Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel 9811995222, 9789811995224

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Shucai Li · Zhenhao Xu · Xin Huang · Yuchao Du

Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel

Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel

Shucai Li · Zhenhao Xu · Xin Huang · Yuchao Du

Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel

Shucai Li Geotechnical and Structural Engineering Research Center Shandong University Jinan, Shandong, China

Zhenhao Xu Geotechnical and Structural Engineering Research Center Shandong University Jinan, Shandong, China

Xin Huang School of Civil Engineering Henan Polytechnic University Jiaozuo, Henan, China

Yuchao Du Geotechnical and Structural Engineering Research Center Shandong University Jinan, Shandong, China

ISBN 978-981-19-9522-4 ISBN 978-981-19-9523-1 (eBook) https://doi.org/10.1007/978-981-19-9523-1 Jointly published with Science Press The print edition is not for sale in China (Mainland). Customers from China (Mainland) please order the print book from: Science Press. © Science Press 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 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 publishers, 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 publishers 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 publishers remain neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Preface

In recent years, China’s economy has been developing rapidly, its comprehensive national strength has been continuously improved, and the scale of infrastructure construction such as transportation, water conservancy and hydropower, and municipal engineering has been expanding. At present, China has become the country with the largest scale and greatest difficulty in the construction of tunnels and underground projects in the world. Different types of geological disasters are often encountered in the process of tunnel construction, and water and mud inrush is one of the most severe geohazards encountered in tunnel construction. Water and mud inrush in the tunnel will not only cause significant economic losses and casualties in the construction stage, resulting in adverse environmental and social impacts; there are also major potential safety hazards in the operation stage. The frequent occurrences of water and mud inrush disasters in tunnels have attracted the extensive attention of many colleagues in the tunnel engineering field. In view of this, design, construction, scientific research and other units and relevant practitioners have carried out a lot of research. The geological environment in which the tunnel is located is the basis for studying the problem of water and mud inrush. Therefore, the research on the identification method, hazard-causing mechanism, prediction and early warning, and disaster treatment of the water and mud inrush hazard-causing system shall also “start from geology and settle down in geology”. From the perspective of geology, it is particularly important for the research and disaster control of water and mud inrush in tunnels to categorize and identify the types of hazard-causing systems of water and mud inrush in tunnels and clarify the hazard-forming mode. It is an important way to avoid the water and mud inrush disaster from the source to carry out the research on the route selection of karst tunnels. In addition, to establish a practical and effective risk assessment method for water and mud inrush of tunnel and a scientific and systematic evaluation method for the stability of resistance body, and to construct a dynamic management and analysis platform for water and mud inrush of tunnels, are all of important guidance and reference significance for the safe construction of tunnels.

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The authors and team members have long been engaged in the research on geological identification, prediction and early warning and disaster prevention and control of water and mud inrush hazard-causing systems in tunnels, and have always followed the guiding ideology of “combining theory with practice”, “learning from the project and serving for the project”, and “all for the service and welfare of the project”. We have cooperated with many universities and scientific research institutes, such as Nanjing University, China University of Mining and Technology, Chang’an University, Central South University, Army Engineering University of PLA, Institue of Rock and Soil Mechanics, Chinese Academy of Sciences, as well as many construction units (China Railway Tunnel Group Co., LTD, Railway No. 10 Engineering Group Co., LTD, China Railway 12th Bureau Group Co., LTD, China Railway 14th Bureau Group Corporation Limited, China Railway 15th Bureau Group Corporation Limited, China Railway 17th Bureau Group Co., LTD, China Railway 19th Bureau Group Corporation Limited, China Railway 21st Bureau Group Corporation Limited, Shaanxi Road & Bridge Group Co., Ltd, Construction Headquarters of E’xi Expressway (Hubei Expressway), Qingdao Metro Group Co., Ltd, Construction Headquarters of Hurongxi Expressway, Yonglong Expressway Construction and Development Co., Ltd, Construction Office of Ji’an-Lianhua Expressway (Department of Transportation of Jiangxi Province), Construction Headquarters of YichangWanzhou Railway (Ministry of Railways, PRC), Construction Headquarters of Dianxi Railway, and Construction Headquarters of Cenxi-Shuiwen Expressway, to name a few). In the cooperation, we follow the principle of “combination of production, academics, research and application”, take the tunnel construction site as the practice base, take theory and method research as the core, discover and refine scientific problems and development direction from practice, constantly break through key theories and solve technical problems, and then return to the project for verification, application and promotion. Specifically, with the goal of “classifying and identifying the types of water and mud inrush hazard-causing systems in tunnels and assessing the water and mud inrush disaster”, we proposed 3 categories and 11 types of tunnel water and mud inrush hazard-causing systems and another 4 typical water and mud inrush disaster-forming modes, so as to reveal the structural characteristics and occurrence laws of the water and mud inrush hazard-causing systems in tunnels. Then, we developed the geological identification methods of the water and mud inrush hazard-causing systems in tunnels and proposed the principles and evaluation methods for the route selection of karst tunnels. Afterwards, we established the interval risk dynamic evaluation method of tunnel construction and the resistance body evaluation method of water and mud inrush. In addition, the identification method of tunnel water and mud inrush hazard-causing system is finally developed, which organically integrates geological identification, geophysical exploration identification and drilling identification. Furthermore, we constructed the dynamic management and analysis platform for water and mud inrush cases in tunnels based on the above research work. This book introduces in detail the research status and results of the water and mud inrush hazard-causing system and disaster-forming evaluation in tunnels. It consists of eight chapters. Chapter 1 mainly expounds the research background and

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significance of water and mud inrush in tunnel, defines the concepts of water and mud inrush hazard-causing system and the resistance body, and summarizes the research status, existing problems and development trend of water and mud inrush hazardcausing system, risk assessment and identification methods. Chapter 2 analyzes and summarizes a large number of cases of water and mud inrush in tunnels, puts forward the categories and types of hazard-causing systems and disaster-forming modes, and expounds in detail the geological identification methods of various types of hazardcausing systems. Chapter 3 focuses on the analysis of typical cases of water and mud inrush in tunnels that are induced by different types of hazard-causing systems, so as to strengthen readers’ understanding of geological identification of different types of water and mud inrush hazard-causing systems in tunnels. Chapter 4 clearly expounds the types, structural characteristics and identification methods of karst water system and their influence on the route selection of karst tunnels, and then proposes the basic principles and evaluation methods of the route selection of karst tunnels. In Chapter 5, based on the interval fuzzy comprehensive evaluation method, the conceptual model of risk evaluation of water and mud inrush in tunnel is established, the weights of risk factors of water and mud inrush are deeply studied, and the construction permit mechanism is proposed based on the interval evaluation system of risk evaluation. In Chapter 6, based on the rock mass quality evaluation and classification method, the resistance body evaluation method of water and mud inrush in tunnel is put forward, the grade classification and evaluation system of each influencing factor is established, and the implementation process of the resistance body evaluation is elaborated. In Chapter 7, based on the geological characteristics, geophysical response characteristics and drilling exposure characteristics of the hazard-causing systems, a comprehensive identification method of water and mud inrush hazardcausing system in tunnel is proposed, which integrates geological identification, geophysical exploration identification and drilling identification. Chapter 8 focuses on the dynamic management and analysis platform of water and mud inrush cases in tunnels. This book is a summary of the research results of the authors and team members in this field over the years. It is expected that it can provide a useful reference for the research and practice of water and mud inrush hazard-causing system and disaster-forming evaluation in tunnels. The identification of water and mud inrush hazard-causing system and disasterforming evaluation covers many scientific research topics and involves a wide range of subjects, such as geology, geophysics, rock mechanics, tunneling and underground engineering, computer science and electronic information science. Therefore, there are many challenges ahead and still a lot of research works need to be further carried out. In the process of preparation, we have also referred to the work of our predecessors and relevant professional books and documents on geotechnical engineering, geological engineering and tunnel engineering. We would like to express our sincere thanks to the scientific researchers for the contents quoted in this book. The preparation and publication of this book have received the enthusiastic support and hard work of the experts in the industry and the comrades of the publishing house. Here, we would like to express our heartfelt thanks!

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This book has been supported by the National Basic Research Program of China (973 project, 2013CB036000), National Natural Science Foundation of China Science Fund for Creative Research Groups (52021005), NSFC Excellent Young Scientists Fund (52022053), Natural Science Foundation of Shandong Province Distinguished Young Scholars Fund (ZR2020JQ26) and other funds, for which we would like to express our gratitude. We would like to thank the team members for their contributions in theoretical research, indoor and field tests over the years, and the many cooperative units and engineering technicians who have provided field test conditions and strong support for this research. And special thanks are devoted to Research associate Dong Xiaoyan who assisted in translating the book from Chinese to English and the proofreading of the book, and her rigorous and meticulous work greatly benefited this book. Due to the limitation of the authors’ professionalism and ability, the book inevitably has some defects. We are grateful to all readers who use this book for their comments and suggestions. Jinan, China Jinan, China Jiaozuo, China Jinan, China

Shucai Li Zhenhao Xu Xin Huang Yuchao Du

Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Background and Significance of Research on Water and Mud Inrush in Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Water and Mud Inrush Hazard-Causing System and Resistance Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.1 Water and Mud Inrush Hazard-Causing System . . . . . . . . . . . 1.2.2 Resistance Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Research on the Hazard-Causing System of Water and Mud Inrush in Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Summary of Research on Construction Risk Dynamic Evaluation of Tunnel Water and Mud Inrush . . . . . . . . . . . . . . . . . . . . 1.5 Summary of Research on Identification Methods of Tunnel Water and Mud Inrush Hazard-Causing System . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Classification and Geological Identification of Water and Mud Inrush Hazard-Causing Systems in Tunnels . . . . . . . . . . . . . . . . . . . . . . . 2.1 Karst Category of Hazard-Causing System . . . . . . . . . . . . . . . . . . . . . 2.1.1 Corrosion Fissure Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.2 Karst Cave Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.3 Pipe and Underground River Type . . . . . . . . . . . . . . . . . . . . . . 2.2 Fault Category of Hazard-Causing System . . . . . . . . . . . . . . . . . . . . . 2.2.1 Water-Rich Fault Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.2 Water-Conductive Fault Type . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.3 Water-Resistant Fault Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Other Category of Hazard-Causing System . . . . . . . . . . . . . . . . . . . . . 2.3.1 Intrusive Contact Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.2 Structural Fissure Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.3 Unconformable Contact Type . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.4 Differential Weathering Type . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.5 Special Condition Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 1 5 5 6 8 14 18 23 29 30 40 41 42 44 48 49 49 50 51 57 61 62 64

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2.4 Disaster-Forming Pattern of Water and Mud Inrush Hazards in Tunnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.1 Directly Revealed Type of Water and Mud Inrush . . . . . . . . . 2.4.2 Progressive Failure Type of Water and Mud Inrush . . . . . . . . 2.4.3 Seepage Instability Type of Water and Mud Inrush . . . . . . . . 2.4.4 Intermittent Failure Type of Water and Mud Inrush . . . . . . . 2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Typical Cases and Analysis of Water and Mud Inrush in Tunnels . . . 3.1 Typical Cases of Water and Mud Inrush in Karst-Category Hazard-Causing System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1 Typical Case of Corrosion Fissure Type Water and Mud Inrush—Qiyueshan Tunnel of Lichuan-Wanzhou Expressway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.2 Typical Case of Karst Cave Type Water and Mud Inrush—Daba Tunnel of Longshan-Yongshun Highway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.3 Typical Case of Pipe and Underground River Type Water and Mud Inrush—Qiyueshan Tunnel of Shanghai-Chengdu West Highway . . . . . . . . . . . . . . . . . . . 3.2 Typical Cases of Water and Mud Inrush in Fault-Category Hazard-Causing System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 Typical Case of Water-Rich Fault Type Water and Mud Inrush—Baiyun Tunnel of Nanning-Guangzhou Railway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2 Typical Case of Water-Conductive Fault Type Water and Mud Inrush—Yonglian Tunnel of Ji’an-Lianhua Highway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.3 Typical Case of Water-Resistant Fault Type Water and Mud Inrush—Qiyueshan Tunnel of Yichang-Wanzhou Railway . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Typical Cases of Water and Mud Inrush in Other-Category Hazard-Causing System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.1 Typical Case of Intrusive Contact Type Water and Mud Inrush—Xiangyun Tunnel of Guangtong-Dali Railway . . . . 3.3.2 Typical Cases of Structural Fissure Type Water and Mud Inrush . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.3 Typical Case of Unconformable Contact Type Water and Mud Inrush—Changlashan Tunnel of Qinghai Provincial Highway 309 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.4 Typical Case of Differential Weathering Type Water and Mud Inrush—Junchang Tunnel of Cenxi-Shuiwen Highway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3.3.5 Typical Cases of Special Condition Type Water and Mud Inrush . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 4 Tunnel Route Selection in Karst Region . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Underground River System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.1 Underground River System Structural Characteristics and Its Macro-geological Identification . . . . . . . . . . . . . . . . . . 4.1.2 Engineering Identification of Underground River Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.3 The Influence of the Underground River System on Tunnel Route Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.4 Principles of Tunnel Route Selection in the Underground River System . . . . . . . . . . . . . . . . . . . . . . 4.2 Karst Spring System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.1 Karst Spring System Structural Characteristics and Its Macro-geological Identification . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2 Engineering Identification of Karst Spring Systems . . . . . . . 4.2.3 The Influence of Karst Spring Systems on Tunnel Route Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4 Principles of Tunnel Route Selection in Karst Spring System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Dispersed Drainage Karst Water System . . . . . . . . . . . . . . . . . . . . . . . 4.4 Evaluation of Karst Tunnel Route Selection . . . . . . . . . . . . . . . . . . . . 4.4.1 Evaluation Model for Karst Tunnel Route Selection . . . . . . . 4.4.2 Evaluation Factors and Weight Analysis of Karst Tunnel Route Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.3 The Complete Hierarchical Order . . . . . . . . . . . . . . . . . . . . . . 4.4.4 Grading Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 Engineering Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.1 Project Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.2 The Development Characteristics of Underground Rivers in the Tunnel Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.3 Engineering Analogy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.4 Tracer Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.5 Geophysical Prospecting and Investigation Inside the Tunnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.6 Evaluation of Karst Tunnel Route Selection . . . . . . . . . . . . . . 4.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

147 148 148 149 150 153 154 154 155 156 157 158 159 159 160 168 168 169 170 171 172 177 181 185 188 189

5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush During Tunnel Construction . . . . . . . . . . . . . . . . . . . . . 191 5.1 Risk Assessment Conceptual Model and Index Rating . . . . . . . . . . . 191 5.1.1 Hydrogeology and Geological Engineering Conditions . . . . 192

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5.1.2 Tunnel Construction Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.3 Dynamic Feedback of Construction Information . . . . . . . . . . 5.2 Fuzzy Evaluation of Water and Mud Inrush Interval Risk . . . . . . . . . 5.2.1 Construction of Interval Risk Calculation Model . . . . . . . . . . 5.2.2 Interval Risk Membership Calculation . . . . . . . . . . . . . . . . . . 5.2.3 Interval Factor Weight Analysis . . . . . . . . . . . . . . . . . . . . . . . . 5.2.4 Relative Dominance Analysis of Interval Matrix . . . . . . . . . . 5.3 Tunnel Construction Permit Mechanism and Risk Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.1 Construction Permit Mechanism and Risk Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.2 Implementation Procedures of the Construction Permit Mechanism and Risk Management . . . . . . . . . . . . . . . 5.3.3 Principle of Construction Permit Mechanism . . . . . . . . . . . . . 5.4 Case Study of the Qiyueshan Tunnel: Dynamic Evaluation and Control of Water and Mud Inrush Risk . . . . . . . . . . . . . . . . . . . . . 5.4.1 Preliminary Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4.2 Secondary Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4.3 Dynamic Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Assessment Method of the Resistance Body Against Water and Mud Inrush in Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Influencing Factors of the Resistance Body Stability . . . . . . . . . . . . . 6.1.1 Influencing Factors of the Disaster Source . . . . . . . . . . . . . . . 6.1.2 Influencing Factors of the Resistance Body . . . . . . . . . . . . . . 6.2 Establishment of the Resistance Body Assessment Method . . . . . . . 6.3 Grading and Scoring of Factors Affecting the Resistance Body Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.1 Grading and Scoring of Factors Affecting Disaster Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.2 Grading and Scoring of Factors Affecting Resistance Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 Implementation Procedure of the Resistance Body Assessment . . . . 6.5 Engineering Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Recognition Methods for Hazard-Causing Systems of Water and Mud Inrush in Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Implementation of the Recognition Method for Water and Mud Inrush Hazard-Causing System . . . . . . . . . . . . . . . . . . . . . . . 7.1.1 Implementation Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.2 Implementation Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Typical Hazard-causing System Characteristics . . . . . . . . . . . . . . . . .

196 198 199 199 202 203 204 205 205 206 208 209 211 214 215 221 223 225 225 226 227 228 231 231 233 237 238 245 246 247 248 248 251 252

Contents

7.2.1 Geological Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.2 Geophysical Prospecting Recognition . . . . . . . . . . . . . . . . . . . 7.2.3 Drilling Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 Engineering Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.1 Project Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.2 Geological Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.3 Geophysical Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Dynamic Management and Analysis Platform for Tunnel Water and Mud Inrush Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Design Objectives and Requirements of the Case Management and Analysis Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.1 Design Objectives of the Platform . . . . . . . . . . . . . . . . . . . . . . 8.1.2 General Requirements for Platform Design . . . . . . . . . . . . . . 8.2 System Development Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3 Platform Composition and Architecture . . . . . . . . . . . . . . . . . . . . . . . . 8.3.1 Platform Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3.2 B/S Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4 Main Functions of the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.1 User Authentication Login . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.2 Case Display, Retrieval, and Download . . . . . . . . . . . . . . . . . . 8.4.3 Case Submission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.4 Case Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.5 Case Comment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.6 Case Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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252 260 267 268 268 268 270 280 280 283 284 284 284 286 288 288 289 290 291 293 293 294 294 295 301 302

Appendix 1: Karst Category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 Appendix 2: Fault Category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347 Appendix 3: Other Category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379

Chapter 1

Introduction

1.1 Background and Significance of Research on Water and Mud Inrush in Tunnels With the continuous economic development, the improvement of comprehensive national strength and the increasing application of high-tech, China’s tunnel and underground engineering construction has achieved unprecedented development, and it has become the country with the largest scale and the greatest difficulty in tunnel construction in the world (Qian 2017). In recent years, the construction of major national projects has accelerated. Large-scale geotechnical projects represented by urban rail transit construction, expressway network construction, high-speed railway network construction, and major water conservancy and hydropower projects have shown a “leaping forward” development trend (Xiong et al. 2018). The “Three-year Action Plan for Major Transportation Infrastructure Construction Projects” jointly issued by the National Development and Reform Commission and the Ministry of Transport pointed out that the “13th Five-Year Plan” period is an important stage in the construction of major transportation infrastructure projects. Important engineering fields such as traffic engineering (railway tunnel, highway tunnel) and water conservancy and hydropower engineering (water conveyance tunnel and underground powerhouse), etc., have gradually become an important part of the construction of major national infrastructure projects. During the implementation of the “13th FiveYear Plan” and the Belt and Road Initiative. The focus of China’s major engineering construction has gradually shifted to the western mountainous and karst areas with complex topographic and geological conditions. A large number of tunnels under construction or planning are facing unprecedentedly severe water and mud inrush geological hazards. The prevention and control of water and mud inrush disasters in tunnels are of world-class difficulty (Li et al. 2017a). Throughout the history of tunnel construction in the world, water and mud inrush has always been one of the most serious geological disasters, which can easily cause serious engineering losses and casualties. © Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1_1

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1 Introduction

We statistically analyzed more than 381 cases of water and mud inrush in tunnels, and the overall characteristics are as follows (shown in Fig. 1.1). (1) Tunnels occurring water and mud inrush are mainly concentrated in karst areas in the central and western regions, such as Hubei, Chongqing, Sichuan, Guizhou, Yunnan, and other places. Special karst geology and hydrogeological conditions have formed different surface and underground karst forms, such as peak clusters, peak forests and other surface karst landforms, depressions, sinkholes, funnels, underground river skylights, and other negative topography or vertical karst morphology, as well as karst fissures, karst pipelines, karst caves, etc., that receive infiltration or injection replenishment. The surface and underground karsts have formed groundwater migration channels and accumulation spaces, forming a complex hazard-causing system, which is extremely prone to water and mud inrush disasters. (2) The large-scale and extra-large water and mud inrush with greater catastrophability are mainly distributed in the southern karst areas, especially the large-scale karst water system distribution areas, such as the Maluqing Tunnel and Yesanguan Tunnel of Yichang-Wanzhou Railway and Chaoyang Tunnel of GuizhouNanning High-speed Railway. The karst distribution areas in the north are dominated by medium-and small-scale water and mud inrush. The reasons for the difference between the north and the south lie in the different geological structures, stratum lithology, and underground hydrodynamic conditions. The southern karst areas are mainly distributed in the Yangtze stratum, and the northern karst areas are mainly distributed in the North China stratum. There are obvious differences between the two in terms of geological structure and stratigraphic lithology. In addition, the amount of precipitation in the south is generally greater than that in the north, and the south has a longer rainy period, larger total amount, and higher intensity than the north. Therefore, there are obvious differences in the groundwater dynamic conditions for karst development. In the Yangtze stratum: the upper Sinian to the Ordovician are mainly composed of shallow sea carbonate rocks, which are deposited and several kilometers thick. The Upper Sinian is dominated by dolomite, with uniform lithology and a thickness of about one kilometer. The Cambrian Sichuan-Guizhou area is dominated by dolomites, and the Sichuan-Hubei area is dominated by muddy limestone. The Ordovician is dominated by limestone with stable lithology and several hundred meters thick (Yuan and Mao 2001). The Middle-Upper Devonian, Carboniferous, and Lower Permian are all carbonate rock formations with stable lithofacies and small thickness. Except for the middle and upper Carboniferous strata that are missing in the middle of the Sichuan strata, it is almost widespread throughout the region. The lower part of the Lower Triassic in the western part of the Yangtze platform is a coastal shallow marine facies red formation represented by the Feixianguan Formation, and the eastern part is a carbonate formation represented by Daye limestone. Therefore, the soluble rock stratum in the south of China is widely distributed, with great thickness and pure lithology, and it is easy to form pipelines, cave-type karst springs and underground river systems.

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Fig. 1.1 Distribution map of water and mud inrush tunnels in China

1.1 Background and Significance of Research on Water and Mud Inrush …

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1 Introduction

In the North China stratum: The Cambrian-Middle Ordovician is mainly composed of neritic carbonate deposits overlying from south to north, and the Upper Ordovician-Lower Carboniferous stratigraphic deposits are missing. The Upper Carboniferous-Middle Permian is a sea-terrestrial coal-measure strata, which entered continental deposits after the Late Permian. The Middle Triassic is a set of clastic rock series deposited from coastal marsh facies and continental coal measures to red beds. The Yanshanian intrusive rocks and volcanic rocks began to develop extensively during the Jurassic, while the Ordos area in the western part of the North China Platform remained stable, and the Mesozoic lacustrine strata still maintained nearlevel occurrences. Therefore, the soluble rock in the northern region is dominated by buried, small-area sporadic pre-dolomite limestone and dolomite, often forming fractures and pipeline-type karst spring systems. (3) The karst category hazard-causing system is the primary reason for water and mud inrush in tunnels, accounting for 43% of the statistics, followed by the fault category, accounting for 26%, and the other category accounts for 31% (see Table 1.1). Among them, extra-large, large, medium and small water inrushes accounted for 40%, 28%, 6%, and 26%, respectively. It needs to be particularly emphasized that the extra-large water inrush disasters caused by karst and fault categories of hazard-causing system accounted for 22% and 10% of the total disasters, respectively; thus, the karst category and fault category hazard-causing systems have the characteristics of large proportions and severe catastrophability (see Chapter 2 for detailed introduction of the hazard-causing system). The contradiction between the demand for large-scale and wide-area tunnel construction and the lack of engineering technology has become increasingly prominent, resulting in frequent water and mud inrush disasters during the tunnel construction. Tunnel water and mud inrushes have the characteristics of high concealment, strong catastrophability, and great suddenness, which often lead to mechanical damage, delays in construction schedules, and even serious casualties and project abolishment (Li et al. 2017b). With the great buried depth and length of the tunnel, it is difficult to find out all the unfavorable geological conditions along the line before the tunnel construction. The complex geological environment and the strong and sudden disaster characteristics have brought difficulties to effectively avoid water and mud Table 1.1 Classification statistics of water and mud inrush hazard-causing systems Water inflow Water inrush Q/(×103 m3 /d) scale

K-HS (case number, percentage)

F-HS (case number, percentage)

O-HS (case number, percentage)

Total (case number, percentage)

Q> 10

Extra-large

85, 22

37, 10

29, 8

151, 40

1 < Q≤ 10

Large

36, 9

30, 8

39, 10

105, 28

0.1 < Q≤ 1

Medium

7, 2

6, 2

11, 3

24, 6

Q ≤ 0.1

Small

36, 9

Total (case number, percentage) 164, 43

27, 7

38, 10

101, 26

100, 26

117, 31

381, 100

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inrush disasters. Tunnel water and mud inrush hazard-causing system identification and disaster prevention have become a major challenge facing tunnel construction (Li et al. 2018a). Carrying out scientific research on the hazard-causing system of water and mud inrush in tunnels, disaster-forming mode, karst tunnel route selection, resistance body evaluation, construction risk dynamic assessment, and identification of the hazard-causing system of water and mud inrush are important for the safe and rapid construction of tunnel. It is also a major requirement for national infrastructure construction and has great guiding significance for ensuring the safety of tunnel construction and operation.

