on Vickers scales in accordance with GOST R ISO 6507–1-200, using a

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Fig. 3. Corrosion resistance of samples. a—sample with obtained oxide coating, b—uncoated sample.

NEXUS 4504-IMP hardness tester (INNOVATEST). The measurement was carried out at points 1–5 with an exposure of 10 s. The test results are presented in Fig. 4.

Fig. 4. Test results.

The results of the study on microhardness showed the heterogeneity of the obtained values, which is associated with insufficient firing temperature of the coating. In this regard, studies were carried out at an elevated firing temperature—850 °C. The results obtained by determining the hardness of the coating are shown in Fig. 5. From the obtained results it follows that the coatings obtained by the proposed method have high biocide, corrosion resistance and sufficient hardness and can be used to protect parts from weathering. This work was realized in the framework of the Program “Priority 2030” on the base of the Belgorod State Technological University named after V G Shukhov, using equipment of High Technology Center at BSTU named after V. G. Shukhov.

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Fig. 5. Test results.

References 1. Erofeev VT, Bogatov AD, Bogatova SN, Smirnov VF, Zakharova EA (2011) Study of the biostability of building materials taking into account their aging. Bull Volgogr State Univ Archit Civil Eng 22(41):73–78 2. Cambers LD, Stokes KR, Walsh FC, Wood RJK (2006) Modern approaches to marine antifouling coatings. Surf Coat Technol 201:3642–3652 3. Semenov SA, Gumargalieva KZ, Zaikov GE (2008) Process characteristics and peculiarities of damages of materials by microorganisms in the exploitation conditions. Fine Chem Technol 3(2):3–23 4. Tsygankova JIE, Vigdorovich VI, Pozdnyakov AP (2002) Introduction to the theory of metals. Publishing House of TSU named after G.R.Derzhavin, Tambov, p 311 5. Kudryavtsev BB, Gurova NB, Revina AA (2002) Paint material with biocidal properties. Patent RU. 2195473 6. Dobrovolsky IP, Kapkaev YuS, Barkhatov VI (2021) Method for obtaining biocide, zinc oxide and crystalline hydrates of magnesium and calcium chlorides from industrial waste. Patent RU. 2746731 7. Kondratieva VS, Urminsky AV, Marinchuk ON (2002) Composition with bactericidal properties. Patent RU. 2186810 8. Tamayo LA, Zapata PA, Rabagliati FM, Azócar MI, Muñoz LA, Zhou X, Thompson GE, Páez MA (2015) Antibacterial and non-cytotoxic effect of nanocomposites based in polyethylene and copper nanoparticles. J Mater Sci - Mater Med 26(3):129. https://doi.org/10.1007/s10 856-015-5475-6 9. Shankar S, Teng X, Rhim JW (2014) Properties and characterization of agar/CuNPbionanocomposite films prepared with different copper salts and reducing agents. Carbohyd Polym 114:484–492. https://doi.org/10.1016/j.carbpol.2014.08.036 10. Gunawan C, Teoh WY, Marquis CP, Amal R (2011) Cytotoxic origin of copper (II) oxide nanoparticles: comparative studies with micron-sized particles, leachate, and metal salts. ACS Nano 5:7214–7225 11. Goncharova EN, Vasilenko MI (2013) Algocenoses of the damaged surfaces of urban buildings and constructions. Fundam Res 8:85–89 12. Goncharova EN, Vasilenko MI, Nartsev VM (2014) The role of microalgae in the processes of urban buildings decay. Bull BSTU Named After V.G. Shukhov 6:192–196

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13. Kaverinsky VS (2011) PWM and their usage. Journal 9:14–21 14. Biocidal activity modifiers against building materials corrosion (2001) Stroitelnaya gazeta, Moscow 023:20 15. Baum R, Schmidt H-J, Antony-Zimmermann D, Wunder T (2006) Synergistic biocidal composition. Patent 2278515 16. Finny AA, Price C, Ramsden RM (2013) Polymer with salt groups and an antifouling coating composition, containing this polymer. Patent RU 2502765C2 17. Airey P, Verran J (2007) Potential use of copper as a hygienic surface; problems associated with cumulative soiling and cleaning. J Hosp Infect 67:271–277 18. Mehtar S, Wiid I, Todorov SD (2008) The antimicrobial activity of copper and copper alloys against nosocomial pathogens and Mycobacterium tuberculosis isolated from health care facilities in the Western Cape: an in-vitro study. J Hosp Infect 68:45–51 19. Singer H, Müller S, Tixier C, Triclosan PL (2002) Occurrence and fate of widely used biocide in the aquatic environment: field measurements in wastewater treatment plants, surface waters, and lake sediments. Environ Sci Technol 36:4998–5004 20. Chernorukova ZG, Novospasskaya NJu, Smirnov VF, Smirnova ON, Emelyanov DN (2001) Biologically-active broad-spectrum stannum- and zinc-containing copolymers. Bulletin of Nizhny Novgorod State University. Chemistry 1(3):14–18 21. Kuznetsova NV, Kabanova LV, Smirnov VF (2000) New biologically-active zinc-containing polymers and their properties regulation. Collection of materials of the 3rd Russian national conference “Environmental problems of industrial building materials and industrial waste biodegradation”. Penza, pp 168–170 22. Politano AD, Campbell KT, Rosenberger LH, Sawyer RG (2013) Use of silver in the prevention and treatment of infections: silver review. Surg Infect 14:8–20 23. Lansdown AB (2006) Silver in health care: antimicrobial effects and safety in use. Curr Probl Dermatol 33:17–34 24. Kong H, Jang J (2008) Antibacterial properties of novel poly (methyl methacrylate) nanofiber containing silver nanoparticles. Langmuir 24(5):205–12056 25. Biocide nanostructural composition (2010) Patent 2407289 26. Rubanov YK, Tokach YE (2009) Methods of reducing the environmental impact of electroplating industry waste. Bulletin of BSTU named after V.G. Shukhov 4:113–115 27. Tokach YE, Rubanov YK (2015) Using target components, based on local industrial waste, to protect building materials against microbiological damage. Fundam Res 2(1):36–41 28. GOST 9.049-91 (1992) Unified system of corrosion and ageing protection, Methods of laboratory tests of the mold fungi resistance, put into action 01.07.92

Influence of Modifying Additives on the Structure and Properties of Porous Geopolymer Building Materials Based on Solid Fuel Combustion Waste of Arctic Thermal Power Plants E. A. Yatsenko, B. M. Goltsman, S. V. Trofimov, Yu.V. Novikov(B) , and T. A. Bondareva Platov South-Russian State Polytechnic University (NPI), 132, Prosveshcheniya St., Novocherkassk 346428, Russia [email protected]

Abstract. During the analytical review, the negative impact of ash and slag waste from coal-fired power plants on the environment was considered. Data on the world experience of processing ash and slag into a number of useful materials are given. The method of a fundamentally new method of processing ash and slag into geopolymer materials is considered. The definition of a geopolymer is given and their possible use as building materials is described. The chemical composition of ash and slag waste of Severodvinsk CHPP-1 and Apatity CHPP is considered. The content of natural radionuclides Ra-226, Th-232, K-40 was studied and the class of materials according to GOST 30,108-94 “Building materials and products. Determination of the specific effective activity of natural radionuclides”. Formulations for the synthesis of porous geopolymers have been developed. The effect of powder-forming additives of them—aluminum powders and a 30% solution of hydrogen peroxide (H2 O2 ), modifying additives—sodium stearate (NaC18 H35 O2 ), gypsum of the construction grade G-5 B (CaSO4 0,5 H2 O) on the structure and properties of synthesized porous geopolymers. Keywords: Coal generation · Ash and slag waste · Geopolymer · Blowing agent · Gypsum · Sodium stearate

1 Introduction At present, the issue of improving the environmental situation in Russia and the world is an open question. One of the promising solutions to this problem is the disposal of ash and slag waste generated at a thermal power plant during the combustion of solid fuels. In the Russian Federation, according to the report of the “System Operator of the United Power System” Joint-stock Company, as of January 1, 2021, the share of CHPP is 66.56% of the total generated electricity in the country, of which about 21% use coal as the main fuel [1]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_51

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According to various estimates, about 1.8–2 billion tons of ash and slag waste have been accumulated to date, and this figure is increasing by 20 million tons annually. Ash and slag wastes are placed at ash and slag dumps, which, in turn, are located on an area of more than 22.000 hectares. A colossal area of land is withdrawn from the economic turnover of the country. Despite the fact that ash and slag wastes are considered practically non-hazardous and belong to the 5th hazard class, they still have negative effects on the surrounding area in the form of erosion of ash and slag dumps by melt water and rain streams, as well as dusting of ash from their surface, which together can lead to pollution surface layer of the atmosphere and the accumulation of erosion products in surface and underground waters, as well as alienation and pollution of soils [2–4]. It is known that the experience gained in the world in the processing of ash and slag waste is quite extensive. Thus, in the EU countries, 40 million tons of ash and slag waste are produced annually, the volume of their processing reaches 90%, mainly due to the current policy of these states, which encourages the use of secondary raw materials. In addition, the high cost of renting land for ash dumps makes it unprofitable for power plants to store waste for a long time. The main part of ash and slag waste is used in the production of Portland cement, as well as an additive for concrete [5]. India generates more than 215 million tons of ash and slag waste annually, with coalfired generation accounting for 72% of all electricity. The volume of their processing in this country reaches 78%. Basically, ash and slag are used in the production of ceramic bricks and tiles, in the cement industry, in agriculture as a reclamation agent [6]. In China, with the annual formation of about 200 million tons of ash and slag waste, the volume of their processing is about 65%. As well as in the EU countries, the largest number of them is used in the production of Portland cement and as an additive to concrete, as well as for the production of inexpensive building materials [7]. In the United States, the annual increase in the amount of ash and slag waste is 70 million tons. At the same time, about 60% of them are processed, mainly in the cement industry and the construction of protective dams and dams [8]. Based on the fact that the volume of processing of ash and slag waste in Russia is about 10–15%, it is advisable to look for new ways to involve them in the economic turnover of the country. Since ash and slag waste is a mineral non-combustible residue of coal fuel in the form of under burn, consisting of various aluminosilicate components (55–90%), unburned coal (5–25%) and magnetic minerals (5–20%), as well as having a high dispersion, it is of interest to process them into promising geopolymer materials [9, 10]. Geopolymers are hydraulic binders obtained by alkaline activation of aluminosilicate raw materials, such as ash and slag waste. These materials were first obtained by a French scientist, Joseph Davidowitz, in the early 70 s of the last centuries. They are aluminosilicate materials formed by silica and alumina-oxygen tetrahedrons connected into strong branched polysylate chains, so that geopolymers have increased strength. The composition of the geopolymer material is expressed by formula 1: Mn {(SiO2 )z AlO2 }n,wH2 O

(1)

where: M is an alkali metal atom; z–a value equal to 1, 2, 3 or more, describing the ratio Si/Al; n is the degree of polymerization or polycondensation [11].

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Depending on the Si/Al ratio, geopolymers are classified into 3 types: polysialate (–Si–O–Al–O–) with Si/Al ratio = 1; polysialate-siloxo (–Si–O–Al–O–Si–O–) at a ratio of Si/Al = 2; polysialate-disiloxo (–Si–O–Al–O–Si–O–Si–O) at Si/Al ratio = 3. As the Si/Al ratio increases, the SiO2 content increases and the Al2 O3 content decreases. This factor leads to a simplification of the formation of a stable structure and an increase in the strength of geopolymers [8]. On their basis, depending on the area of use, it is possible to obtain both geopolymer concrete and highly efficient porous heat-insulating materials: for example, geopolymer concrete is used in traditional construction in European countries, since the available studies characterize it as a durable and environmentally friendly material with high frost resistance 150 cycles. The use of geopolymers as porous heat-insulating materials is especially important in the construction of frost-protective road layers and asphalt pavement in areas with extreme climates in permafrost conditions, such as Norway or the Arctic zone of the Russian Federation. The main difficulty that arises during the construction of the roadway in permafrost conditions is the problem of “frost heaving”, in which the deformation of the roadway occurs due to the freezing of unevenly distributed capillary moisture in the soil layer. The use of porous geopolymer materials in the climatic conditions of the Arctic zone will ensure the drainage of moisture deep into the soil and increase its stability [12–16]. Since the most important properties for porous geopolymers used in road construction are strength and porosity, it is advisable to develop compositions and study the effect of modifying additives on the structure and properties of porous geopolymers based on ash and slag waste from thermal power plants in the Arctic zone of the Russian Federation. Severodvinsk CHPP-1 and Apatity CHPP were chosen as sources of ash and slag waste. This decision is due to the fact that these power plants are among the most powerful, and as a result, produce the largest amount of ash and slag waste. Severodvinsk CHPP-1 is a combined heat and power plant geographically located in Severodvinsk, Arkhangelsk Oblast. It is one of the main suppliers of thermal energy for the population of the Arkhangelsk region. The electric capacity of the combined heat and power plant is 188.5 MW, the thermal capacity is 679 Gcal/h. Coal from the Kuznetsk and Khakass fields is used as fuel at the CHPP. It is known that the ash content of this coal reaches 40%, which leads to increased formation of fireproof mineral residue and the need to store a large amount of ash and slag waste. Apatity CHPP is the largest thermal power plant in the Murmansk region, geographically located in Apatity. The electric capacity of the power plant is 230 MW, the thermal capacity is 535 Gcal/h. Stone coals of the Kuznetsk, Khakass and Kansk-Achinsk fields are used as fuel at the Apatity CHPP. It is known that 7.5 million tons of ash and slag waste are stored at the preserved ash dump No. 1 with an area of about 47 hectares, and more than 3 million tons of ash and slag are stored at ash dump No. 2 in operation. The use of the same type of coal at the Apatity CHPP made it possible to achieve a constant chemical, mineralogical and granulometric composition of ash and slag waste [17].

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2 Experimental Part. Synthesis of Samples and Studies The synthesis of porous geopolymers was carried out according to the following technology: ash and slag waste was dried to a constant mass at a temperature of 100 ± 5 °C, followed by grinding to a particle size of less than 250 µm [18]. For alkaline activation of aluminosilicate components, a mixture of liquid glass and NaOH solution, prepared in a separate container, was used as an activating agent. Water was added to a predetermined amount of Chemically Pure brand NaOH powder to obtain a 12 M solution. The resulting solution was mixed with a sample of liquid glass (silicate modulus = 2, water content 55 wt.%), after which the resulting suspension was poured onto a sample of ash and slag waste. Stirring of the geopolymer suspension was carried out for 10 min in a drum mill (ratio “geopolymer mixture: grinding media” = 1: 1.5) [19, 20]. After preparing the mixture in an amount in over of 100%, a pore former (aluminum powder or a 30% hydrogen peroxide solution) and modifiers (sodium stearate of the Chemically Pure brand to stabilize pore formation, building gypsum of the G-5 B brand to intensify hardening) were added to the compositions, after which the mixture was stirred for another 10 min under the same conditions [21–23]. The resulting compositions were placed in cylindrical molds with a diameter of 37 mm and a height of 40 mm and sent to dry. Drying was carried out indoors without direct sunlight at room temperature 25 ± 2 °C for 14 days at a relative humidity of 60 ± 5% [24, 25]. The linear dimensions of the samples after drying were determined with a vernier caliper, after which the volume V, cm3 , was calculated from their values in accordance with Eq. 2. The mass of the samples was measured with a laboratory balance with an accuracy of 0.01 g. The average density of the samples ρ, kg/m3 , was determined by the Eq. 3: V = πh

D2 , cm3 4

(2)

where h—is the sample height, cm; D—sample diameter, cm. ρ=

m · 1000, kg/m3 V

(3)

where m—sample weight, g; V—sample volume, cm3 . Strength characteristics were determined using a test press brand TP-1-350 with a force measurement range from 0.1 to 350 kN with a measurement accuracy: in the range from 0.1 kN to 7 kN— ± 2%, from 7 to 350 kN— ± 1%. The strength R, MPa, of the samples was determined by the Eq. 4: R=

P · 103 , MPa S

where P—crushing load, kN; S—sample base area, cm2 . Each recorded test value is the average of 3 measurements.

(4)

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3 Results and Discussions Previously, the authors of the article studied the content of natural radionuclides and the chemical composition of ash and slag waste from the Apatity CHPP and Severodvinsk CHPP-1, presented in Table 1 [24]. Table 1. Chemical composition of ash and slag waste. Name

The content of oxides, wt. % SiO2 Al2 O3 Fe2 O3 MgO Na2 O K2 O

Ash and slag Apatity CHPP

52,86 22,35

7,80

2,65

0,79

1,96

Ash and slag Severodvinsk CHPP-1 61,55 17,91

6,01

2,74

3,61

2,32

The content of oxides, wt. % CaO

TiO2

MnO

P2 O5

SO3

Loss on calcination

3,62

1,06

0,07

0,36

0,37

6,10

2,11

0,83

0,07

0,21

0,32

2,32

Analysis of the data presented in table 1 shows that the main components are oxides of silicon and aluminum. The content of basic oxides “CaO + MgO” does not exceed 12% in both cases, therefore, the studied ash and slag wastes are classified as acidic. The content of sulfur oxide does not exceed 2%, “loss on calcination” in the form of unburned fuel (carbon particles) does not exceed 3% in the case of Severodvinsk CHPP1 and ranges from 3 to 10% in the case of Apatity CHPP, highlighting the former as more promising option, since the increased content of “under burnt” can have a negative impact on the long-term use of porous geopolymers in the conditions of the Arctic zone of the Russian Federation. In Fig. 1 shows the microstructure of the studied ash and slag. Figure 1 shows that ash and slag waste contain a significant content of hollow aluminosilicate spheres formed during high-temperature coal combustion. They are glass crystal balls with a smooth surface, mostly filled with carbon dioxide and nitrogen [26]. The diameter of aluminosilicate spheres in the ash and slag of the Apatity CHPP is mainly in the range of 1–25 µm, in the ash and slag of the Severodvinsk CHPP-1—in the range of 5–90 µm. The content of natural radionuclides Ra-226, Th-232, K-40 in the ash and slag waste of the Severodvinsk CHPP is 157 ± 19 Bq/kg, in the case of the Apatity CHPP it is 271 ± 26. Since both investigated ash and slag waste have a specific effective activity of up to 370 Bq/kg, then they are classified as class I materials, which does not impose restrictions on their use [27]. For the synthesis of porous geopolymers, the compositions presented in Table 2 were developed. As mentioned earlier, to study the effect of additives on the structure and properties of porous geopolymers, aluminum powder and a 30% solution of hydrogen peroxide (H2 O2 ) were used as pore formers, modifying additives were sodium stearate

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Fig. 1. Microstructure of the studied ash and slag waste. No. 1—ash and slag of Apatity CHPP; No. 2—ash and slag of Severodvinsk CHPP-1.

(NaC18 H35 O2 ) and building gypsum brand G-5 B (CaSO4 2H2 O). All of the above additives were added to the raw mix in over of 100%. Table 2. Component compositions of raw mixes. № composition

The content, wt. % Ash and slag

Alkali [NaOH]

Water [H2 O]

Liquid glass

1

71.0

2.5

5.0

21.5

2

71.0

2.5

5.0

21.5

3

71.0

2.5

5.0

21.5

4

71.0

2.5

5.0

21.5

The content, wt. % Hydrogen peroxide [H2 O2 ], over 100

Aluminum powder, over 100

Sodium stearate [NaC18 H35 O2 ], over 100

Gypsum [CaSO4 ·2H2 O], over 100

–

2.0

1.0

–

2.0

–

1.0

–

–

2.0

1.0

1.0

2.0

–

1.0

1.0

Based on the presented component mixtures and the developed technology described earlier, samples with the structure shown in Fig. 2 were obtained. According to Eqs. 2, and 3, the main characteristics of the synthesized porous geopolymers were calculated, presented in Table 3. The mechanism of pore formation when using aluminum powder is its interaction with a solution of sodium hydroxide—a component of an alkaline activator, during

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Fig. 2. The structure of the synthesized compositions of porous geopolymers based on ash and slag waste: a—Severodvinsk CHPP-1; b—Apatity CHPP; 1, 2, 3, 4—№ composition.

Table 3. Average characteristics of the synthesized samples. № composition

Severodvinsk CHPP-1

Apatity CHPP

Density, ρ, [kg/m3 ]

Strength, R, [MPa]

Density, ρ, [kg/m3 ]

Strength, R, [MPa]

1

736

2.03

704

0.72

2

635

1.78

657

0.70

3

514

1.83

596

0.60

4

723

2.09

644

0.55

which hydrogen gas is released and the formation of the Na[Al(OH)4 ] hydroxocomplex according to reaction (5): 2Al + 2NaOH + 6H2 O = 2Na[Al(OH)4 ] + 3H2

(5)

With the interaction of 30% of the aqueous solution of hydrogen peroxide with the reaction mixture, there is a catalytic decomposition of H2 O2 , as well as interactions with its components according to reactions (6)–(8): H2 O2 = H2 O + O2

(6)

H2 O2 + 2NaOH = Na2 O2 + 2H2 O

(7)

2Na2 O2 + H2 O = 4NaOH + O2

(8)

As can be seen from the obtained data, the synthesized samples of compositions 1 and 2 based on Severodvinsk CHPP-1 are characterized by a uniform distribution of pores throughout the sample volume, however, in composition 2 with the addition of a pore

Influence of Modifying Additives on the Structure

541

former of 30% hydrogen peroxide solution, in contrast to aluminum powder, a decrease in density is observed by 14% and a decrease in strength by 12% due to more intense pore formation and the presence of larger macropores. In the case of the Apatity CHPP, samples of compositions 1 and 2 demonstrate a decrease in strength by almost 2.5 times at an identical density relative to the samples based on the Severodvinsk CHPP. Such a difference in strength is probably associated with the Si:Al ratio, since it is decisive in the formation of the structural lattice and the properties of geopolymers (Severodvinsk CHPP-1–3.4; Apatity CHPP–2.4). In compositions 3 and 4 based on ash and slag waste from Severodvinsk CHPP-1, the introduction of a modifying additive of gypsum as a hardening intensifier made it possible: in the case of composition 3, to reduce the density by 30%, while reducing the strength by 10% relative to composition 1, and in the case of composition 4, to increase density and strength, respectively, by 14 and 17% relative to composition 2. In the case of the Apatity CHPP, compositions 3 and 4 show a decrease in density at the level of 15 and 2%, and a decrease in strength, respectively, by 16 and 21% relative to compositions 1 and 2, which is the worst result. The data obtained are probably related to the fact that the grade B gypsum used is normally hardening, that is, the setting time starts from 360 s. It was found that the most intense pore formation in compositions with aluminum powder is completed after approximately 240 s, and with a 30% hydrogen peroxide solution after 500 s after the end of the stage of mixing the components, which is a longer time than the setting time of gypsum. As a result, the pore formation reaction with a 30% hydrogen peroxide solution does not have time to complete, which leads to an increase in the density of the synthesized samples. The effect of the surfactant—sodium stearate acting as a foam stabilizer is due to a weakening of the inter-film flow of the liquid, a decrease in the free surface energy of the gas bubble, an increase in its impact viscosity. As a result, there is a decrease in the adhesion of gas bubbles and stabilization of the foam frame of the geopolymer [28].

4 Conclusion Based on the results obtained, the following conclusions can be drawn: 1. According to the chemical composition, the studied ash and slag wastes are classified as acidic; “loss on ignition” in the form of unburned fuel does not exceed 3% in the case of Severodvinsk CHPP-1 and ranges from 3 to 10% in the case of Apatity CHPP; Si:Al ratio in ash and slag waste from Severodvinsk CHPP-1 is 3.4 from Apatity CHPP-2.4, which may eventually affect their technical and operational properties. 2. For samples with aluminum powder based on ash and slag waste from Severodvinsk CHPP-1, the addition of 1% hardening intensifier in the form of building gypsum made it possible to reduce the density and strength by 30 and 10%, respectively; with a 30% hydrogen peroxide solution, the density and strength increased by 14 and 17% due to the longer reaction time of the pore formation relative to the setting time of gypsum. 3. Samples based on ash and slag waste from the Apatity CHPP, with a density difference of no more than 15%, demonstrate a decrease in strength by more than

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2.5 times relative to the samples from the Severodvinsk CHPP-1, which noticeably distinguishes the latter as a more promising option. 4. At this stage of development of compositions of porous geopolymers, a blowing agent in the form of aluminum powder is a more promising option, since it has greater strength with a slight increase in density compared to a 30% hydrogen peroxide solution.

Acknowledgements. The work was supported by the Russian Science Foundation, Project # 21-19-00203 « Efficient temperature-solidificable eco-geopolymers for road construction in the Arctic zone of the Russian Federation based on waste from the local thermal power plants solid fuel combustion» (supervisor Yatsenko E.A.), in the framework of the 2021 competition «Conducting fundamental scientific research and exploratory scientific research by separate scientific groups».

References 1. Report on the functioning of the UES of Russia in 2020 (10.06.2022). https://www.so-ups. ru/fileadmin/files/company/reports/disclosure/2021/ups_rep2020.pdf 2. The Ministry of Energy of the Russian Federation “Round Table” on the topic “Legislative regulation of the use of ash and slag waste of coal-fired chPP”. https://minenergo.gov.ru/node/ 14014 3. Shamray EI, Taskin AV, Ivannikov SI, Yudakov AA (2017) Study of the possibilities of integrated waste processing of energy enterprises of Primorsky Krai. Mod Sci-Intensiv Technol 3:68–75 4. Cherentsova AA, Olesik SM (2013) Evaluation of ash and slag waste as a source of environmental pollution and as a source of secondary raw materials. Min Inf Anal Bull (Sci Tech J) 3:230–243 5. Jin S et al (2021) Comparison and summary of relevant standards for comprehensive utilization of fly ash at home and abroad. IOP Conf Ser: Earth Environ Sci 621(1):012006 6. Yousuf A et al (2020) Fly ash: production and utilization in India-an overview. J Mater Environ Sci. 11(6):911–921 7. Luo Y et al (2021) Utilization of coal fly ash in China: a mini-review on challenges and future directions. Environ Sci Pollut Res 28(15):18727–18740 8. Yatsenko EA, Goltsman BM, Trofimov SV, Kurdashov VM, Novikov YV, Smoliy VA, Ryabova AV, Klimova LV (2022) Improving the properties of porous geopolymers based on TPP ash and slag waste by adjusting their chemical composition. Materials 15:2587 9. Goltsman BM, Yatsenko LA, Goltsman NS (2020) Production of foam glass materials from silicate raw materials by hydrate mechanism. Solid State Phenom 299 SSP:293–298 10. Ahmed MF, Nuruddin MF, Shafiq N (2011) Compressive strength and workability characteristics of low-calcium fly ash-based self-compacting geopolymer concrete. Int J Civil Environ Eng 3(2):72–78 11. Mucsi G, Ambrus M (2017) Raw materials for geopolymerisation. MultiScience—XXXI. microCAD International Multidisciplinary Scientific ConferenceUniversity of Miskolc, Hungary, pp 21–22 12. Davidovits J (2011) Geopolymer chemistry and applications, 3rd edn. Institute Geopolymer, France, Saint-Quentin 13. Dudnikov AG, Regzhani A (2018) Geopolymernye beton i ego application. Stroitelnye materials, kommunopriy, tekhnologii XXI veka 1–2:38–45

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14. Razorenov YI, Yatsenko EA, Goltsman BM (2021) Building materials based on manmade waste of the mining industry and solid fuel energy – an environmental trend of the modern time. Gornyi Zhurnal 11:95–98. https://doi.org/10.17580/gzh.2021.11.13 15. Feng J, Zhang R, Gong L, Li YS, Cao W, Cheng X (2015) Development of porous fly ash-based geopolymer with low thermal conductivity. Mater Des 65:529–533 16. Milad A, Ali A, Babalghaith A, Memon Z, Mashaan N, Arafa S, Md. Yusoff N (2021) Utilisation of waste-based geopolymer in asphalt pavement modification and construction-a review. Sustainability 13(6) 17. Pak AA (2013) On the issue of using industrial waste from enterprises of the Murmansk region in cellular concrete. Build Mater, Equip, Technol XXI Century 8:18–19 18. Yatsenko EA, Smolii VA, Klimova LV et al (2021) The possibility of using in technology ecogeopolymers of waste combustion of solid fuels of the CHPP of the Arctic zone of the Russian Federation. Glass Ceram 9:40–44 19. Wu J (2018) Preparation and characterization of ultra-lightweight foamed geopolymer (UFG) based on fly ash-metakaolin blends. Constr Build Mater 168:771–779 20. De Rossi A (2018) Waste-based geopolymeric mortars with very high moisture buffering capacity. Constr Build Mater 191:39–46 21. Tan J, Caia J, Li X, Pan J, Lia J (2020) Development of eco-friendly geopolymers with ground mixed recycled aggregates and slag. J Clean Prod 256 22. Yatsenko EA, Goltsman BM, Klimova LV, Yatsenko LA (2020) Peculiarities of foam glass synthesis from natural silica-containing raw materials. J Therm Anal Calorim 142(1):119–127 23. Wongmaneerung R (2019) Effect of ZrO2 and MgO addition on structure, mechanical and thermal properties of metakaolin-based geopolymer composites. Key Eng Mater 798:298– 303. https://doi.org/10.4028/www.scientific.net/KEM.798.298 24. Yatsenko EA, Goltsman BM, Parshukov VI (2022) Analysis of suitability of TPP ash-slag waste as materials for hydrogen fuel storage. Int J Hydrogen Energy 47:3906–3917 25. Silva G, Kim S, Aguilar R, Nakamatsu J (2020) Natural fibers as reinforcement additives for geopolymers—a review of potential eco-friendly applications to the construction industry. Sustain Mater Technol 23:e00132 26. Panizza M, Natalia M, Garbin E, Ducman V, Tamburini S (2020) Optimization and mechanical-physical characterization of geopolymers with Construction and Demolition Waste (CDW) aggregates for construction products. Constr Build Mater 264 27. Yatsenko EA, Smolii VA, Klimova LV et al (2022) Solid fuel combustion wastes at CHPP in the arctic zone of the Russian Federation: utility in eco-geopolymer technology. Glass Ceram 78(9–10):374–377 28. Cui Y et al (2018) Effect of calcium stearate-based foam stabilizer on pore characteristics and thermal conductivity of geopolymer foam material. J Build Eng 20:21–29

Structural Ceramics Low-Temperature Phases Colouring Theoretical Basics and Its Colour Management N. D. Yatsenko1(B) , A. I. Yatsenko1 , N. A. Vilbitskaya2 , O. I. Sazonova1 , and R. V. Savanchuk1 1 Shakhty road-transport institute (affiliated subdivision), 1, Platov SRSPU (NPI), Lenina St.,

Shakhty 346500, Russia [email protected] 2 Platov South-Russian State Polytechnic University SRSPU (NPI), 132, Prosvesheniya St., Novocherkassk 346428, Russia

Abstract. The features of obtaining a light to white color of a ceramic shard using iron-containing clay raw materials due to the formation of the phase composition of the material, ensuring the incorporation of iron oxide into the structure of crystalline phases and reducing the amount of free iron oxide due to this, have been established. The synthesis of the main crystalline phases of ceramics of low-temperature sintering and amorphous clay substance—metakaolinite was carried out, the features of their coloring at different contents of iron oxide were revealed. The basic physical and chemical principles of clarification of ceramic material based on iron-containing clays using the method of nuclear gammaresonance spectroscopy (NGRS), which is selective to iron compounds, have been established. Theoretical and technological conditions for the formation of silicate (wollastonite) and aluminosilicate phases (anortite), in which Fe2 O3 has a high solubility of up to 60…70%, are determined, which ensures a decrease in the color of the ceramic shard. The role of the mineralizing additive in the form of carbonates and chlorides of alkali metals has been revealed, and the dependence of the reflection coefficient on its amount and the content of calcium carbonate has been established. Keywords: Iron-bearing clays · Body color · JGRS · Crystalline phases · Clarification · Reflection coefficient · Mineralizing additives

1 Introduction In the production of construction walling ceramic products, the main raw materials are clays with a high content of impurities, including ferrous oxide—Fe2 O3 , which, after burning, give a stained colour of ceramic body. However, the contemporary market gravitates to the use of ceramic bricks of lighter beige and yellow tones. The use of highquality white-burning clays for these purposes is inappropriate both from an economic point of view and due to their reserves depletion. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_52

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545

Obtaining the products of lighter or even white colour using painted clays is a difficult scientific, technical and technological task. In this regard, the study of physical and chemical processes and conditions for producing light clay body based on traditional iron-containing clay raw materials, carbonate natural and by-products, mineralizing additives and the possibility of controlling these processes is extremely relevant [1–3]. As is known [4–7], ceramic bricks firing occurs at temperatures not exceeding 1000 °C. In clays, at these temperatures, removing physically and chemically combination water removing processes occur, as a result of which an amorphized clay substance, metakaolinite (Al2 O3 ·2SiO2 ), is formed. Besides, iron oxide during oxidative firing turns into α-Fe2 O3 , which provides red-brown colouration of the clay body depending on its amount, as well as in the presence of alkaline and alkaline-earth oxides, a significant amount of molten mass is formed. The material strength properties depend on the formation of a structure with homogenously distributed amorphous metakaolinite in the glass melt, which solidifies after cooling. In this case, Fe2 O3 can be both in glass and in metakaolinite, increasing the colour of the material.

2 Investigations by the NGR Method of Coloring the Phases of Low-Temperature Ceramics Using the iron oxide-selective method of nuclear gamma-resonance spectroscopy (NGRS) studies of iron burned at a temperature of 1000 °C during oxidative firing of clay raw materials with an iron oxide content of 7.5% showed (Fig. 1) the phase crystallographic state of iron.

Fig. 1. Burned clays NGR spectra.

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The calculated parameters of the components δ, EQ G and Neff , where δ is a chemical shift mm/s,  EQ is a quadrupolar splitting, G is the width of the spectral line and N is the magnetic field strength, kOe, made it possible to identify the crystallographic position of Fe ions, its fraction in % and the phase state in the material composition (Table 1). Table 1. NGRS parameters. Column Column Column NGRS Parameters Amount Spectrum mm/s of Type δ EQ G Neff ,kOe Fe2 O3 , % 7.5

Column Crystallographic position of Fe ion

Column Column Fe Ion Fe phase state fraction, %

Six-bit byte 1

0.373 −0.212 0.559 500.1

[Fe3+ O6 ]

38.65

Fe2 O3

Two-bit byte 1

0.281

0.661 0.594

–

[Fe3+ O4 ]

5.19

In the glass rim

Two-bit byte 2

0.329

0.783 0.566

–

[Fe3+ O6 ]

9.16

In the metakaolinite

The spectra obtained show that the largest amount of Fe2 O3 (52.19%) is in the glass phase, 38.65% in the free state and the smallest amount in the X-ray amorphous metakaolinite [8–10]. It is therefore necessary to establish which of the above listed phases as well as the crystalline phases which can also be formed in the construction of ceramic structure in low temperature firing reduce or increase the colour of the ceramic body. For conducing these studies, the metakaolinite phases, silicates and aluminosilicates of calcium and glass phase, which are the main ones in the structure of construction ceramics, have been synthesized. The phases studied have been synthesized by solid-phase sintering of masses, except glass phase, from pure materials, including from chemical reagents, in the oxidizing environment and calcined at the corresponding temperatures, ˚C: metakaolinite–900; β-wollastonite and anorthite—1350; and glass phase at the full melting—1400˚C. The results of the experiment (Table 2) have been evaluated using photometric method with determination of the reflection coefficient (RC) with built-in light screen: blue, green and red SS5, ZS10 and KS14 [11]. As a reference standard, amphor glass MS-20 has been used, the reflection coefficient of which was 96%. As is evident from the above data, the ability to stain low temperature phases with Fe2 O3 oxide depends on its amount, phase structure and the crystal chemical and phase state of Fe therein. Thus, the reflection coefficient of metakaolinite, which is usually contained in low-temperature calcination ceramics (maiolica, pottery, facing tiles, bricks, etc.) is significantly reduced from 91.8 to 64.7% even at a content of Fe2 O3 = 0.5% due to the low solubility of Fe2 O3 in metakaolinite and its presence in the free state (Fig. 2 and Table 3).

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Table 2. Dependence of RC phases of construction ceramics on Fe2 O3 amount. Column phases

Column Formulae (system)

Column Fe2 O3 content, Column RC,% by % by weight MS-20

Red hematite

α- Fe2 O3

100.0

6.5

Metakaolinite

Al2 O3 ·2SiO2

–

91.8

0.5

64.7

2.0

36.7

–

86.1

0.5

79.0

1.0

70.9

3.0

48.3

–

90.5

1.0

32.6

3.0

18.8

–

90.1

0.5

37.0

1.0

25.7

3.0

20.6

Makeup glass phase, % K2 O-Al2 O3 -SiO2 by weight SiO2 -76,0; Al2 O3 -15,0; K2 O (Na2 O)-9,0 β—wollastonite

Anorthite

β- Ca3 Si3 O9

CaO·Al2 O3 ·2SiO2

Fig. 2. NGR—metakaolinite spectrum with Fe2 O3 1,5% content.