1.2 Water and Mud Inrush Hazard-Causing System and Resistance Body 1.2.1 Water and Mud Inrush Hazard-Causing System The water and mud inrush hazard-causing system is formed by the interaction among the geological bodies, groundwater and underground engineering activities, and it is a system that is prone to water and mud inrush disasters. The system is composed of the following three parts that interact and depend on each other as a whole with certain catastrophability. (1) The geological conditions for the formation, migration and accumulation of groundwater are equivalent to the water-bearing system in hydrogeology; (2) The groundwater with a unified temporal and spatial evolution from the source to the catchment, is equivalent to the flow system in hydrogeology; (3) Human underground engineering activity is an indispensable inducing factor and an important factor resulting in the dynamic evolution of groundwater systems (aquifer systems and flow systems). The system here refers to a whole of positive and negative feedback interactions between geological bodies, groundwater, and underground engineering activities. It has both the natural attributes of forming, transporting, and accumulating groundwater and the social attributes of water and mud inrush catastrophability. Natural attributes refer to the geological conditions of the formation, migration, and accumulation of groundwater and the hydrodynamic and hydrochemical properties of groundwater, which is only one aspect of the attributes of the water and mud hazard-causing system. The social attribute refers to the catastrophability of water and mud inrush, which is another important attribute of the water and mud inrush hazard-causing system, and it is also an important aspect that is easily overlooked. Only within the disturbance range of engineering activities can the hazard-causing system be catastrophic, which is clearly different from the traditional concept of water storage structure based on water supply considerations. Different from the concept

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1 Introduction

of disaster-causing structure, the hazard-causing system emphasizes the holistic and systematic nature. The authors have clearly pointed out that the word “structure” in the water and mud hazard-causing structure cannot be simply equated with the concept of geological structure; on the contrary, it is a complex that reflects the interaction between geological conditions and underground engineering activities (Li et al. 2018b). Engineering disturbance is an indispensable key factor. For example, abandoned waterfilled mines, water-filled tunnels, etc. are not originally concepts of geological structure, but if they are within the disturbance range of underground engineering activities, they are essential and highly catastrophic hazard-causing structures of water and mud inrush. Here, although it has been pointed out that the “structure” concept of hazard-causing structures is different from the traditional geological structure concept; in practical applications, it often misleads readers and fails to fully describe the systemic interaction among geological bodies, groundwater, and underground engineering activities. Therefore, the concept of a “hazard-causing system” is further defined in this book. By analogy, the water inrush hazard-causing system, mud inrush hazard-causing system, water inflow hazard-causing system, mud inflow hazard-causing system, etc. can be defined separately. The difference lies in the differences between the inrushed materials and the inrush state. Except for special conditions that need to be emphasized particularly, they are collectively referred to as the water and mud inrush hazard-causing system.

1.2.2 Resistance Body The resistance body is the rock-soil body that exists between mud and water migration, accumulation space, and excavation space, occurs in a certain natural stress state, groundwater environment, and other geological conditions, and has certain structural and tectonic characteristics. Water and mud inrush is an evolutionary process of the dynamic damage of a hazard-causing system, and the resistance body is a barrier against the occurrence of water and mud inrush. The purpose of proposing the concept of the resistance body is to clarify and unify the concept. In traditional tunnel water and mud inrush research, many similar concepts such as water and mud blocking structure, anti-outburst structure, antioutburst layer, rock plate, soil plate, etc. have been proposed, but most of them lack a clear definition or are sort of one-sided, failing to fully describe the connotations. (1) The anti-outburst structure, anti-outburst layer, etc. based on the concept of water inrush and mud outburst disaster prevention and control, are highly subjective, while the resistance body exists objectively, and there is no active disaster prevention or treatment concept. It is a more appropriate concept that exists objectively and resists the occurrence of water and mud inrush disasters, which is similar to the concept of compression, tension, and bending resistance that

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are widely used in mechanics. Therefore, this book does not use anti-outburst structures, anti-outburst layers, and similar concepts that signify prevention. (2) “Structure” has different connotations in geology and mechanics. Concepts such as water and mud blocking structure and anti-outburst structure emphasize more of a component concept based on mechanical thinking. The geological term “texture” emphasizes the size, shape, arrangement, and spatial distribution of the minerals inside the resistance body, reflecting the resistance body composition feature. The geological term “structure” refers to the arrangement and filling methods between the mineral aggregates of the resistance body or between the aggregates and other rock and soil components, as well as the morphology of each part and the way and appearance characteristics of each part in the resistance body. Therefore, this book will not use the “structure”-like concepts such as water and mud blocking structure or anti-outburst structure. (3) The concepts of rock plate and soil plate do not consider the internal texture, structure and external geological conditions of the resistance body. First of all, in terms of material basis, the resistance body may be rock mass, soil mass, or rock-soil body; Secondly, the concept of rock and soil plates does not emphasize the geological environment such as the ground stress and groundwater of the resistance body; Finally, the concept of rock and soil plates give researchers the impression that the resistance body experiences failure in the form of thin plate. In fact, the resistance body has various shapes, sizes, and failure modes, including plate failure and slab failure, as well as complete rock failure, overall protruding of loose media, and seepage failure of loose media. In addition, the resistance body is not a layered structure, and hence its failure is not a layered failure mode (like the anti-outburst layer concept); to be specific, it is the rock-soil body between the mud and water migration, accumulation space and excavation space in the hazard-causing system, which is an important part of the system. Finally, the resistance body may also be a complex of artificial structures such as geological body and lining, etc., which cannot be simply generalized into rock plate or soil plate. Many water inrush from tunnels and mining roadways during operation are effective circumstantial evidence for this. Therefore, this book will not adopt the concept of “plate” or “layer” such as rock plate, soil plate, and anti-outburst layer. (4) The resistance body of water and mud inrush has a certain texture, structure and exists under certain natural stress states and groundwater environment and other geological conditions. The research on the resistance body must focus on its internal structure while emphasizing the geological conditions such as the external ground stress state and the groundwater environment. The structure of the resistance body is the material basis for the water and mud inrush disaster. The geological conditions such as the ground stress state and the groundwater environment are the external conditions for the water and mud inrush disaster. The interaction between mud and water movement, accumulation space, and construction disturbance in excavation space is the inducing factor of water and mud inrush.

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1 Introduction

1.3 Research on the Hazard-Causing System of Water and Mud Inrush in Tunnels Groundwater and filling media are stored in a certain geological environment, and water and mud inrush disasters occur due to excavation disturbance. The geological characteristics of the hazard-causing system largely determine the characteristics and scale of the water and mud inrush. The type of hazard-causing system is the basis for the study of tunnel water and mud inrush problem. Only by recognizing the type of hazard-causing system can we more accurately carry out targeted detection and prediction, as well as research on hazard mechanism and treatment. The research on the hazard-causing system of water and mud inrush originated from the research on water storage structure. Based on the practice of finding, developing and using groundwater, the types and characteristics of water storage structures with different structures are proposed through the study of the laws of groundwater occurrence. Liu Guangya proposed the theory of water storage structure in 1975, and successively published articles in 1978, 1979, 1981 and 1985, expounding the geological water control theory in detail, and how to use geological water control theory to guide water search in bedrock mountainous areas and mine drainage (Liu 1978, 1979, 1981; Shen et al. 1985). Liu believes that stratum lithology is the basis for the occurrence of groundwater, geological structure is the dominant factor controlling groundwater burial, distribution and migration, and geomorphology, hydrology, meteorology, etc. are important conditions for controlling groundwater recharge, runoff, drainage and dynamic changes. A water storage structure is defined as a geological structure capable of enriching and storing groundwater, and it is considered that any water storage structure is composed of three basic elements of a permeable rock layer or a permeable zone of a rock layer, a water barrier or a water blocking body, and a permeable boundary. And the water storage structure is divided into 6 categories and 15 types, i.e., horizontal layered water storage structure (stagnation type and submerged type), monoclinic confined water storage structure, fold water storage structure (syncline confined water basin, syncline phreatic basin, anticline), fracture water storage structure (fault, fault water-blocking, fault block), contact water storage structure (intrusive contact zone, rock mass water-blocking, rock vein, unconformity of buried depression, unconformity of ancient buried hill) and weathering crust water storage structure. The “Geological Dictionary” (1986) compiled by the Ministry of Geology and Mineral Resources defines a water-bearing structure as a geological structure composed of aquifers and water barriers and having certain hydrogeological laws. The water-bearing structure is divided into bedrock water-bearing structures (syncline basin water-bearing structures, monoclinic layered water-bearing structures, fracture water-bearing structures and fissure pressure-free water-bearing structures) and loose sedimentary water-bearing structures (piedmont alluvial water-bearing structures, valley alluvial water-bearing structures, lacustrine sedimentary water-bearing structures). This is an improvement over simply thinking that a water-bearing structure is a water-bearing geological structure, but it still fails

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to express the dynamic storage process of groundwater, and the concept is not as clear as the water storage structure. Qian (1990) studied the theory of water storage structure, summarized the forms of water storage structure in China, and defined the water storage structure as a pore system composed of geological bodies, which is meaningful for water supply and drainage, and accumulates groundwater. That is to say, the water storage structure is the place where groundwater forms, moves, and stores. According to the nature of the natural geography and the nature of the pore, the water storage structures in China are divided into 4 categories, and further into 25 types according to different division principles. They are pore water storage structures (mountain valleys, mountain basins, alluvial plains, glacial water deposits, semi-cemented sandstones), fracture water storage structures (fracture karst, interlayer karst, fault karst, intrusive karst, gypsum breccia rocks, underground rivers and pipelines, covered karst, concealed karst), fissure water storage structures (weathered fissures, joint fissures, interlayer fissures, fault fissures, intrusive body fissures, basalt fissures) and regional water storage structures (arid areas, loess areas, desert areas, coastal and inland areas, frozen soil areas, hot water areas). Hu et al. (2000) established the concept of four-level hydrogeological water storage structure and zone division. Among them, the Level I and Level II water storage structures belong to regional divisions, and the Level III and Level IV hydrogeological zones (belts) belong to the specific classification within the hydrogeological units. Therefore, the water storage structure is a systematic concept suitable for the study of groundwater dynamic storage. The research on karst storage, waterrich and water-bearing structures is also based on regional water search results. For example, the Shanxi Provincial Comprehensive Survey Bureau (1973) discussed water storage structures and surveys in karst areas, and the research proposed 8 types of water storage structures that are relatively common in China. They are syncline axis and its vicinity, overturning anticline axis area, karst and non-karst layer contact boundary area, karst water drainage area on both sides of limestone valley, runoff drainage area of monoclinic structure, fault fracture zone area, deeply buried bedrock areas, areas distributed with strip-shaped sinkholes, and low-lying areas in the lonely peak plain. Han (1980) divided the karst water-rich structures in the western Hunan and eastern Guizhou area into 4 categories, i.e., fold water-rich structures (syncline waterrich structures, anticline water-rich structures, monoclinic water-rich structures), fault water-rich structures (fault water-rich structures, fault block water-rich structure), water-blocking water-rich structure (fault blocking water-rich structure, formation blocking water-rich structure, large rock mass blocking water-rich structure), structural plane water-rich structure (igneous structural plane water-rich structure, sedimentary structure plane water-rich structure). Zhang and Chen (2000) defined karst water-bearing structures as components of consolidated and compact karst aquifers. Due to the strong development of fissures and dissolution forms of secondary structures, their water permeability is higher than that of surrounding rocks, so they can gather and transfer groundwater in the aquifer. Taking Xiaopingyang, Laibin, Guangxi as an example, they summarized and sorted

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1 Introduction

out 8 types of karst water-bearing structures, i.e., fault zone, buried funnel (shaft), piedmont drainage zone, carbonaceous limestone, dolomite sand sac, dolomite sand layer, red bottom gravel, and negative basement. And this is systematic research result of karst water-bearing structures. Bateer et al. (2008) took the Karo anticline in Guizhou as an example to study the development and utilization of groundwater in the typical water storage structures in the exposed karst rock mountain area, which has guiding significance for the development of groundwater in the anticline confluence water storage structures. However, in general, the occurrence types of the above-mentioned water storage structures (water-bearing structures or water-rich structures) and the hydrogeological conditions for their formation are still dominated by regional results, which are not systematic. The studies on water-containing structure, water storage structure, water-rich structure or water-bearing structure focus on the burial, distribution and movement of groundwater under different geological structure conditions in natural state, so as to provide theoretical guidance for the search, development and utilization of groundwater resources. With the rapid development of tunnel construction in China, the water and mud inrush disasters in tunnels are becoming more and more serious. Many scholars have studied the geological mode of water and mud inrush in the tunnel according to the disaster cases during tunnel construction. Liu (2004) analyzed the water and mud inrush disasters of Yuanliangshan Tunnel, and based on the spatial position relationship between the karst water-bearing hazard-causing structure and the tunnel, the water inrush disaster geological modes in karst tunnel were divided into transverse cross-sectional staggered patterns (top intersection, bottom intersection, upper lateral intersection, lower lateral intersection) and longitudinal cross-sectional staggered patterns (upper lateral cross, lower lateral cross). Zhang and Liu (2005) analyzed the water and mud inrush of 5 filling-type karst caves in Yuanliangshan Tunnel, and summarized the water inrush characteristics, types and karst water dynamic characteristics of Yuanliangshan Tunnel. Jiang et al. (2006) divided water inrush into three types by studying the types of faults and the spatial relationship between fault fracture zones and tunnels, and they are tensile fracture, compressive fracture activation and fracture extension. Taking the extra-long Daxiangling deep-buried tunnel as an example, Shao et al. (2011) analyzed the formation characteristics of volcanic sedimentary rocks and different structural characteristics in the later period, and summarized the water inrush disaster mode of the tunnel in the volcanic rocks. There are fault water control type, rock vein water control type, fault control lagged type, and tuff-columnar jointed rock belt type, and they also analyzed the hazard-causing mechanism of various water inrush modes. Su et al. (2012) analyzed the hydrogeological characteristics of the water and mud inrush section in the Pingyang Tunnel and concluded that there are two karst types of the geological modes, i.e., the homogeneous carbonate rock and the contact zone between soluble rock and local non-soluble rock. At the same time, according to the relative spatial relationship between the water inrush point and the source of the water inrush, the water inrush of the Pingyang Tunnel can be classified into two modes,

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i.e., top intersection and upper intersection. Li et al. (2015) pointed out that the main unfavorable geology during the construction of the cross-river or cross-sea tunnel is the weathered deep trenches, water-bearing sand layers, intrusive rock veins, faults, cavities, etc., and they also studied the patterns of water inrush. The above-mentioned studies on the geological mode of water and mud inrush disasters in tunnels are mainly aimed at a specific engineering case or a certain type of geological mode. It has certain reference significance for the study of the hazard-causing system of water and mud inrush in tunnels. However, different types of hazard-causing geological modes are not fully considered. Besides, no systematic classification and identification method of hazard-causing geological patterns has been established yet. The application of the research results into the study of water and mud inrush in tunnel engineering is limited, let alone the promotion and actual engineering application. When tunnels are built in soluble rock areas, water and mud inrush disasters occur frequently. By analyzing the occurrence characteristics of disaster sources and following the concept of water storage structures, many scholars have carried out research on water storage structures in karst tunnel sites. Zou (1994) divided karst groundwater into three types: karst fissure type, vascular type, and pipe type according to the occurrence form and movement characteristics of karst groundwater. Wang et al. (2001) analyzed five types of hydrological media, including fracture karst water storage structures, fault karst water storage structures, underground rivers and pipeline water storage structures, interlayer karst water storage structures, and other water storage structures. And they conducted a hydrogeological analysis on the water inrush mode, and summarized the following types: water leakage type, construction exposed water-filled karst pipeline network type, construction crossing water blocking fault type, hydraulic fracturing type, and bottom swelling destruction type. Guo (2011) classified karst water inrush hazards into high pressure fissure water inrush, karst cave and cavity water inrush, underground river and karst pipeline water inrush, and fault water inrush according to the storage conditions of karst water, and analyzed the water inrush mechanism in karst tunnels. Ma (2012) established 6 hydrogeological conceptual models of karst tunnels based on the combination of surrounding rock types and spatial relationships of karst tunnels, namely, uniform fracture-fissure water inrush model of the vadose zone, uniform fracture-fissure water inrush model of the shallow circulation zone, uniform fracture-fissure water inrush model of the deep circulation zone, non-uniform karst pipeline water inrush model of the vadose zone, non-uniform karst pipeline water inrush model of the shallow circulation zone and non-uniform karst pipeline water inrush model of the deep circulation zone. Lu et al. (2013) proposed five types of hazard-causing structures for water and mud inrush in karst tunnels, namely, closed filling caves, water-rich karst pipelines, underground rivers, karst cracks or pipelines, and faults. Zhou (2015) divided the karst water inrush hazard sources into fracture karst water storage structures, cavern karst water storage structures, fault karst water storage structures, interlayer karst water storage structures, underground rivers, and karst pipeline water storage structures

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1 Introduction

according to the development form of karst water storage structures. The above researches have great reference value for the analysis of the geological cause of water and mud inrush in karst tunnels. In non-soluble rock areas, water and mud inrush disasters are equally serious, which often have a nonnegligible impact on tunnel safety. Therefore, many scholars have gradually extended the research on the hazard-causing structure of water and mud inrush in the tunnel to non-soluble rock areas, and established a universally applicable classification system for the hazard-causing structure of water and mud inrush. According to the different water inrush sources and water-bearing structure types, Zuo (2011) classified tunnel water inrush types into structure control types (fault fracture zones, including water-rich faults, water-conducting faults, and water-blocking faults; karst pipelines, including karst caves, underground rivers; other structural fracture zones, including anticline fracture zones, syncline fracture zones and interlayer fracture zones) and non-structure control types (surface water or groundwater, water-bearing rock formations). Zhang and Sun (2011) analyzed the water and mud inrush disaster cases in the tunnel and pointed out that the main disaster types caused by the water and mud inrush are the inundation of the reverse slope tunnel, the surface collapse and the casualties. The main reason is that the tunnel construction exposes the high-pressure water-rich karst or faults and the rock plate thickness is insufficient. Zhao et al. (2013) divided the water and mud hazard-causing structures into four types based on the geological conditions and the engineering characteristics of the surrounding rock, namely, karst cave type, fault and fracture zone type, karst pipeline type and weathered cavity type. He et al. (2009), He and Zhang (2011) divided the water-bearing bodies that tunnel face may encounter during tunnel construction into four types and analyzed their occurrence characteristics: karst water filled bodies, broken rock masses with dense joints developed and water-bearing bodies of structurally broken rock mass, water-bearing bodies of underground syncline structural units, and water-bearing bodies in structural fracture zone connected with water-bearing structural units with good water conductivity and storage characteristics. Luo and He (2014) divided the water and mud hazard-causing structures into five forms, namely, strong fracture zone in the hanging wall of unconsolidated waterrich compressive fault, unconsolidated water-rich tensile fault zone, unconsolidated water-rich and bedding-dislocation (joints densely developed) fracture zone, waterfilled karst aquifer, underground syncline water storage structure, and analyzed their water-filling characteristics and water inrush modes. Based on a large number of case statistics, Shi (2014) classified water and mud hazard-causing structures into four types: fissure type, fault type, karst cave type, pipeline and underground river type. From the perspective of water-bearing rock masses, Li et al. (2018a) divided the water inrush disaster-causing structures into 2 categories and 5 types, namely, waterrich and muddy fault zones (water-rich fracture zone and muddy fault zone) and water and mud filled karst (deep water-filled karst, surface fractured karst zone and filled karst cave), and analyzed its typical geological characteristics.

1.3 Research on the Hazard-Causing System of Water and Mud Inrush …

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Water and mud inrush disasters occur under the combined effects of unfavorable geology and human underground engineering activities. Adverse geology is an internal factor, and underground engineering activities are external inducements. The concepts of traditional water storage structures (water storage structures, water-rich structures, etc.) do not consider the process of water and mud inrush due to the interaction of the groundwater system and the tunnel during the construction. Such concepts are too broad and unsuitable for the advanced forecasting of tunnel unfavorable geology and the research on the hazard-causing mechanism and control of unfavorable geology (such as landslide, water inrush, mud inrush). In addition, only under the disturbance of manual excavation will the water storage structure cause water and mud inrush, and be catastrophic. Therefore, under the specific conditions of "tunnel site area", it has greater theoretical research value and engineering application value to adopt the concept of hazard-causing structure to study the form and occurrence law of water and mud inrush in tunnels. The authors of this book have defined the hazard-causing structure of water and mud inrush and analyzed its meaning in detail (Li et al. 2018b). However, because the structural concept has formed a fixed cognition in geology and has been widely used and recognized, it still causes misunderstandings to readers in the practical application of tunnel water and mud inrush engineering. Besides, the word “structure” only reflects one of the main bodies of water and mud inrush in the tunnel, that is, unfavorable geology, and fails to reflect the interaction between unfavorable geology, groundwater (system) and underground engineering activities. However, groundwater is another important hazard-causing body in tunnel water and mud inrush. Its importance is reflected in the fact that geological bodies, water-storage conditions of rock strata and surface water replenishment will jointly determine the scale of disasters. In addition, underground engineering activities are the direct cause of water and mud inrush in tunnels. As an inseparable system, geological body, groundwater and underground engineering activities induce water and mud inrush through interaction. In order to distinguish from the concept of the geological structure, this book proposes the concept of a hazard-causing system based on the concept of disaster-causing structure, see Sect. 1.2.1 for details. The water and mud inrush hazard-causing system of the tunnel not only includes the concept of geological structure that causes the water and mud inrush in the tunnel but also includes the “structural” system in a broad sense, such as the karst cave disaster-causing system, manual excavation spaces, water-filled mines and other special systems. Based on the concept of the tunnel water and mud inrush hazard-causing system, this book has carried out a systematic and comprehensive study on the tunnel water and mud inrush disasters, and realized the categorization of tunnel water and mud inrush hazard-causing systems under different geological conditions, revealed the occurrence laws of different types of tunnel water and mud inrush hazard-causing systems, and established a geological identification method for water and mud inrush hazard-causing systems.