In the structure of low-temperature ceramics, in the presence of a significant amount of CaO, which is in the clay raw material in the form of impurities or is specially introduced to regulate some properties, in particular thermal insulating ones, the most common ones are phases such as β-wollastonite CaSiO3 and calcium aluminosilicate -anorthite CaO · Al2 O3 · 2SiO2 . The study Fe impurities influences on the colour of

548

N. D. Yatsenko et al. Table 3. NGRS parameters iron phase state in metakaolinite.

Column sample material

Metakaolinite Al2 O3 2SiO2 + 1,5%Fe2 O3 , Firing temperature = 900 °C

Column spectrum type

Column NGRS parameters

Column Fe crystallographic position

Column Fe content, %

Column Fe phase state

G

Neff , kOe

δ

E˛o

Six-bit byte 1

0.382

−0.209

0.511

523.5

[Fe3+ O6 ]9−

9.56

α -Fe2 O3

Two-bit byte 1

0.341

0.794

0.775

-

[Fe3+ O6 ]9−

5.44

Solid solution (Al2-x FexO3) 2SiO2

mm/s

these phases is significantly complicated due to the more complex structures of aluminosilicates, which are characterized by a layered or framework structure with complex bonds of silicate and aluminosilicate polyhedra of their associations different degrees (Fig. 3).

Fig. 3. β-wollastonite Ca3 Si3 O9 structure, single with limited number of radical ions [Si3 O4 ]6− chain-like.

This makes it possible to form structures of Fe-containing clusters in nanocells, which cause strong light absorption and a sharp decrease in KO [12–14]. NGRS parameters and Fe states in the synthesized samples of β-wollastonite and anorthite CaO·Al2 O3 ·2SiO2 , containing 3% of Fe2 O3 have revealed the following (Table 4). The obtained results show that the proportion of free iron oxide in calcium silicate and aluminosilicate samples compared to metakaolinite has decreased significantly. However, the decrease in RC in calcium silicates and aluminosilicates (Table 2) is due to the fact that Fe2 O3 is practically not included in the structure of these phases and remains in the free state, which enhances the colour of the ceramic body.

0.33

0.18

0.42

0.26

Six-bit byte

Two-bit byte 1

Two-bit byte 2

Two-bit byte 2

0.300

Two-bit byte 1

In anorthite

0.380

Six-bit byte 1

In wollastonite

0.66

1.11 0.530

0.570

0.770

0.520

−0.13

1.28

0.656

0.418

0.89

−0.21

Q

Fe2 O3 CS2 A2 O8 :F CS2 A2 O8 :F CS2 A2 O8 :F

[FeO6 ]9− [Al O4 ]5− [Si O4 ]4− [CaO10 ]18−

512.0 − − −

22.04

19.73

36.44

21.79

67.71

Fe3+ in the wollastonite lattice

6

−

Column Fe3+ content in the sample 32.29

Column Fe Phase state Fe2 O3

6

Column Fe3+ Coordination

513.9

Column Parameters, mm/s Column Neff , kOe δ E G

Column Spectrum type

Column phase

Table 4. NGR spectra parameters with Fe2 O3 3%.

0.78

0.68

Column Fe2 O3 solubility limit, % Structural Ceramics Low-Temperature Phases Colouring 549

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The obtained results based on the synthesized crystalline phases will certainly differ when studying the effect of Fe2 O3 on the colour change of ceramic bodies based on ironcontaining clays and carbonate materials of natural and technogenic origin, mineralizing additives that contribute to the formation of silicates and calcium aluminosilicates. For confirming these results, the clay of the Vladimirovskoye deposit has been used as clay raw material: VKV-2 (Fe2 O3 = 4.49%). In order to form a low-temperature sintering tile structure of calcium-containing crystalline phases, chemical chalk has been added in the amount of 10 to 20% and various alkali-containing additives in the form of chlorides and carbonates LiCl, NaCl, KCl, Li2 CO3 , Na2 CO3 , K2 CO3 in the amount of 0.5 to 3%. The samples based on the test masses have been formed into 60 × 25 × 10 mm tiles by soft-mud process, dried to a constant weight and calcined at temperature of 1000 ° C with isothermal exposure for two hours. The RC of the test samples has been determined by photometric method. The results of the studies made it possible to establish the dependence of RC both on the amount of mineralizing additive and the combined influence of chemical chalk and mineralizing additive (Fig. 4) [15–17]. As it can be seen from the data shown in Fig. 4, the samples staining degree with an increase in the content of mineralizing additives in the form of chlorides and carbonates LiCl, NaCl, KCl, Li2 CO3 , Na2 CO3 , K2 CO3 decreases, as evidenced by an increase in their RC [18, 19]. The greatest effect is achieved with chemical chalk content of 20% (the curve 3 in the graphs), especially with a mineralizing additive content of 2%. It should be noted that the highest RC corresponds to the samples containing 20% of chemical chalk and 2% of mineralizing additives NaCl and Na2 CO3 . These samples have RC of 44.3 and 40.1% and a light beige colour. With the same content of other mineral additives, the colour remains pink or unevenly coloured over the surface and volume of the samples. The change in colour intensity depends on the phase composition, the formation of which is ensured by the introduction of chemical chalk and a certain amount of mineralizing additive to form the required amount of molten mass [20]. To identify specific qualitative and quantitative indicators of both independent ironcontaining phases and in the form of solid solutions and in glass phase, the method of nuclear gamma-resonance spectroscopy (NGRS) has been used (Table 5). The clarified and colored samples NRS spectra parameters analysis (Table 5) shows the difference between the iron-containing phases crystallizing in them. Thus, phases have been identified in the stained sample: red hematite α-Fe2 O3 and Fe3+ ions in the glass phase and metakaolinite. This predetermines the red colour of the sample with a predominant content of crystalline red hematite phase α-Fe2 O3 = 52.29%. The light beige colour of the clarified sample, in which, according to the NGRS, there is no red hematite phase of α- Fe2 O3 at all, is due to the introduction of Fe3+ into the anorthite and into the solid solution of hedenbergite and diopsid of the composition Ca(Mg0,41 Fe0,59 )· Si2 O6 ] in an amount of 29.64%, as well as into solid solutions of the type (Al2-x FexO3)·2SiO2 in a significant amount of 70.36%.

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Fig. 4. a RC samples depending on LiCl and chalk; b RC samples depending on NaCl and chalk; c RC samples depending on KCl and chalk; d RC samples depending on Li2 CO3 and chalk; e RC samples depending on Na2 CO3 and chalk; d RC samples depending on K2 CO3 and chalk.

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Column sample type

Column Column NGRS parameters spectrum mm/s Neff , type kOe δ EQ G

Coloured Six-bit byte 1

Clarified

Column CP Fe

Column Column Fe Fe ion phase state content,%

0.37 −0.22 0.52 502.4 [Fe3+ O6 ]9− 52.29

Fe2 O3

Six-bit byte 2

0.37 −0.22 0.52 466.9

Two-bit byte 1

0.35

0.99 0.74 –

[Fe3+ O6 ]9− 47.71

Solid solution (Al2-x FexO3) 2SiO2 and in the glass phase

Two-bit byte 1

0.37

0.88 0.54 –

[Fe3+ O6 ]9− 70.36

Solid solution (Al2-x FexO3) 2SiO2

Two-bit byte 2

0.25

1.59 0.54 –

10(Ca2+ )

Solid solution CS2 A2 O8 :F

29.64

3 Conclusions Thus, in order to clarify the ceramic tile based on iron-containing clays, it is necessary to ensure the formation in its structure of calcium-containing crystalline phases—anorthite and gedenbergite, the formation of which is facilitated by the presence of a liquid phase during low-temperature firing. The influence of glass phase on the item colouring depending on Fe2 O3 content will largely depend on the amount, viscosity of the forming molten mass and the firing temperature.

References 1. Zubekhin AP, Yatsenko ND, Golovanova SP (2014) Ceramics and portland cement whiteness and coloring theoretical foundations. LLC RIF Build Mater 152 2. Zubekhin AP, Yatsenko ND, Filatova EV, Bolyak VI, Veryovkin KA (2008) Influence of chemical and phase composition on ceramic brick colour. Build Mater 4:31–33 3. Zubekhin AP, Yatsenko ND, Veryovkin KA (2011) Effect of redox firing conditions on the phase composition of iron oxides and the colour of ceramic bricks. Build Mater 8:8–11 4. Guzman IYa (2012) Ceramics chemical technology: study guide. LLC RIF Building materials, Moscow 5. Krupa AA, Gorodov VS (1990) Ceramic materials chemical technology: study guide. Higher School, Kiev 6. Avgustinnik AI (1975) Ceramics. Stroyizdat, Leningrad 7. Kanaev VK (1990) Building ceramic new technology. Stroyizdat, Moscow 8. Boot LA, Van Dillen AJ, Geus JW, Van Der Kraan AM, Van Der Horst AA, Van Buren FR (1996) Mössbauer spectroscopic investigations of supported iron oxide dehydrogenation catalysts. Appl Catal A: Gen 1–2:389–405

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9. Heller-Kallai L, Rozenson I (1981) The use of Mössbauer spectroscopy of iron in clay mineralogy. Phys Chem Miner 5:223–238 10. Yatsenko ND, Verevkin KA, Zubekhin AP (2010) Mössbauer Spectroscopy of Phase and Crystal-Chemical States of Iron Oxides in Ceramic Brick. Glass Ceram 5–6:176–178 11. Yurchak IYA, Avgustinnik AI, Zaporozhets AS (1971) Methods of research and control in the production of porcelain and faience ware. Light Industry, Moscow 12. Yatsenko ND, Zubekhin AP (2014) Scientific basis of ceramic bricks innovative technologies and management of its properties depending on chemical and mineralogical composition of raw materials. Constr Mater 4:28–31 13. Zubekhin AP, Yatsenko ND (2014) Construction materials innovative technology theoretical bases. Constr Mater 1–2 14. Zubekhin AP, Yatsenko ND, Veryovkin KA (2010) Ceramic brick based on various clays: phased composition and properties. Constr Mater 11:47–49 15. Zubekhin AP, Yatsenko ND, Bolyak VI (2010) Physicochemical bases of phase composition, structure and ceramic brick properties formation nanosystems scientific reserach and resource saving technologies in building industry. Research-to-practice proceedings–belgorod. Shukhov BGTU Publ House 2:6–13 16. Vilbitskaya NA, Golovanova SP, Zubekhin AP, Yatsenko ND (2001) Crystalline phases formation peculiarities in high-calc ceramic. higher educational establishments publishing house. North-Cauc Reg Eng Sci 4:87–89 17. Bogdanov AN, Abdrakhmanova LA, Gordeev AS (2013) Evaluation of efficiency of carbonate-containing additive in clay raw material for creation of facing ceramics. Kazan State Univ Arch Eng Bull 2(24):215–220 18. Yatsenko ND, Vilbitskaya NA, Yatsenko AI (2021) Role of the liquid phase in the formation of the phase composition and characteristics of structural cladding ceramics. Glass Phys Chem 1:56–61. https://doi.org/10.31857/S013266512101013314 19. Yatsenko ND, Yatsenko AI, Vilbitskaya NA, Sazonova OI, Savanchuk RV (2021) The patterns of phase composition and properties of high-calcium low-density ceramics formation based on argillous raw materials of various chemical and mineralogical composition. Mater Sci Forum 1037:167–173. https://doi.org/10.4028/www.scientific.net/MSF.1043.101 20. Yatsenko ND, Vilbitskaya NA, Yatsenko Alexander I, Popova Liliya D (2019) Phase composition and properties of the low-temperature structural ceramics in the clay-calcium containing material system. Mater Sci Forum 974:331–335. https://doi.org/10.4028/www.scientific.net/ MSF.974.33

Bayesian Network Modeling for Analysis and Prediction of Accidents in Railway Transportation of Dangerous Goods M. V. Chikir1(B) and L. V. Poluyan1,2 1 Ural Branch, Russian Academy of Sciences, 54-A, Studencheskaya, Yekaterinburg 620049,

Russia [email protected] 2 Ural Federal University Named After the First President of Russia B.N. Yeltsin, 19 Mira, Yekaterinburg 620002, Russia

Abstract. The article is devoted to forecasting and preventing the development of accidents and expert assessment of accidents that have occurred on the example of railway transportation of dangerous goods. Bayesian belief networks are used, which make it possible to assess the uncertainty of the initial data, the causal relationships of events. Causal relationships are modeled using conditional probabilities that evaluate the degree of confidence in the truth of new incoming (causing) information based on previously received information. The Bayesian net method allows carrying out procedures that are not available for traditional quantitative risk assessment. Networks can be corrected by supplementing the constructed model with data on the failure rates of a real object. Computer modeling of the accident using a probabilistic graphical model was performed in the “GeNIe” software package with an analysis of its main factors. Accident modeling is accompanied by color thematic visualization of dependencies between random factors with the construction of a directed path in an acyclic graph, the vertices of which are the factors, and the edges determine the dependencies between them. On the example of a real catastrophe at a railway station, the effectiveness of the constructed model is confirmed. The analysis of the results obtained in the modes of sensitivity assessment and diagnostics was carried out, which made it possible to determine the main factors of the accident. Keywords: Bayesian networks · Modeling · GeNIe software package · Railway accident · Transportation of dangerous goods · Human factor

1 Introduction Rail transportation is considered one of the most effective ways to move people and goods. The volume of rail traffic is growing every year. Often the cargo is hazardous substances (explosive, flammable, toxic, radioactive, etc.), the transportation of which, against the background of a high level of wear and tear of railway equipment and the active manifestation of the human factor, becomes a serious threat. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_53

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Any railway accident is the result of a complex of factors that constantly arise during the operation of the railway. This is primarily due to the complication of the railway system, with which it becomes more difficult for a person to work and easier to make mistakes. The purpose of this study was to predict the development and expert evaluation of a railway accident during the transportation of dangerous goods using Bayesian networks.

2 Research Methodology The main causes of railway accidents are considered in detail in the works of Repina I. B., Zamyshlyaev A. M., Protopopov V. A., Slyusar N. N., Martynyuk I. V. and others [1–5]. Most of them use a deterministic method of quantitative risk assessment (QRA). It has many limitations related to risk calculation and further processing of the results. Existing probabilistic approaches (for example, Bayesian networks) have great advantages over QRA. However, their application is limited by the imperfection of the regulatory framework of the Russian Federation in the field of security, which is almost completely focused on the traditional method. This led to the use of Bayesian networks in this study as a reasonable replacement for the QRA method for assessing the risk of railway accidents involving dangerous goods. To study the factors of a railway accident, a classification of potential causes was compiled based on the methodology of Hoła [6]. All factors are divided into 4 categories: “Technical”, “Human”, “Organizational”, “External”. Each group of factors was supplemented with more detailed reasons. The leading position among all causes is occupied by the human factor (HF), which triggers the development of an accident. The rest are derivatives of human error. Figure 1 shows the developed scheme of possible causes of a railway accident, according to which a complex of technical, organizational, human and external factors becomes the key to creating an accident on the railway. The simulation was carried out in the “GeNIe “ [7].

Fig. 1. The system of factors of railway accident.

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2.1 Simulation of an Accident on the Railway During the Transportation of Dangerous Goods To determine the detailed causes of the accident, scientific publications devoted to the study of engineering systems safety issues were studied [1–6, 8–18]. According to them, a set of possible causes of a railway accident was compiled. A fragment of the list of causes is presented in Table 1. Table 1. External factor. Road accident (with another vehicle) Illegal actions

Terror Illegal crossing of railway tracks

Absence of pedestrian infrastructure Absence of protective fences This is the shortest way Proximity to administrative buildings (school, hospital, etc.)

Random values were used as input for network modeling. Figure 2 shows a fragment of the developed model.

Fig. 2. Fragment of the Bayesian network model.

The main danger was the main node “Railway accident”. Its manifestation is influenced by the main reasons (human, organizational, technical and external factors) and detailed reasons (“Behavioral factor”). The frequency of manifestation of the "Behavioral factor “ node is influenced by many small factors: violation of discipline, panic, haste, etc. Let’s highlight some important features of creating a network.

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2.2 Logical Operations AND and OR For nodes of the “Deterministic” type, a link was built on the basis of Booler algebra using the logical operations AND and OR. For example, the nodes “Substance abuse” and “Smoking” (the category of factors “Behavioral factor”) are connected by logical OR operations (see Fig. 2). Those it is enough for an employee to smoke to confirm the fact of having bad habits. Modeling of deterministic relationships is more common than others. On the one hand, this can lead to a distortion of the calculation results, on the other hand, it makes it possible to more rigorously estimate the model parameters. 2.3 Building Canonical Nodes “Chance-NoisyOr” For any child node that has n parent nodes, 2n+1 conditional probabilities must be specified. This regularity sharply complicates the model. But using canonical nodes requires only n + 1 conditional probabilities. The canonical node models not only individual causes, but also implicit ones. Implicit causes equally affect the implementation of a Leak Probability Event (LEAK). The relationship between parent and canonical (child) nodes is given by formula (1):   (Effect Reason1, Reason2, . . . Reasonn) = = NoisyOR Effect, leak, Reason 1, p1 , Reason 2, p2 , . . . , Reasonn, pn ,

(1)

An example of a canonical node is the “Behavioral factor” network element (see Fig. 3).

Fig. 3. Canonical node “Behavioral factor (Behavior)”.

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2.4 Accounting for the Wear and Tear of Railway Equipment The impact of physical and chemical processes leads to the accumulation of defects in the equipment. Gradually, it begins to age faster than in the initial period. This increases the likelihood of equipment wear. To simulate wear, a two-parameter Weibull distribution law was used [19]. It is more accurate and “flexible” than the other one-parameter laws, it describes quite accurately the probability of equipment failure at the wear stage. Wear nodes are of type “Equation nodes”. For them, possible states and intervals of their probabilities are specified (“Efficient”, “Partially efficient”, “Emergency”). Figure 4 shows the result of building the “Rail wear” node.

Fig. 4. Properties of the “Rail wear” node.

As a result of modeling the development of a railway accident involving dangerous goods, a hybrid Bayesian network model (196 nodes) was obtained. Under given conditions, the probability of an accident is 85% (see Fig. 5). The greatest contribution to its development is made by technical and organizational reasons closely related with HF. Consequently, it is the HF that is considered initiating and more important in the development of the accident. Let’s assume that an accident actually happened. Set the probability to 100% for the “Railway accident” node, the network is automatically recalculated. In this case, the following factors become the main causes of the accident: human (the probability changed from 30 to 34%), technical (from 91 to 96%) and organizational (from 69 to 76%). 2.5 Testing the Model on an Example of a Real Disaster The developed model was tested on the example of a real disaster at a railway station in the city of N. A train with an explosive load secretly passed through the station, which

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Fig. 5. The result of the model calculation.

for some reason rolled down the hump and collided with a transit train carrying coal. The result was a massive explosion followed by a fire. Experts called the official causes of the disaster. “The reason for the crash of a freight train with a subsequent explosion of cars was a violation of safety rules during shunting work, which was aggravated by the presence in the railway track development of intersecting routes for passing transit freight trains and rolling trains onto the marshalling yard, as well as exceeding the allowable longitudinal slopes of the railway tracks in the reception park…” [20]. To determine the causes of the disaster, a network model was built (Fig. 6), edited in accordance with archive data. The contribution of human and organizational factors is noticeable. Persons responsible for the transportation of dangerous goods, employees and management of the station performed their duties poorly. The combination of a number of factors led to an accident with a 97% probability. 2.6 Analysis of Calculation Results “GeNIe” [7] can operate in the “Sensitivity Analysis” and “Diagnosis” modes, necessary to determine the critical parameters of the model. This significantly improves the quality of engineering system management. These procedures were used to analyze the most important causes of the catastrophe under study at the station. “Sensitivity Analysis”. Sensitivity analysis is an express assessment of the relationship between model elements. The result of the procedure is the coloring of the network nodes in shades of red. The brighter the node, the higher its “sensitivity” relative to the node under study. Figure 7 shows the analysis result for the State of railway tanks and vehicles node. “Diagnosis”. The diagnostic mode is more detailed and is designed to rank network nodes depending on the assigned “role”: “Fault”, “Observation”, “Auxiliary”. As a result,

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Fig. 6. The result of testing the network model.

Fig. 7. Sensitivity Analysis for the node “State of railway tanks and vehicles”.

ranked lists of “faults” and “observation” are formed for the node under study. Figure 8 shows the result of diagnosing the “Freight handling” node. An analysis of the constructed network showed that the most serious malfunctions that led to the development of a disaster at the station in the “Freight handling” category of causes were: • lack of labeling of dangerous goods, incorrect packaging (“Yes” = 100%); • the presence of oncoming trains on the route (for example with coal) (“Yes” = 97%); • high traffic intensity on the site (“Yes” = 93%);

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Fig. 8. Fragment of the ranking of node faults “Freight handling”.

• critical section of the route (“Steep slope” = 82% on the 3rd path), etc. If the management of the railway station had the opportunity to use the developed network model, then the accident could be predicted and prevented from developing to the level of a catastrophe.

3 Future Work In the future, it is planned to actively introduce Bayesian networks into the process of analyzing the safety of railway industry facilities in the following areas. 1. Creation of a network library for various types of equipment, adapted to real objects. 2. Creation of a clear methodology for taking into account human, organizational and other factors when building models. 3. Modeling and evaluation of the operation of protective barriers. 4. Construction of dynamic Bayesian networks to take into account the time parameter in the transportation of dangerous goods by rail.

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4 Conclusion In this study, the causal mechanisms of a railway accident during the transportation of dangerous goods are studied in detail. Based on the materials of publications [1–6, 8–18], the main causes of the accident were identified and a Bayesian network was developed to calculate the risk of an accident during the transportation of dangerous goods by rail. On the example of a real railway accident, diagnostics and sensitivity analysis of the model were carried out, demonstrating the “flexibility” of Bayesian networks in determining the main causes of the accident. The results of the study allow us to draw the following conclusions. 1. The Bayesian net method is more practical, allows for procedures that are not available for QRA, and is a reliable tool for risk assessment, taking into account the uncertainty of the initial data. 2. Bayesian networks create a complete, visual picture of the causes and consequences of a railway accident. Networks can be corrected by supplementing the constructed model with failure data of a real object of the railway industry. 3. Analysis of the results in the modes of sensitivity and diagnostics makes it possible to determine the main factors of the accident. 4. Bayesian network modeling makes it possible to solve problems related to both forecasting and warning, and expert evaluation of realized accidents at railway industry facilities.

References 1. Repina IB (2015) Taking into account the influence of the human factor on the organizational and technological reliability of the production processes of the railway infrastructure. Dissertation, Siberian Transport University 2. Zamyshlyaev AM (2013) Automation of the processes of integrated management of the technical content of railway transport infrastructure. Dissertation, Russian University of Transport 3. Protopopov VA (2015) Aggregated vulnerability assessment of transport infrastructure facilities. Dissertation, University of Irkutsk State Transport University 4. Slyusar NN (2004) Management of environmental risks of transportation of explosives by rail. Dissertation, University of Perm National Research Polytechnic University 5. Martynyuk IV (2007) Improving the safety of rail transportation of dangerous goods, taking into account interaction with other kindes of transport and the environment. Dissertation, Rostov State Transport University 6. Hoła A et al (2018) Methodology of classifying the causes of occupational accidents involving construction scaffolding using Pareto-Lorenz analysis. Appl Sci 8(1):48 7. GeNIe Modeler. https://support.bayesfusion.com/docs/GeNIe/. Accessed 29 Jan 2022 8. Muginstein LA et al (2020) The main causes of increased wear of rails and ridges of wheel sets of freight cars. Railway Transp 6:25–33 9. Umanets VV (2020) Issues of analysis of logistics risks in the transportation of goods by rail. Probl Risk Anal 3(17):66–73

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10. Dindar S et al (2017) Derailment-based fault tree analysis on risk management of railway turnout systems. IOP Conf. Ser Mater Sci Eng 245:1–8 11. Fabiano B et al (2005) Dangerous good transportation by road: from risk analysis to emergency planning. J Loss Prev Process Ind 18(4–6):403–413 12. Oblasov AA (2010) Risk management in cargo transportation. Russ Entrep 4(1):48–50 13. Murylev OV (2012) Features of emergency situations in case of accidents on railway transport. Bull Med Internet Conf 2:157 14. Smolyak AS (2017) On probabilistic models for estimating the residual service life and wear of machinery and equipment. Econ Manag Natl Econ Prop Relat Russ Fed 2(185):75–87 15. Poluyan LV, Malukova MG (2018) Assessment of human factor in critical infrastructures. Safety 2018:1–6. https://doi.org/10.1088/1757-899X/481/1/012001 16. De Felice F, Petrillo A, Fabio FZ (2018) Human factors and reliability engineering for safety and security in critical infrastructures decision making, theory, and practice. Italy 17. De Felice F, Petrillo A, Zomparelli F (2017) Human factors challenges in disaster management scenario 27th European safety and reliability conference. CRC Press, pp 171–187 18. The standard of the SSSRIEC 62508–2014 (the Russian State Standard Specification, the International Electrical Commission) Risk management. Impact analysis to dependability of human aspects 2015 19. Weilbull distribution. Data analysis. https://docs.cntd.ru/document/1200146523. Accessed 4 April 2022 20. Sortirovka-88. https://66.ru/news/incident/236106/#i_agree_152. Accessed 29 March 2022

Waste from Extraction, Enrichment and Combustion of Solid Fuels is a Promising Raw Material for the Synthesis of Geopolymer Materials A. V. Ryabova(B) , V. D. Tkachenko, I. V. Rusakevich, I. D. Morozov, and A. N. Ivanov Platov South-Russian State Polytechnic University (NPI), 132, Prosveshcheniya St., Novocherkassk 346428, Russia [email protected]

Abstract. Methods of obtaining and qualitative characteristics of dense and porous carbon-neutral functional geopolymer materials based on aluminosilicate raw materials of natural and man-made origin for “green” and energy-efficient construction have been studied. It is established that there are two types of geopolymers depending on their structure parameters and possible applications—dense and porous. 3 methods of obtaining dense geopolymers were studied: casting method, compression molding method, hot pressing method. The main methods of foaming are also investigated: the method of direct foaming, “Sacrificial” filler, additive manufacturing (3D printing). The analysis of the studied methods for obtaining dense and porous geopolymers based on aluminosilicate raw materials of natural and man-made origin showed that as a method of synthesis of geopolymers, the pouring method is optimal, as the most stable and allowing to obtain products of various shapes. As a foaming method, the method of direct chemical foaming. The possible mechanism of synthesis of geopolymers based on technogenic aluminosilicate raw materials and the main physico-chemical stages of formation of the geopolymer structure have been studied. The chemical composition of large-capacity fuel energy waste, including waste from extraction, enrichment and combustion of solid fuels of the Southern Federal District, has been determined. A comparative analysis of the chemical compositions of fuel waste was carried out in order to assess the possibility of their use as raw materials for the production of geopolymers. Keywords: Recycling · Fuel energy · Fuel waste · Mining waste · Enrichment waste · Fuel ash · Fuel slag · Geopolymer materials

1 Introduction The growing rates of housing and industrial construction cause the need for new ecofriendly materials, in their properties (strength, durability, thermal conductivity, biological compatibility) corresponding or superior to existing firing materials, but obtained by © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_54

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carbon–neutral non-firing technologies. Such materials can be functional geopolymer materials for green and “energy-efficient” construction, using carbon–neutral technology for recycling large-tonnage waste of fuel energy. Due to its advantages—a high degree of durability of use and high efficiency—the technology of synthesis of environmentally friendly geopolymers has become one of the key and trending areas of research on the use of industrial waste.

2 Experimental Part To determine the optimal technology for obtaining these building materials, an analysis of existing methods for the production of geopolymers was carried out. It is established that there are two types of geopolymers depending on their structure parameters and, accordingly, possible applications—dense and porous. Dense geopolymers with high density and strength values are currently proposed to be produced in three main ways [1]: 1. Casting method: this is the most widely used method, similar to the traditional concrete production process. Since this cooking method requires good fluidity of the paste, more water is required for cooking, usually 20–40% of the total weight of the binder. The casting process is considered promising for on-site application, especially for products of complex shape. However, the compressive strength of materials is usually below 100 MPa [2–4]. 2. Compression molding method: In this process, a solid aluminosilicate material and an alkaline activator solution are mixed into a viscous colloidal suspension. After mixing, the mixture is pressed and molded under 5–10 MPa conditions to obtain a relatively high final strength of more than 100 MPa. This process is suitable for precast concrete, as alkaline solutions are difficult to process. 3. Hot pressing method, including simultaneous heating and pressing to achieve higher mechanical strength in a shorter time. Thus, it is possible to form a more developed geopolymer matrix and an almost nonporous structure [5, 6]. Highly porous geopolymers include geopolymers in which macroporosity is specially introduced into the micro- and mesoporous geopolymer matrix and having porosity ≥50 volume. %, bulk density ≤0,7 g/cm3 . It should be noted that a clear advantage of using geopolymers for the manufacture of porous inorganic components compared to traditional porous silicates is that no sintering or high-temperature heat treatment steps are required (unless high-temperature applications are provided). Analysis of methods for obtaining porous geopolymers revealed three main methods. 1. The direct foaming method is the most commonly used method for the production of porous geopolymers by processing a suspension or liquid system without sintering. In the direct foaming method, wet geopolymer foams are obtained by incorporating air or gas into a homogeneous suspension, which then solidifies at certain temperatures to produce solid porous bodies. During curing, geopolymerization reactions are completed, forming a continuous three-dimensional inorganic grid.

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Gas generation in a homogeneous liquid or suspension can be realized by adding foaming agents, which can be classified into chemical and physical foaming agents. Chemical foamers form gases (such as O2 and H2 ) and other by-products as a result of thermal decomposition or chemical reactions. Physical pore-forming agents create porosity due to a phase transition, for example, a liquid volatilizes or a gas dissolved in a system under high pressure can be desorbed during decompression, but this approach is not used for geopolymer systems. In any case, the suspension must have a suitable rheology that allows the gas to be retained for a sufficient time to ensure the stabilization of the wet foam by gelation and/or drying. 2. The method of “sacrificial” filler allows you to obtain cellular materials with a structure that is a copy-negative of the original template. Porosity is created by removing fillers by dissolving, melting or thermal decomposition of a dense two-phase composite containing a continuous geopolymer matrix and a dispersed consumable phase, which may or may not be interconnected. The method of removing the filler from the consolidated composite primarily depends on the type of pore forming agent used and its connectivity. 3. Additive manufacturing (3D printing) is successfully used to manufacture a wide range of porous components (such as frames, filters, lightweight materials), using the fact that additive technologies allow you to create structures with complex nonstochastic porosity and precise control of the size, shape and number of pores that cannot be obtained by traditional processing technologies. Despite the possibility of developing formulations capable of maintaining a properly constant viscosity value for a period of time equal to 1 h, more effort is needed to find suitable retarders for the geopolymerization reaction in order to achieve a longer printing time window. The analysis of the studied methods for obtaining dense and porous geopolymers based on aluminosilicate raw materials of natural and man-made origin showed that as a method of synthesis of geopolymers, the pouring method is optimal, as the most stable and allowing to obtain products of various shapes. As a foaming method, the method of direct chemical foaming. In order to determine the main raw materials and technological parameters of geopolymer production, it was necessary to study the possible mechanism of geopolymer synthesis based on aluminosilicate raw materials. The main physico-chemical stages of geopolymer structure formation are dissolution-depolymerization and reconstructionpolycondensation [7]. A schematic diagram of the reaction mechanism is shown in Fig. 1. At the first stage, the chemical bonds of aluminosilicate minerals are destroyed by the action of alkaline activation, and the minerals break down into silicon-oxygen monomers [SiO4 ]4− and aluminum—oxygen [AlO4 ]5− tetrahedra. As the monomers dissolve, they interact with each other to form dimers, and the dimmers react with other monomers to form a trimmer, multimeter, etc., which regroup and finally polycondense to form an amorphous gel of sodium aluminosilicate hydrate (N–A–S–H) with a three-dimensional network structure. In the initial stage, when the reaction reaches saturation, the content of Al3+ higher, since the dissolution Al in an aluminosilicate mineral under alkaline conditions occurs

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Fig. 1. Schematic diagram of the reaction mechanism of polymers obtained from aluminosilicate materials.

faster than Si. Hence, an aluminum-rich metastable gel N–A–S–H (ratio Si/Al ≈ 1,0– 1,3, gel I, saturated with aluminum) it will be deposited as an intermediate product [8]. As the reaction proceeds, more Si–O groups dissolve, increasing the concentration Si4+ in the solution and its proportion in the gel N–A–S–H (ratio Si/Al≈2, Si- saturated gel II). This structural reorganization determines the final composition of the threedimensional mesh structure of the polymer, consisting of an aluminosilicate main chain and a charge-balanced metal cation, as well as the structure and distribution of pores in the material.

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Based on the ratio of silicon to aluminum (Si/Al) in the product reaction, F. Davidowitz classified the structure of the geopolymer into three types: polysialate (PS) (–Si– O–Al–), polysialate-siloxo (PSS) (–Si–O–Al–O–Si–) and polysialate-disiloxo (PSDS) (–Si–O–Al–O–Si–O–Si–), shown in Fig. 2 [9].

Fig. 2. Block diagram of polymer compounds.

Their general formula is as follows: Mn {−(SiO2 )z − AlO2−}n · wH2 O

(1)

where z is 1, 2 or 3; M is an alkali metal (Na+ , K+ etc.); n—degree of polymerization, w—total water content. The gel structure of geopolymers is similar to zeolites [10, 11], but the difference is that natural zeolites are usually crystalline, while geopolymers are amorphous or semicrystalline and have relatively dense mesoporous structures. This may be due to the rapid dissolution of glassy components when mixing aluminosilicate materials with an alkaline solution. In this case, there is not enough time and space for the gel to develop into a well-crystallized structure, which leads to the formation of microcrystalline, amorphous or semi-crystalline structures [12]. The rheological properties of the geopolymer are related to the concentration of the alkaline activator and the molar Si/Na ratio. With a corresponding increase in the molar Si/Na ratio, the dissolution and polymerization rates increase, which leads to an increase in the yield strength and viscosity of the geopolymer paste. However, an ultra-high ratio leads to the opposite effect, which can be caused by the fact that a large number of reacting ions dissolve too late and the repulsive forces between them prevent the formation of a grid. The preservation of the Si/Na molar ratio remains unchanged and an increase in the concentration of the alkaline activator will lead to a decrease in the yield strength and viscosity of the geopolymer paste [13, 14]. Similarly, an increase

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in temperature increases the particle velocity and increases the viscosity of the paste by increasing the reaction energy. To improve the rheological properties of geopolymer paste, air-entrapping additives and surfactants are often used. The addition of an appropriate amount of air-entrapping additive can reduce the plastic viscosity of the paste by creating stable and evenly distributed air bubbles. After the addition of surfactants, some surfactant molecules are adsorbed at the air–water interface, which contributes to the formation of bubbles and increases the stability of the foam [15, 16]. When curing geopolymers, an important role is played by: the size and chemical composition of the raw material, the water–solid ratio, the type of activator and the curing temperature, etc. [17]. As a rule, a high ratio H2 O and the binder dilutes geopolymer solutions, which slows down the reaction between mineral particles and the activator and prolongs the setting time. However, residual water can form pores that reduce the mechanical properties of materials. The reduction in the compressive and tensile strength of the geopolymer can reach about 20% [18]. The activator is directly involved in the hydration and curing reaction, which is one of the main factors of the reaction and requires a reasonable choice in accordance with the real situation. Properly selected activators make it possible to increase the efficiency of the dissolution and polycondensation reactions, thereby accelerating the curing process and increasing strength [19]. As a result, alkaline activators are widely used. In most cases, higher alkalinity can accelerate the dissolution and polymerization reaction of the active aluminosilicate mineral, which usually contributes to a higher initial strength [20]. However, this can also lead to a rapid hardening of the paste. In addition, the concentration of Si/M and alkali metal cations in the activator also have a great influence on the course of the reaction and curing. The analysis of promising materials on the basis of which geopolymers can be synthesized for the production of composite materials and products representing semicrystalline three-dimensional aluminosilicate materials has shown that these can be natural and synthetic aluminosilicate minerals or industrial aluminosilicate by-products or wastes such as: metacaolin, fly ash, slag, red sludge, glass, perlite, sand, rice husk ash, clay or a combination thereof, mixed with an aqueous solution containing reactive ingredients: potassium hydroxide or sodium hydroxide, phosphoric acid, potassium or sodium silicate, etc. The purpose of these studies was to investigate the possibility of obtaining carbon– neutral functional geopolymer materials for “green” and energy-efficient construction based on large-tonnage waste of fuel energy, including waste from extraction, enrichment and combustion of solid fuels. The waste of the fuel and energy industry includes products obtained in the form of waste from the extraction, enrichment and combustion of solid fuels. This group of waste is divided according to the source of formation, the type of fuel, the number of plasticity of the mineral part of the waste, the content of the combustible part, grain composition, chemical and mineralogical composition, the degree of fusibility, the softening interval, the degree of swelling. The main categories of solid fuels are coal and brown coals. During the extraction and enrichment of coal by-products are mine and overburden rocks, coal enrichment waste. With the underground mining method, less associated