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1.4 Summary of Research on Construction Risk Dynamic Evaluation of Tunnel Water and Mud Inrush Tunneling and underground engineering are high-risk construction projects, which have the characteristics of large investment, long construction period, complex construction technology and many unforeseen risk factors (Qian and Rong 2008). During the construction of tunnels and underground projects, geological disasters such as water and mud inrush are extremely prone to occur. Disaster risk assessment and control have gradually become one of the key issues in the construction of tunnels and underground projects (Hu 2007; Xu et al. 2011a; Li et al. 2018b). Therefore, it is of great necessity to establish a supporting management system for tunnel and underground engineering construction risks, so as to carry out risk assessment of the proposed and under construction tunnel engineering projects, and then proceed risk control. Through carrying out dynamic assessment of the construction risk of water and mud inrush in tunnels, various risk factors in tunnel engineering projects and the characteristics and activities of the crisis phenomenon are taken as the research objects, and various risks that may induce water and mud inrush disasters in tunnel construction, the causes of the risks and its early warning principles and methods are explored. A monitoring and early warning method system to solve all-round risks in tunnel construction projects is established and ultimately it provides theoretical guidance and countermeasures for the decision-making of tunnel construction projects. The construction risk assessment of tunnel water and mud inrush is a systematic project. Through conducting the dynamic assessment of construction risk, risk warning information can be released in time, and water and mud inrush risk control measures can be taken in the process of planning, design and construction to ensure that the potential risk of water and mud inrush for the tunnel under construction is reduced to a reasonable and feasible level. The ultimate goal of guiding tunnel construction and ensuring construction safety can be realized (Ma et al. 2009; Li et al. 2013). Since the 1970s, scholars at home and abroad have successively carried out a series of theoretical studies on the construction risks of tunnel engineering, mainly focusing on the establishment of concepts and qualitative research. There are few quantitative evaluation studies and most stop at the calculation of reliability (Benardos and Kaliampakos 2004; Shin et al. 2009; Beard 2010; Sousa and Einstein 2012). In order to further promote the standardization of tunnel engineering risk assessment and management processes, a series of tunnel engineering risk management norms and regulations have been compiled and issued at home and abroad. For example, the British Tunnelling Society (2003) prepared jointly “THE JOINT CODE OF PRACTICE FOR RISK MANAGEMENT OF TUNNEL WORKS IN THE UK”, the International Tunnelling and Underground Space Association issued the “Guidelines for tunnelling risk management” (Eskesen et al. 2004), the International Tunnelling Insurance Group (2006) formulated the “A Code of Practice for Rick Management of Tunnel Works”, the Ministry of Railways of the People’s Republic of

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China (2007) promulgated the “Interim Provisions on Risk Assessment and Management of Railway Tunnels”. The above specifications, guidelines, norms and regulations provide a systematic reference standard and method basis for engineering risk management. With the vigorous development of tunnel construction, the requirements for the quantification of engineering construction risks are increasing. However, the theoretical research on risk management of tunnel engineering started relatively late, and most of them are risk assessment studies for urban subways. Besides, the research on the theory and method system of tunnel construction safety risk assessment is obviously insufficient. In recent years, with the large-scale development and utilization of underground space around the world, the research on risk assessment and risk management of tunnelling and underground engineering has received unprecedented attention. Domestic and foreign scholars have successively carried out a large number of risk assessment studies for specific tunnels and coal mines and other underground engineering disasters. For example, American scholar Einstein et al. applied risk assessment to the field of tunnelling and underground engineering, analyzed the characteristics of tunnel engineering risks, and proposed the concept of tunnelling risk assessment. They introduced uncertainty analysis into tunnel engineering, greatly improved the application effect of risk management theory in actual engineering practice. In addition, they took long-term construction risks into consideration, giving investors a theoretical basis for program evaluation (Einstein et al. 1994; Einstein 1996). Ding (2001) applied risk management and control theory and engineering contract management concepts to actual engineering projects, and carried out systematic and in-depth research on construction engineering contracts and risk management. Huang Hongwei et al. studied the risk management in the subway construction and operation stage, discussed the effect of strengthening the design and construction risk research on reducing the subway cost, proposed the risk acceptance criteria for tunnelling and underground engineering, and established a unified calculation model of risk acceptance criteria, which provided important research ideas for project risk management and assessment research (Huang and Chen 2003; Chen and Huang 2005; Hu and Huang 2006; Huang 2006). Mao (2003) introduced the risk index method to the risk assessment of tunnel engineering. This method has been widely used in the research on risk assessment of tunnel engineering in China. Wang (2005) conducted an in-depth risk analysis of the Xiamen Subsea Tunnel, applied the risk concept to the tunnel design, construction, and later operation, and summarized the risks and treatment measures at each stage. Qian and Rong (2008) clarified the current situation of China’s underground engineering safety risk management, and put forward suggestions for the problems occurring in the safety risk management practices of specific tunnels and other underground engineering projects. Based on the above-mentioned risk management and control theory and risk analysis research, Chinese scholars have carried out a series of studies on different types of tunnels, and have obtained many useful conclusions about the risk assessment

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of tunnel construction. In view of the construction risks of shield tunnels, Wu et al. (2007) identified various existing risks in Wuhan Yangtze River shield tunnels, used semi-quantitative methods to analyze and classify the probability and consequences of risks, and proposed corresponding treatment measures and avoidance methods. In terms of the risk assessment of tunnel tube-curtain construction, Zhu et al. (2005) carried out a risk analysis and research on tube-curtain tunnel construction in saturated soft soil, revealing the overall risk level of the entire tunnel construction. In terms of the drilling and blasting tunnel construction risk assessment, Yan et al. (2007) identified and analyzed the construction risks of the Dalian Bay Subsea Tunnel, used the confidence index-based expert survey method to evaluate the risks, and proposed control measures based on the characteristics of the construction risk of the subsea tunnel. It provides a reference for the decision-making on route selection and construction management of the subsea tunnel project. In terms of the risk assessment and analysis of geological disasters caused by water and mud inrush in tunnels, expert judgments, mathematical methods, hydrogeological theories and supporting testing techniques are often used to determine and analyze the geological factors such as the types of groundwater systems, vertical and horizontal hydrodynamic conditions, adverse geology, topography and landforms, and underground water level. In this way, through carrying out the construction risk assessment of water and mud inrush, the risk level of water and mud inrush disaster and its occurrence area can be predicted and evaluated (Chen and Huang 2005; Huang 2006; Qian and Rong 2008; Peng et al. 2008; Chen et al. 2009). At present, the evaluation methods used mainly include attribute mathematical theory, weighted average method, fuzzy comprehensive evaluation method, expert evaluation method, etc. (Zhu et al. 2015; Li and Chang 2015; Yang and Zhang 2018). Among them, Zhang et al. (2009) carried out research on the theory and method of water inrush risk assessment for high-risk karst tunnels, and established a quantitative evaluation method for water inrush risk and a four-color disaster warning mechanism. Kuang et al. (2010) used a fuzzy comprehensive evaluation model to evaluate the hazard of water and mud inrush in karst tunnels. Mao et al. (2010) studied the mechanism of karst water and mud inrush and proposed a risk classification system of water and mud inrush in tunnels, which integrated qualitative and quantitative evaluation. Ge (2010) combined the characteristics of tunnel construction and put forward the grading standard of water and mud inrush risk early warning indicators, formulated the early warning mechanism and early warning release process, and established water inrush disaster emergency plans for different warning levels. Based on the analytic hierarchy process, Xu et al. (2011b) studied the control factors and factor weights of water and mud inrush in karst tunnels through the combination of statistics and theoretical analysis, and proposed a three-stage assessment and control method for the risk of water and mud inrush in karst tunnels, which realizes the dynamic correction and control of the water and mud inrush risk. Li et al. (2011a) established a fuzzy hierarchical evaluation model for the risk of water and mud inrush in karst tunnels using the comprehensive weighting method, and further carried out pre-evaluation and dynamic assessment of the water and mud inrush risk. Li Shucai et al. established an attribute recognition model for the evaluation of the water and

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mud inrush hazard in karst tunnels (Li et al. 2013; Zhou et al. 2013), and carried out the water and mud inrush risk evaluation during the design and construction stages. Li and Li (2014) carried out dynamic prediction of the water and mud inrush risk in tunnels, formulated corresponding prevention and control measures, and established water and mud inrush risk assessment models for karst tunnels with and without adverse geology. Existing theories and methods have achieved remarkable results in many practical engineering applications, but the application of the above-mentioned theoretical methods to guide engineering construction also has certain deficiencies. For example, when using the analytic hierarchy process, the evaluation results are subjective due to the expert’s personal preference, the judgment matrix deviates from the objective reality, and the evaluation conclusion is distorted; as to the fuzzy comprehensive evaluation method, when the number of index sets is large, the relative membership degree weight coefficient is often small, and the weight vector does not match the fuzzy matrix, which is prone to super-fuzzy phenomenon, resulting in unclear classification and unreasonable final judgment results. Frequent tunnel water and mud inrush disasters are the result of the interaction of internal geological factors and external human factors, and their influencing factors have great ambiguity, complexity, uncertainty and high nonlinearity. It is difficult for current water and mud inrush risk assessment methods to objectively and comprehensively characterize hazard factors, and it is also difficult to quantitatively determine some indicators. In the process of specific tunnel construction, it is often necessary to comprehensively evaluate the construction risk of water and mud inrush in a certain tunnel section. The use of discrete fixed values to characterize various influencing factors in existing studies often results in one-sided evaluation. A risk assessment method with interval attributes can be considered as an alternative plan to carry out construction risk interval assessment work for the risk of water and mud inrush in specific sections of tunnel engineering. In addition, most of the current tunnel water and mud inrush risk assessments are in the static assessment stage, and the real-time dynamic information of the construction process is not fully utilized, and there is a lack of efficient risk management operation mechanism. The key to carrying out the risk assessment of tunnel water and mud inrush construction is to minimize the influence of subjective judgment and improve the reliability and scientificity of evaluation factors and evaluation methods. The assessment method with interval characteristics is used to carry out effective and dynamic assessment of the disaster risk of water and mud inrush in tunnels, so as to realize timely perception of the occurrence, existence and evolution of external risks, and analyze the types of regional risks and their cause factors. Through identifying the risk level of water and mud inrush and the possibility and trend of disaster development, corresponding countermeasures and suggestions specific to certain sections of the tunnel can be proposed, thus achieving risk avoidance and ensuring construction safety. Based on the existing research on the risk assessment and analysis of the tunnel water and mud inrush disaster, this book introduces the interval fuzzy comprehensive evaluation method, and carries out a more in-depth risk dynamic assessment study

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for the tunnel water and mud inrush disasters, and constructs a conceptual model of the risk assessment of tunnel water and mud inrush. The weights of the risk factors of water and mud inrush disasters are discussed, the construction permit mechanism is proposed based on the evaluation of the water and mud inrush interval risk assessment, and the theory and method for the interval dynamic evaluation of the water and mud inrush construction risk in the tunnel are established.

1.5 Summary of Research on Identification Methods of Tunnel Water and Mud Inrush Hazard-Causing System The hazard-causing system is the geological basis for the occurrence of water and mud inrush disasters, and it is also an internal factor. How to ascertain the geological conditions ahead, identify the occurrence characteristics of the water and mud inrush disaster system, and formulate a reasonable construction plan, so as to “prevent for a rainy day and prevent trouble before it happens”. These are all difficult problems that must be solved in the prevention and control of disasters such as water and mud inrush in tunnel construction. The detection and identification of hazard-causing systems is regarded by the industry as an important pilot work, which can provide effective three-dimensional spatial location, occurrence form, filling characteristics, scale and other geological information for later disaster monitoring, early warning, avoidance and treatment. It plays an irreplaceable and important role. Before the design and construction of the tunnel, a detailed survey of the engineering geological conditions in the tunnel site must be carried out. However, there is great complexity of the terrain and geological conditions, especially in the western mountainous areas of China where there are numerous deep-cut canyons and steep terrains. Besides, some tunnels are buried in depths of more than 1,000 m or even over 2,000 m, and faults, karst caves, broken rock bodies and other adverse geologies have strong concealment (Li et al. 2014), which bring great difficulties to geological survey and identification of hazard-causing systems. Therefore, it is often difficult to know all the engineering geology of the tunnel site in the preliminary survey, and there are great unknowns, uncertainties and dangers, resulting in extremely high risks of geological disasters such as water and mud inrush, which are difficult to prevent and control. Therefore, how to dynamically detect the water and mud inrush hazard-causing system in front of the tunnel face during the tunnel construction process with the excavation progress, has become the primary problem for the prevention and control of water and mud inrush disasters and the safety of tunnel construction, and this is also the main task of tunnel advance geological forecast. Based on the analysis and research of the engineering geological conditions, the geological occurrence environment and the development laws of adverse geologies in the tunnel site, the advance geological prediction of the tunnel uses a variety

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of geophysical prospecting techniques (such as seismic reflection methods, electromagnetic methods, electrical methods), supplemented by advance geological drilling, geological sketching of the tunnel face, geological inference analysis, groundwater chemical analysis and other means, to detect and obtain the engineering geological conditions within a certain range in front of the tunnel face and the spatial location, occurrence form, scale, and engineering nature of the water and mud hazard-causing system during the tunnel construction. The advance geological prediction of the tunnel has played an important role in the identification of the hazard-causing system of the water and mud inrush, and it has become an indispensable routine procedure in the tunnel construction. In order to more accurately and effectively grasp the geological conditions in front of the tunnel face during the construction, and to reduce or even eliminate the geological disasters caused by the water and mud inrush during the construction period, since the 1970s, the global community has begun to pay attention to advance geological exploration theory, technical research and engineering practice during tunnel construction. At the Rapid Tunnelling and Tunnel Engineering Conference held in Chicago, the United States in 1972, the advance geological prediction of tunnels received attention. Afterwards, Japan, Germany, France, Switzerland and other countries successively included advance geological forecasting of tunnels in their key research plans, and made certain progress in the research and development of advance geological forecasting technology and instruments for tunnels. For example, in 1984, American scholar Benson et al. used geological radar to conduct advance forecasting in a military railway tunnel in southwest of Wilmington, North Carolina (Fu and Li 2007). In 1992, the Swiss Amberg company introduced the tunnel seismic prediction (TSP) method for tunnel advance prediction. In recent years, it has updated the TSP203 and TSP303 devices. In 1995, Japan introduced horizontal sound probing (HSP) method. In 2000, with further development of tunnel reflection seismic wave computed tomography (CT) technology, the American National Security Agency (NSA) engineering company developed the tunnel reflection tomography (TRT) technology (Li et al. 2007). Since the 1950s, China has carried out the research and application of advance geological prediction technology for tunnels. It has successively adopted advance geological pilot pits, horizontal advance drilling and other methods for advance geological prediction, and combined with the geological exposure of the tunnel face to infer the possible hazard-causing system ahead. However, either advance pilot pits or advance drilling methods have great interference to tunnel boring construction, and relying on these methods alone cannot meet the needs of rapid and scientific tunnel construction. In order to develop a scientific forecasting method with long forecasting distance, low construction interference and accurate forecasting, China began to use geophysical methods to carry out geological forecasting in tunnels from the late 1970s and early 1980s. In the early 1980s, China proposed to use geophysical prospecting methods to carry out advance geological forecasting of tunnels. In view of the possible karst water problem that might occur in the Shangbengtang shaft—Huashipai No.2 inclined shaft of the Dayaoshan Tunnel, the key projects of the Ministry of Railways

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pointed out the research content of using geophysical prospecting methods to carry out advance geological forecasting. China has successively carried out experiments and applications of tunnel advance forecasting in the Dayaoshan Tunnel, Nanling Tunnel, Jundushan Tunnel and other projects. For example, in 1986, the Tunnel Engineering Bureau of the Ministry of Railways used Radar and Rayleigh surface wave methods to carry out exploration tests on the geology in front of the tunnel face during the exploration and karst treatment in the Nanling Tunnel. In the late 1980s, during the construction of the DatongQinhuangdao Railway Tunnel, the Tunnel Engineering Bureau of the Ministry of Railways cooperated with Academician Wang Sijing of the Institute of Geology and Geophysics of the Chinese Academy of Sciences and they used a construction drilling rig to drill a 15 m deep hole in the tunnel face to investigate the situation of the hazard-causing system ahead. From 1992 to 1993, the geophysical prospecting team of Guiyang Survey, Design and Research Institute Co., Ltd. of Power Construction Corporation of China used American geological radar to conduct advance forecasting of hazard-causing system during the construction of the 5 km exploration tunnel of Jinping II Power Station (mainly detecting large fissures and faults). The Institute of Railway Construction, China Academy of Railway Sciences, after conducting field tests and practical applications of a variety of geophysical prospecting methods, determined to apply a comprehensive geophysical exploration methods based on vertical seismic profiling (VSP) and land sonar in 1995, supplemented by ground penetrating radar and horizontal acoustic profiling (HSP), to carry out advance prediction of the hazard-causing system in front of the tunnel, and have achieved good results (Li et al. 2007). China began to introduce the TSP tunnel earthquake prediction system developed by the Swiss Amberg company in the 1990s. This technology has been developed rapidly and widely applied in China, but there are still some problems. After 2000, the Southwest Branch of the Chinese Academy of Railway Sciences further improved the horizontal sound probing (HSP) method and developed the CT imaging technology (Chen and He 2005). Since 2000, the advance geological forecast for the identification of hazardcausing systems in front of the tunnel face has entered a stage of standardization and rapid development, and its role in ensuring the safety of tunnel construction has been further recognized. Now the advance geological forecast of the tunnel has gradually become an indispensable task in the construction of the tunnel (Zhao 2007; Ye 2011). Facing the increasing engineering needs and huge technical challenges of advance geological forecasting of tunnels, many research institutions and application units in the fields of tunnel engineering, geophysical prospecting at home and abroad have carried out a large number of basic theoretical research, technology and instrument system research and development, and engineering applications. After years of research and hard work, Chinese scientific researchers have grasped the “golden period” of large-scale construction of tunnel engineering. Through independent original innovation and introduction-absorption-reinnovation and other means, China has mastered the tunnel advance geological prediction technology to identify the hazard-causing system in front of the tunnel face. At present, it has caught up with and even surpassed foreign advanced technology, and is in a leading position.

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The occurrence characteristics of different types of hazard-causing systems are different, and the characteristics and scales of water and mud inrush are also different. At present, many scholars have used different identification methods to carry out advance forecasting work for fractures, faults, karst, underground rivers and other types of hazard-causing systems, and have made some new progress. In tunnel construction, the tunnel seismic wave method, as one of the most commonly used hazard-causing structure advance prediction technology, is widely used in actual engineering. The typical technology includes the TSP technology developed by the Swiss Amberg company (Liu and Liu 2003; Xu et al. 2008), the TRT technology developed by the American NSA Engineering Company (Chen 2009; Xiang et al. 2012), land sonar technology developed by Professor Zhong Shihang in China (Zhong et al. 2012), the TST (tunnel seismic tomography developed by Zhao Yonggui, et al.) Technology (Jiang et al. 2013), etc. All of them have achieved good results in detecting large faults, karst caves and surrounding rock grade evaluation in front of the tunnel face. Ground penetrating radar (GPR) is also a commonly used advance geological forecasting technology (Liu et al. 2009; Ling et al. 2012). It is fast in data collection and data process, and it has a more sensitive response to water-rich or waterbearing hazard-causing systems. However, it has such disadvantages as short detection distance, weak anti-interference ability, and it is difficult to detect the rear boundary of the hazard-causing system due to interference such as multiple reflections. In recent years, with the increase construction of karst tunnels, submarine tunnels, and cross-river tunnels that have a high risk of water and mud inrush, the need for detection and identification of water-rich or water-bearing hazard-causing systems has become more urgent, and some new advance geological forecast technology came into being. Among them, the tunnel transient electromagnetic method (TEM) and induced polarization (IP) technology are typical representatives of the tunnel advance water detection technology (Xue et al. 2007; Xue and Li 2008; Li et al. 2011b). The detection range of the TEM is 60–80 m, which can identify and locate the water-bearing body in front of the tunnel face; the IP advance prediction technology is mainly used to detect the water-bearing condition in the range of 30 m ahead the tunnel face. Based on the sensitivity of the attenuation characteristics of induced polarization to water volume, Shandong University has carried out an experimental study on the relationship between induced polarization parameters and water volume in the field of tunnel geological prediction. We tried to use this method to estimate the water content of the water-bearing body and carry out three-dimensional positioning of the water-bearing body, and achieved successful applications (Liu 2010; Li et al. 2011b, 2014; Nie Lichao et al. 2012). In addition to the IP technology, magnetic resonance sounding (MRS) is also a quantitative method of water exploration. At present, the MRS technology has been successfully applied to find water on the ground (Lin et al. 2012; Yi et al. 2013). Due to the narrow space of the mine/tunnel and the limitation of the complex electromagnetic environment, there are still many technical difficulties in using the MRS technology to directly detect groundwater for advance detection and early warning of water inrush in the mine/tunnel.

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With the development of advance geological forecasting technology, the concepts and ideas of comprehensive forecasting and quantitative identification of hazardcausing systems have gradually been formed and developed. Multi-solution is an inherent problem in geophysical exploration. The geological forecast results of a single forecast method are not very reliable, and different methods have different forecast effects on different hazard-causing systems. Currently, there is no prediction method that can accurately predict and identify various hazard-causing systems. Due to the diversity of the hazard-causing system and the complexity of its occurrence characteristics, to accurately identify the type, location, scale, and water-bearing characteristics of the hazard-causing system, it is necessary to understand and comprehensively analyze the geological characteristics, geophysical response characteristics and drilling revealed features of the hazard-causing systems. Therefore, there is an urgent need to propose a comprehensive identification method that integrates the geological characteristics, the geophysical response characteristics, and the drilling revealed features of the hazard-causing systems. In view of this, we explored a comprehensive advance geological prediction technology of “combination of survey outside the tunnel and detection and analysis inside the tunnel, combination of geology and geophysical prospecting, combination of long-distance detection and short-distance detection, and combination of different geophysical prospecting methods” in practice. A variety of advance geological forecasting technologies are combined, verified, supplemented, and restricted with each other, which can reduce the multiplicity of solutions and improve the reliability of hazard-causing system identification. Comprehensive advance geological forecasting technology is gradually accepted and widely applied in tunnel construction, especially in tunnels with complex geological conditions and high risks of geological disasters. Comprehensive advance geological forecasting technology is effective in ensuring construction safety and disaster prevention and mitigation. At the same time, the application of comprehensive advance geological prediction technology and the successful research and development of some new detection technologies have made it possible for quantitative detection of tunnel advance geological prediction. In general, after more than 40 years of development, the tunnel advance geological forecast technology has experienced the development process of “qualitative forecast → partial quantitative forecast → quantitative forecast”. The so-called quantitative advance geological prediction is to use advance geological prediction technology to realize the qualitative identification and quantitative prediction of the three core attributes of hazard-causing structures (spatial location, occurrence form, and filling characteristics), so as to infer the types of disasters that may occur and quantitatively analyze the risk probability of their occurrence. And this represents an important direction for the development of tunnel advance geological forecasts in the future. In general, the traditional advance geological forecasting technology has made some new progress in the detection and identification of the water and mud inrush hazard-causing system of the tunnel, but the demand, pressure and situation of the future development of the detection and identification technology of the water and mud inrush hazard-causing system in the tunnel are still very urgent. On the one hand, there are many problems in the current advance detection technology that need to be

References

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solved. On the other hand, various typical hazard-causing systems put forward higher requirements for the accuracy and reliability of quantitative detection and identification technology, which requires the industry peers to work and coordinate together to tackle these key problems. In this book, we carried out some in-depth research and applications onto the identification of the water and mud inrush hazard-causing system of the tunnel, developed some technical countermeasures, and proposed some technical suggestions. It is expected to make contributions to the research and identification of the water and mud inrush hazard-causing system and help improve the overall accuracy of adverse geology identification, thus ultimately help ensure the safe construction of tunnels.

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24

1 Introduction

He FL, Guo RJ, Li CS, Ding JF (2009) Water inflow prediction ahead of tunnel face by geothermal measurement. Southwest Jiaotong University Press, Chengdu He FL, Zhang YC (2011) Geohazards and unfavorable geological body and prediction methods in tunnel construction. Southwest Jiaotong University Press, Chengdu Hu ZP (2007) Design of disaster-preventing and alarm system for water gushing and mud outburst in complex karst tunnels. Modern Tunn Tech 44(6):48–54 Hu QF, Huang HW (2006) Study on the modeling of risk acceptance criteria for tunnel and underground engineering. Chin J Undergr Space Eng 1:60–64 Hu KR, Cao YQ, Hu ZY, Liu X (2000) Hydrological impounded structure classification and its zone division. J Changchun Univ Sci Technol 30(3):246–250 Huang HW (2006) State-of-the-art of the research on risk management in construction of tunnel and underground works. Chin J Undergr Space Eng 2(1):13–20 Huang HW, Chen GX (2003) Role of risk management in the cost reduction of metro construction. Modern Tunn Tech 5:1–6 Jiang JP, Gao GY, Li XZ, Luo GY (2006) Mechanism and countermeasures of water bursting in railroad tunnel engineering. China Railway Sci 27(5):76–82 Jiang H, Jia C, Zhao YG (2013) TST tunnel advance forecasting technology and application. Road Tunnel 3:59–62 Kuang X, Ba MZ, Wuang CL, Guo JX (2010) Research of comprehensive warning of water inrush hazards in karst tunnel based on fuzzy evaluation method. J Highw Transp Res Dev 27(11):100– 103 Li J, Chang L (2015) Study on karst water inrush risk assessment model based on karst distribution analysis. Tunn Constr 35(8):792–801 Li LP, Li SC, Chen J, Li JL, Xu ZH, Shi SS (2011a) Construction license mechanism and its application based on karst water inrush risk evaluation. Chin J Rock Mechan Eng 30(7):1345– 1355 Li SC, Liu B, Li SC, Zhang QS, Nie LC, Li LP, Xu ZH, Zhong SH (2011b) Study of advanced detection for tunnel water-bearing geological structures with induced polarization method. Chin J Rock Mechan Eng 30(7):1297–1309 Li SC, Li SC, Zhang QS, Xue YG, Ding WT, Zhong SH, He FL, Lin YS (2007) Forecast of karstfractured groundwater and defective geological conditions. Chin J Rock Mechan Eng 2:217–225 Li SC, Zhou ZQ, Li LP, Shi SS, Xu ZH (2013) Risk evaluation theory and method of water inrush in karst tunnels and its applications. Chin J Rock Mechan Eng 32(9):1858–1867 Li SC, Liu B, Sun HF, Nie LC, Zhong SH, Su MX, Li X, Xu ZH (2014) State of art and trends of advanced geological prediction in tunnel construction. Chin J Rock Mechan Eng 33(6):1090–1113 Li SC, Li XZ, Jing HW, Yang XL, Rong XL, Chen WZ (2017a) Research development of catastrophe mechanism and forecast controlling theory of water inrush and mud gushing in deep long tunnel. China Basic Sci 19(3):27–43+2+63 Li SC, Wang K, Li LP, Zhou ZQ, Shi SS, Liu S (2017b) Mechanical mechanism and development trend of water-inrush disasters in karst tunnels. Chin J Theor App Mechan 49(1):29–37 Li XZ, Huang Z, Xu ZH, Fan J, Song JL, Zhang PX, Lu JJ (2018a) Hazard-causing structures for water and mud inrush in tunnels and the corresponding detailed multiscale observation technology. China J Highw Trans 31(10):79–90 Li SC, Xu ZH, Huang X, Lin P, Zhao XC, Zhang QS, Yang L, Zhang X, Sun HF, Pan DD (2018b) Classification, geological identification, hazard mode and typical case studies of hazard-causing structures for water and mud inrush in tunnels. Chin J Rock Mechan Eng 37(5):1041–1069 Li XP, Li YN (2014) Research on Risk Assessment System for Water Inrush in the Karst Tunnel Construction Based on GIS: Case Study on the Diversion Tunnel Groups of the Jinping II Hydropower Station. Tunn Undergr Sp Tech 40:182–191 Li XY, Zhang DL, Fang Q, Song HR (2015) On water burst patterns in underwater tunnels. Modern Tunn Tech 52(4): 24–31, 40

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26

1 Introduction

Su C, Chen HY, Zhou N, Guan YT, Zhou XJ (2012) Research on formation mechanism and types of karst water inrush in Pingyang Tunnel. Resour Environ Eng 26(S1):7–10 The British Tunnelling Society (2003) The Association of British Insurers: Joint code of practice for risk management of tunnel works in the UK-09[Z]. Br Tunn Soc, London The International Tunnelling Insurance Group (2006) A code of practice for risk management of tunnel works Wang MS (2005) Design, construction and operation safety risk analysis of the Xiamen Submarine Tunnel. Constr Technol S1:7–10 Wang JX, Yang LZ, He J (2001) The hydro-geological analysis of karst groundwater’s blow in large-scaleunderground engineering. Hydrogeol Eng Geol 4:49–52 Wu XG, Wu G, Luo HB (2007) Risk research on shield construction of Wuhan Changjiang River Tunnel. China Munic Eng 1:51–53 Xiang XH, Deng XP, Wang P (2012) Application of TRT for geological advanced prediction in tunnel construction. Chin J Undergr Space Eng 8(6): 1282–1286, +1327 Xiong ZM, Lu H, Wang MY, Qian QH, Rong XL (2018) Research progress on safety risk management for large scale geotechnical engineering construction in China. Rock Soil Mech 39(10):3703–3716 Xu ZH, Li SC, Li LP, Chen J, Shi SS (2011a) Construction permit mechanism of karst tunnels based on dynamic assessment and management of risk. Chin J Geotech Eng 33(11):1714–1725 Xu ZH, Li SC, Li LP, Hou JG, Sui B, Shi SS (2011b) Risk assessment of water or mud inrush of karst tunnels based on analytic hierarchy process. Rock Soil Mech 32(6):1757–1766 Xu ZH, Li SC, Zhang QS, Liu B, Zhang X, Ge YH (2008) Reflection characteristic of seismic wave in TSP advance geological prediction. Chin J Undergr Space Eng (4):640–644+716 Xue GQ, Li X (2008) The technology of TEM tunnel prediction imaging. Chin J Geophys 3:894–900 Xue GQ, Li X, Di QY (2007) The progress of TEM in theory and application. Prog Geophys 4:1195–1200 Yan YR, Huang HW, Hu QF, Cheng Y (2007) Risk assessment on drill and blasting method of Dalian Bay Subsea Tunnel. Chin J Rock Mechan Eng 26(S2):3616–3624 Yang XL, Zhang S (2018) Risk assessment model of tunnel water inrush based on improved attribute mathematical theory. J Central South Univ 25(2):379–391 Ye Y (2011) Advanced geological forecast for tunnel construction. China Communications Press, Beijing Yi XF, Li PF, Lin J, Duan QM, Jiang CD, Li T (2013) Simulation and experimental research of MRS response based on multi-turn loop. Chin J Geophys 56(7):2484–2493 Yuan BH, Mao Y (2001). Groundwater resources in the karst mountainous area in Southwest China. Hydrogeol Eng Geol (5):46–47+55 Zhang ZG, Chen WH (2000) Karst water-storage structures and water searching: a case study of Xiaopingyang, Laibin, Guangxi. Hydrogeol Eng Geol 6:1–5 Zhang MQ, Liu ZW (2005) The analysis on the features of karst water burst in the Yuanliangshan Tunnel. Chin J Geotech Eng 27(4):422–426 Zhang MQ, Sun GQ (2011) Technology for treating mud and water bursts in tunneling. Modern Tunn Tech 48(6):117–123 Zhang QS, Li SC, Han HW, Ge YH, Liu RT, Zhang X (2009) Study on risk evaluation and water inrush disaster preventing technology during construction of karst tunnels. J Shandong Univ (Eng Sci) 39(3): 106–110 Zhao YG (2007) Analysis and recommendation of tunnel prediction techniques at home and abroad. Prog Geophys 22(4):1344–1352 Zhao Y, Li PF, Tian SM (2013) Prevention and treatment technologies of railway tunnel water inrush and mud gushing in China. J Rock Mech Geotech Eng 5(6):468–477 Zhong SH, Sun HZ, Li SC, Wang R (2012) Detection and forecasting for hidden danger of karst fissure water and other geological disasters during construction of tunnels and underground projects. Chin J Rock Mechan Eng 31(S1):3298–3327

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Chapter 2

Classification and Geological Identification of Water and Mud Inrush Hazard-Causing Systems in Tunnels

Numerous water and mud inrush cases show that among the factors that affect tunnel water and mud inrush disasters, stratum lithology is the basic factor and determines the type of groundwater occurrence; geological structure is the control factor, which dominates the burial, distribution and flow of groundwater, and determines the scale and size of water and mud inrush disasters; topography and geomorphology, hydrogeology, and climate are important conditions that affect groundwater recharge, runoff, discharge and occurrence characteristics; underground engineering activities are the direct cause of water and mud inrush disasters in tunnels. As shown in Table 2.1 and Fig. 2.1, based on the research on groundwater system and water storage structure, combined with the authors’ years of research and engineering practice experiences of water and mud inrush in tunnels, this chapter examines 381 cases of water and mud inrush in China. According to the statistical analysis, the hazard-causing system of water and mud inrush can be divided into 3 categories and 11 types (Li et al. 2018). They are karst category (corrosion fissure type, karst cave type, and pipe and underground river type), fault category (water-rich fault type, water-conductive fault type, and water-resistant fault type), and other category (intrusive contact type, structural fissure type, unconformable contact type, differential weathering type and special condition type) of hazard-causing system. Among them, karst category of water and mud inrush disasters ranks first, accounting for 43% of the total, followed by fault category, accounting for 26%, and other category of water and mud inrush accounts for 31%. The above-mentioned classification is defined as follows. In soluble rock formations, water and mud inrush disasters induced by dissolution are classified into the karst category; water and mud inrush disasters caused by faults and fault impacted zones are classified into the fault category; the rest of water and mud inrush disasters are classified into the other category of hazard-causing system. When multiple hazard-causing systems jointly cause water and mud inrush disasters, a distinction should be made between the hazard-causing system that directly causes the water and mud inrush and the one that indirectly affects the water and mud inrush. And the

© Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1_2

29

30

2 Classification and Geological Identification of Water and Mud Inrush …

Table 2.1 Classification of water and mud inrush hazard-causing systems Category

Percentage (%)

Type

Karst category of hazard-causing system, K-HS

43

Corrosion fissure type of Water inflow hazard-causing system, CF-HS

Fault category of hazard-causing system, F-HS

Other category of hazard-causing system, O-HS

26

31

Disaster description

Karst cave type of hazard-causing system, KC-HS

Water and mud inrush

Pipe and underground river type of hazard-causing system, PUR-HS

Water and mud inrush

Water-rich fault type of hazard-causing system, WRF-HS

Water and mud inrush

Water-conductive fault type of hazard-causing system, WCF-HS

Water and mud inrush

Water-resistant fault type of hazard-causing system, WRF-HS

Water and mud inrush

Intrusive contact type of hazard-causing system, IC-HS

Mud inrush

Structural fissure type of Water inflow hazard-causing system, SF-HS Unconformable contact type of hazard-causing system, UC-HS

Water inrush

Differential weathering type of hazard-causing system, DW-HS

Mud inrush

Special condition type of – hazard-causing system, SC-HS

one that directly causes the disaster should be regarded as the category of the water and mud inrush hazard-causing system.

2.1 Karst Category of Hazard-Causing System When building tunnels in soluble rock areas, the karst-category hazard-causing system is very likely to induce water and mud inrush disasters, which seriously

Fig. 2.1 Schematic diagram of various types of water and mud inrush hazard-causing system

2.1 Karst Category of Hazard-Causing System 31

32

2 Classification and Geological Identification of Water and Mud Inrush …

impacts tunnel safety and engineering construction. Controlled by many factors such as topography and geomorphology, geological structure, stratum lithology, stratum dip direction and angle, and other factors (Yuan 1994; Zhang 2006; Liu et al. 2007; Xu et al. 2011a, c; Li 2015), karst development is complex and changeable, with variable sizes and different shapes. The statistics of karst-category water and mud inrush cases are shown in Table 2.2. According to the different forms and scales of karst development, karst-category hazard-causing systems can be further divided into three types, namely, corrosion fissure type, karst cave type, pipe and underground river type. The degree of karst development is mainly affected by factors such as stratum lithology, rock layer occurrence, lithology combination, geological structure, topography and landforms. Therefore, the geological identification of karst-category hazard-causing systems is carried out from the following five aspects. (1) Stratum lithology is the basis of karst development. Generally speaking, the greater the solubility of soluble rock, the faster the rate of dissolution, the higher the degree of karst development, and the easier it is for large-scale karst such as karst caves, cavities and underground rivers to develop. In addition, strong karst aquifers generally can obtain more water catchment area on the surface, and the amount of surface dissolution is greater than that of medium and weak karst aquifers. Therefore, large trough valleys and depressions are formed on the surface, and a large number of funnels and sinkholes are developed. Among the common carbonate rocks, the degree of karstification of limestone, dolomite, siliceous limestone, and marlstone decreased systematically. (2) The influence of rock layer occurrence on the degree of karst development is reflected by the anisotropic characteristics of rock permeability and its influence on rock layer recharge, runoff, drainage and infiltration conditions. Generally speaking, the horizontally formed rock layer has a low permeability coefficient and poor infiltration conditions; the vertically formed rock layer has a large permeability coefficient and good infiltration conditions. Therefore, the karst development degree in horizontally formed rocks is weak, and that in vertically formed rocks is strong. However, the vertically formed rocks are not conducive to the formation of large-scale karst due to the small surface catchment area and poor dissolution. Therefore, when the dip angle of the thick soluble rock ranges from 25° to 65°, it is most favorable to the rainfall infiltration and catchment conditions, and hence the karst development will be the best. (3) The combination of soluble rock and non-soluble rock is an important factor affecting the development of karst. Non-soluble rock is often the base level of groundwater erosion, which controls the development direction and depth of underground karst. Especially when a permeable layer such as limestone is located above a water-resistant layer such as shale, groundwater seeps inside the permeable layer and concentrates on the top of the non-soluble rock layer, there is high probability that a large karst system will be developed near the top of the non-soluble rock layer. The transverse tensile fault zone is the part with the highest probability of cave development in soluble rock formations. The

Maluqing Tunnel

Yesanguan Tunnel

Moudao link of Qiyueshan Tunnel

Maoxian Tunnel

Hejiazhai Tunnel

Huayingshan Tunnel

Pishuang’ao Tunnel

Tongyu Tunnel

Jianshanzi Tunnel

3

4

5

6

7

8

9

10

11

94 95

YK19+759

YK19+833

K21+780 Yunwushan Tunnel

Baiyangping Tunnel

DK247+785

DK194+039~DK193+980

DK3+728

DK3+733

CK9+543 CK9+539

Changdangzi Tunnel

ZK69+532

ZK151+685

15 m of left line 12 m of right line

RK63+400

93

Yudong No. 1 Tunnel

Yangjiaonao Tunnel

Saimuli Lake Tunnel

RK63+094~+102

RK63+020

91 92

YK34+518

90

YK34+669

D2K1+430~D2K2+620

(continued)

581+585,+595,+853,+925, etc.

YK4+095

YK4+195

No. 1 tranverse tunnel parallel pilot PDK855+973

Unknown

YK4+025 Jiazhuqing Tunnel

Lishuwan Tunnel

Dadushan Tunnel

Unknown

D8K132+314

89

88

87

Xinpai Tunnel

Yanjiaozhai Tunnel

YD8K132+312

GK3+265

DK116+205~DK130+038

PDK255+978

86

85

K35+040

YK16+086~YK15+985

Tianchi Tunnel

2

Unknown K80+210~+270

84

YK16+086~+022

Loushanguan Tunnel

XJK0+093 Meiziguan Tunnel

Unknown XJK0+101

83

Xiakou Tunnel

Disaster chainage

YK16+098~+050

82

YK16+040

Shengjingguan Tunnel

Tunnel

YK16+076~+050

81

YK16+042

Jijiapo Tunnel

1

Serial no.

Disaster chainage

Tunnel

Serial no.

Table 2.2 Water and mud inrush cases of karst category hazard-causing system

2.1 Karst Category of Hazard-Causing System 33

105 106

112 113

YK45+110

DK354+460~+490

YK27+235

DK332+266,+237

ZK98+044

ZK98+027

Z4K32+793

K43+066

K43+000

Shangpilin Tunnel

Dasangyuan Tunnel

Tanchang Tunnel

Tiefengshan No. 2 Tunnel

Changtan Tunnel

Doumo Tunnel

Daliang Tunnel

Pingdong Tunnel

Pingyang Tunnel

Jigongling Tunnel

Pingkan Tunnel

Xulingguan Tunnel

14

15

16

17

18

19

20

21

22

23

24

25

101

YK26+155

Disaster chainage

111

110

Qingshan Tunnel

Guangzhou Subway Line 2

Bailongshan Tunnel

Micangshan Tunnel

3DK320+710

ZDK18+226

DK27+900

K41+720

DK490+373

ZK19+509

YK153+020~+031 Shanggaoshan Tunnel

DK114+570 ZK153+100

YK39+391

109

Yujialing Tunnel Guling Tunnel

YK5+660

ZK23+909

YK33+763.8

YK39+397

107 108

ZK38+790

ZK38+770~+820

Hexiba Tunnel

Dahuashan Tunnel

Qingyantou Tunnel

D1K 871+805

104

LK124+520~+630

LK124+573.5

Left line K13+618

Unknown

K37+199

LK68+730

9+593

YK157+400~+414

YK158+000~+010

DK245+260

D1K842+697

Gangwu Tunnel

Chalinding Tunnel

Foling Tunnel

Pingguan Tunnel

Tuojiashan Tunnel

Dayahe Tunnel

Jinkuidi Tunnel

Baojiashan Extra-long Tunnel

Tunnel

D1K842+893 103

102

100

ZK26+167

YK19+638

99

YK26+170

98

97

96

Unknown

Yanziyan Tunnel

13

Serial no.

Disaster chainage

ZK45+995

Tunnel

Gaojiaping Tunnel

Serial no.

12

Table 2.2 (continued)

(continued)

34 2 Classification and Geological Identification of Water and Mud Inrush …

124 125

Unknown

K3+731

K128+843

ZK112+744

K44+090

ZK39+822~+845

YK23+187.5~+199.5

ZK72+167~+202

DK966+842~DK968+142

DK193+185~+210

PDK132+990

II DK132+914

Nanshanzhai Tunnel

Yangling Tunnel

Dingshang Tunnel

Wulongshan Tunnel

Shijialiang Tunnel

Daluliangzi Tunnel

Yingzuiyan Tunnel

Xiatangkou No. 1 Tunnel

Shanggu Tunnel

Longtan Tunnel

Masangshao Tunnel

Wulong Tunnel

Dazhiping Tunnel

Lazhidong Tunnel

China Academy of Engineering Physics Air Defense Tunnel

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

Disaster chainage

No. 1 and No. 2 shelters, etc.

DK174+610

121

LK29+700 123

122

120

LK29+220

Xiaogaoshan Tunnel

Xitieche No. 2 Tunnel

Jialingshan Tunnel

Xinlongfeng Tunnel

Zhongfu Tunnel

Sandu Tunnel

DK124+420~+405

DK567+162

DK567+106

DK567+100

DK1076+860

K142+568

K142+643

DK926+780~+790

DK188+747

DK135+508

K74+500~+650

K72+900~K73+350

DK124+368~+355

DK124+425~+396

K971+015~+025

K1+512

YK52+164

(continued)

D1K978+704~D1K981+640

PDK978+460~PDK980+380

DK320+803

K42+462 Dahongtian Tunnel

Yinshan Tunnel

Xianrenxi Tunnel

Juyun Tunnel

Zhujiayan Tunnel

Bibanpo Tunnel

Tunnel

K38+664 119

118

117

116

115

114

ZK15+567

Yangmeipu Tunnel

27

Serial no.

Disaster chainage

K170+671

Tunnel

Chaoyang Tunnel

Serial no.

26

Table 2.2 (continued)

2.1 Karst Category of Hazard-Causing System 35

129 130

138 139 140

141

PK1+791

DK365+740

DK302+926

PDK29+203

PDK29+310

DK29+174

PDK35+770

Xinzhai Tunnel

Xiangshan Tunnel

Daqing Tunnel

Guiyang Rail Transit Line 1

Zhongba Tunnel

Youfangping Tunnel

Motianling Tunnel

Huama Tunnel

Tonghai Tunnel

46

47

48

49

50

51

52

53

54

133

YDK24+158

ZK43+090~+125

ZK42+785~+800

DK387+512

D9K55+218

137

136

135

No. 4 branch tunnel 0+175

ZK64+920

ZK64+918

Daba Tunnel

Goupitan Hydropower Station No. 5 Tailrace Tunnel

Maochang Tunnel

Shiruguan Tunnel

YK86+140~+200

K0+320~+355

(continued)

No. 4 branch tunnel 11+316

DK40+430~+460

3+255

Diversion tunnel of Jinyuan 3+240 Hydropower Station 3+252

Dayakou Power Station Tunnel

Shangjiawan Tunnel

DK12+132

ZDK19+200

YK129+435

ZK129+506

ZK40+697

K157+711

LDK0+580

Unknown

K24+971

K438+800

Xianrendong Tunnel

Guanhuchong Tunnel

Guanxi Tunnel

Shagou Tunnel

New Xiakouba Tunnel

Jinyunshan Tunnel

Guangshan No. 1 Tunnel

K438+850 134

131 132

YDK24+098

YDK24+136

128

K7+000~+130

PDK3+484

Geleshan Tunnel

Sanquan Tunnel

Yanling No. 2 Tunnel

45

127

126

K9+675

Upper pilot pit DK132+340

1+620

Baguashan Tunnel

Disaster chainage

44

Tunnel DK567+240

Serial no.

Disaster chainage

1+601

Tunnel

Diversion tunnel of Damo Power Station

Serial no.

43

Table 2.2 (continued)

36 2 Classification and Geological Identification of Water and Mud Inrush …

H3DK0+891

Unknown

DK354+879~+920

DK658+981~+976

Yk43+611

Zk45+200

Yk27+280

Zk72+678

D1K640+145~+473

Qipanshi Tunnel

Tianbaling Tunnel

Yuanliangshan Tunnel

Zijingshan Tunnel

Pengshui Tunnel

Tongren Tunnel

Pingtu Tunnel

Lvliangshan Tunnel

Shuikou No. 3 Tunnel

Shilin Tunnel

Qingping Tunnel

Laozhuang Tunnel

Liujiayu Tunnel

Kedong Tunnel

Baiyanjiao Tunnel

Lichuan-Wanzhou Expressway Qiyueshan Tunnel

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

Serial no.

ZK19+752.9~ZK20+150

155

154

153

152

150 151

DK57+633.8

149

148

147

146

145

144

143

142

DK57+641

No. 1 shaft 05+80

DK1905+098

DK539+734

DIIK238+911

ZK221+960

Disaster chainage

ZK212+884

Tunnel

Munaoshan Tunnel

Serial no.

55

Table 2.2 (continued) Tunnel

Diversion Tunnel of Ganhe Pumping Station

Teke Tunnel

Jinyunshan Tunnel

Yanjiao Tunnel

Naqing Tunnel

Tianbacun Tunnel

A tunnel in the Eastern Yunnan Plateau

Jiudingshan Tunnel

Niandong Tunnel

A highway tunnel in Guizhou

Xiema Tunnel

Qiyaoshan Tunnel

Yanglin Tunnel

Shanghai-Chengdu West Expressway Qiyueshan Tunnel

Disaster chainage

(continued)

No. 2 branch tunnel 2+483.5 m

H2DK0+877

K4+183

DK32+353

DK32+360

DK32+379

DK32+396

ZK24+405

DyK59+298~+192

K9+838.673

ZK281+942

ZK91+081~+086

YK21+125

YK9+011

ZK20+962

K19+903

YK329+893

ZK329+967

2.1 Karst Category of Hazard-Causing System 37

Disaster chainage

Unknown

K27+227~+248

Meihuashan Tunnel

Dazhushan Tunnel

New Dabashan Tunnel

Dabashan Tunnel

Zhongliangshan Tunnel

Nanling Tunnel

75

76

77

78

79

80

DK1936+967,+269,+173,+139,+915.7,+745, etc.

164

Kakiziyuan Tunnel

Xiao’an Tunnel

D3K83+420

D5K355+613

D5K355+489

ZK26+188

163

BK2+637 Yingpanshan Tunnel

AK14+762

BK14+888

BK1+137

AK1+117

YK137+157

YDK434+477

162

Auxiliary tunnel of Jinping Hydropower Station

Yangcangyan No. 2 Tunnel

PDK434+492

Syncline

Unknown

Wumengshan No. 2 Tunnel 2200 m of the parallel pilot in transverse tunnel

74

161

160

No. 2, 3, 4, 5 and 6 inclined shafts

DK362+277

Guanjiao Tunnel

73

ZK48+448~+450 ZK91+093~+063

159

PDK362+144

A tunnel on GuilinLiucheng highway

YK10+401

ZK10+428

158

Xinjie Tunnel

Disaster chainage K41+128

DK362+060

Dejiang Tunnel

157

Tunnel Shangganping Tunnel

Serial no. 156

PDK361+873.5

Tunnel

Yichuan-Wanzhou Railway PDK361+582.5 Qiyueshan Tunnel PDK361+597

Serial no.