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rocks are extracted than with the open, but they also make up significant volumes. For example, for 1 ton of coal, up to 3–5 tons of overburden rocks are formed during open–pit mining, and up to 0.2–0.3 tons of mine rocks are formed during underground mining. Overburden and mine rocks have a heterogeneous chemical and mineralogical composition and represent sedimentary rocks—clays, loams, sandy loams, mudstones, sandstones, clay and sand shales, limestones. Most of them contain mudstones (up to 60%). In addition, they contain in their composition coal up to 20%, sulfur, the content of which is proportional to the content of coal, in small quantities non-ferrous, rare metals. For use in the production of building materials, carbon enrichment waste is of the greatest interest, characterized by the smallest fluctuations in composition and properties. The content of coal not isolated during the enrichment process can reach 20%. In accordance with the standard schemes of the technological process of enrichment, coal from mines after grinding is subjected to hydraulic classification by size, then enriched by gravity, separating concentrate, industrial product and rock (waste of gravitational coal enrichment). When the concentrate is dehydrated, sludge with a grain size of less than 1 mm is isolated, which is sent for flotation. After flotation enrichment, concentrate and flotation waste (tailings) are obtained. Depending on the method of waste production and their size class, the coal content, and accordingly the chemical composition and the number of plasticity vary widely. The largest amount of coal (15–40%) is in flotation waste. In the waste of gravity enrichment of class 1–13 mm, the amount of coal can reach 15%, and in the waste of class 13– 150 mm—4–7%. In coal mining waste, the coal content ranges from 0 to 10%. A very important limiting factor in the use of coal enrichment waste is the presence of sulfur in them. The moisture content of the waste depends on the method of its production. The natural moisture content of mudstones is 4–5%. Coal flotation waste extracted from sludge accumulators has a humidity of 25–30%. In contrast to the dump rocks of coal mines, coal enrichment waste is characterized by a higher coal content, a more stable material composition, a lower content of sandstones and a higher content of mudstones, an increase in sulfur content and a decrease in mechanical strength. When burning solid fuels in the furnaces of thermal power plants, ash is formed in the form of pulverized residues and lump slag, as well as ash and slag mixtures. They are products of high-temperature (1200–1700 °C) treatment of the mineral part of the fuel. To assess the possibility of using fuel waste as raw materials for geopolymers, their chemical composition was studied, which is presented in Table 1. Previously, an analysis of existing methods for obtaining geopolymers revealed that the method of pouring and direct foaming is optimal. Therefore, the main stages leading to the production of a finished product with the necessary qualities and properties are alkaline activation and direct pore formation. Currently, in addition to natural aluminosilicate minerals, such as metakaolin, various types of industrial secondary products are actively used as the main raw materials, such as ash and slag waste, calcined coal waste, glass waste, slag, etc.

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Table 1. Chemical composition of fuel waste of the Rostov region. Name

The content of oxides, wt. % SiO2

Al2 O3

Fe2 O3

MgO

Na2 O

K2 O

Coal mining waste

45.1–62.0

14.89–21.5

1.89–7.72

1.05–2.69

0.85–1.46

3.05–4.89

Gravity enrichment waste

47.78–56.32

15.52–22.39

1.75–6.23

0.95–2.36

0.73–1.28

3.12–4.57

Flotation waste

43.16–49.43

15.71–21.23

1.81–7.95

1.69–3.25

0.45–1.16

3.45–4.31

Ash and slag waste of Novocherkassk GRES

57.07

16.8

10.38

1.9

2.56

4.54

The content of oxides, wt. % CaO

TiO2

MnO

P2 O5

SO3

Loss on calcination

0.68–6.6

0.71–1.27

0.01–0.11

0.14–0.37

0.05–4.27

3.19–21.11

1.87–5.66

0.65–1.12

0.01–0.10

0.12–0.54

0.05–3.47

8.72–20.53

1.63–3.14

0.82–1.15

0.01–0.08

–

0.43–3.56

11.21–19.59

3.53

0.93

0.1

0.14

0.14

1.4

As alkaline activators, in addition to hydroxides (NaOH, KOH) or sodium silicate solution, carbonates, phosphates, alkali metal fluorides, etc. are used. The best activating effect and the most widespread is a mixture of NaOH with sodium silicate or a liquid glass solution (i.e. a two-component activating mixture), However, this type of compound activator still has some disadvantages: • firstly, the sodium silicate solution is prone to self-polymerization in an alkaline environment, which leads to higher viscosity and poor machinability; • secondly, since a large amount of heat is released during the preparation of the activator with NaOH and sodium silicate, the prepared activator must be cooled to ambient temperature before use, which takes time; • thirdly, materials such as sodium hydroxide and sodium silicate are expensive, corrosive and inconvenient to operate. Therefore, some researchers use a mixture of silica with NaOH instead of a mixture of NaOH and sodium silicate to prepare an activator, which ultimately gives a good result. Also under development are studies of single-component geopolymer mixtures, which are powder products made of aluminosilicate material and activator, which can be used simply by adding water. Such technology can solve some disadvantages of traditional two-component geopolymers (liquid activators), such as high viscosity, inconvenience in operation, high cost of transportation, etc.

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3 Results and Discussions The analysis of the chemical compositions of fuel waste in order to assess the possibility of using them as the main raw material for geopolymers showed that the waste of extraction, enrichment and ash slag after combustion are aluminosilicate materials with different ratios of basic oxides and the amount of carbon. Further, a comparative analysis of their chemical compositions was carried out, namely the ratio of silicon to aluminum (Si/Al), on the basis of which it is possible to predict the structure of the geopolymer according to the classification F. Davidovitsa. So, the calculated coefficients were: for mining waste—2.72–2.59, enrichment waste—2.76– 2.26, flotation waste—2.47–2.09 and ash and slag waste of Novocherkassk GRES—3.1. Based on this, it is concluded that geopolymers based on mining, enrichment and flotation waste will have the structure of polysialate-siloxo (–Si–O–Al–O–Si–), and geopolymers based on the Novocherkassk GRES—polysialate-disiloxo (–Si–O–Al–O–Si–O–Si–).

4 Conclusion Thus, it has been established that functional geopolymer materials developed using carbon–neutral technology for recycling large-tonnage waste of fuel energy have a high degree of durability and high efficiency. It is established that there are two types of geopolymers depending on their structure parameters and possible applications—dense and porous. Dense geopolymers are obtained in three main ways: by casting, compression molding and hot pressing. Porous geopolymers have three main production methods: direct foaming, “sacrificial filler” and additive manufacturing. A comparative analysis of the chemical compositions of fuel waste was carried out in order to assess the possibility of their use as raw materials for the production of geopolymers. The Si/Al ratios of fuel waste were obtained, which amounted to 2.72–2.59 for mining waste, 2.76–2.26 for enrichment waste, 2.47–2.09 for flotation waste and 3.1 for ash and slag waste from Novocherkassk GRES. Based on this, geopolymers based on mining, enrichment and flotation waste will have the structure of polisialate-siloxo, and geopolymers based on the ZCO of Novocherkassk GRES—polisialate-disiloxo. Acknowledgements. The work was carried out within the framework of the project implementation under the agreement on the provision of grants from the federal budget in the form of subsidies in accordance with paragraph 4 of Article 78.1 of the Budget Code of the Russian Federation No. 075-15-2022-1111, head of Yatsenko E.A.

References 1. Zhao J, Tong L, Li B et al (2021) Eco-friendly geopolymer materials: A review of performance improvement, potential application and sustainability assessment. J Clean Prod 307:127085 2. Barbosa VF, MacKenzie KJ, Thaumaturgo C (2000) Synthesis and characterization of materials based on inorganic polymers of alumina and silica, sodium polysialate polymers. Int J Inorg Mater 2:309–317

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3. Wang H, Li H, Yan F (2005) Synthesis and tribological behavior of me-takaolinite based geopolymer composites. Lett 59:29–30 4. Ma H, Ling F, Yang J, Wang G (2002) Preparation of mineral polymer from potassium feldspar wastes, an experimental study. Earth Sci 5:576–583 5. Ranjbar N, Kuenzel AJ (2017) Influence of preheating of fly ash precursors to produce geopolymers. Ceram Soc 100:3165–3174 6. Ranjbar N, Mehrali M, Maheri M, Mehrali M (2017) Hot-pressed geopolymer. Cement Concr Res 100:14–22 7. Palomo A, Krivenko P, Garcia-Lodeiro I, Kavalerova E, Maltseva O (2014) A review on alkaline activation: new analytical perspectives. Construccion 64:315 8. Hu Z, Wyrzykowski M, Lura P (2020) Estimation of reaction kinetics of geopolymers at early ages. Cement Concr Res 129:105971 9. Davidovits J, Davidovics M (1991) Geopolymer: ultra-high temperature tooling materials for manufacture of advanced composites. Int SAMPE Symp Exhib 36:1939–1949 10. Granizo N, Palomo A, Fernandez-Jim A (2014) Effect of temperature and alkaline concentration on metakaolin leaching kinetics. Ceram Int 40:8975–8985 11. Khalid HR, Lee NK, Park SM, N. Abbas N, Lee HK, Hazard J, (2018) Syn-thesis of geopolymer supported zeolites via robust one-step method and their adsorption potential. Mater 353:522–533 12. Davidovits J (2011) Geopolymer chemistry and applications, 3rd edn. Institute Geopolymer, France, Saint-Quentin 13. Khale D, Chaudhary R, Mater J (2007) Mechanism of geopolymerization and factors influencing its development: a review. Sci 42:729–746 14. Rifaai Y, Yahia A, Mostafa A, Aggoun S, Kadri E (2019) Rhe-ology of fly ash-based geopolymer: effect of NaOH concentration. Construct Build Mater 223:583–594 15. Yang H, Jiang Y, Liu H, Xie D, Wan C, Pan H, Jiang S (2018) Mechanical, thermal and fire performance of an inorganic-organic insula-tion material composed of hollow glass microspheres and phenolic resin. Colloid Interface Sci 530:163–170 16. Pu X, Yang C, Gan C (1992) Research on retardation of high strength alka-li slag cement and concrete. Cemento 10:32–36 (in Chinese) 17. Malkawi AB, Nuruddin MF, Fauzi A, Almattarneh H, Mo-hammed BS (2016) Effects of alkaline solution on properties of the HCFA geopolymer mortars. Procedia Eng 148:710–717 18. De Rossi A (2018) Waste-based geopolymeric mortars with very high moisture buffering capacity. Constr Build Mater 191:39–46 19. Arnoult M, Perronnet M, Autef A, Rossignol S (2018) How to control the geopolymer setting time with the alkaline silicate solution. Non-Cryst Solids 495:59–66 20. Phair JW, Van Deventer JSJ (2002) Effect of the silicate activa-tor pH on the microstructural characteristics of waste-based geopolymers. Int J Miner Process 66:121–143

The Possibility of Using Lithium-Containing Waste in the Russian Federation K. A. Vorobyev1,2(B) , I. V. Shadrunova2 , and T. V. Chekushina2 1 Technische Hochschule Georg Agricola, 45, Herner Str, 44787 Bochum, Germany

[email protected] 2 Mineral Resources Russian Academy of Sciences, 4, Kryukovsky Tup, Moscow 111020,

Russia

Abstract. This article describes the different technologies of battery recycling, looks at the individual process steps and works out the differences. The disposal of chemical current sources—galvanic cells, batteries and cell batteries—is carried out in order to reduce the amount of toxic substances in solid household waste. Batteries contain heavy metals, acids, alkalis, which, when they get into water or soil, cause significant damage to the environment. The rapid growth of industrial production in the Russian Federation, including the transport sector, and the multiple increase in the number of vehicles inevitably leads to the accumulation of used batteries not only in the warehouses of specialized assemblers, but also in landfills. The article focuses on the Umicore and Accrues processes as examples. It also uses the life cycle analysis technique. The description of the costs of recycling are examined in more detail and their composition is discussed. As in the past, the costs must be determined on the basis of the capital market and the situation. In conclusion, it can be stated that due to the expected increase in batteries, an increasingly profitable business field for battery recycling is emerging. Keywords: Lithium · Lithium geochemistry · Lithium application · Extraction methods of lithium · Batteries

1 Introduction Batteries still represent a large part of our mobile life and our entire energy supply. In electronic components and as suppliers of a wide variety of components, it is impossible to imagine our world today without them as a source of energy. In Europe, 35,000 tonnes of batteries end up in household waste every year. Most of the waste is located in Russia. This figure is only an indicator of the overall global problem of battery waste. However, since these products also contain valuable resources and harmful substances, they must be recycled. To this end, the concept of the battery as well as its components and different compositions are first introduced. Special reference is made to the life cycles of batteries. In accordance with the title of this article, the individual process steps of the recycling option are shown and described in more detail. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_55

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Based on the recycling possibilities, the analysis refers not only to the life cycle analysis but also to the economic aspect of the battery and recycling. The article concludes with an outlook on the possible future development of battery recycling and a summary of the information gathered.

2 Battery Recycling by Type Lead-acid batteries. This type of batteries is used in cars, electric vehicles, motorcycles, uninterruptible power supplies, various industrial equipment (Fig. 1).

Fig. 1. Lead-acid batteries [1].

Lead is a toxic metal, once it enters the body, it accumulates in the bones, causing their destruction [2]. Acids, in particular sulfuric acid, which is the most common in the production of batteries, are also quite dangerous. When processing such batteries, the acid is first neutralized, then the case is separated from the lead plates, and all this is used in processing, including for the production of new batteries. Mercury batteries. Mercury battery is most often used in wristwatches, children’s toys, medical devices and other small-sized equipment (Fig. 2). Mercury-zinc batteries contain extremely harmful to the environment and human health mercury, which eventually begins to corrode the walls of the battery and leak, so they should be disposed of with extreme care [4]. Lithium-ion batteries. Lithium-ion battery (Li-ion) is a type of electric battery that is widely used in modern household electronic equipment and finds its application as an energy source in electric vehicles and energy storage devices in energy systems (Fig. 3) [5].

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Fig. 2. Mercury batteries [3].

Fig. 3. Lithium-ion battery [6].

3 Battery Recycling in Russian Federation Used batteries. The rapid growth of industrial production in the Russian Federation, including the transport sector, and the multiple increase in the number of vehicles inevitably leads to the accumulation of used batteries not only in the warehouses of specialized assemblers, but also in landfills [7]. At the same time, both represent, on the one hand, one of the potentially dangerous types of solid waste, and on the other hand, valuable secondary lead-containing raw materials. Currently, global lead production is about 8 million tons per year, of which more than 60% is obtained as a result of waste processing, primarily used batteries. Disposal of used batteries. Among the environmental problems facing Russia, the prevention of further lead pollution of the environment is a problem whose solution must be implemented immediately [8].

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The experience of many countries shows that solving this problem makes it possible to improve the ecological situation of the environment and, most importantly, to preserve the health of the population. Lead regeneration is currently not only an environmental, but also an economic necessity, since the production of lead from ores cannot cover the needs for it. At the same time, the regeneration technology should be optimized both from an economic point of view and from the point of view of environmental protection. The main and most difficult source for recycling secondary lead is spent lead batteries. Their share in the balance of secondary lead—containing raw materials is at least 70–80%. Of particular importance is the development of an environmentally safe, as well as cost-effective technology for extracting lead from batteries. Disposal of used batteries in the Far East region. The Russian Far East is a region in Northeast Asia. It is the easternmost part of Russia and the Asian continent; and is administered as part of the Far Eastern Federal District, which is located between Lake Baikal in eastern Siberia and the Pacific Ocean. The region’s largest city is Khabarovsk, followed by Vladivostok (Fig. 4) [9].

Fig. 4. The Russian Far East [10].

According to experts, about 30 thousand tons of battery scrap are formed annually in the territory of the Far East of the region: Battery scrap is a valuable raw material containing 42–67% lead, 22–35% organic matter, 0.1–6% electrolyte, 3–10% moisture, oxygen, sulfur. The relative lead content depends on the type of battery. On the other hand, Russian battery plants that produce cable products and other enterprises that use refined lead in their production, which is a product of battery recycling, are experiencing an acute shortage in these products. The production of lead from secondary raw materials is in the near future the basis for the development of the lead industry of the region. The reserves of ore raw materials prepared for production and the absence of modern enterprises for its processing are currently unable to meet the needs of the country’s industry. Lead consumption has doubled over the past 20 years and continues to grow, primarily due to an increase in the production of various types of lead-acid batteries, since there

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are no alternative current sources for transport, communications, and defense equipment in the near future. Analysis of existing technologies for recycling used batteries. Most of the existing technologies for processing these wastes include preliminary separation of scrap into a number of fractions: metal, oxysulfate, polypropylene or ebonite housings, polyvinyl chloride separators and electrolyte. In a number of countries, mine melting of undivided battery scrap is used. At the same time, the formation of chlorine-containing dusts (due to the destruction of PVC separators) and substandard matte is inevitable, which creates additional environmental problems. There is a low-waste and environmentally friendly technological scheme for processing secondary lead raw materials, which is distinguished by the use of electrometric melting and provides complete processing of all components of battery scrap and revolutions (Fig. 5).

Fig. 5. Installation for refining rough lead.

This scheme of this technology includes: • • • • •

mechanized separation of battery scrap, melting of metal fractions in a boiler, electrometric melting of the oxide sulfate fraction, refining of rough lead and processing of revolutions to obtain commercial products.

Technology of processing of secondary lead-containing raw materials in Primorsky Krai. Primorsky Krai is a federal subject of Russia, located in the Far East region of the country and is a part of the Far Eastern Federal District [11]. The city of Vladivostok is the administrative center of the krai, and the second largest city in the Russian Far East, after Khabarovsk (Fig. 6). Lead scrap comes to the plant in the form of marine and automotive batteries, ingots, lead braid, etc.

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Fig. 6. Primorsky Krai [12].

Marine batteries are pre-cut into metal, oxide sulfate fractions and copper scrap. The oxidosulfate fraction of marine batteries, automotive batteries (without cutting) are loaded into a mine furnace. When using the mine smelting technology implemented at the plant, rough lead is obtained and it is possible to dispose of all organic components by burning, but obtaining soft lead from a rough alloy is associated with high costs. When processing batteries using this technology, substandard copper matte is formed and due to the impossibility of desulfurization of raw materials, sulfur utilization from waste gases is inevitable, which, given their large volumes, requires huge cleaning costs, additional losses of lead occur, with slag and an increase in the cost of processing lead scrap [13]. Soda-free melting. In fact, the soda-free melting is carried out in an electrothermal furnace using a technology that differs from the traditional one in that it is carried out without the use of soda as a fluxing additive (Fig. 7) [14].