72

Table 2.2 (continued)

38 2 Classification and Geological Identification of Water and Mud Inrush …

2.1 Karst Category of Hazard-Causing System

39

reasons are as follows. First, there is an external source of water supply from the relative water-resistant layer at the water-proof floor, which generates new corrosiveness due to the mixing of different chemical types of water; Second, it is easy to form a stable aquifer continuously recharged by external water in the aeration zone and seasonal fluctuation zone along the water-proof floor (Lin 2008). When the soluble rock layer is under the non-soluble rock layer, the contact part between the bottom plate of the non-soluble rock layer and the top plate of the soluble rock layer often develops bedding karst. When soluble rock layers and non-soluble rock layers are interbedded, interlayer karst often develops. As the number of non-soluble rock layers increases, the degree of karst development gradually weakens. (4) Geological structure plays a dominant role in the development of karst, and controls the direction and scale of karst development. Due to the varying development degrees of longitudinal extensional faults in different parts of folds, generally, karst develops stronger at the core than at the wings, and caves and cavities are prone to develop in the core. Similarly, at the uplift end of the syncline, the dip end of the anticline, and the turning end of the fold structure, structural fissures are relatively developed, and the karst development is also obvious. Extensional faults provide good migration space for groundwater. The karst development is relatively strong, but it is also easily filled by clay, which in turn affects the development of karst. The karst development in compressive faults is relatively weak, but very few faults may have strong karstification due to compression or when the fault zone is relatively broken. The secondary structural fractures of shear faults are extremely developed, and the depth of karstification is generally large. Large-scale caves and corridors are often developed near dense tension-torsional fault zones. (5) Topography can directly reflect the karst hydrodynamic conditions. The surface karst form is the surface representation of the underground karst water system. Depressions, funnels, and sinkholes are all input points of the underground karst water system. The input water volume depends on the surface catchment area of each input point (Lin 2008). The larger the surface water catchment area, the deeper the surface karst trenches and troughs develop, the easier the karst water infiltrates, which promotes the development of deep karsts. Large-scale input points such as depressions and underground extensions of underground river entrances are the channels of high-level tributaries of underground rivers. In addition to the above factors, the emergence of the following geological phenomena during the tunneling also helps to identify dissolution fissures, especially large karst caves, cavities, pipes and underground rivers (Xu et al. 2011c; Guo et al. 2013). (1) Frequent occurrence of iron rust dyeing or clay cracks or dissolution cracks; (2) Wetting and softening of rock layers are obvious, with water droplets adhering or water dripping; (3) Small karst caves appear frequently, containing water flow or traces of water flow and river sand; (4) The water inflow from the borehole has increased drastically, spray-like, and filled with sand or well-rounded gravel; (5) There is cold wind coming out of the borehole, or a clear sound of running water

40

2 Classification and Geological Identification of Water and Mud Inrush …

is heard; (6) When there is water seepage or water inflow from the rock layers, the water is clear and turbid from time to time, or mud appears; (7) The air temperature is obviously lowered, it is cold and humid, and mist appears.

2.1.1 Corrosion Fissure Type As shown in Fig. 2.2, corrosion fissures are formed by dissolution and expansion of rock fissures, joints, beddings and other structural surfaces during the movement of groundwater. They are wider than the original fissures, have better connectivity and strengthened water conductivity and water-bearing property. The scale of single corrosion fissure is small, but they are widely distributed in soluble rock formations. When karst occurs in the form of high-angle fractures and the karst fissures are filled, a common, highly catastrophic but easily overlooked type of hazard-causing system can be formed at this time, that is, steeply inclined and filling type of karst fissures (Xu et al. 2011b; Li 2015), for example, the Jijiapo Tunnel of Sanxia Fanba Expressway. The characteristics of corrosion fissures are closely related to the properties of rocks. Generally speaking, in pure limestone, dolomite, marble and other soluble rock formations that are easy to be dissolved, corrosion fissures similar to karst caves can be formed, with relatively wide fissure channels. In impure limestones with low solubility such as siliceous limestone, the dissolution of groundwater on the fissures

Fig. 2.2 Schematic diagram of corrosion fissure type hazard-causing system

2.1 Karst Category of Hazard-Causing System

41

is weak, with minor change of the dissolution channel, and the characteristics of the corrosion fissures are similar to those of diagenetic fissures. Under the action of high-pressure karst water, corrosion fissures develop, expand, and then form a wide and connected network of corrosion fissures, which are connected to water sources such as main pipes and water storage caverns. After the tunnel is excavated, the corrosion fissure connects the water source in the rock body (such as underground river, cave water and other karst water) to act as a water channel and provide a continuous source of underground water for water inrush in tunnels. Therefore, the corrosion fissure type hazard-causing system is mainly characterized by the continuous drainage of water inflow, which is of relatively low disaster severity. But it lasts for a long time, usually the time for groundwater draining. In addition, the existence of corrosion fissures reduces the integrity and strength of the surrounding rock, and adversely affects the stability of the surrounding rock.

2.1.2 Karst Cave Type As shown in Fig. 2.3, the karst cave type hazard-causing system is a large cavity formed by chemical corrosion and mechanical erosion of groundwater along various discontinuous surfaces of soluble rock (faults, joints, beddings, cracks, etc.). And it is the further development and expansion of corrosion fissures.

Fig. 2.3 Schematic diagram of karst cave type hazard-causing system

42

2 Classification and Geological Identification of Water and Mud Inrush …

The karst caves have different sizes, complex shapes and diverse filling properties. When the tunnel is excavated to the vicinity of the karst cavern, if it is directly exposed or the thickness between the tunnel and the karst cavern is less than the minimum safe thickness, water and mud inrush disasters will occur. Compared with the corrosion fissure type, the karst cave type hazard-causing system is mainly characterized by the instantaneous drainage of water and mud inrush. It has a strong suddenness and a higher degree of disaster severity, but the disaster time is shorter, usually the time for the water in the karst cave to be drained. For example, the “+978 karst cave” was revealed during the construction of the Maluqing Tunnel on the YichangWanzhou Railway. Large-scale water and mud inrush disasters occurred, causing huge economic losses, casualties and construction delays (Jin et al. 2007). The occurrence characteristics of karst cave type hazard-causing system are as follows. Generally speaking, pure limestone with a large thickness is conducive to the development of karst caverns, followed by dolomitic limestone and dolomite, and siliceous limestone and argillaceous limestone. The greater the solubility of carbonate rocks and the thicker the rock formations, the better the development of karst. Fault damage zones, especially extensional fault fracture zones, often develop large karst caves at the intersection of faults; At the axis of the fold structure, the tension cracks expand under the action of groundwater dissolution, and it is likely to develop karst caves; In the saturated zone, karst caves mostly develop along the bedding strike; the contact zone between soluble rock and non-soluble rock, and the zone with strong groundwater activity are conducive to the development of large karst caves.

2.1.3 Pipe and Underground River Type Generally, the length direction of the pipe and underground river type hazard-causing system is much longer than the other two directions, as shown in Fig. 2.4, and its development law is similar to that of the corrosion fissure type and karst cave type. During the tunnel construction, if the karst pipe is exposed or the water flow direction of the underground river is changed, large-scale water and mud inrush disasters will be induced in the tunnel (Shi et al. 2012). The pipe and underground river type hazardcausing system is mainly characterized by climatic instantaneous drainage of water and mud inrush, with strong suddenness, high disaster severity, long disaster duration, and high disaster frequency. Each rainfall process may cause different degrees of water inrush. For example, during the construction of the Yesanguan Tunnel on the Yichang-Wanzhou Railway, the “+602” karst cavern was exposed, which eventually connected to the karst pipe above the tunnel under the action of high-pressure water, and seized the No. 3 underground river, causing large-scale water and mud inrush disasters, and huge economic losses and casualties (Sun 2010). Karst pipes often develop below karst landforms such as karst depressions, sinkholes, and karst funnels, and are also likely to develop in soluble rock layers below the surface sediments with strong water storage capacity. Large-scale karst pipe

2.1 Karst Category of Hazard-Causing System

(a) Pipe type

(b) Underground river type

Fig. 2.4 Schematic diagram of pipe and underground river type hazard-causing system

43

44

2 Classification and Geological Identification of Water and Mud Inrush …

networks are likely to develop in the steeply inclined soluble rock formations, and strong geological tectonic movement and high water-rich zone are favorable for the development of karst pipes. In the karst hydrodynamic zone, karst pipes are mainly developed vertically in the vertical circulation zone, as a pipe network in the seasonal alternation zone, and mainly developed horizontally in the horizontal circulation zone. Most of the karst pipes in the latter two conditions are rich in water (Zhou 2015). The development degree of the underground river is closely related to the hydrodynamic conditions and geological structures in the area. Generally speaking, underground rivers have different karst forms exposed on the surface, such as strip depressions, beaded depressions, karst wells, and sinkholes. In view of the above, underground rivers can be identified, and tracer tests can be used to analyze the hydraulic connection and connectivity of underground rivers. From the perspective of the plane layout, the common types of underground rivers include single-line underground rivers, bifurcated underground rivers, lateral feather-shaped underground rivers, dendritic underground rivers and network underground rivers.

2.2 Fault Category of Hazard-Causing System The water-bearing property of the fault is related to the degree of damage suffered during the tectonic movement. Generally speaking, during the formation of a fault, the voids and fissures in the fracture zone of the fault are developed, and there is plenty of water storage space, and the rocks of two sides become relatively waterresistant layers. When the filling medium in the fault fracture zone has a good degree of cementation and a compact structure, it can be used as a water barrier to block water. The division of fault types considering mechanical properties of tension, pull, and torsion cannot reflect characteristics of the occurrence of water in tunnel water and mud inrush. The traditional classification of water-rich faults, water-conducting faults, water-storing faults, water-blocking faults, and water-free faults (Liu 1979) can not only indicate the water content of the fault, but also reflect the control role that the fault plays in water and mud inrush, i.e., its role to bear, conduct, store and block the groundwater. Combining the actual situation of water and mud inrush in engineering, the water-rich faults and water-bearing faults are classified into one category. For water-free faults where basically no water and mud inrush disasters would occur, they are not taken into consideration here. Therefore, according to characteristics of the fault structure and engineering characteristics of water and mud inrush disasters, the fault category hazard-causing system can be further divided into water-rich fault type, water-conductive fault type and water-resistant fault type. The statistics of the fault category hazard-causing system cases are shown in Table 2.3. Fault category hazard-causing systems can be identified through geomorphological and geological signs.

K72+625 ZK71+215

Dapingshan Tunnel

Panling Tunnel

8

9

Jingyuankou Tunnel

14

YK9+238

K88+597

K23+708

Feixianguan Tunnel

Hanlingjie Tunnel

12

13

K101+558,+549

Kangjialou Tunnel

Cangling Tunnel

10

11

60

59

58

Dagangshan Hydropower Station No. 3 Belt Conveyor Tunnel

Qiyueshan Tunnel on Yichang- Wanzhou Railway

Nanling Tunnel

Songnan Tunnel

57

Dawushan Tunnel Baiyun Tunnel

55

YK48+836~+925

Yanmenguan Tunnel Maoba No. 1 Tunnel

56

53 54

YK43+135~+170 ZK45+058~+977

Unknown

Unknown

PDK365+313

DK1936+269

DK1936+967

DK1937+010

Unknown

DK334+733

K18+427

ZK297+624, etc.

(continued)

DK118+645~+740, etc.

DzK114+777

DzK114+780

Beitianshan Tunnel

Unknown YK2390+046

RK78+055~+085

52

ZK3+970.4~+980.8 ZK3+980.8

YK2390+030

Xiapu Tunnel

Changliangshan Tunnel Wushaoling Tunnel

Disaster chainage K3+140

YK2390+021

7

50 51

Tunnel Huinongshan Tunnel

LK77+850~+870

Yangpeng Tunnel

6

Serial no. 49

RK78+030~+028.5

K14+030 K48+860

Shibanling Tunnel

Galongla Tunnel

4

5

ZK150+411 YK17+070

Sanyang Tunnel

Henglutou Tunnel

2

3

Disaster chainage K255+281~+285

Tunnel

Dafengyakou Tunnel

Serial no.

1

Table 2.3 Water and mud inrush cases of fault category hazard-causing system

2.2 Fault Category of Hazard-Causing System 45

62

DK74+202~+162

K47+013.5 K47+194

Zoumaling Tunnel

24

Wuzhishan Tunnel

28

Longjinxi Diversion Tunnel

(continued)

No. 3 Branch cave 0+950

77

ZK91+320~+385

K31+390~+638

Yonglian Tunnel

K4101+814

DK17+495

K1+13

ZK104+910~ZK105+310

K5+573

YK91+360~+410

76

Palong No. II Tunnel

Tangcun Tunnel

Yakexia Snow Mountain Tunnel

Huangshaling Extra-long Tunnel

Mingyueshan Tunnel

K29+542

K28+880

74 75

K90+900~+930 K92+180~+215

Xingyi No. II Tunnel

27

73

YK31+390~+365

Baolin Tunnel

Zhengyang Tunnel

25

72

71

26

Unknown

YK5+379 YK5+398

DK1911+398

DK156+330 K64+664

New Dayaoshan No. 1 Tunnel

Jinzhushan Tunnel

23

70

YK22+136 ZK190+637

Tianchengshan Tunnel

DK105+990~DK106+970

K049+935~K050+112

Unknown

DK87+998

DK172+818

DK172+824

K2+738

Lianhuashan No. 1 Tunnel

Sipujian Tunnel

DK79+110~DK78+380 DK78+153~+190

21 69

Disaster chainage YK29+816, etc.

22

Shenghongqing Tunnel

Dabeiling Tunnel

68

67 K201+510

Xiaopiliu Tunnel

20

Yanying’an Tunnel Shimian Nanyahe Diversion Tunnel

Zangga Tunnel

Jiaoxi Reach of Qinling Tunnel

Qinling Tunnel

65

LK76+358

Maozhanling Tunnel

19

Tunnel Xinwuji Tunnel

66

64

YK61+982~+995

Lingjiao Tunnel

18

EK18+215

63

Unknown ZK61+058~+068

Daxiangling Tunnel

Zhucangdong Tunnel

16

17

DK91+284

DK91+284

Serial no. 61

Disaster chainage No. 3 inclined shaft

Tunnel

Liupanshan Tunnel

Serial no.

15

Table 2.3 (continued)

46 2 Classification and Geological Identification of Water and Mud Inrush …

Disaster chainage

Diversion tunnel of Dafa Hydropower Station

New LuonaTunnel

34

35

85

DK95+435~+735

Dongqinling Tunnel

Dayaoshan Tunnel

47

48

F9 fault 1994+213

ZK46+963 DK2081+097

Beilingshan Tunnel

Pingling Tunnel

45

46

K160+274 DK502+230

Tiezhaizi No. 1 Tunnel

Qingyunshan Tunnel

43

44

(R) 0+310~+316.5 D1K151+460

Baoxing Power Station Diversion Tunnel

Xianghe Tunnel

41

42

D1K79+352 K1+186

Xinzhai No. 2 Tunnel

Lenglongling Diversion Tunnel

39

40

89 90

DK262+388 DK262+411

Dananshan Tunnel

38

87

100

99

98

97

96

95

94

93

92

91

88

DK129+393 YDK472+234

Kekeqiaoke No. 3 Tunnel

Gaogaishan Tunnel

36

37

86

D6+093~8+283.66

Baolin Tunnel

Bijiashan Tunnel

Xinping Tunnel

Huajiaopo Tunnel

Dazhongshan Tunnel

Hongtu Tunnel

Dongtianshan Tunnel

Shixia Tunnel

Xiangyun Tunnel

Gantasi Tunnel

A tunnel in Xinjiang

Jiufeng Tunnel

Dengloushan Tunnel

Zheduoshan Tunnel

Sanqingshan Tunnel

Longyan Jiangshan Tunnel

Dongzhou Xincheng Tunnel

Nanchong Tunnel

83 84

Diversion tunnel of Jinwo Hydropower Station

D4+805~+832

DK175+807

Huangjialing Diversion Tunnel Donghu Power Station Diversion Tunnel

82

D5+120~6+093

D4+361~+366

81

80

DK29+424

DK406+422

Jiubu Tunnel

247+395

YK274+610,+649

Unknown

D1K78+933

Unknown

ZK94+351

ZK9+186

ZK31+595

PDK143+074

V1K108+263.4

82+184.7~+177

B0+883

2XJK0+697

K1+035

DK430+211

K3+370~+500

K0+735

DK1133+394

7+363

No. 2 Branch cave 8+776

K209+830

YK22+136

33

Denghuozhai Tunnel

ZDK47+252

79

K1+499~+557 DK406+680~+710

Bieyancao Tunnel

32

No. 3 Branch cave 7+925 No. 2 Upstream 3+062

0 km+543 K1+230~+250

Tianzhushan Tunnel

No. 2 Branch cave 3+551

Cimushan Tunnel Caijiazhai Tunnel

Tunnel

30 78

Serial no.

31

Disaster chainage DK150+934

Tunnel

New Wanshansi Tunnel

Serial no.

29

Table 2.3 (continued)

2.2 Fault Category of Hazard-Causing System 47

48

2 Classification and Geological Identification of Water and Mud Inrush …

(1) The geomorphological signs mainly include fault cliffs, fault triangles, faulty ridges, contact belts between plains and mountains that cross the direction of the ridge, beaded lakes and depressions, zonal springs, faulty water systems and rivers, etc. These geomorphological signs provide an effective basis for the geological identification of faults. (2) Geological signs mainly include non-continuous structural line; tectonic strengthening phenomena caused by fault activity, such as tectonic lenses, rapid, variably and steeply changes of rock formations, jointed, cleavable and even foliated narrow bands, sharp increase in small folds, squeezing and fracture, and occurrences of various scratches, steps, traction folds or folds, etc.; the duplication or lack of the strata; magmatic activity and mineralization; sudden changes in the lithofacies and the strata thickness; existence of fault rocks. In addition, in the process of tunnel excavation, the following geological phenomena also can help to determine and identify the faults and fracture zones in the tunnel. (1) The number of joint groups in surrounding rocks has increased sharply, even as many as 6 to 12 groups; (2) There are small broom-like structures or anti-dip joints composed of arc-shaped joints; (3) The rock is broken, the strength is significantly reduced, and rust-stained crushed rock, cataclastic rock and so on appear; (4) The mudstone, shale and other water-resistant rock formations near the footwall of the water-rich fault are significantly wetted and softened, and the water splashing phenomenon is obvious, and other traces of water flow appear.

2.2.1 Water-Rich Fault Type Water-rich faults are generally developed in thick water-permeable rock formations. The fault fracture zone and its affected zone have good water permeability, rich groundwater, large water storage space and sufficient groundwater replenishment source, and the two walls of the fault have relatively poor water permeability, which is conducive to the accumulation of groundwater inside the fault (sometimes enriched in the fault fracture zone). As shown in Fig. 2.5, when the tunnel is excavated to the vicinity of the fractured zone of the fault, groundwater carries sand and gravel and so on into the tunnel from the inside of the fault, causing water and mud inrush disasters. The faults developed in limestone, marble and other permeable rock formations are often water-rich faults. The rock fractures and pores in the fault fracture zone are continuously dissolved or eroded to form larger groundwater storage and migration spaces. In addition, some extensional faults that are not cemented and filled by late materials are also water-rich faults (Liu 1978). The main characteristics of waterrich faults are large storage space inside the fault, sufficient recharge sources, and unobstructed recharge channels. In particular, the water-rich faults developed in limestone have large static reserves of groundwater and obvious seasonality in dynamic reserves. The scale of water and mud inrush disasters is large, and the consequences of disasters are serious.

2.2 Fault Category of Hazard-Causing System

49

Fig. 2.5 Schematic diagram of water-rich fault type hazard-causing system

2.2.2 Water-Conductive Fault Type As shown in Fig. 2.6, water-conductive faults connect groundwater in different layers of aquifers to make them hydraulically connected. The groundwater storage and migration spaces are usually smaller than that of water-rich faults. Groundwater is dominated by dynamic reserves, mainly from the two walls of aquifers. Waterconductive faults mainly exist in weakly permeable or impermeable rock formations, and play a role in water conduction by connecting aquifers. After the tunnel is excavated to the fault, the sources of water and mud inrush disasters are mainly the water source inside the fault and the water source of the aquifer that is hydraulically connected through the water-conductive fault. For example, the tension and tensiontorsion faults developed in the stratum of sandstone and shale intercalated with limestone play a role of water conduction by connecting various limestone aquifers (Liu 1978).

2.2.3 Water-Resistant Fault Type Water-resistant faults play a role in blocking water through fault walls or internal tectonites (calcification and mylonitization). The water content inside the fault fracture zone is generally low, but the water blocking effect of the fault makes the drainage

50

2 Classification and Geological Identification of Water and Mud Inrush …

Fig. 2.6 Schematic diagram of water-conductive fault type hazard-causing system

channel of the aquifer not smooth; meanwhile, the groundwater is enriched, and the water level rises. As shown in Fig. 2.7, when the tunnel passes through the waterresistant fault, the water-blocking structure is exposed, and its water blocking effect becomes invalid. The tunnel becomes a groundwater drainage space. Groundwater carries sediments and other filling media from the excavated section into the tunnel, causing water and mud inrush disasters. The water blocking of the fault wall means that the lower aquiclude contacts with the upper aquifer due to the up-and-down displacement of the stratum during the formation of the fault, which blocks the movement and drainage of groundwater in the aquifer, so that the groundwater is collected in the aquifer and the groundwater level is raised. Internal tectonite water resistance occurs in large faults in permeable rock formations, mostly in compressive or compressive torsion faults. The structural rock belts inside the faults have a much smaller water permeability than the two walls developed by fissures, forming a water blocking structure to block the drainage and flow of groundwater in the layer, raising the groundwater level; alternatively, the filling medium inside the fault is compacted and cemented by extrusion, with low porosity, which plays a role of water blocking.

2.3 Other Category of Hazard-Causing System According to literature statistics, water and mud inrush disasters caused by karst and fault hazard-causing systems account for about 69% of the total number of water and

2.3 Other Category of Hazard-Causing System

51

Fig. 2.7 Schematic diagram of water-resistant fault type hazard-causing system

mud inrush cases in tunnels. In addition, large-scale water and mud inrush can also be induced when the tunnel exposes or penetrates through igneous rock intrusive contact with water-rich zone, structural fracture development zone, unconformity contact zone, granite weathering deep trough, artificially excavated water-rich space and other unfavorable geologies. Sometimes the disaster severity is no less than the aforementioned two categories of hazard-causing systems, requiring enough attention. In order to distinguish from the karst and fault category hazard-causing systems, the other types of hazard-causing systems that induce water and mud inrush disasters are unified into the other category of hazard-causing systems, including: intrusive contact type, structural fissure type, unconformable contact type, differential weathering type and special condition type. The case statistics are shown in Table 2.4.

2.3.1 Intrusive Contact Type As shown in Fig. 2.8, during magma intrusion, due to compression, alteration, etc., joints and fracture development zones are formed near the contact zone between the intrusive rock and the surrounding rock. After the geological tectonic movement or weathering and water erosion in later period, the fissures have developed further, and the water conductivity and water-bearing property of the originally closed fissures or hidden fissures have been enhanced. The fracture zone provides a large amount of

71

76

k2+260~+320

Guantian Tunnel

Tiezhaizi No. 1 Tunnel

8

9

K24+445 DIK752+869~+890

Dongtoushan Tunnel

Hushan Tunnel

12

13

No. 3 shaft X3 K0+152.5

Heluoshan Tunnel

18

DyK154+901 Unknown

Zhongtianshan Tunnel

Fu’an Tunnel

16

17

DK28+700

Cao’an Tunnel

Huayoushan Tunnel

14

15

YK37+915

LK68+730 No. 3 shaft XK0+283

Dayahe Tunnel

Baotashan Tunnel

10

11

YK161+315

84

83

82

81

80

79

78

77

75

k2+185~+225 Right tunnel K52+265

74

k2+140~+160

Nanshan Tunnel

7

73

ZK47+067 K35+680~+700

Yaozhai Tunnel

Baofuling Tunnel

5

72

6

DK466+608 Unknown

Shuangfeng Tunnel

Ganquan Tunnel

3

70

4

69

DK150+137

Deli Tunnel

2

Serial no. 68

DK150+133

Disaster chainage ZK84+828

Tunnel

Qinglong Tunnel

Serial no.

1

Table 2.4 Water and mud inrush cases of other category hazard-causing systems Tunnel

Gaoligongshan Tunnel

Shigushan Tunnel

Yilu Tunnel

Diversion tunnel of Shidou reservior

Qinling tunnel of water diversion project from Han river to Wei river

Gaoyangpo Tunnel

Yanggongkeng Tunnel

Liangfutai Tunnel

Tianheshan Tunnel

Qiandiao No. 3 Tunnel

Yanglin Tunnel

Tongsheng Tunnel

Huajiaoqing Tunnel

Kuibalu Tunnel

Changheba hydropower station highway Tunnel

Fubaoshan Tunnel

Zhongyang Tunnel

Disaster chainage

226+010

PDZK221+481

D1K224+200~+230

YK12+198

YK174+988

D0+760

K26+760~+810

DK13+747

ZK55+931.5

DK12+126

No. 2 shaft

No. 1 shaft

K77+820~+827

ZK14+190

ZK114+395

ZK114+377

K40+113

YK4+570

BK1+491

DK257+578

ZK158+567

(continued)

52 2 Classification and Geological Identification of Water and Mud Inrush …

DK 349+409 LK106+851

Shilin Tunnel

Gangcheng Tunnel

Jijiacun Tunnel

24

25

26

Disaster chainage

Baofeng Tunnel

33 Unknown

DK442+660~+668 DK127+427

Qingshui Tunnel

Qinyu Tunnel

31

32

DK4+973 DK230+950

Taoshuping Tunnel

Baosen Tunnel

29

30

K218+581 Unknown

Bairenyan Tunnel

Humaling Tunnel

27

28

95

94

93

92

91

Tabaiyi Tunnel

Guanyinyan Tunnel

Wangbei’ao Tunnel

Shizishan 1# Tunnel

Cushishan Tunnel

Hongdoushan Tunnel

K63+035~+050

DK418+344

RK100+261

LK100+308

LK100+310

LK100+370 RK100+383

DLII30+738

K100+490

PKD121+661

ZK28+448

90

DK7+939

YK14+260~+267

DK7+963

CK7+838

K45+200

DK218+871.2

Unknown

220+855~+835

CK7+835 Guling Tunnel

Junchang Tunnel

Daxingxiang Tunnel

Banshan Tunnel

Anshi Tunnel

Tunnel

YK14+194~+205 89

88

87

86

85

Serial no.

YK14+175~+191

DK332+237

PDK34+570 DK332+266

Xiushan Tunnel

Daliang Tunnel

22

23

K100+636 YK194+046

Weijiashan Tunnel

Yangdongtan No. 2 Tunnel

20

21

Disaster chainage K4+760

Tunnel

Nanshan Tunnel

Serial no.

19

Table 2.4 (continued)

(continued)

2.3 Other Category of Hazard-Causing System 53

A Tunnel on Nanlong Railway

35

Unknown K0+57.8

Mantan Diversion Tunnel

44

Datang Linzhou Thermal Power Diversion Tunnel

51

K2+738

CX32+843.7

0+493~+501

Unknown

0+502~+504

0+504.0

K80+982

K80+978

K80+970

K6+045~+047

K3+402

YK32+531

CX33+152.2

CX33+066.4

CX33+058.0

Xiaozhongdian Tunnel

50

Fengtun Tunnel

Xianglushan Tunnel

Changlashan Tunnel

Feishuiyan 3 # Tunnel

CX32+963.0

105

K100+490

YK41+857.1

ZK11+866

ZDK25+343

Qinling Tunnel of K2+692.5 Hanjiang-Weihe Water Transfer Project K2+706.9

Cushishan Tunnel

Pingtian Tunnel

A tunnel in Yunnan Province

Jingganglu-Shazikou tunnel of Qingdao Metro Line 4

Disaster chainage YK92+093

DK727+510~+480

PDK727+508

Xinlian Tunnel

49

Tunnel Zhongjiashan Tunnel

PDK726+963

DK93+715 ZK46+963~+965

Jingxi Tunnel

Beilingshan Tunnel

47

48

K20+070~+075

Urban cable Tunnel

A Tunnel on Nanjing Metro Line 2

45

46

104

103

DK34+485

K127+104

Liulangshan Tunnel

43

101

100

99

98

97

102

DK90+850

Serial no. 96

K127+242

Hengchaji Bailu No. 1 Tunnel

Baihe Tunnel

Tunnel entrance section and No. 1 shaft

41

Dongkongdui Tunnel

40

K173+109 etc. Unknown

42

Pusagang Tunnel

Changshu Power Plant Water Intake Tunnel

38

39

DK179+767 DK96+505

Lianhuashan Tunnel

Liangshan Tunnel

36

37

DK230+950

Disaster chainage Unknown

Tunnel

Jiulongjiang Tunnel

Serial no.

34

Table 2.4 (continued)

(continued)

54 2 Classification and Geological Identification of Water and Mud Inrush …

Pimiao Tunnel on Qingdao metro line 2

54

DZK209+390

Guandi hydropower station No. 1 Tunnel

Liweizhai Tunnel

66

67

Right line K43+194

Shizizhai Tunnel

Paiqian No. 2 Tunnel

64

65

K23+133

K0+576

DK125+163 117

116

115

114

113

D8+229~+227

ZK61+290

Water diversion tunnel of Qinglong Power Station

63

111

110

109

108

107

112

ZK27+629

Serial no. 106

ZK61+300

Shamaoshan Tunnel

Yangkou Tunnel

61

LK15+195~+235

62

New Qilin Tunnel

Yufengshan Tunnel

59

60

K2+287 K35+680

Yezhuping Tunnel

Baofuling Tunnel

57

58

Unknown N8+058

Xizhai Tunnel

New Yongchuan Tunnel

55

56

ZSK39+576

Unknown

Qiaoyuan Tunnel

53

Disaster chainage K68+995

Tunnel

Deep and long tunnel of water diversion project from Han river to Wei river

Serial no.

52

Table 2.4 (continued) Tunnel

Yan’an Road-Zhongshan Road Interval Tunnel

Yangbajing No. 1 Tunnel

Ao’zailing Tunnel

No. 2 shaft of Dongzhimen Beixinqiao Interval Tunnel on Capital Airport Line

Bojiwan Tunnel

Shijingshan Tunnel

Dabieshan Tunnel

Namicun No. 2 Tunnel on China-Laos Railway

Ningchan Tunnel

Wangjiazhai Tunnel

Songqinggang Tunnel

Changyucun Tunnel

Disaster chainage

YDK23+603

K3787+397~+415

YK53+723,+665

1st floor transverse passage K0+022, K0+024, K0+028.5

K42+142

1.16 km away from the tunnel exit

YK20+040~+050

ZK20+000~+010

YK20+000~+030

YK19+670~+703

Unknown

Unknown

YK37+500

K22+073

YK2+614

DLI114+043~+042

2.3 Other Category of Hazard-Causing System 55

56

2 Classification and Geological Identification of Water and Mud Inrush …

Fig. 2.8 Schematic diagram of intrusive contact type hazard-causing system

water storage space for the collection of groundwater. Under suitable conditions, the groundwater is enriched in the fracture zone. When the tunnel excavation exposes this section of surrounding rock, water and mud inrush disasters are prone to occur. This kind of hazard-causing system that fissure zones develop in the surrounding rocks due to magmatic rock intrusion and become water-rich, is regarded as the intrusive contact type hazard-causing system, which is prone to water and mud inrush disasters (mainly mud inrush) during later tunnel construction. When the intruded surrounding rock has different water permeability and different water-rich parts, the water and mud inrush situation during tunnel excavation will also change. If magma intrudes into the strong permeable rock formation, the igneous rock is located downstream of groundwater movement, blocking or changing the groundwater migration path, so that the groundwater is enriched or transported in the strong permeable layer. When the tunnel is excavated to the water-rich rock layer in contact with the intrusive rock, water and mud inrush disasters will occur. If magma intrudes into the weakly permeable or water-resistant surrounding rock, the fractured zone in the contact belt is the main water retaining and storage space. When the tunnel is excavated to the fractured zone, water and mud inrush disasters may occur. If the rock fissures in the contact zone between the intrusive rock mass and the surrounding rock are not developed, the groundwater cannot be enriched. In this case, no water and mud inrush disaster will occur. The characteristics of water and mud inrush for the intrusive contact type hazard-causing system are also related to factors such as the occurrence of the intrusive rock mass, the lithology of the intruded

2.3 Other Category of Hazard-Causing System

57

surrounding rock, the degree and type of metamorphism of the contact zone, and the development of fractures caused by tectonic movement in the later stage. Geological identification of the intrusive rock is based on the morphological characteristics of the contact surface between the intrusive rock mass and the intruded surrounding rock. (1) The intrusive rock has a clear boundary with the surrounding rock mass. There are edge zones, condensation edges, and baking edges at the edges of the rock mass. In addition, there are directional fabrics developed; (2) During the intrusion process, the early rock fragments were brought into the magma. Therefore, there are surrounding rock xenoliths in the intrusive rock mass, which are mainly distributed on the edge and top of the intrusive rock mass; (3) There are small rock branches or veins protruding from the intrusive rock mass in the surrounding rock; (4) The surrounding rock near the rock mass has contact metamorphism or alteration, and even contamination, and gradually weakens or shows zoning outward from the contact surface; (5) Intrusive rock walls, veins, etc. cut through the surrounding rock, and the original structures or veins and ore veins oriented in the early rock body were cut.

2.3.2 Structural Fissure Type As the storage space and migration channel of groundwater, the fissures are widely distributed inside the rock formations, and their development scale and connectivity have a great influence on the flow of groundwater. Generally speaking, structural fissure type hazard-causing systems have a high frequency and a long duration of water inflow disasters, but the hazard severity is generally low, so they are often ignored. However, under special circumstances such as abundant groundwater, particularly developed fissures with strong connectivity, and reverse slope construction of tunnels, the structural fissure type hazard-causing system is likely to cause large-area seepage inside the tunnel and flooding of the tunnel face, resulting in suspension of construction and increased construction and treatment costs (Li 2015). The fissures in the rock mass have different properties and characteristics. The open fissures have large water-containing space and strong water conduction capacity, and the closed fissures have small water-containing space and poor water conduction capacity. The hidden fissures basically contain no water and do not conduct water. Therefore, for wide fissures, open fissures, unfilled fissures and fissures with good connectivity, more groundwater can be stored, with fast recharge and migration. Under this condition, the water inflow disaster induced by tunnel excavation is more serious. As shown in Fig. 2.9, according to the different structural positions of the rock strata where the fractures are located, structural fissure type hazard-causing systems are further divided into monocline type, syncline type, and anticline type. Generally speaking, in areas where monoclinic layered rocks are distributed, the fissures gradually close as the depth increases. Therefore, the water-rich property of the aquifer also decreases with the increase of depth, and the water-rich property of deep structural fissures is generally not good. Generally, the aquifer at the

58

2 Classification and Geological Identification of Water and Mud Inrush …

(a) Monocline type

(b) Syncline type

(c) Anticline type Fig. 2.9 Schematic diagram of structural fissure type hazard-causing systems

2.3 Other Category of Hazard-Causing System

59

structural transition part, such as the parts where the strike of the rock strata or the dip of the rock strata changes sharply have better water-bearing property. Due to the development of tensional fissures, a local water-rich zone can be formed. The occurrence characteristics of groundwater in monoclinic rocks are closely related to the inclination angle and lithology of the rocks (Liu 1978). Groundwater permeability has obvious anisotropy characteristics, with a small permeability coefficient perpendicular to the rock layer and a large permeability coefficient along the rock layer (Xu et al. 2011c). When the inclination angle of the monoclinic rock layer is small (generally 65°), the water catchment area of the exposed surface is small, and the supply water source is relatively small; therefore, when the inclination angle of the monoclinic rock layer ranges from 25° to 65°, it is most conducive to the enrichment of groundwater. In addition, groundwater is also likely to accumulate in depressions or valleys with dense torsional fissures, top parts of water barriers, and thin brittle rock layers mixed with thick plastic rock layers. As to the identification of syncline and anticline, it is as follow. From the perspective of topography, if the rock strata have not been weathered and denuded in the later stage, positive terrain peaks are often formed in the anticline, negative terrain valleys are easily formed in the syncline, and the exposed stratum on the surface is the newest stratum. In most cases, however, the top of the anticline is subjected to tension and long-term weathering and denudation to form a valley topography. The syncline axis is not susceptible to weathering and erosion due to the dense rock layers, and the two wings are loose and easily weathered and denuded, thus forming mountainous terrain. That is, weathering and denudation have led to the emergence of “anticlines form valleys and synclines form mountains”. During the formation of folds, due to the differences in the deformation competence of each rock layer, some small folds, joints, small faults, large interlayer scratches, interlayer fracture zones, cleavage, lineation and other secondary small structures are associated or derived. And they are mainly developed from the thin weak rock formations between strong rock formations, or the thin strong rock formations in thick weak rock formations. The subordinate folds located on the wings of the main fold are often asymmetric folds, and their axial planes are at a certain angle with the plane of the main fold. The direction of the acute angle indicates the relative sliding direction of adjacent rock formations, so that the relative sequences of the rock formations and the positions of anticlines and synclines can be determined. When the syncline structure is composed of permeable layers and impermeable layers, the permeable rock layers serve as the water storage space, and the impermeable layers interbedded with the permeable layers or distributed under the permeable rock layer serve as the water-proof boundary. Under this condition, the syncline structure receives water recharge from the exposed surface part and then water migrates and enriches to the axis or wings. The syncline structure is conducive to the collection of groundwater, and its axis is the main area where groundwater is enriched, especially when there is soluble rock, it is likely to form large karst caves and conduits.

60

2 Classification and Geological Identification of Water and Mud Inrush …

Therefore, when the tunnel traverses the syncline axis, water and mud inrush disasters are prone to occur. The longitudinal tension cracks of the fold are perpendicular to the rock layer, and their strike is consistent with the fold axis direction. The cracks open to the convex side of the rock formation and gradually close to the concave side. It is the most developed at the fold axis where the cracks are wide and dense; to the two wings, the fissures become smaller and sparser, and eventually disappear (Zhong 2010). The development of longitudinal tension cracks on the syncline axis is related to the stress conditions. When the confining pressure is not large, longitudinal tension cracks are easy to develop; when the confining pressure is large, structural deformation occurs in the form of plastic rheology or torsional breakage. If the rock layer is not deeply depressed when the folds are formed, the syncline axis may also develop tension fractures. Therefore, for rock formations with uniform water permeability, the axis is rich in water when the axis is buried shallow, and when the axis is deeply buried, the wings are rich in water. In addition, the fracture zone produced by the brittle rock formation during the fold development is also the main water-bearing part. The depth of groundwater enrichment is greater when the scale of syncline development is large and the two wings are relatively gentle. When the scale of syncline development is small and the two wings are steep, the depth of groundwater enrichment is smaller. The syncline structure generally has a large water content. In rock formations with poor water-bearing property and inhomogeneity, the synclinal axis often has high water pressure (Shi 2014; Li 2015). When the aquifers are connected by joint fissures and tensile faults and there is stable surface water recharge, the amount of water inrush during tunnel construction is large and the disaster time is long. In an anticline structure composed of permeable layers and impermeable layers, the permeable layers conduct water, and the impermeable layers act as a water barrier, blocking groundwater drainage channels. With suitable surface water replenishment, groundwater will collect in the permeable layers. At this time, the anticline structure has the water storage capacity, and its water-rich characteristics are affected by the degree of denudation of the anticline, the buried and exposed state of the aquifer, the structural form, and the topographical conditions, etc. Generally speaking, longitudinal tension cracks are developed in the axis of anticline, and the rock is relatively broken. After weathering and denudation, valleys develop along the axis of anticline, which facilitates the collection of groundwater in topography. The fractured development zone can store groundwater, and the impermeable layer prevents the discharge of groundwater, therefore, groundwater is generally concentrated in the axis of the anticline. When the exposed rock layers of the anticline are eroded with a small thickness, the two wings of the anticline and the deep compression zone remain in their original state. If it is not affected by weathering, the fissures will be closed, with poor water permeability, forming a relatively water-resistant layer. Anticline axial tension fissure zone and broken rocks receive surface water supply to form a groundwater storage space. In addition, the ground surface is denuded and presents valley topography, which has good water catchment conditions. As a result, a water-rich zone with tensional fissures of banded distribution in the anticline axis is formed. At this time, the water-bearing property near the axis of the anticline is the

2.3 Other Category of Hazard-Causing System

61

strongest, and the groundwater is not pressure-bearing. Therefore, when the tunnel passes through the anticline axis or the core of the dome with low terrain, it is most prone to water inrush disasters.

2.3.3 Unconformable Contact Type Unconformable contact is a type of contact with sedimentary discontinuities between new and old strata, including parallel unconformable contact and angular unconformable contact. When the underlying stratum of the unconformable contact surface is an impermeable rock layer or a weakly permeable layer that acts as a water blocking layer, the overlying stratum is a strongly permeable layer, and the unconformable contact surface and the fracture zone formed by weathering and erosion provide water storage space. Under good groundwater replenishment conditions, groundwater tends to be enriched near the unconformable contact surface. When the underlying stratum is soluble rock, the karst near the ancient dissolution surface is relatively developed, often forming water-filled caves or pipes. When tunnels are excavated within this range, water and mud inrush disasters are prone to occur. As shown in Fig. 2.10, during tunnel excavation, water and mud inrush occurred due to the water-rich unconformable contact surface and this type of hazard-causing system is called the unconformable contact type hazard-causing system. The greater the contact surface undulates, the more developed the fracture zone caused by weathering and erosion of the contact surface, the easier it is for groundwater to be enriched, and the greater the scale and the disaster severity of the water and mud inrush during tunnel excavation. When the contact surface ancient terrain is low-lying, it is most conducive to groundwater enrichment, such as buried ancient erosion valleys, ancient gullies, ancient depressions, ancient valleys and other negative terrains. The geological identification features of the unconformable contact type hazardcausing system are as follows. (1) Generally speaking, the lithological structures near the unconformable contact surface are relatively complete rock formations above the unconformable surface and semi-weathered rock formations below the unconformable surface; and the unconformable surface contains weathered clay, gravel layer and so on; (2) The bedrock at the lower part of the contact surface has undergone weathering and denudation and is relatively fragmented, with an obvious erosion surface, and this surface often contains basal conglomerate, ancient weathering crust or ancient soil layer, etc.; (3) The occurrence of rock formations above and below the contact surface are different, the stratigraphic age is not continuous, and some strata are obviously missing; (4) The lithology and palaeontology above and below the unconformity surface are obviously different due to the different diagenetic historical periods.

62

2 Classification and Geological Identification of Water and Mud Inrush …

Fig. 2.10 Schematic diagram of unconformable contact type hazard-causing system

2.3.4 Differential Weathering Type The rock weathering fissures are densely distributed and interconnected in an irregular network. They often play a role in water storage and conduction in the hazardcausing system. Since its degree of development decreases with the increase of depth, and the fissures are mostly filled with mud, the water-bearing property is generally relatively poor, and hence the disaster severity of water inrush during tunnel excavation is not very high. However, under some special weathering effects, the geological conditions have changed significantly, such as weathered interlayers and weathered deep troughs formed by differential weathering. These geological structures have significantly intensified the water and mud inrush diaster severity during tunnel excavation and are categorized as the differential weathering type of hazardcausing systems. And they are further divided into weathered interlayer type and weathered deep trough type based on their different shapes (see Fig. 2.11). Differential weathering refers to the different weathering speeds, degrees and depths of rocks that is due to the different physical and mechanical properties of rocks or different geological structures. The weathered interlayer type hazard-causing system mainly refers to the situation where there are severely weathered weatherable rock layers in the middle and the hardly weathered rock layers on the two sides. For example, when there are weatherable rock layers such as granite interbedded in the hardly weathered rock layers such as gneiss. The downward weathering depth of the weatherable rock layers is large due to the severe weathering and hence it has good

2.3 Other Category of Hazard-Causing System

63

Fig. 2.11 Schematic diagram of differential weathering type hazard-causing system

water storage space. At the same time, the unweathered rock at the bottom and the rock formations on the two sides form a relatively water-resistant layer. Under this condition, more groundwater can be accumulated and a hazard-causing system of water and mud inrush is formed. The weathered deep trough type hazard-causing system means that under the long-term effects of differential weathering and weathering forces, the weathering develops rapidly at the weak part of geological weathering, resulting in the deepening of the boundary at the bottom of weathering and the formation of deep troughs or sac-like structures for water storage. And these structures are prone to water and mud inrush during tunnel construction. For example, in the fault zone and the structural fracture zone of the anticline axis, the rocks are relatively broken, which provides good conditions for weathering intrusion. The development depth of weathering fissures can reach 100 m or even deeper. Weathered interlayers or weathered deep troughs are generally filled with weathered debris, clay and other filling media that would flood into the tunnel along with the groundwater after excavation and exposure, causing water and mud inrush disasters. Differential weathering type hazard-causing systems mostly develop downwards from the surface and receive replenishment from atmospheric rainfall, and thus are significantly affected by rainfall. In addition, the hazard scale of water and mud inrush is closely related to the degree of weathering, depth, rainfall and other factors.

64

2 Classification and Geological Identification of Water and Mud Inrush …

2.3.5 Special Condition Type As shown in Fig. 2.12, apart from the above-mentioned hazard-causing systems, when the tunnel passes through the Paleogene, Neogene or Quaternary water-rich sand layer, loess, artificially excavated water-rich space and other special geological conditions, it is also prone to water and mud inrush disasters. The Paleogene and Neogene water-rich sand layers have “poor water stability, poor injectability, poor uniformity, and large deformation” (Zhang et al. 2016), and water and sand inrush disasters often occur during construction. During the construction of loess tunnels, loess will easily lose its structural stability when encountering water, causing water and mud inrush disasters. When tunnels pass through artificially excavated water-rich spaces, such as abandoned mine roadways or mined-out areas, the old kiln water therein is easily connected and flow into the tunnel, thus resulting in water and mud inrush disasters. In addition, the excavation of tunnels under some special terrain, lithology and structure conditions can also cause a certain scale of water and mud inrush disasters, which are collectively categorized as the special condition type hazard-causing systems.

Fig. 2.12 Schematic diagram of special condition type hazard-causing system

2.4 Disaster-Forming Pattern of Water and Mud Inrush Hazards in Tunnel

65

2.4 Disaster-Forming Pattern of Water and Mud Inrush Hazards in Tunnel The disaster-forming pattern is the evolution process of water and mud inrush disasters in tunnel, that is, under the excavation disturbance, the tunnel face gradually approaches the hazard-causing system, and the resistance body changes from “stability to deterioration to failure” and ultimately the water and mud inrush occurs. Through the summary and analysis of a large number of tunnel water and mud inrush disaster cases, according to the difference in the development process and damage characteristics of the disaster, this book divides the water and mud inrush disasterforming patterns into 4 types: directly revealed type, progressive failure type, seepage instability type, and intermittent failure type (Li et al. 2018).

2.4.1 Directly Revealed Type of Water and Mud Inrush As shown in Fig. 2.13, the directly revealed type of water and mud inrush disaster occurs in this way: the tunnel is gradually approaching the hazard-causing system during excavation and finally directly exposes the hazard-causing system, then the water body and the filling medium in the hazard-causing system rush out under the action of gravity and water pressure, and flood into the tunnel, causing water and mud inrush disasters. The characteristics of the directly revealed type of water and mud inrush disasters are as follows. Disaster water sources are mainly static reserves; if the hazard-causing system is exposed, the disaster will happen immediately, with the characteristics of immediacy; the initial stage is more harmful, and it has a greater destructive effect on the construction personnel and equipment at the tunnel face; after the water and mud

Fig. 2.13 Schematic diagram of the directly revealed type of water and mud inrush

66

2 Classification and Geological Identification of Water and Mud Inrush …

inside the hazard-causing system rush into the tunnel at one time, the inrush disaster will come to an end, with relatively weak subsequent damage; it mostly occurs in large-scale hazard-causing systems such as faults, high-pressure water-filled caves, and underground rivers. The scale and intensity of disasters are closely related to the scale of the hazard-causing system and the water pressure.