Fig. 7. Soda-free melting [Presentation by Kirill Vorobyev].

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This process is carried out without the formation of a matte. The amount of slag is determined only by the ash content of coke and the quality of scrap cutting and is reduced to a minimum. The processing of the products of electric melting of secondary lead raw materials (slags, slips, removals) and the ebonite fraction is carried out in a furnace of the original design (Fig. 8) [15].

Fig. 8. Electrothermal furnace [16].

Method of galvanic dissolution in acidic (acetic acid) medium. At the same time, the process proceeds at room temperature at a significant rate without the release of toxic gas products and secondary insoluble lead compounds [17]. Batteries are crushed by a guillotine crusher. The crushed mass is sent to the electrochemical dissolution reactor. The lead acetate formed in the solution is filtered, the pH is adjusted, and then, depending on the type of target product, the solution is sent for sale as a commercial product, either for the synthesis of tribasic lead sulfate, or for the synthesis of dibasic lead stearate [18]. After separation of the target product, the acetic acid solution is again sent for electrochemical dissolution. Thus, the lead turnover cycle is closed [19]. In this case, the active mass of an acid-lead battery is processed, consisting mainly of metallic lead, lead oxide, lead sulfate, into the target product - tribasic lead sulfate, lead stearate. These products are the most important components in the production of PVC insulation of cable products. It becomes possible to organize parallel production of lead salts as raw materials for the paint and varnish industry, glass production, etc. The remaining parts of polypropylene housings are supposed to be crushed and further used in the production of plastic pipes or composite materials [20].

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Thus, in this way we not only almost completely dispose of lead batteries, but at the same time we remove a significant amount of highly toxic lead-containing material from environmental circulation, while obtaining the most valuable raw materials–lead salts.

4 Conclusion The sustainable pollution of the environment, as well as enormous economic damage, is caused when batteries of various types are improperly disposed of or dumped. This is due to the components and construction of these batteries. To recycle a battery properly, a combination of mechanical, physical and chemical processes is used. Due to the different nature of the batteries, a variety of different approaches are found. The process begins with mechanical sorting and separation of the protective layers. After this procedure, it is possible to shred the batteries and thus break them down into small parts. These mixtures can now be further treated by using the pyrometallurgical and hydrometallurgical process. The goal of these process is to recover valuable materials such as cobalt, nickel, manganese, copper, and lithium from waste batteries. The basis of the cost calculation of the analysis shows that it is not simple to carry out, as it depends on many different factors and variables. For example, the cost calculation shows that the aspects of the capital market (inflation) as well as the operation and maintenance of the plant have a massive influence on the economic efficiency and overall cost situation of battery recycling.

References 1. Akanova NI, Sheudzhen AKh, Vizirskaya MM, Andreev AA (2018) Agroecological efficiency of neutralized phosphogypsum as chemical meliorant and phosphate-containing mineral fertilizers in conditions of rainfed agriculture of Krasnodar Territory. Int Agric J 2(362):32–37. 10.24411 / 2587-6740-2018-12022 2. Belyuchenko IS (2014) Features of mineral waste and the expediency of their use in the formation of complex composts. Sci J KubSAU 101(07). http://ej.kubagro.ru/2014/07/pdf/ 54.pdf 3. Kotelnikova AL, Ryabinin VF (2018) The composition features and perspective of use for the copper slag recycling waste. Lithosphere 18(1):133–139. https://doi.org/10.24930/16819004-2018-18-1-133-139 4. Elwert T, Römer F, Schneider K, Hua Q, Buchert M (2018) Recycling of batteries from electric vehicles. Behaviour of Lithium-Ion batteries in electric vehicles. Springer, Cham, pp 289–321 5. Elwert T, Goldmann D, Römer F, Buchert M, Merz C, Schueler D, Sutter J (2015) Current developments and challenges in the recycling of key components of (hybrid) electric vehicles. Recycling 1(1):25–60 6. Tytgat J, Treffer F (2011) Recycling of Li-ion and NiMH batteries from electric vehicles: technology and impact on life cycle. In: Proceedings of the Belgian platform on electrical vehicles, vol 31 7. Kotelnikova AL, Ryabinin VF, Korinevskaya GG, Khalezov BD, Reutov DS, Muftakhov VA (2014) To the rational use of copper slag processing tails. Nedropol’zovanie XXI vek (Subsoil Use. XXI Century) 6(50):14–19

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8. Panishev NV, Bigeev VA, Galiullina ES (2015) Perspectives of utilization of coal enrichment as well as thermoelectric plants wastes. Theory Technol Metall Prod 2(17):69–76 9. Sharonova NL, Rakhmanova GF, Yapparov IA, Ilyasov MM, Sukhanova IM (2018) Growth and development indicators of plants when using nanomaterial in mineral nutrition. PNRPU Bulletin Chem Technol Biotechnol 4:7–19. https://doi.org/10.15593/2224-9400/2018.4.01 10. Sukhanova IM, Yapparov IA, Gazizov RR, Bikkinina LM-K, Nurtdinova GH (2018) Assessment of the qualitative indicators of grain when using natural fertilizers and their nanoanalogues. PNRPU Bulletin Chem Technol Biotechnol 4:47–58. https://doi.org/10.15593/22249400/2018.4.04 11. Yapparov IA, Gazizov RR, Ismagilov ZR, Zherebtsov SI, Sukhanova IM, Bikkinin LMK, Ilyasov MM, Yapparova LM (2016) Development of a fertilizer composition based on nanoscale brown coal and glauconite and its influence on crop yields. Her Kazan Technol Univ 19(23):170–173 12. Tazhibayeva I, Beckman I, Shestakov V, Kulsartov T, Chikhray E, Kenzhin E, Kiykabaeva A, Kawamura H, Tsuchiya K (2011) Tritium accumulation and release from Li2 TiO3 during long-term irradiation in the WWR-K reactor. J Nucl Mater 417:748–752 13. Mensah AK, Mahiri IO, Owusu O, Mireku OD, Wireko I, Kissi EA (2015) Environmental impacts of mining: a study of mining communities in ghana. Appl Ecol Environ Sci 3(3):81– 94. https://doi.org/10.12691/aees-3-3-3 14. Elwert T, Goldmann D, Schirmer T, Strauß K (2012) Proceedings of the European Mineral Resources Conference, p 575 15. Bernardes AM, Espinosa DCR, Tenório JS (2004) Recycling of batteries: a review of current processes and technologies. J Power Sources 130(1–2):291–298 16. Velázquez-Martínez O, Valio J, Santasalo-Aarnio A, Reuter M, Serna-Guerrero R (2019) A critical review of lithium-ion battery recycling processes from a circular economy perspective. Batteries 5(4):68 17. Huang B, Pan Z, Su X, An L (2018) Recycling of lithium-ion batteries: Recent advances and perspectives. J Power Sources 399:274–286 18. Xudong L, Yingchun L, Zhihua Z, Hong L, Yong-Sheng H, Zhaoxiang W, Yanming Z, Quan K, Youzhong D, Zhiyong L, Qinghua F, Liquan C (2014) Nanotube Li2MoO4: a novel and high-capacity material as a lithium-ion battery anode. Nanoscale 6:13660–13667. https://doi. org/10.1039/C4NR04226C 19. Pilson MEQ (2013) An introduction to the chemistry of the sea, 2nd edn. University of Rhode Island. Cambridge university press, NY, p 543 20. Meganne L (2012) Christian and Kondo-François Aguey-Zinsou. Core–shell strategy leading to high reversible hydrogen storage capacity for NaBH4, ACS Nano 6(9):7739–7751. https:// doi.org/10.1021/nn3030018

Artificial Intelligence for Water Supply Systems M. Novosjolov, D. Ulrikh(B) , and M. Bryukhov Lenin Prospect, South Ural State University, 76, 454080 Chelyabinsk, Russia [email protected]

Abstract. The article offers an overview of publications from 2011 to 2022 on the use of artificial intelligence for water supply systems. Active implementation of artificial intelligence technologies in water supply systems began in 2019, 7 years after the concept of Industry 4.0 had been announced in Germany. A topical collection was conducted, and 67 papers were chosen—46 publications from the Scopus database (69%) and 21 from the RSCI database (31%). The samples were classified by their object of study and the function of the technology being discussed and divided into 3 groups: water supply sources (27%); water treatment (19%); water supply systems (54%). The largest group of papers cover water supply systems, effective distribution of drinking water, control of water leaks, and water supply repairs (54% of the total selection). Our study confirmed the knowledge-intensive nature of the water supply field and the relevance of issues related to resource conservation and environmental monitoring. The most popular artificial intelligence technologies among the studied papers were classification and clustering algorithms, neural networks, and ensemble and genetic algorithms. These technologies are used to process big data for prediction and optimization. Keywords: Water supply · Artificial intelligence · Support-vector machines · Artificial neural network · Random forest · Bayesian trust networks

1 Introduction A little more than 11 years have passed since the Industry 4.0 concept was announced in Germany. The Industry 4.0 concept includes the following key technologies: information modeling, 3D printing, Internet of things, robotics, augmented reality, cyber-physical systems, digital doubles, machine learning, artificial intelligence, drones, new building materials, big data, 3D scanners, cloud technology, and smart city. Scientists research the elaboration of these technologies, monitor their development, and identify issues preventing their implementation in the economy. One such study was conducted in the construction industry. The authors highlighted two key technologies: information modeling technologies and 3D-printing [1]. Innovation activity was estimated for separate forms of economic activity in Russia (information technology, manufacturing industry, mining, energy supply, construction, water supply, water disposal and waste management) in [2]. They concluded that 8.1% of enterprises in the Russian Federation are in the field of artificial intelligence technologies. The main factor hindering the development of digital transformation is the lack of funding. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_56

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The water supply sector is actively researching the introduction of artificial intelligence with the use of big data. Water conservation and effective management of water demands are major challenges in densely populated areas. In [3], it was determined that the best solution is to implement advanced methods of machine learning and data analysis. Water losses and water scarcity are unacceptable, so effective control requires a good methodology for leak detection and active decision-making. The authors in [4] offer a review of papers on decision support systems for leak detection and control in water supply systems. Digitalization of the water supply industry in Germany within the WaterExe4.0 project is explored in [5], the authors of which believe that the industry must be reformed in light of climate change and water scarcity. They also identify issues related to digitalization. The aim of this paper is to analyze scientific publications on the use of artificial intelligence (machine learning) in the water supply field.

2 Main Text We completed a bibliographic review of publications indexed by Scopus (unified bibliographic and abstract database of peer-reviewed scientific literature) and Russian Science Citation Index (RSCI) (bibliographic database of scientific publications from Russian scientists and citation index of scientific articles). The first stage was to search for publications in the Scopus and RSCI databases using a set of keywords: “artificial intelligence”, “water supply”, and “neural networks 2011–2022”. Table 1 shows the sample size for each keyword in each database. Samples 4 and 5 were subject to further restriction by subject area (engineering). Table 1. Results returned for each keyword in the Scopus and RSCI databases. Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

Keyword

Water supply

Artificial intelligence

Neural networks

Water supply systems and artificial intelligence

Water supply systems and neural networks

Scopus

61,054

239,255

183,372

739

972

2291

3401

19

22

RSCI

12,137

18,384

17,585

1—engineering subject area

We searched for our search terms in the titles, abstracts, and keywords of publications in the databases across all subject areas and recorded the number of results: In the Scopus database, Sample 4 consisted of 229 publications, and Sample 5–340; in the RSCI database, Sample 4 consisted of 19 publications, and in sample 5–22 publications. Articles meeting the selection criteria were classified by object and function. The object classification describes the water supply system object being discussed: water

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bodies, water supply source, water intake, water treatment technology, water supply networks, and consumers. The functional classification describes the life cycle phase of water supply system projects to which the research applies: the design stage (water quality, process modeling, calculating diagrams and constructions); construction; operation (planning of repairs, leakage control, water supply optimization, utilities management). Table 2 presents the papers grouped by object and function. In total, 67 sources were selected—46 publications from the Scopus database (69%) and 21 publications from the RSCI database (31%). Table 2. Paper classification. Water supply sources Water treatment Water supply systems Water quality Process modeling, calculating diagrams and constructions Managing and controlling leaks and failures

5 6 1 1

0 1 8 0

2 0 3 0

5 0

2 2

20 11

Scopus/RSCI

The authors of [6, 7] developed methods to assess the quality of natural waters using spectrometry, microwave radiometry, and machine learning algorithms for spectral image recognition. Methods for assessing the quality of natural waters through chemical analyses and artificial intelligence algorithms were developed by the authors of [8– 11]. In [12] the possibility of predicting river water consumption is investigated using machine learning. In [13] it is described how to manage water treatment in real time using a system of sensors and neural networks. The authors of [14] developed an intelligent measurement and control system for chlorine treatment and chloroform content control at water treatment stations using the Mamdani fuzzy inference algorithm (neural network). In [15], a process approach to automating the intelligent management of drinking water treatment is described. The authors of [16] propose methods to assess the water purity and technical condition of centralized and non-centralized water supply systems using Big Data processing with the help of machine learning based on artificial neural networks. The authors of [17, 18] use neural networks to solve issues of pump control. The authors of [19–21] use cluster analysis and neural networks to estimate the state of an operating water supply system in normal and emergency states. A telemetric system with integrated water supply (artificial and natural) of agricultural objects is being developed using artificial intelligence and the experience of creating telemetric systems for the space industry [22, 23]. The authors of [24] created an expert system for the future development of water supply networks in urban areas using a model of inverse fuzzy logic inference (neural network). The author of [25] considers the principles of building an intelligent decision support system for managing a targeted water supply program. In [26], the author investigates the possibility of classifying the technical condition of pumps by

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using modern machine learning models on the data from vibration testing conducted during the maintenance of pumps. A study on the impact of storm and sewage water entering Lake Mead (Las Vegas, USA) on pollution content was conducted in [27] using machine learning and online tools to take corrective measures in the water supply system. The authors of [28] developed a method to monitor water quality in water bodies using laser-induced deep UV Raman spectroscopy and artificial intelligence. They trained a neural network to recognize typical spectral patterns of individual pollutants in samples after processing with mathematical filters and machine learning algorithms. Researchers in [29] studied the performance of artificial intelligence methods, including particle swarm optimization, a naive Bayesian classifier, and support-vector machines, to predict the water quality index in the Pindrawan basin of Chhattisgarh, India. The authors of [30] propose a novel application of a Kalman filter ensemble and artificial neural network to predict water quality index using physico-chemical parameters from two rivers—Klang and Langat (Malaysia). In [31], the use of artificial neural networks to predict the concentration of total suspended solids in the Fei-Chui Reservoir in Taiwan is investigated. They determined the average monthly statistics over 10 years and the average annual statistics over 13 years for 26 indicators and compared these averages with the concentrations of suspended solids. Trophic state index, nitrate concentration, total phosphorous concentration, iron concentration, and turbidity had the strongest correlation with the concentration of suspended solids. The authors of [32] created a 30-year prediction of the impact of human activity and climate change on groundwater for irrigation in the inland river basin in northwest China based on historical data from the region from 1981 to 2010. They applied a variable infiltration capacity model with particle swarm optimization of parameters. In [33], new hedging rules are presented for generating hydroelectricity at the Indirasagar dam (India). The hedging rules were optimized using a two-level model optimization algorithm using an artificial bee colony algorithm and imperialist competitive algorithms. In [34] one can find an outline of a new application of four improved artificial intelligence models to predict changes to the water level of Lake Huron (Michigan, USA): minimax probability machine regression, vector relevance machine, Gaussian process regression, and extreme learning machine. The authors of [35] developed a probabilistic nonlinear regression prediction model on water supply for the U.S. Department of Agriculture, which manages the largest autonomous water supply in the western United States. The model was created using machine learning, nonparametric statistical modeling, ensemble learning, and evolutionary optimization. The authors of [36] developed a sophisticated decision-making method to manage the cascades of hydraulic facilities in the basin of Nechí River in Northwestern Columbia. The researchers in [37] designed an autonomous, automated dam. The authors of [38] focused on the use of artificial intelligence regression models to predict the solar-power driven desalination of water. Their research helps manufacturers and other scientists determine the performance of the desalination system in beta testing (prior to implementation). In [39], a convolutional neural network coupled with a long short-term memory model is developed to predict the pH of the membrane-capacitive deionization filtrate. The authors of [40] examine the performance of neural network, random forest, and accelerated tree methods to predict the gradient of hydraulic head

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(target variable) with non-linear filtration through granular porous media. Flow velocity, media size, porosity, kinetic viscosity, and shape factor were used as the input variables. In [41], an overview is offered of artificial neural networks developed for membrane processes used for wastewater treatment and desalination. A new hybrid approach to modelling and optimizing a technology consisting of adsorption and filtration is presented in [42]. The authors used an artificial neural network, response surface methodology, and a genetic algorithm to this end. In [43], an artificial neural network was used to simulate distillation with a membrane purge used for desalination. The model predicted the performance index, defined as the product of distillate flow and desalting coefficient. The performance of artificial neural networks capable of predicting the filtered volume and parameters of dissolved oxygen and turbidity after a sand filter is evaluated in [44]. Data from 770 experimental filtration cycles of a sand filter operating in effluent were used to train, cross-validate, and test artificial neural networks. The authors of [45] offer a strategy to simultaneously optimize the performance design of membrane modules with ion separation. This method of machine learning describes the performance of a membrane as a function of its synthesis protocol. In [46], a predictive model and artificial neural network controllers are used to manage ultrafiltration processes. The improved plant control system is able to reduce water losses incurred during the filtration of river water with low turbidity. The authors of [47] offer a systemic approach to analyzing and optimizing desalination systems with multi-effect distillation-thermal vapor compression. Multi-objective optimization to minimize total annual expenses and maximize the output gain coefficient and fresh water output rate was performed using a genetic algorithm based on an artificial neural network model. In [48], the authors investigate a model for predicting excess iron and manganese concentration and turbidity in British water supply networks using the RUSBoost algorithm. In [49], the researchers describe several approaches to detecting changes in water quality over time through telemetric monitoring of the water supply networks of the state company Thüringer Fernwasserversorgung (Germany) using several models: logistic regression, linear discriminant analysis, support vector machines, artificial neural network, deep neural network, recurrent neural network and long-short term memory. The authors of [50] present a new algorithm to identify water pollution sources using sensors placed throughout a water supply network. The algorithm uses a combination of artificial neural networks to classify pollution sources with random forests for regression analysis to determine important variables such as start time, end time, and pollutant concentration. In [51], artificial neural networks are used to predict the coefficient of irregularity in water supply networks and connection to home systems using operating data from a water supply and wastewater disposal company in a mid-sized city in Poland. Artificial neural networks were used to create models in Statistica 10.0. In [52], the authors use a swarm agent to optimize the design of a water distribution system, including choosing the size of various components, quality control, reliability, strategies for renewal and repair, etc. The authors of [53] focus on identifying the best location for a new pipeline within an existing water supply network to maximize the capacity of a node. Combining fitness function transformation with an expanded genetic algorithm, the authors optimized the topology of eleven water supply networks. The authors of [54] from the University of Cordova (Argentina) worked with a provincial water