2.4.2 Progressive Failure Type of Water and Mud Inrush As shown in Fig. 2.14, the progressive failure type of water and mud inrush disaster occurs in this way: as the tunnel is approaching the hazard-causing system, cracks are generated in the resistance body, which gradually develop and penetrate, and eventually lead to the weakening and failure of the resistance body; and then the groundwater and filling medium rush into the tunnel, causing water and mud inrush disasters. The characteristics of the progressive failure type of water and mud inrush disasters are as follows. Disaster water sources are mainly static reserves; the resistance body is usually a water-proof rock body; affected by excavation disturbance, the resistance body is weakened, with cracks generating, developing and penetrating inside until it is damaged and destabilized; before the water and mud inrush, there are water spraying and seepage phenomena. The clear or turbid water quality is related to the filling medium of the hazard-causing system; it mainly occurs in hazard-causing systems such as water-filled caves and underground rivers with good rock integrity and complete resistance bodies.

Fig. 2.14 Schematic diagram of the progressive failure type of water and mud inrush

2.4 Disaster-Forming Pattern of Water and Mud Inrush Hazards in Tunnel

67

Fig. 2.15 Schematic diagram of the seepage instability type of water and mud inrush

2.4.3 Seepage Instability Type of Water and Mud Inrush As shown in Fig. 2.15, the seepage instability type of water and mud inrush disaster occurs in this way: during tunnel excavation, the filling medium in the hazard-causing system produces seepage under the action of high-pressure water, and the fine particles in the filling medium are gradually taken out to form a penetrating seepage channel, which leads to the failure of the resistance body and induces water and mud inrush disasters. The characteristics of the seepage instability type of water and mud inrush disasters are as follows. The filling medium gradation inside the hazard-causing system is relatively reasonable, with good cementation, dense filling and certain permeability; after the hazard-causing system is exposed, the inrush disasters do not occur immediately, which has the characteristics of time-lag. The lag time is related to factors such as the nature of the filling medium, water supply conditions and construction disturbances; before the inrush disasters occur, there are water spraying, water seepage, etc.; the amount of water seepage gradually increases, and the water quality becomes turbid; the filling medium in the earlier stage acts as the resistance body, and when the disaster occurs, the filling medium flows into the tunnel together with groundwater; it mainly occurs in corrosion fissures, karst pipes and faults that are filled with certain permeable medium.

2.4.4 Intermittent Failure Type of Water and Mud Inrush As shown in Fig. 2.16, the intermittent failure type of water and mud inrush disaster occurs in this way: the hazard-causing system where water and mud inrush disasters have occurred, due to the blockage of the water inrush channel, the inrush

68

2 Classification and Geological Identification of Water and Mud Inrush …

Fig. 2.16 Schematic diagram of the intermittent failure type of water and mud inrush

phenomenon has been weakened; however, the groundwater reaccumulates in the hazard-causing system, and when the accumulation reaches a certain level, the disaster water source breaks through the resistance body of the tunnel, causing water and mud inrush disasters again. The characteristics of the intermittent failure type of water and mud inrush disasters are as follows. The hazard-causing system has a large static storage of filling medium (sediment, groundwater, etc.) and a dynamic storage of groundwater (continuous water supply), a large amount of water supply, and an unobstructed supply channel; with the replenishment of water sources such as surface rainfall, the same hazard-causing system may experience two or even multiple water inrush disasters, and disasters occur intermittently; after a disaster occurs, it is easy to ignore the possibility and severity of the secondary disaster, and hence the lack of foresight in the time and scale of the secondary disaster often cause more serious safety accidents; the groundwater inrush channel contains weakly permeable filling medium, with poor permeability. Therefore, after the first disaster occurs, it can effectively block the water inrush channel and continue to store water; this type inrush disaster mainly occurs in the geological structures such as the corrosion fissure, karst pipeline, rock stratum interface zone or cemented compressive fault that are filled with soft plastic clay, sandstone and soil.

2.5 Summary Based on the statistical analysis of 381 cases of water and mud inrush in tunnels in China and the authors’ research results and engineering experiences in water and mud inrush disaster for many years, this chapter proposes a classification system which consists of 3 categories and 11 types of water and mud inrush disasters hazard-causing systems. The 3 categories refer to the karst, fault and other categories. Specifically,

References

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the karst category includes the corrosion fissure type, karst cave type, and pipe and underground river type; the fault category includes the water-rich fault type, waterconductive fault type, and water-resistant fault type; and the other category covers the intrusive contact type, structural fissure type, unconformable contact type, differential weathering type and special condition type. This chapter elaborates on the structural forms, occurrence characteristics and geological identification methods of various types of water and mud inrush hazard-causing systems. And we also propose four types of disaster-forming patterns, i.e., the directly revealed type, progressive failure type, seepage instability type, and intermittent failure type, so as to characterize the development process and the characteristics of water and mud inrush disasters. It is expected to lay the foundation for the research on the detection method, hazardcausing mechanism and disaster control of the tunnel water and mud inrush hazardcausing systems.

References Guo RJ, Ding JF, Liao YK (2013) On the application of comprehensive geological forecasting techniques to karst tunnels. Mod Tunn Technol 50(5):158–163 Jin XF, Xia RY, Lang B (2007) Analysis of bursting water source of Maluqing Tunnel, YichangWanzhou Railway. Hydrogeol Eng Geol 34(2):71–74 Li SC (2015) The theory and method of advance geological prediction for disaster sources of water and mud inrush in tunnels. Science Press, Beijing, 22–56 Li SC, Xu ZH, Huang X, Lin P, Zhao XC, Zhang QS, Yang L, Zhang X, Sun HF, Pan DD (2018) Classification, geological identification, hazard mode and typical case studies of hazard-causing structures for water and mud inrush in tunnels. Chin J Rock Mechan Eng 37(5):1041–1069 Lin CN (2008) Study on prediction and treatment technology of karst fissure water of Qiue Mountain Tunnel. Chin J Undergr Space Eng 4(4):789–729 Liu GY (1978) Water-storage structures in bedrock. J Shijiazhuang Univ Econ 1:19–39 Liu GY (1979) Bedrock groundwater. Geological Publishing House, Beijing Liu ZW, Zhang MQ, Wang SR (2007) Prediction and treatment technology of disaster in karst tunnel. Science Press, Beijing Shi SS (2014) Study on seepage failure mechanisim and risk control of water inrush induced by filled disaster structure in deep-long tunnel and engineering applications. PhD thesis, Shandong University, Jinan Shi SS, Li SC, Li LP, Xu ZH, Wu K, Gao Y, Yuan XS (2012) Comprehensive geological prediction and management of underground river in karst areas. Rock Soil Mech 33(1):227–232 Sun MB (2010) 602 Karst cave treatment in Yesanguan Tunnel on Yichang-Wanzhou Railway. Mod Tunn Technol 47(1):91–98 Xu ZH, Li SC, Li LP, Chen J, Shi SS (2011a) Construction permit mechanism of karst tunnels based on dynamic assessment and management of risk. Chin J Geotech Eng 33(11):1714–1725 Xu ZH, Li SC, Li LP, Chen J, Zhang ZG, Shi SS (2011b) Cause, disaster prevention and controlling of a typical kind of water inrush and lining fracturing in karst tunnels. Chin J Rock Mechan Eng 30(7):1396–1404 Xu ZH, Li SC, Li LP, Hou JG, Sui B, Shi SS (2011c) Risk assessment of water or mud inrush of karst tunnels based on analytic hierarchy process. Rock Soil Mech 32(6):1757–1766 Yuan DX (1994) Chinese Karstology. Geological Publishing House, Beijing, 13–32 Zhang ZG (2006) Techniques to deal with the mud-outburst in a karst in Lazhidong Tunnel. Mod Tunn Technol 43(6):56–59

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Zhang MQ, He ZJ, Xiao GZ, Ren CM (2016) Research on the tunnel engineering characteristics and construction technology of the tertiary water rich sand. J Railway Eng Soc 33(9):76–81 Zhong JX (2010) Study on the risk of water busting hazard in Balangshan Tunnel. Master thesis, Chengdu University of Technology, Chengdu Zhou Y (2015) Study on water inrush mechanism and early warning of filled Piping-type disaster and its engineering applications in tunnels. PhD thesis, Shandong University, Jinan

Chapter 3

Typical Cases and Analysis of Water and Mud Inrush in Tunnels

Based on the statistics of numerous water and mud inrush catastrophic events occurred during tunnel construction, this chapter selects the following typical cases to analyze the geological conditions, the inrush processes, and the causes of the aforementioned 3 categories and 11 types of water and mud inrush hazard-causing systems. The detailed analysis strengthens the understanding of the water and mud inrush hazard-causing system in tunnels and provides references and foundations for analyzing inrush disasters of similar projects that have been built, under construction, or to be constructed. The typical cases in this chapter include: water inflow of corrosion fissure type hazard-causing system in Qiyueshan Tunnel of Lichuan-Wanzhou Expressway, water inrush of karst cave type hazard-causing system in Daba Tunnel of Longshan-Yongshun Expressway, water and mud inrush of underground river type hazard-causing system in Qiyueshan Tunnel of Shanghai-Chengdu West Expressway, water and mud inrush of water-rich fault type hazard-causing system in Baiyun Tunnel of Nanning-Guangzhou Railway, water and mud inrush of water-conductive fault type hazard-causing system in Yonglian Tunnel of Ji’an-Lianhua Expressway, water and mud inrush of water-resistant fault type hazard-causing system in Qiyueshan Tunnel of Yichang-Wanzhou Railway, water and mud inrush of intrusive-contact type hazard-causing system in Xiangyun Tunnel of Guangtong-Dali Railway, water and mud inrush cases of structural fissure type hazard-causing system in Mopanshan Tunnel of Lichuan-Wanzhou Expressway, Daliang Tunnel of Lanzhou-Urumqi High-speed Railway and Xiushan Tunnel of Yuxi-Mengzi Railway, water and mud inrush of unconformable contact type hazard-causing system in Changlashan Tunnel of Qinghai Provincial Highway 309, water and mud inrush of differential weathering type hazard-causing system in Junchang Tunnel of Cenxi-Shuiwen Expressway, and water and mud inrush cases of special condition type hazard-causing system in Pimiao Interval Tunnel of Qingdao Metro Line 2, Taoshuping Tunnel of Lanzhou-Chongqing Railway, and Gangcheng Tunnel of Taiyuan-Zhongwei-Yinchuan Railway (Li et al. 2018).

© Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1_3

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3.1 Typical Cases of Water and Mud Inrush in Karst-Category Hazard-Causing System Karst water is a type of groundwater that exists and migrates in soluble rock formations, which often leads to water and mud inrush disasters in tunnels, and brings serious dangers and severe damages to the safe construction and operation of tunnels. This category of the hazard-causing system has gradually become the main geohazard that restricts the development of tunnels in karst areas. In consequence, vigilance must be strengthened and precautions must be taken during tunnel construction. This section starts from the typical inrush cases of the corrosion fissure type, karst cave type, and pipe and underground river type hazard-causing systems, to elaborate on the hazard-causing geological conditions, the inrush processes, and the root causes.

3.1.1 Typical Case of Corrosion Fissure Type Water and Mud Inrush—Qiyueshan Tunnel of Lichuan-Wanzhou Expressway (1) Project overview Qiyueshan Tunnel is a key project of the Lichuan-Wanzhou Expressway, located 21 km northwest of Lichuan City, under the jurisdiction of Lichuan City, Hubei Province, China. The tunnel starts from the Wulong Temple, Nanping Town in the east, across the Qiyueshan Mountain and Deshengchang trough valley in the middle, and extends to a gulley at 1 km south of the Xiangshuidong Village, Moudao Town in the west, with an overall strike of SE-NW. The left line of the tunnel has a chainage of ZK19+005~ZK22+380, a total length of 3,375 m, and a maximum buried depth of about 567 m. The chainage on the right line of the tunnel is YK326+043~YK330+130, with a total length of 3,386 m and a maximum buried depth of 543 m. The tunnel belongs to a deep-buried extra-long complex karst tunnel. (2) Geographical overview Qiyueshan Tunnel lies in the subtropical humid climate zone. The main climate characteristics are low temperature, short sunshine, cool summer and cold winter, long freezing period; cloudy and foggy, high humidity, abundant rainfall, long rainy season, changeable weather; clear climatic vertical zoning. According to the data from the Lichuan Meteorological Bureau, the average annual temperature of the tunnel area is 12.8 °C, the lowest temperature in the past years is −15.4 °C, and the highest is 35.4 °C. Temperatures are generally the highest from July to August and the lowest from December to January. The average annual precipitation is 1,400 mm, the maximum annual precipitation was 1701.9 mm (1982), and the minimum annual precipitation was 861.0 mm (1966). Precipitation is mainly concentrated from May

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to September, accounting for about 70% of the annual precipitation. The maximum daily rainfall was 166.9 mm (June 25, 1975). The tunnel area surface elevation is 1,100–1,710 m, and the overall terrain is wavelike undulating. There is an underground watershed near the chainage of K20+260. Large-scale funnel-shaped depressions, sloping troughs, and sinkholes are scattered on the mountain surface, and karst caves and underground rivers in the subsurface are well developed. The slope angle of the tunnel entrance is 25° and the aspect is 120°; the slope angle for the tunnel outlet is 40°, and the aspect is 313°. The natural slope angle of the tunnel area is generally 20°–40°. (3) Geological overview The exposed formations in the tunnel area are mainly Upper Paleozoic–Mesozoic (Permian and Triassic systems). The lithology is mainly medium-thick layered limestone and locally interbedded with shale and coal, i.e., it is a typical strong karst aquifer, as shown in Figs. 3.1 and 3.2. The tunnel area is located in the west Hubei fold, where the Lichuan fold of the upper Yangtze platform is in contact with the eastern Sichuan fold of the Sichuan platform, belonging to the NNE tectonic system. The main structural features are Qiyueshan anticline and its associated Qiyueshan fault. The tunnel cuts across the Qiyueshan anticline, which is a dense line-shaped fold extending 226 km. The two flanks of the anticline are asymmetrical, where the dip direction and dip angle of the southeast flank are 115°∠70°, and that of the northwest flank is 320°∠60°. The Qiyueshan fault (F1 ) is developed along the anticline axis, with a length of 70 km and a width of 20–80 m. Its strike direction follows the anticline axis. The fault dip direction and angle are 349°∠45°–60° and part of the fault is nearly vertical. It is a high-dip compressional fault with an offset larger than 200 m. The joints in the same direction with the fault on both sides and the tensional fissures perpendicular to them are well developed. Under the NWW-SEE tectonic stress, longitudinal tension cracks, transverse tension cracks, and “X” shear joints in the same period as the fold are all well developed. (4) Characteristics of the karst water systems The karst water in the tunnel area is controlled by tectonic structures (faults, anticlines) and water barriers at the bottom of the Lower Triassic Daye Formation and in the Middle Triassic Badong Formation. Combined with the characteristics of karst water recharge, runoff, and discharge in the Qiyueshan Tunnel area, there are three karst water systems in the tunnel area. The details are as follows: (1) Deshengchang underground river system: It is developed in the Qiyueshan Anticline west flank of the Lower Triassic Jialingjiang Formation (T1 j), which receives the precipitation from the Deshengchang trough valley. On the west side of the aquifer, there is the breccia limestone of the fourth Lower Triassic Jialingjiang Formation (T1 j4 ), which acts as a water barrier; and on the east side, the shale of the first Lower Triassic Daye Formation (T1 d) acts as a

Fig. 3.1 Geological profile of the Qiyueshan Tunnel of Lichuan-Wanzhou Expressway

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Fig. 3.2 Geological layout of the Qiyueshan Tunnel of Lichuan-Wanzhou Expressway

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water barrier. Groundwater mostly migrates to the northeast (toward the Yangtze River) along with the stratigraphy of the Lower Triassic Jialingjiang Formation (T1 j), and along with the medium-thick layered limestone and breccia limestone of the T1 j formation. The boundary is continuously eroded, forming an underground river channel. Due to erosion, water cuts through the contact areas of the limestone and the breccia limestone in T1 j formation, forming several concentrated discharge points (underground river outlets, such as the Xiangshuidong, Dongxikou, and Longkong), of which the flow rate from the Xiangshuidong reaches 100–1,000 L/s. (2) Nanping dispersed drainage karst water system. It is developed in the Triassic Daye-Jialingjiang Formation on the east flank of the Qiyueshan anticline. The west boundary of the system is Wujiaping Formation shale and coal in the center of the Qiyueshan anticline, and the eastern part is bounded by the Lanheba syncline Badong Formation clastic rock formation, and the southern part is bounded by the underground watershed with the Dayuquan underground river system (Liang 2016). It mainly receives atmospheric precipitation supplied by the carbonate rock in the Triassic Daye-Jialingjiang Formation on the southeast flank of the Qiyueshan anticline. The precipitation penetrates or flows to small underground karst pipes through corrosion fissures developed in the slopes of the eastern Qiyueshan and some small karst troughs and sinkholes. Blocked by the insoluble rock at the bottom of the T1 d Formation, groundwater overflows in karst fissure springs or cave springs along with the contact of T1 j and T2 b on both sides of the tunnel, becoming the source of Meizixi. (3) The karst water system in the core of the anticline: It is developed in the core of the Qiyueshan anticline. Water from the surface trough penetrates into the karst aquifer along faults and karst fissures. Due to its small catchment area and limited migration conditions, no large-scale underground river system has been formed. (5) Water inflow conditions and characteristics During the rainy season in 2014, several water inflows occurred in the chainages of ZK19+750~ZK20+150 and of YK19+740~YK20+155 in the Qiyueshan Tunnel entrance (Figs. 3.3 and 3.4) (Li 2015), causing tunnel flood and construction being shut down for ten times and significant schedule delay. The maximum water inflow rate reached 8.7 × 104 m3 /d. After the tunnel was reopened, the maximum measured inflow rate was 1.153 × 104 m3 /h during the rainy season in 2015, with a maximum predicted inflow rate of 4.15 × 104 m3 /h (based on the historical maximum daily rainfall of 166.9 mm). The water inflow has the following characteristics (Li 2015): (1) It is the typical water inflow of corrosion fissure type. The water inflow channels are mainly karst fissures developed along the formation beddings and local karst pipes that cut through rock layers. The interlayer corrosion fissures have a good hydraulic connection. The results from advanced geological prediction

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Fig. 3.3 Locations of the water inflow spots in the Qiyueshan Tunnel (Li 2015)

and excavation reveal that corrosion fissures are developed in the water inflow section, and there is no large water-filled karst cave. (2) Strong connectivity is developed between groundwater and the surface. The water inflows in the Qiyueshan Tunnel are closely related to surface precipitation. Large-scale water inflows often occurred after excavation, which decreased over time. The amount of water inflow increased dramatically after storms, and then again reduced and eventually stopped. This means that the water flow in the tunnel is closely related to the rainfall and groundwater supply and has a good hydraulic connection. Water inflows after rainfall increase significantly, indicating that water is certainly supplied by the precipitation. It is possible that only part of the branch pipes of the karst spring system are exposed, but the overall water volume is greatly affected by atmospheric rainfall. (3) Water inflow exhibits seasonal characteristics. On consecutive sunny days, the amount of water inflow rate is small or even no water inflow occurs at all. However, once there is rainfall, the water inflow increases significantly after a few hours of rain. The amount of water inflow is positively correlated with precipitation and rainfall intensity. (4) Large water volume and long duration. Because of the first Daye shale formation acting as water barrier, the formations in which the tunnel was excavated becomes the primary karst water drainage channel in the region, and the karst water is mainly of corrosion fissure type. In addition, because of the long rainy season and heavy rainfalls in the tunnel area, karst water inflow events often occur during the construction, resulting in construction interruption or even long-term shutdown, and high pumping and drainage costs.

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Fig. 3.4 Photos of water inflows occurred in the Qiyueshan Tunnel (the top two photos are water inflows from the sidewalls and the bottom two are water inflows from the floor) (Li 2015)

(6) Water inflow conditions and cause analysis The entrance section of the Qiyueshan Tunnel is mainly located in the Nanping dispersed karst water drainage system. It is developed in the Triassic DayeJialingjiang Formation from the southeast flank of the Qiyueshan anticline to the north of Ganyantang. The west boundary of the system is the shale and coal of the Wujiaping Formation in the core of the Qiyueshan anticline; the east boundary is a clastic rock formation in the Lanheba syncline of the Badong Formation; the south is bounded by the underground watershed of the Dayuquan underground river system. The catchment area is about 15 km2 (Liang 2016). The groundwater is mainly supplied by atmospheric precipitation from the carbonate rocks of the Triassic Daye-Jialingjiang Formation on the southeast flank of the Qiyueshan anticline. Atmospheric precipitation forms surface runoff, which infiltrates or flows into small underground karst channels through corrosion fissures developed in the eastern slopes of the Qiyueshan and some small karst troughs and sinkholes in karst depressions, and flows towards northeast to Meizixi along the beddings. Then it is discharged in a series of descending springs in the stratigraphic contact zone of the Jialingjiang Formation and Badong Formation at the foot of the Qiyueshan slope, becoming the source of Meizixi. When the tunnel exposes karst

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fissures or small karst pipes, the tunnel becomes the main drainage channel of the karst water system. The comprehensive advanced geological forecast results also show that the water inflow channels are mainly karst cracks developed along the beddings and karst pipes that cut through rock layers, and the interlayer corrosion fissures have good hydraulic connections. (7) The relationship between tunnel water inflow and rainfall Affected by the combination of the shale barrier in the Daye Formation and the Qiyueshan anticline, the water level at both ends of the tunnel is relatively low. The groundwater level rises from the entrance and exit below the tunnel floor to the core of the tunnel anticline. Water inflow spots are mainly in the contact zone between shale and limestone at the entrance of the tunnel. In addition, the tunnel is in the seasonal fluctuation zone. The groundwater level can rise to more than 50 m above the tunnel floor in the rainy seasons, and drop to lower than the tunnel floor in the dry seasons. In the rainy seasons, the maximum water inflow rate in the Qiyueshan Tunnel exceeds tens of thousands of cubic meters per hour, which is directly affected by rainfalls. After rainfalls, the tunnel water inflow is lagged by 8–12 h, and the measured maximum water inflow rate is several times of the drainage capacity of the tunnel ditch. (8) Estimation of the maximum water inflow rate According to the statistical results of precipitation in the Lichuan area, it is found that the precipitation in this area is concentrated and the rainfall intensity is high. The dry season is from December to February, and the rainy season is from May to September. Largest rainfalls take place from June to August, accounting for about 50% of the entire year. The average annual rainfall is 1,400 mm, with a maximum daily rainfall of 166.9 mm (June 25, 1975) and a local rainfall of 324 mm. Based on the historical maximum daily rainfall, it is estimated that the total maximum water inflow rate of the tunnel is 4.15 × 104 m3 /h, and it can reach 8.06 × 104 m3 /h in extreme cases (rainfall of 324 mm).