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supply company (EMPROACSA) to develop and implement the wAIter web tool for water distribution system failure management and repair. The tool consists of a network of wireless water pressure sensors and an Internet of Things platform. The authors of [55] developed a decision support system to help water utilities companies plan the maintenance of water supply and sewage networks for a large company in Spain. A multi-objective genetic algorithm optimizes work program configurations, integrating the water company’s strategic policy into an innovative multi-objective function. The authors of [56] presented a methodology to use artificial intelligence to verify the concept of collecting data on failures in the water supply networks of SA Water (Adelaide, South Australia) from open data sources and identifying common causes of failures. In [57], the authors propose a supervised energy monitoring-based machine-learning approach to detecting faults in a water system. A testbed water system was developed in the Festo MPA Control Process Rig. The machine learning algorithms (support vector machine, knearest neighbors, and random forest) performed classification in three datasets obtained from the testbed. In [58], a framework is presented for extracting and processing network data and historical failure records to train decision tree-based machine learning methods. In [59], the authors propose a decision support system for emergency management of drinking water distribution systems which combines a vulnerability assessment model based on Bayesian belief networks with an uncertainty assessment model with an impact model and related uncertainty assessment based on a Bayesian belief network. The researchers in [60] present a smart solution to combine key factors of energy consumption and water supply in water supply management to obtain improvements in the water and energy fields. In [61], a decision support system is presented for prognostic and diagnostic analyses of water distribution system failures consisting of four models: a reliability assessment model, a leakage potential model, a leakage detection model, and a potential water quality failure model. The decision support system integrates customer complaints, laboratory testing results, and historical data using the Dempster-Shafer theory. The prognostic capabilities of the decision support system ensure the hydraulic quality and water quality of water distribution systems, while the diagnostic capabilities of the decision support system help identify the location of a failure as quickly as possible and help reduce the quantity of false predictions. In [62], the authors use SWANP software to achieve network clusterization using two algorithms based on multilevel recursive bisectioning and community-structure procedures (groups of network nodes). After this, the authors introduce and apply a novel multi-objective function to the city of Matamoros (Mexico), integrating cost and energy parameters, thereby providing a smart decision support system. The goal of [63] was to conduct a sensitivity analysis based on pressure analysis and an artificial neural network-based classification method to evaluate the behavior of the water distribution system in Spezzano Albanese, a town in Calabria (a region in southern Italy). In [64], the authors examine various methods of predicting time series (Seasonal ARIMA, bat swarm, and support vector machines) and present a set of statistically-validated time series models. These models, integrated with a model predictive control strategy, allow for accurate operational forecasting and flow management in water distribution systems. The authors of [65] propose a system with a small number of Water Nilm non-intrusive vibration sensors to control water consumption. Signals of pipe vibration in a home indicate the operation of water consuming

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appliances, which can be classified through cluster algorithms trained during system installation. The authors of [66] developed a method to localize losses in water distribution systems, requiring the installation of flow meters and pressure sensors and the construction of a mathematical model. The model is calibrated to match the pressure and flow rate by searching for an optimal set of water demands at system nodes. Comparing the optimal and standard sets makes it possible to identify the areas where leakages are most likely to occur. Minimization of water consumption is determined by optimizing the objective function based on simulated annealing, genetic algorithms, and modified particle swarm optimization. The researchers in [67] consider a method of detecting leaks in the water distribution networks of a city in the south of Poland. The method involves the discretization of the water supply system in predefined areas and determination of an approximate location where a leak can occur. The location of the leak is determined using a group of neuro-fuzzy classifiers, the number of which corresponds to the number of areas into which the network has been divided. The authors of [68] analyzed water consumption data from consumers on the Greek island of Skiathos to build a model of water consumption by a group of consumers. In [69], the authors propose a probabilistic modeling scheme to analyze malicious events (cyberattacks) occurring in telecommunications and water supply systems and interdependent critical structures. In [70], it is compared and analyzed how accurately a Bayesian network structure can be obtained with a large and highly variable dataset. The first method involved the use of automated learning algorithms to build the Bayesian network, while the second method involved a guided method using a combination of historical failure data, prior knowledge, and premodelling of data from studies of the water supply system. By understanding the most common types of failure (circumferential, longitudinal, pinhole, and joint), a guided learning Bayesian network was able to capture the interactions between the surrounding soil environment and the physical properties of the pipes. The researchers in [71] examine the task of creating accurate water demand models for cities using machine learning methods (multilayer perceptrons, support vector machines, extreme learning machines, random forests, adaptive neural fuzzy inference systems, and the group method of data handling). Their analyses were checked on two datasets on water demand from Franca (Brazil). In [72], smart water meters were implemented, distributed, and installed in a rural area of Cairo. Data were collected at uniform intervals and sent to the cloud instantaneously. A long-short term memory method was used to analyze the collected data to predict future water demand. Two alternative machine learning methods were used for a comparative analysis (support vector regression and random forest). We created a diagram to display the distribution of the number of articles for each year of the examined period (see Fig. 1). The diagram does not include data for 2022. In the examined papers, experimental (telemetric) and statistical data were processed using statistical models (logistic regression; linear discriminant analysis; hidden Markov models; Bayesian belief networks; Bayesian ridge regression); algorithms of classification and clusterization (RUSBoost, k-nearest neighbor); neural networks and deep learning (support vector machines, artificial neural networks, convolutional neural networks, deep neural networks, recurrent neural networks, long-short term memory, multilayer perceptron); ensemble algorithms (random forest, adaptive acceleration); genetic algorithms (artificial bee colony algorithm, imperialist competitive algorithm,

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Fig. 1. Studies per year.

particle swarm). Other methods included the Kalman filter, business rules, and the group method of data handling.

3 Conclusions Implementing algorithms of machine learning in the development of water treatment methods opens up new possibilities for modeling and optimization of water processing and the production of new filtering materials. Artificial intelligence is most often used in experiments and telemetry involving large volumes of data. For example, using smart water meters can provide insight into when and where water is being consumed, which allows utilities companies to achieve efficient management of water distribution systems. As a result of our analysis, we determined the following: • Out of 67 publications, 27% were in the “water supply sources” group, 19% belonged to the “water treatment” group, and 54% were in the “water supply systems” group, confirming the knowledge-intensive nature of the water supply field and the relevance of issues related to effective resource management and environmental monitoring; • In the field of water supply, researchers primarily focus on water supply networks (54%), efficient distribution of potable water, leakage control, and network repairs; • Artificial intelligence technologies began to be actively implemented in the water supply industry in 2019—7 years after the concept of Industry 4.0 had been announced; • Popular machine learning technologies are used to solve tasks of prediction and optimization as well as relevant tasks—classification and clustering of data. Neural networks and ensemble and genetic algorithms were the most frequently mentioned methods in the literature.

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Using Wheat Straw for Treatment of Urban Surface Water Run-Offs O. A. Samodolova1 , A. P. Samodolov1(B) , D. V. Ulrikh1 , and S. S. Timofeeva1,2 1 South Ural State University, 76 Lenina Prospect, Chelyabinsk 454080, Russia

[email protected] 2 Irkutsk National Research Technical University, 83 Lermontova Str., Irkutsk 664074, Russia

Abstract. Wheat straw is one of the most widespread renewable resources in the world, a valuable material used both in traditional (forage raw materials; mulching material; suitable for plants fertilizing and sheltering) and innovative industries (production of building and sorption materials; bioethanol and energy; paper and other useful components). Every year, about 40 million tons of straw is produced in Russia, and a third to a half of it is ploughed back into the ground to restore fertility. The remaining straw is taken out of the fields and disposed of in various ways. One of the promising ways to utilize straw is to use as a sorbent it in wastewater treatment technologies. This work is aimed at studying the possibility of using heat-treated wheat straw as a sorption material for the treatment of surface water run-offs at urban territories. As a sorbent we have used straw from the fields in the Chelyabinsk Region, preliminarily shredded and heat-treated at 80 °C. For the experiment, we have used real wastewater taken from the storm-water sewer in Chelyabinsk. The research has been conducted under static and dynamic conditions at different temperatures and exposure times. It has been determined that the effectiveness of extracting ions of the metals under study ranges from 80 to 100% under static and 60–70% under dynamic conditions. Keywords: Surface water run-offs · Natural sorbents · Wheat straw · Sorption · Local treatment

1 Introduction Wheat is a widely cultivated crop the seeds of which are used all around the world as a staple food. Wheat is the second most produced cereal after corn, and the world trade in wheat constitutes a greater portion than in all other crops combined [1]. The leading wheat-producing countries in the world, according to the USDA statistics over 2020–2021, are China, India and Russia [2], Fig. 1. Since 2018 Russia has taken the first place in wheat export, being ahead of such suppliers as the European Union, the USA, Canada and Australia [2], Fig. 2. In the nearest future, Russia will maintain its wheat-producing leadership and significantly increase the production of wheat. The main share of durum wheat produced in our country belongs to the Orenburg, Chelyabinsk, Saratov and Samara regions, as well to © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_57

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Fig. 1. Wheat-producing leaders (million tons).

Fig. 2. Wheat export leaders over 2020–2021 (million tons).

the Altai and Stavropol territories. The area sown with durum wheat in the Chelyabinsk Region will expand to 169 thousand hectares in 2022. Under favorable climatic conditions, farmers will harvest from 210 to 230 thousand tons of this valuable crop [3–5]; therefore, the volume of a by-product of grain production, which is straw, will increase significantly. Every year, about 40 million tons of straw is produced in Russia, and a third to a half of it is ploughed back into the ground to restore fertility. Straw is removed from the fields and disposed of in various ways. For example, straw is used as raw material for obtaining a complex of products of fine organic synthesis: vanillin, lilac aldehyde, para-hydroxybenzaldehyde and levulinic acid, and for cellulose production [6]. Quite often, straw is used as feed for animals after preliminary biotechnological treatment that increases digestibility and nutritional value [7, 8], as well as for the production of ethyl alcohol [9–11]. An innovative technology has been developed for obtaining granular activated carbon-containing product and liquid biofuel by compacting (pelletizing) pre-shredded straw, accelerated hydrolysis, pyrolysis, followed by activation. During the pyrolysis of the obtained pellets, granulated carbon residue, liquid biofuel and combustible vapor– gas mixture are produced. From the granulated carbonaceous residue activated carbons are obtained, which have an iodine adsorption activity comparable to that of charcoal of the DAK rank [12]. Straw is often used as mulching material and fertilizer. In particular, wheat straw is utilized to mulch the soil surface between rows of corn [13]. The introduction of wheat straw into the soil under millet as an organic fertilizer, both separately and in combination with the Baikal EM-1 solution and the N10 nitrogen mineral supplement, has increased the yield of millet grain by 1–7% [14]. Straw has been used as building material since ancient times. It was used to make thatched roofs and to construct dwellings. Today, pressed straw is one of the best insulations and load-bearing building materials. Thermal conductivity of straw is four times lower than that of wood and seven times lower than that of brick. This property helps

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prevent cold from entering a house and preserve the warmth inside it. The thermal conductivity coefficient of a bale from a baler equals to 0.05–0.06 (which is better than that of wood). Thus, the price of heating will be significantly lower [15, 16]. It is a paradox that straw is superior to wood in terms of fire resistance thanks to the fact that a building block is very tightly pressed, as well as thanks to plaster, which the walls of a house are necessarily covered with both inside and outside. This means that the house made of straw can withstand the heating up to 1000 °C for several hours straight. Straw has good soundproofing properties. To build a one-storey frameless house, it is necessary to use straw bales of up to 0.5 m thick, and for a two-storey house—up to 1 m thick. A straw frame building can have any number of storeys. Another perspective field of use of wheat straw is its application as sorption material [17–23]. Straw and ash, mixed in a ratio of 1 to 0.1 and treated with a 5% to 15% solution of ferric chloride, effectively remove oil products (4.1 g/g oil absorption, 36% oil absorption degree), and reduce the color of water [17]. Straw is used to make coals, which have a high sorption activity for metals [18–22]. Each of the considered methods of utilization of wheat straw has its advantages and disadvantages, primarily, of economic kind. The objective of this work was to evaluate the possibility of using wheat straw as a sorbent for treating surface water run-offs at urban territories with minimal heat treatment.

2 Objects and Methods of Research As a sorbent we used straw taken directly from the fields in the Chelyabinsk Region, preliminarily shredded and heat-treated at 80 °C. According to the data from literature, wheat straw contains 32% of cellulose, 18% of lignin, 23% of pentosans, 14% of hexose hemicelluloses, 5.9% of soluble in alcoholbenzene and 8.2% of ash [6]. Table 1 shows the results of the study of the chemical composition of wheat straw. Table 1. Chemical composition of wheat straw (% of mass of raw substance mass). Easily hydrolysable polysaccharides

Hardly hydrolysable polysaccharides

Lignin

Ash

Galactan

Mannan

Arabinan

Xylan

20–38

31.3–48.6

5.0–24.5

1.4–10.2

0.7–1.5

0.2–0.9

2.3–3.2

17.0–19.7

In its structure, straw is heterogeneous, what is explained by the specifics of the structure and functions of anatomical elements of plant tissue. It consists of stems and leaves. In the straw under study, the mass content (%) of the stems equaled to 58–73, and the leaves—to 18–30. Shredded by cutting wheat straw contained particles of the size of 2 to 10 mm. In the study, as a potential sorbent for wastewater treatment at urban territories, wheat straw was carbonized at 80 °C for 10 min, which was supposed to destroy possible pathogenic microorganisms and increase the treatment efficiency.

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Electron-microscopic analysis of straw samples was conducted using a JEOL JSM6460 LV electron scanning microscope, shown in Fig. 3.

Fig. 3. Electron-microscopic analysis of wheat straw.

The microrelief of the surface of the object was estimated at different degrees of magnification: the top and middle figures are a 100- and 500-times magnified “wall” of the sample, and the bottom figure is a 1000-times magnified “section” of the sample. The element distribution map is presented in Fig. 3 and shows that wheat straw contains C, O, Si, K, and Ca. The elemental composition of straw taken from two spectra at different points is shown in Table 2. Table 2. Elemental composition of wheat straw, %. Spectrum

C

O

Si

K

Ca

Total

1

36.88

35.37

25.72

1.56

0.47

100

2

45.05

45.06

6.83

2.39

0.68

100

The assessment of the sorption characteristics was carried out on real wastewater taken from the storm-water sewer in the city of Chelyabinsk. The content of metals in the wastewater samples and model solutions under study was evaluated on an inductively coupled plasma emission spectrometer of Perkin-Elmer OPTIMA 2100DV ICP-OES (USA). Specially purified water obtained with a Simplicity UV water purification device (France) was used as a background solution.

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The average composition of surface water run-offs from an urban territory is given in Table 3. Table 3. Average chemical composition of surface water run-offs in the city of Chelyabinsk, ml/l. Indicator

Maximum value

Hydrogen index (pH)

6.66

Aluminum

2.707

Cobalt

0.004

Chromium

0.002

Copper

0.028

Iron

2.624

Manganese

0.307

Zinc

0.286

The research has been conducted under static and dynamic conditions at different temperatures and exposure times according to the known methods [22–24]. In the static mode, the sorption process was examined by the limited volume method at a solid–liquid ratio of 1 to 20. The sorbent was placed in a beaker, the test water sample was added in it and left for 3, 6, 9, 24, 168 h at an ambient temperature of 0, 10, 20 °C. After the sorption process was completed, the sample of the solution over the sorbent was taken for chemical analysis. The analysis was performed using the inductively coupled plasma spectrometry method on an OPTIMA 2100DV inductively coupled plasma atomic emission spectrometer. Under dynamic conditions, the sorbent-wastewater system was studied on a specially designed installation allowing to change the above characteristics of the dynamic mode. The speed of water movement in the system was set by the experimental conditions as of 0.3; 0.6; 1.2; 15 l/h. The thickness of the sorption layer equaled to 8 cm and the weight of the sorbent—to 19 g. The experiment was performed as follows: the given rate of the test liquid feed was set, and the pH and content of metals in the filtrate was measured at certain time intervals.

3 Results and Discussion The study of the effectiveness of sorption removal of metals under static conditions on shredded straw showed that the sorption of all studied metal ions reaches its maximum value after 3 h from the beginning of the experiment. The data which shows the dependence of the adsorption of metal cations on the type of sorbent and the time of contact with the sorbent at different temperatures is given in Table 4. It has been revealed that under static conditions, aluminum is most effectively removed at 10 °C after 168 h. Other metals, such as cobalt, chromium and copper

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Table 4. Effectiveness of multicomponent run-off treatment with natural sorbents at different temperatures in static mode. No

Indicator

Treatment efficiency, % 00 C

10 °C

20 °C

3h

6h

168 h

3h

6h

168 h

3h

6h

168 h

Shredded straw 1

Aluminum

10.11

15.12

62.30

–

2.81

85.20

65.31

66.09

75.65

2

Cobalt

98.36

98.9

99.58

98.59

98.98

99.87

98.41

98.87

99.79

3

Chromium

98.14

98.94

99.89

98.63

98.69

99.57

98.57

98.82

99.50

4

Copper

99.01

99.32

99.81

99.08

99.87

100

99.37

99.41

99.92

5

Iron

61.18

69.81

73.57

33.61

45.94

62.94

37.15

48.17

63.58

6

Manganese

30.86

37.69

40.00

25.86

37.64

57.75

34.98

44.37

67.55

7

Zinc

56.12

56.78

56.79

45.98

57.61

68.34

28.96

52.89

59.43

8

pH

6.17

6.01

5.01

5.7

5.81

5.7

5.87

6.01

5.12

Heat-treated straw 1

Aluminum

17.65

23.53

76.47

–

5.88

94.12

82.35

82.35

88.24

2

Cobalt

100

100

100

100

100

100

100

100

100

3

Chromium

100

100

100

100

100

100

100

100

100

4

Copper

100

100

100

100

100

100

100

100

100

5

Iron

78.67

78.67

81.33

45.33

50.67

74.67

57.33

62.67

77.33

6

Manganese

45.45

49.35

62.34

37.66

55.84

72.73

44.16

62.34

76.62

7

Zinc

66.67

66.67

66.67

50.00

66.67

66.67

33.33

66.67

66.67

8

pH

6.17

6.16

5.09

5.86

5.84

5.73

6.16

6.04

5.78

are effectively removed after 3 h. As the temperature rises, the cleaning effectiveness increases. Acidification observed under static sorption conditions confirms chemical sorption by interaction with straw components (see Fig. 4). 0 °С

20 °С

10 °С

pH

6.3 5.8 5.3 4.8 0

3

6

9

24

Fig. 4. Change of pH under various temperature and time conditions.

168

hr

602

O. A. Samodolova et al. Al

Level of purification, %

100.0

Fe

Mn

Co

Cr

Cu

80.0

60.0 40.0 20.0 0.0 0.3

0.6

1.2

15

l/hr

Fig. 5. Effectiveness of metals removal from wastewater at different filtration rates, %.

Under dynamic conditions, the effectiveness of removal of such metals as aluminum, cobalt, chromium and copper does not depend on the filtration rate. The optimal filtration rate for the removal of iron equals to 0.3 l/h, and for manganese—to 15 l/h. Thus, when evaluating the sorption characteristics of straw, it has been found that it can be applied as a sorbent under static and dynamic conditions.

4 Conclusion It has been experimentally determined that surface water run-offs from the territory in the city of Chelyabinsk are characterized by a high content of heavy metals and it is advisable to intercept them at the stage of discharge into storm-water sewers by placing structures made of straw. They will retain suspended solids, sorb heavy metals, and serve as local treatment facilities. In future studies, it is necessary to resolve the issues of further processing of the waste sorbent.

References 1. Wheat Production by Country 2022. https://worldpopulationreview.com/country-rankings/ wheat-production-by-country. Accessed 06 June 2022 2. Major Exporters of Grain (Wheat) in the World: Top 10 Leading Countries. https://lin deal.com/news/krupnejshie-ehksportery-zerna-pshenicy-v-mire-top-10-stran-liderov-otr asli. Accessed 06 June 2022 3. South Ural Region to Grow More Durum Wheat. https://agroxxi-ru.turbopages.org/agroxxi. ru/s/rossiiskie-agronovosti/yuzhnyi-ural-budet-vyraschivat-bolshe-tvyordoi-pshenicy.html. Accessed 06 June 2022 4. Most Interesting Facts about the Agro-industrial Complex of the Chelyabinsk Region. https:// https://gubernia74.ru/articles/society/1099981/. Accessed 06 June 2022 5. Sowing of Durum Wheat to Be Expanded at the South Ural Region. https://rg-ru.turbopages. org/rg.ru/s/2022/02/24/reg-urfo/na-iuzhnom-urale-rasshiriat-posevy-pshenicy-tverdyh-sor tov.html. Accessed 06 June 2022 6. Tarabanko VE, Gulbis GR, Ivanchenko NM, Koropachinskaya NV, Kuznetsov BN (1996) A study of wood and lignosulfonates processing into organic fine chemicals. Chem Sustain Dev 4–5:405–417

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7. Lesnov AP, Leontiev SV, Nikitenkov AI (2009) Production of cattle feed made of low-value vegetable raw materials. Effic Anim Husb 9:44–45 8. Lesnov AP, Leontiev SV, Kovalev AN (2011) Low-value vegetable raw materials in biotechnologies of fodder production. APK YuG 5:40–43 9. Sergeenko LA, Logvinova AS, Boltovsky VS (2020) Grain crops straw preparing for biotechnological processing. Proc BSTU 2(1):173–182 10. Yu Z, Oya M (2011) Bioethanol production from wheat Straw. J Int Acad Refrig 4:21–23 11. Swain M, Singh A, Sharma A.K., Tuli D.K. (2019) Bioethanol production from rice- and wheat straw: an overview. bioethanol production from food crops. Sustain Sources, Interv, Refrig Chall 213–231 12. Spitsyn AA, Belousov II, Tursunov TB, Khen VA (2018) Thermochemical conversion of grinded pressed plant biomass. Proc St Petersburg State For Tech Univ 224:256–272. https:// doi.org/10.21266/2079-4304.2018.224.256-272 13. Ryazantseva NV (2016) Straw application for soil surface mulching in maize. agrotechnological processes within the framework of import substitution. In: Proceedings of the International Science-to-practice Conference Dedicated to the 85th Anniversary of the Honored Worker of the Higher School of the Russian Federation, Doctor of Sciences (Agriculture), Professor Yu.G. Skripnikov, Michurinsk, October 25–27, 2016. Michurinsk: OOO “BIS”, pp 63–64 14. Alekseeva T, Volkova ES, Nematov AM (2020) Effectiveness of Winter Wheat Straw in the System Millet Fertilizers. Environmental Problems and Ways to Solve Them: Naturalscience and Sociocultural Aspects: Collected Papers of the 6th Youth Interregional Scientific and Practical Conference of Students, Undergraduates and Graduate Students, Nizhny Novgorod, November 25, 2020, Minin University, Nizhny Novgorod: Federal State-funded Educational Institution of Higher Education “Kozma Minin Nizhny Novgorod State Pedagogical University”, pp 84–85 15. Zasypkina EM (2019) Construction of a house of straw. Bull MITU-MASI 1:15–17 16. Zamuraev AL (2020) Hot-pressed Straw Blocks as an Environmentally-friendly, reliable and cheap building material. Young Sci 41(331):39–41. https://moluch.ru/archive/331/74041/. Accessed 05 July 2022 17. Veprikova EV, Tereshchenko EA, Chesnokov NV, Shchipkoa ML, Kuznetsov BN (2010) Peculiarity of water purifying from oil products with make use of oil sorbents, filtering materials and active coals. J Sib Fed University Chem 3:285–304 18. Peng F, Sun RC (2010) Modification of cereal straws as natural sorbents for removing metal ions from industrial waste water. Cereal Straw Resour Sustain Biomater Biofuels 219–237 19. Guerin T, Ghinet A, Hossart M, Waterlot C (2020) Wheat and ryegrass biomass ashes as effective sorbents for metallic and organic pollutants from contaminated water in lab-engineered cartridge filtration system. Bioresour Technol 318. https://doi.org/10.1016/j.biortech.2020. 124044 20. Gao L, Goldfarb JL (2019) Solid waste to biofuels and heterogeneous sorbent via pyrolysis of wheat straw in the presence of fly ash as an in situ catalyst. J Anal Appl Pyrol 137:96–105 21. Dashti N, Ali N, Khanafer M, Radwan SS (2017) Oil uptake by plant-based sorbents and its biodegradation by their naturally associated microorganisms. Environ Pollut 227:468–475 22. Timofeeva SS, Lykova OV (1986) Extraction of metals from wastewater of galvanic productions by wastes of woodworking and pulp and paper industries. Enrichment of Ores, Irkutsk, pp 87–92 23. Timofeeva SS, Lykova OV (1990) Sorption extraction of metals from wastewaters of galvanic productions. Chem Technol Water 12(5):440–443 24. Timofeeva SS, Lykova OV, Kukharev BF (1990) The use of sorbents for the extraction of metals from wastewater. Chem Technol Water 12(6):505–508

Sorption Properties of Composite Materials Based on Hemp Hulls and the Byproducts of Silicon Production Used to Remove Antibiotics from Wastewater S. S. Timofeeva(B) , M. S. Tepina, and O. V. Tukalova Irkutsk National Research Technical University, 83, Lermontova Str, Irkutsk 664074, Russia [email protected]

Abstract. Removing residual amounts of antibiotics from wastewater is an important area of study. The uncontrolled use of antibiotics has led to their accumulation in the ecosystem and to antibiotic resistance in microorganisms. Each year 700 thousand people die because of antibiotic resistance. By 2050, this number may reach 10 million people. Antibiotics enter the waterways after being excreted by humans and animals and pass through wastewater treatment plants, posing an environmental risk to human and biota health. The goal of this paper is to study the use of hemp hull (a byproduct of hemp oil production) and a complex sorbent based on hemp hulls to remove tetracycline from the wastewater of hospitals and pig farms. To conduct our study, we created a wastewater system model and added antibiotics to the system. We used spectrophotometric determinination of antibiotics to examine the feasibility of removing antibiotics from a wastewater system in static and dynamic modes. A method of synthesizing complex sorbents based on hemp hull and dust from silicon and aluminum production is proposed. Our experiment has shown that composite sorbents based on byproducts of hemp hull processing and silicon production (dust and scraps) can be used to treat water contaminated with antibiotics. We have determined that composite sorbents show better sorption of tetracyclines and the largest capacity in both static and dynamic operation. These sorbents almost fully removed the antibiotics from the solution. Keywords: Hemp hull · Silicon production byproducts · Flue dust · Pelletizing · Composite sorbents · Tetracycline · Wastewater treatment

1 Introduction The widespread use of antibiotics and their accumulation in ecosystems has led to the global issue of antimicrobial resistance when microorganisms mutate and lose their susceptibility to antibiotics that were previously successfully used to treat infections. The World Health Organization (WHO) has listed bacterial resistance as one of the ten most serious threats that humanity is facing. Each year 700,000 people die because of © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 A. A. Radionov et al. (eds.), Proceedings of the 6th International Conference on Construction, Architecture and Technosphere Safety, Lecture Notes in Civil Engineering 308, https://doi.org/10.1007/978-3-031-21120-1_58

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antibiotic resistance. Experts estimate that by 2050, the number of deaths could rise to 10 million, 2.4 million of which could be in high-income countries [1]. The United States suffers more than $20 billion in losses annually due to antimicrobial resistance [2]. In Russia, spending on antimicrobial therapy accounts for more than 30% of the budget of medical organizations [3]. High resistance to antibiotics is not just the result of using antibiotics in medicine, but also their growing and poorly-controlled use in veterinary practice and agriculture. Statistics show that antibiotics are used twice as often in veterinary practice than in medicine. However, not all countries keep records of antibiotic use in veterinary practice [4]. Annual global consumption of antibiotics reached 200,000 tons in 2015. A study of antibiotic consumption in 76 countries found that global antibiotic consumption increased from 21.1 to 34.8 billion defined daily doses (DDD) from 2000 to 2015. Antibiotic consumption increased slightly in high-income countries, but increased significantly in low- and middle-income countries to 19.5 DDD per 1000 inhabitants per day [5, 6]. Antibiotics are excreted by human and animals after consumption. Since most antibiotics are not fully metabolized, a significant portion of the drugs administered are released into the water and soil via municipal wastewater, animal manure, and sewage transported to agricultural fields as fertilizer. 30 to 90% of orally administered drugs and antibioticrelated materials enter the environment as active metabolites in urine (64 + 27% on average). Some products of drug metabolism are also excreted in feces (35 + 26% on average). These substances pass through wastewater treatment plants and pose a potential environmental risk to the public. Many papers have been published on determining the antibiotic content in wastewater in China [7, 8], India [9, 10], Japan [11], USA [12], and in several European countries: Poland, Germany, UK, Switzerland, Italy, Spain [13, 14]. The detectable concentrations of antibiotics in wastewater vary widely and range from nanograms to micrograms per milliliter [15]. The highest concentrations of antibiotics are detected in the wastewater of hospitals [16], pig farms, and livestock agricultural holdings [17]. In Russia, antibiotic content is only regulated in food [18]—it is not regulated in wastewater and drinking water. Nevertheless, antibiotic resistance and contamination of aquatic ecosystems is a pressing issue, including in the Irkutsk Region [19]. We must develop technologies to remove these dangerous pollutants from wastewater; the existing treatment facilities cannot perform these functions. Different methods of removing antibiotic pollutants from wastewater have been proposed, including ozonation, chlorination, coagulation, enzyme treatment, and more [20–23]. Sorption is the simplest method. Researchers have proposed activated carbon, natural clays [21], and composite materials as sorbents for antibiotic removal [24]. The goal of this paper is to study the use of hemp hull (a byproduct of hemp oil production) and a complex sorbent based on hemp hulls to remove tetracycline, an antibiotic widely used in medicine and veterinary practice, from the wastewater of hospitals and pig farms.

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2 Objects and Methods of Research We have studied the sorption characteristics of hemp hull (shell) and a composite sorbent based on hemp hull. There is increasing interest in technical hemp as a source of raw materials for the textile and food industries. Hemp seeds contain up to 48% of valuable oil and up to 31% of protein. The hemp fruit is a round nut consisting of a hard fruit shell and a soft seed shell; large volumes of hull (shell) are produced through hemp processing. At this time one of the only practical applications of the hull is to create mulch. We used hemp shells from Konoplektika, a well-known manufacturer of hemp seed products in Chelyabinsk, Russia. To create our composite sorbent, we created pellets from hemp husk and biochar from a hemp fire, then injected liquid glass and microcrystalline silica and thoroughly mixed the pellets. The interaction between liquid glass and microcrystalline silica releases hydrogen, creating the porous structure of the sorbent (1) Si + 2NaOH + H2 O = Na2 On · SiO2 + 2H2 ↑

(1)

Fine silica, also called pot scrap, is a byproduct of silicon production consisting of fragments, scraps, and other waste products formed on crucibles and linings with traces of oxidation and slag (see Table 1). Table 1. Chemical composition of fine silica. Trace elements

Si

Fe

Al

Ca

Ti

P

Average content, % wt

99

0.45

0.34

0.067

0.0348

0.0025

We also used flue dust from silicon production (OC–Si) and aluminum production as a source of microcrystalline silica. Each year, AO Kremniy disposes of up to 2500 tons of this waste. We used homogenized dust samples from the sludge fields of AO Kremniy in the city of Shelekhov. The chemical composition of the dust is presented in Table 2. Table 2. Chemical composition of flue dust from silicon production. Component

Content, % wt

Component

Content, % wt

SiO2

86.3

Na2 O

0.07

SO3

0.14

Al2 O3

0.37

Fe2 O3

0.30

P2 O5

0.12

CaO

1.4

K2 O

0.28

MgO

1.20

TiO2

0.02

Ccv

5.8

SiC

4.15

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We studied the chemical composition of flue dust at the INRTU Technosphere Safety Collective Use Center on an ARL-9900 X-ray fluorescent spectrometer (USA) designed to measure the mass fraction of elements in metallic and non-metallic samples in solid, liquid, and powder states. Dust from the electrostatic precipitators of the Irkutsk Aluminum Factory was used as an additive. This dust is formed from particles of alumina, fluoride salt, and carbon created during the electrochemical destruction of carbon anode, the products of electrolyte evaporation, and the electrolyte itself. Using this fine-grained material in the pellet increases the strength of the pellet due to the presence of resinous substances (Table 3). Table 3. Chemical composition of dust from aluminum factory electrostatic precipitators. Component

Content, % wt

Component

Content, % wt

Na3 AlF6

12.14

Al2 O3

30.80

Na5 Al3 F14

11.02

Fe2 O3

2.02

NaF

2.5

SiO2

0.5

AlF3

0.7

Na2 SO4

4.05

K2 NaAlF6

2.8

C

CaF2

1.5

Resinous substances

MgF2

1.35

26.55 4.68

The sorption properties of the composite sorbents were tested on tetracycline solutions. Tetracyclines are yellow crystalline substances that are stable in a solid state. They are amphoteric, giving these antibiotics the ability to form salts with organic and inorganic acids, alkaline and alkaline-earth metals. They form insoluble complexes with cations of multivalent metals, boric acid, salts of α-oxycarboxylic acids (gluconic, malic, citric, etc.). Under certain conditions, tetracycline solutions fluoresce. When dry, tetracyclines are stable; the stability of tetracyclines in solutions depends on pH of the medium. They are most stable in an acidic environment; in an alkaline environment their activity decreases rapidly. Chlortetracycline is the most labile in alkaline media. Tetracycline is the most stable in acidic media. A Shimadzu 1800 spectrophotometer was used to control tetracycline concentration in the test solutions. In a neutral medium, tetracycline has a UV absorption band which peaks at around 360 nm due to the electronic structure of the molecule formed by four condensed aromatic rings and substituents near them. In a strongly alkaline environment, tetracycline isomerization occurs with the formation of yellow isomers with maximum UV absorption at 380 nm. This reaction is used in the identification and spectrophotometric quantification of tetracycline 2 g of the sorbent were placed in 100 ml conical flasks. 100 ml of solution with varying concentration of antibiotics (5, 10, 20, 30, 60, 100, 150, and 200 mg/l) were added to the flask and mixed in a shaker for 24 h. The solutions were separated from the sorbents by filtration. The concentration of antibiotics in the filtrate and eluate was determined spectrophotometrically (Fig. 1).

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Fig. 1. The process of studying the sorption of a composite sorbent based on hemp hulls and silicon production byproducts.

The degree of extraction was calculated as the difference between the initial mass of the antibiotic placed in the solution and the mass of the antibiotic in the filtrate divided by the initial mass of the antibiotic and multiplied by 100%.

3 Results and Discussion Figure 2 shows the UV absorption spectra of tetracycline solutions with an initial antibiotic concentration of 150 and 200 mg/l with composite sorbents based on hemp husk (OC–H) and fine silica (OS–Si). The hemp hull sorbents were as effective as sorbents based on silicon production dusts at removing tetracycline from the solutions [3, 10].

Fig. 2. Sorption of tetracycline from solutions with an initial antibiotic concentration of 150 and 200 mg/l.

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Figure 3 shows the sorption of tetracycline from solutions with an initial antibiotic concentration of 5, 10, 20, 30, 60, 100, 150, and 200 mg/l by the silica dust sorbent and hemp hull sorbent.

Fig. 3. Sorption of tetracycline by composite materials. a composite materials based on silicon production flue dust; b composite materials based on hemp hull and fine silica.

Table 4 presents the calculated degree of extraction and degree of elution of tetracycline by the considered sorbents. Table 4. Degree of extraction and degree of elution of tetracycline by the studied sorbents, %. Sorbent

Degree of extraction Degree of elution

Hemp husk

48.7 ± 9.4

17.9 ± 3.6

Hemp husk and fine silica (OC-H)

> 99.0

< 1.0

Hemp husk and flue dust (OC-Si)

> 99.0

< 1.0

Hemp husk and aluminum production dust (OC-Al) > 96.0

< 2.5

4 Conclusions Our experiments showed that composite sorbents based on industrial waste from hemp seed processing and silicon production (dust and scrap) can be successfully used to remove antibiotics from wastewater. We determined that composite sorbents have the best sorption properties for tetracyclines and the highest maximum capacity in both static and dynamic modes. In our experiments, these sorbents nearly completely removed the antibiotics from the model wastewater system.

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