3.1.2 Typical Case of Karst Cave Type Water and Mud Inrush—Daba Tunnel of Longshan-Yongshun Highway (1) Project overview Daba Tunnel of Longshan-Yongshun Highway runs between Xihe village of Daba Town and Qijiazuo village of Zejia Town, Yongshun County, Xiangxi Tujia-Miao Autonomous Prefecture, Hunan Province. It is a two-way four-lane long tunnel. The left line extends 2,250 m from the chainage of ZK85+830 to ZK88+080, and the right line extends 2,263 m from YK85+832 to YK88+095. The minimum spacing

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between the left and right tunnels is 12.59 m at the end of the Longshan section, and it is 10.31 m at the end of the Yongshun section. Both ends of the tunnel have very narrow rock pillars in the middle. The left-line tunnel section in Longshan is within a circular curve of R = 1,250 m and A = 491.3 m, and the right-line tunnel section is within a circular curve of R = 1,250 m, A = 596.48 m. The maximum cross slope of the left tunnel pavement is −2% and the maximum cross slope of the right tunnel floor is 2%. (2) Geographical overview Daba Tunnel area belongs to subtropical monsoon humid climate, with clear seasons and abundant rain. The rainy season is from April to August, the average annual precipitation is 1,326–1,468.4 mm, the average annual evaporation is 1,379.02– 1,390.3 mm, and the maximum rainfall is 1,992.7 mm. The tunnel is located in Youshui, the first-level tributary of the Mengdong River Basin. The surface water system of the tunnel area is a tributary or sub-tributary of the Mengdong River. The inlet ditch at the end of Longshan has water all year round. The flow rate of the stream is 50–100 m3 /d, which rises sharply during the rainy seasons. The ditch in the Yongshun exit section is a seasonal stream, and there is no water flow in the dry seasons. The tunnel area is a middle-level mountain stratigraphy caused by tectonic erosion. The terrain is undulating with high hills, steep slopes, and developed ditches. These “V”-shaped ditches have a primary strike direction of north-east, followed by north-west. (3) Geological overview The primarily exposed rocks in the tunnel area are dolomite, dolomitic limestone, marl with limestone, calcareous shale of the Middle-Upper Cambrian (Loushanguan Formation), and limestone, dolomitic limestone, nodular limestone, and marl with calcium shale of the Lower Ordovician (Nanjinguan, Fenxiang, Honghuayuan, and Dawan Formations). The tunnel generally crosses through the north flank of the compound anticline, the core is Cambrian, and the flank belongs to Ordovician. The tunnel segment from K86+660 to the exit is in dolomite and dolomite-limestone of the Middle-Upper Cambrian Loushanguan Formation. The strike of the formation is SE, the dip direction is 125°–135°, and the dip angle is 25°–40°. The section from the entrance to K86+660 is limestone, dolomitic limestone, nodular limestone of the Lower Ordovician, as shown in Figs. 3.5 and 3.6. (4) Hydrogeological characteristics The formations in the tunnel area contain regional strong karst aquifers. Part of atmospheric precipitation recharges the groundwater through karst trenches and karst fissures, and the other part forms surface runoff. Groundwater is stored and flows in joint fissures, especially in karst development areas such as densely jointed zone and fault damage zone. Rock masses are loosened and prone to develop caves and cavities, allowing for ample storage space and abundant groundwater. Due to the development of folds, the karst fissures around the tunnel are very developed. Groundwater is stored and migrated in the joint fissures, which can cause

Fig. 3.5 Geological profile of the Daba Tunnel of Longshan-Yongshun Highway

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Fig. 3.6 Geological layout of the Daba Tunnel of Longshan-Yongshun Highway

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fissure-type water inrush hazards. At the entrance of the Longshan, due to the development of faults, the fault damage zone becomes water storage and conducting channels, which is prone to water inrushes. The survey data show that there are seasonal ditches and karst springs developed in the tunnel area. The groundwater system, in general, belongs to the dispersed drainage karst water system. (5) Water inflow conditions and characteristics Many large karst caves were exposed during the Daba Tunnel excavation, and massive water inflows repeatedly occurred, with a maximum flow rate of 1.4 × 104 m3 /h, as shown in Fig. 3.7 and Table 3.1. On December 6, 2013, at 7 a.m., when the right-line tunnel was excavated to the chainage of YK86+083, a large area collapsed on the right side of the tunnel vault. After the derisk operation, a karst cave about 10 m long, 6 m high and 9 m wide was observed near the tunnel vault and spandrel. The cave had a 45° angle with the tunnel heading direction, extending to the right side of the tunnel vault and spandrel, and the slag from the cave is mud-like. As the excavation reached to the chainage of YK86+145 in the right-line tunnel, the rock began to fall off from the tunnel vault,

(a) Large karst cave

(c) Water inflow from the floor

(b)Water inflow from the side wall

(d) Inlet water inflow

Fig. 3.7 Karst cave and water inflow photos of the Daba Tunnel

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Table 3.1 Overview of disasters occurred in the Daba Tunnel Date

Chainage

June 12, 2013 YK86+083

YK86+145

Disaster description A large area collapsed on the right side of the tunnel vault, and a cave about 10 m × 6 m × 9 m was found at the top. The cave had a 45° angle with the tunnel heading direction, and the slag in the cave is mud-like The tunnel face collapsed and exposed a cave of about 4.5 m long and 6 m wide. The cave had a 45° angle with the tunnel heading direction, and a puddle was formed at the left abutment

May 24, 2014 YK86+140~+200 A large amount of water inflow occurred with a maximum flow rate of 4.14 m3 /s, lasted for 4–5 days before it gradually reduced. Some initial spray got damaged, and uplift was seen in the leveling layer of the surrounding rock

Fig. 3.8 Diagram of the karst caves and water inrush section in right line of Daba Tunnel (Cui and Li 2017)

causing the initial collapse, and created cavities above the tunnel face and the right spandrel, as shown in Fig. 3.8 (Cui and Li 2017). After the derisk operation, a karst cave appeared in the right spandrel, which extended to the left abutment and had an angle of 45° with the tunnel heading direction and formed a puddle in the left abutment. The cave in the right spandrel was about 4.5 m long and 6 m wide, as shown in Fig. 3.9. On May 24, 2014, at 10 a.m., a large water inflow occurred in the Daba Tunnel right line in the chainage of YK86+140~+200 (initial spray completed, second lining not yet started). The water flowed rapidly, with a maximum flow rate of 4.14 m3 /s, and lasted for 4–5 days before it gradually reduced. The inrush damaged part of the initial spray, and there was uplift in the leveling layer of the surrounding rock (Grade 3). In the chainage of YK86+080~+200, due to the wide range of catchment area, after heavy rainfall, a large amount of surface water flowed down the slope, through erosion fissures and fault damage zone, and rushed into the tunnel. Large groundwater infiltration broke the lining and caused floor uplift, which seriously impacted the safety of the project and construction progress. Water inflow characteristics in Daba Tunnel: (1) The water inflow spots were scattered, and the impacted range was small. Drilling revealed many cavities, large water flow spots, karst, fissures, and unfavorable geological bodies. These features were scattered, showing apparent

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Fig. 3.9 Profile diagram of No. 1 and No. 2 karst caves in Daba Tunnel

regional distribution. The area of influence was small, generally no more than a few or a dozen adjacent borehole exploration areas. (2) A good hydraulic connection exists between the left-line and right-line tunnels, but no hydraulic connection exists between the water inflow sections. Influenced by tectonic structures, underground karst caves were mainly developed along with the formation or bedding direction. When the tunnel axis and the tectonic structure direction intersect obliquely, the left-line and right-line tunnels were cut through by tectonic or bedding fissures at the same time. (3) The tunnel is in a vertical downward seepage zone, which is prone to seasonal transit water inflows. (6) Water inflow conditions and cause analysis There are two faults, F2 and F6 , in the water inflow section. Fault F2 has a strike of SE and the dip angle ranges from 35° to 45°. Fault F2 intersects obliquely with the tunnel at the chainage of YK86+130. The damage zone is 15–30 m wide. Fault F6 has a strike of SE, along the slope, and the dip angle ranges from 40° to 45°. Fault F6 intersects obliquely with the tunnel at the chainage of YK86+025, and the damage zone width is 15–20 m. The lithology near the two faults is mainly nodular limestone, and the karst fissures and caves are very developed, which provide good storage space and drainage channels for groundwater. The tunnel surrounding rock is mainly dolomite and limestone, and locally interbedded with shale. Because the tunnel excavation section is in the strong weathering zone, the stability of surrounding rock is poor, and as a result, medium and large-scale landslides are easy to occur and mud inflow is prone to occur in rainy seasons. The Daba Tunnel area belongs to Central Asia’s tropical monsoon humid climate, with abundant rain and rainfall is concentrated from April to August. Therefore, the infiltration of a large amount of surface water during rainy seasons is the root cause and the primary source of water and mud inrush in the tunnel.

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Full-space transient electromagnetic and high-density resistivity precise detection results show that in the detection range, the surrounding rock has poor integrity, karst fissures are developed, and local rock masses are loosened and water-rich. As a result, karst caves are distributed randomly in space, without a complete or large-scale karst water flowing channel. In summary, the water inflow section is controlled by tectonic structures, and karst fissures, pipes, and karst caves developed along the beddings. Good hydraulic connection exists between the left-line and right-line tunnels. The tunnel is located in the vertical infiltration-erosion zone, so seasonal transit water inflows occur frequently. The types of water inflows are diverse, and the amount of water inflow varies with the amount of precipitation. In the chainage section of YK86+080~+200, due to the large area of catchment water, a huge number of surface runoffs along the erosion fissures and fault damage zone flow into the tunnel after rainfall, resulting in broken lining, floor uplift, and seriously affecting the safety of the project and construction progress.

3.1.3 Typical Case of Pipe and Underground River Type Water and Mud Inrush—Qiyueshan Tunnel of Shanghai-Chengdu West Highway (1) Project overview Qiyueshan Tunnel of Shanghai-Chengdu West Highway extends from Qingjiang Village to Baiyangtang Village in Wangying Town, Lichuan City. The geographical coordinate of the entrance is 108°36' 26'' east longitude and 30°11' 15'' north latitude, and the exit is 108°34' 10'' east longitude and 30°10' 49'' north latitude. It is a separated tunnel, with the left line chainage of ZK326+053~ZK330+145, and the right line chainage of YK326+043~YK330+130. The maximum depth of the left line is 354 m and the right 342 m. The entrance elevation is 1,355.45 m, and the exit elevation is 1,424.62 m. The longitudinal slope ratio is 1.697%. (2) Geographical overview Qiyueshan lies at the intersection between Lichuan City and Wanzhou District, Chongqing City, on the western edge of Gaotaiyuan, Western Hubei Province. The landform is a typical karst ridge trough, which is in the tectonic denudation of the middle-high mountain. The mountain strike is NNE, consistent with the regional tectonic and strata direction. The elevation is 1,100–1,830 m. The tunnel area is humid subtropical with a high mountain climate, exhibiting distinct vertical zoning. The average temperature is 12.8 °C and the average precipitation is 1,280.1 mm over years, mainly from May to September (Chen et al. 2003).

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(3) Geological overview The exposed formation in the tunnel area is mainly the Upper Paleozoic-Mesozoic (Permian and Triassic). Permian is composed of coastal to shallow sea phase carbonate rock (including silicious rock) and debris rock, and Triassic is composed of carbonate rock. The tunnel area is in the E’xi bulge fold zone where the Lichuan fold belt of the Upper Yangtze Platform and the Chuandong fold belt of the Sichuan Platform Depression come into contact and belongs to the NNE tectonic system. The primary tectonic terrain is the Qiyueshan anticline and the companion Qiyueshan fault, seen in Figs. 3.10 and 3.11 (Shen et al. 1996; Chen et al. 2003). The tunnel crosses the Qiyueshan anticline as a narrow line-shaped fold, extending 226 km. The two flanks of the anticline are asymmetrical, where the dip directions and angles of the southeast and northwest flanks are 115°∠70° and 320°∠60°, respectively. The tunnel crossing area is in the southwest section of the anticline, where the anticline axial direction is NNE15°. The rock formation east of the two flanks is steep, and gentle west of the flanks. The dip angle of the northwest flank is 35°– 40°, and that of the southeast flank is 72°–85°, partially vertical and upside down. Qiyueshan fault (F1 ) is developed along the Qiyueshan anticline axis, 70 km long and 20–80 m wide. Its strike is entirely consistent with the anticline axis. The fault dip direction and angle are 349°∠45°–60° and the fault is partially vertical. As a high dip compressive fault, the fault offset is over 200 m. The aligned compressive structural planes (joints and splittings) on both sides of the fault and the tensile face of fissure perpendicular to them are all very developed. Under NWW-SEE ground stress, vertical and horizontal tensile fissures and “X” shear joints of the same period with the fold are well developed. (4) Hydrogeological characteristics The tunnel area lies in the Qiyueshan anticline, the bulge fold zone in Western Hubei. The anticline flank is a concentrated groundwater area. The anticline has formed a giant fissure with large width and length due to stress concentration, with bedding fissures open. A strong axial groundwater runoff channel is formed under the combination of boundary conditions and medium permeability (Shen et al. 1996; Chen et al. 2003). Affected by the fold structure and water-resistant formation (in the Badong Formation and lower section of the Daye Formation), the karst water in the tunnel area migrates in three systems: the Longdong underground river (with Qingjiang as the source), the anticline core drainage, and the Macaodong underground river. The Macaodong underground river system is developed at the exit of the Qiyueshan Tunnel and intersects the left-line tunnel at the chainage of ZK329+967. At the intersection, the lowest elevation of the tunnel is 1,413.78 m, and the bottom is about 8 m below the tunnel floor. The cave is about 16 m high, 8 m higher than the tunnel. The tunnel cuts through the cave by about 28 m. In addition, 2 m away from the intersection in the small chainage direction, there is a near-circular deep puddle, with a diameter of about 8 m and a depth of about 5 m, where the underground river

Fig. 3.10 Geological profile of the Qiyueshan Tunnel of Shanghai-Chengdu West Highway

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Fig. 3.11 Geological layout of the Qiyueshan Tunnel of Shanghai-Chengdu West Highway

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direction changes from 190° to 140°. The cave intersects the right line at the chainage of YK329+893, with an elevation of 1,413.77 m and a height of about 16 m. The tunnel cuts through the cave by about 10 m. The bottom of the cave is 10 m below the tunnel floor, and the top is about 6 m above the tunnel roof (Li et al. 2010). Macaodong underground river system belongs to the layer-controlled overflow type karst water system. The main river channel is at the bottom of the middle section of the Jialingjiang Formation near the tunnel exit, and the formation is composed of microcrystalline limestone and microcrystalline dolomite sandwiched loose breccia. Controlled by vertical tensile fissures of the NNE strike, the underground stream of 1.2 km long intersects with the tunnel body. Its inlet is Yangliutang on the south side of the tunnel, and the outlet is Macaodong Cave on the north side of the tunnel. The source of underground river water consists of two parts. One part comes from the surface rainwater through the Yangliutang and Jiaohuadong (the inlet of the underground stream), mountain spring water, and Baiyangtang reservoir discharge. It accounts for 55–60% of the river’s total flow during the flood period. The other part is the atmospheric precipitation in the Hongchuncao and Chenjiacao areas (on the karst platform above the tunnel line). Rainwater penetrates through sinkholes and depressions to form the underground tributary along the transverse tensile fissure. It accounts for 40–45% of the river’s total flow during the flood season. (5) Water inflow conditions and characteristics Rainfall continued in mid May 2006, with the highest rainfall taking place on May 12, reaching 30 mm. Three to four hours after the rain, the water flow rate was 2.5 m3 /s at the Macaodong exit, while the swallet stream inflow at the Yangliutang was 1.05 m3 /s, the Jiaohuadong had an inflow rate of 0.35 m3 /s, and the remaining 1.1 m3 /s was from the underground river tributary, in the SEE direction on the east side of the river. Rainfall on June 17, 2007 was 58.3 mm. On June 18, the water inflow from both tunnel lines was 0.7 m3 /s (infiltrated from the underground tributaries of the east platform). At that time, the water inflow in the left line was 0.56 m3 /s and in the right line was 0.14 m3 /s. Three pumps ran at a rate of 180 m3 /h to keep the water level in the tunnel stable. The flow rate of the Macaodong outlet was 1.58 m3 /s. The swallet stream outlet of the Yangliutang—Jiaohuadong was flooded, so its flow rate was unobservable, but the estimated flow rate was 1.6–1.7 m3 /s. On June 22, the daily rainfall was 39.4 mm, and the flow rate of Macaodong was 1.54 m3 /s. The water flow in both tunnel lines was 0.45 m3 /s, and the amount of water discharged from the Yangliutang swallet stream outlet (including the water discharged from the Jiaohuadong to Yangliutang) was 0.9 m3 /s. (6) Water inflow conditions and cause analysis The tunnel is located in the groundwater seasonal variation zone and intersects with the primary channel of the Macaodong underground river at an angle of 125°. The cavity is 7–27 m wide and 15–22 m high. The flow rate of the underground river is 100–200 L/s in the dry season. The water level of the main channel is 7.5–9.7 m lower than the tunnel floor, but it is higher than the tunnel floor in the rainy season, especially after continuous heavy rain. From June 16 to 22, 2007, seven consecutive

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days of rain brought a total precipitation of 230 mm, and the main underground river surface elevation reached 1,418.11 m. The water level was higher than the tunnel floor and merged with the underground tributaries that flew out of the tunnel. Underground river flows are closely related to the rainfall, which is very sensitive. The water source of the Macaodong underground river is still composed of two parts during the flood period. One is the surface water from the Yangliutang swallet stream, and the other is the underground river tributary of the east platform, where the underground water flows along fissures of the SEE strike. Swallet stream collects an extensive range of surface water and is an essential source of underground river recharge. The blockage of a part of the underground river channel causes the underground river level to rise, which is the main reason for the underground river inflow into the tunnel. The maximum flow rate of the underground river outlet was 2.5 m3 /s on May 12, 2006. While in the same period of 2007, under the conditions of increased rainfall, surface ponding and abundant recharge of underground river water sources, the maximum flow rate measured by the same method was only 1.6 m3 /s, and 0.9 m3 /s less than a year ago, indicating that some sections of the underground river were blocked and the drainage capacity was relatively weakened. With 58.3 mm of rainfall on June 17, 2007, the estimated supply for Macaodong was 20.0 × 104 m3 /d, while the underground river outlet flow was only 13.8 × 104 m3 /d (1.6 m3 /s). Based on the estimation, 6.2 × 104 m3 of water could not be discharged downstream through the Macaodong in one day on June 17 but had accumulated in surface depressions and expanded into ponds. As the water level of the swallet stream raised, the water pressure increased, and the water level in the underground river was bound to grow, hence water inflowed into the tunnel. Therefore, the heavy rainfall and the blockage of Macaodong river channels led to a smaller cross-section and the aggravation of bottlenecks. Poor drainage is the main reason for flooding of large farmlands on the surface, the rising of the underground river level, and the tunnel water inflow during this rainfall period. (7) Underground river blockage analysis On the afternoon of June 22, 2007, the level of Macaodong underground river was 0.8 m lower than the tunnel floor. At that time, the surface water at the Yangliutang—Jiaohuadong was converging, and the water level was 1.67 m higher than the underground water level in the tunnel. On the morning of June 23, the underground river level in the tunnel dropped by 3.15 m, and a large amount of water near the Yangliutang had receded. The water level of the small pond at the swallet stream entrance dropped by 3 m compared with the previous day and was 1.84 m higher than the underground river level in the tunnel. In the Jiaohuadong area, there was still a lot of water due to poor drainage. Some flowed into the Yangliutang, and the water surface dropped only by 0.82 m. From the monitoring results, it can be seen that: first, the underground river level in the tunnel was 1.65–1.9 m lower than the entrance of the Yangliutang swallet stream, with a hydraulic slope of 3.6‰, the two water levels rose and fell simultaneously, and the decline range was the same (3–3.15 m). This indicated that the underground river channel from the Yangliutang to the tunnel was smooth. The blockage of the underground river should be located in the section from

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the tunnel to the Macaodong. Second, the surface water in the Jiaohuadong area gradually separated from the Yangliutang water body, forming a separated residual pond, the water level dropped slowly, and some of the water even flowed to the Yangliutang. It showed that the original water outlet of the Jiaohuadong was seriously blocked, and the blockage should be in the section from the Jiaohuadong outlet to the main channel of the underground river. By analyzing the water level dropping and the receding process from the afternoon of June 22 to the morning of June 23, we can infer that the underground river channel was unobstructed from the Yangliutang to the tunnel. The blockage of the underground river should be in the section from the tunnel to the outlet of the Macaodong, and the blockage of the Jiaohuadong should be between the water outlet of the Jiaohuadong and the main channel of the underground river. The reason may be that during the construction process, buried culverts, landfill slag and slag powder of a stone factory near the Jiaohuadong entered the underground river pipe, resulting in siltation and blockage.

3.2 Typical Cases of Water and Mud Inrush in Fault-Category Hazard-Causing System During tectonic movement, large fault structures are often developed in rock formations, accompanied by small-scale fractures. They are often belt-like to form various fractured zones, also known as faulted zones. Near the fault zone center, the rock formation is often fractured with a large number of cracks, serving as a good storage space and diversion channels for groundwater. Faults sometimes connect aquifers or are exposed to the surface and are connected with surface water systems, thus forming the fault-category hazard-causing system. The number and intensity of disasters induced by such hazard-causing system are second only to the karstcategory in tunnel projects. They are roadblocks for the safe construction of tunnels. The following is an overview of water-rich fault type, water-conductive fault type, and water-resistant fault type water and mud inrush cases, and a discussion of the hazard-causing geological conditions, inflow and inrush processes, and root causes.

3.2.1 Typical Case of Water-Rich Fault Type Water and Mud Inrush—Baiyun Tunnel of Nanning-Guangzhou Railway (1) Project overview Baiyun Tunnel of Nanning-Guangzhou Railway is located in Yun’an County, Yunfu City, Guangdong Province, and is a tunnel with a risk level of Grade I. The tunnel extends 2,285 m from the chainage of DK334+037 to DK336+322 with a maximum

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depth of 234 m. As a double-line single tunnel, it is designed with a travel speed of 250 km/h. (2) Geographical overview The tunnel area is a subtropical humid monsoon climate, with abundant rainfall and an average annual rainfall of 1,586.5 mm, and some years even exceeded 2138.8 mm. Rainfall is mainly from April to October of each year and much less in winter. The tunnel is located on the south bank of the middle section of the Xi River and belongs to the Fengyuan River Basin. (3) Geological overview Baiyun Tunnel is located in a low hilly area. The exposed formations in the tunnel area are mainly quartz sandstone, quartz breccia of the Devonian Dinghushan Group, gray and gray-black glutenite, debris sandstone, powder sandstone, sand shale, and carbon shale of the Triassic Xiaoyunwushan Formation, as shown in Figs. 3.12 and 3.13. (4) Water inflow conditions and characteristics On January 14, 2010, a small water and mud inrush occurred when the upper step of the tunnel reached to DK334+733, and the mud inflow volume was about 200 m3 . Another large-scale inrush took place during dredging, and the volume of mud was approximately 2,000 m3 , and the water inrush rate was about 300 m3 /h. The mud blocked the tunnel face and 150 m behind the working face, as shown in Figs. 3.14 and 3.15. The hazard resulted in five deaths, surface collapse of about 300 m2 and depth of about 20 m. The buried depth of the water and mud inrush spot was about 80 m (Zhou 2011; Zhang et al. 2012). (5) Water inflow conditions and cause analysis The stratum lithology shows that the surrounding rock where water and mud inrush happened is mainly gray-white quartz sandstone with siltstone and shale. Due to the existence of joints, shale and siltstone are soft when in contact with water. The surrounding rock revealed on the tunnel face is gray-white quartz sandstone, solid, weak weathered, full of joints, and of good integrity in general. There are no limestone formations within the tunnel area, so no possibility of developing karst caves. Since shale is a non-soluble rock with poor permeability, it is easy to soften when exposed to water, causing poor engineering stability. Tectonic data show that the water and mud inrush section is close to the Luodong large fault zone. Under strong weathering effect, the tectonic shear zone consists of soil sandwiched breccia and gravel, and is water saturated and in a plastic flow state. In the water and mud inrush section, the regional Luodong large fault zone is just 10 m ahead of the tunnel face. The fault is a combination of two parallel overthrusts (Faults F1 and F2 ) with a distance of 200 m in between, with a dip angle of only 25°. Intense counter-squeezing pressure acts on the area between two faults, forming an extremely fractured shear zone. With strong weathering effect, the fractured zone is

Fig. 3.12 Geological profile of the Baiyun Tunnel of Nanning-Guangzhou Railway

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Fig. 3.13 Geological layout of the Baiyun Tunnel of Nanning-Guangzhou Railway

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Fig. 3.14 Diagram of the mud inrush spot in Baiyun Tunnel (Zhou 2011)

Fig. 3.15 Profile of the mud inrush spot in Baiyun Tunnel (Zhou 2011)

mixed with soil and gravel, water saturated in a plastic flow state, resulting in a quick collapse and water and mud inrush (He 2016). Hydrogeological conditions show that the Fault F1 surface is low and easy to store abundant groundwater. From the engineering geological view, the mud inrush spot has a buried depth of about 80 m, and the surrounding rocks are siltstone and shale, which are prone to weathering and softening when exposed to water. When mud inrush happened in the tunnel, the upper surrounding rock collapsed. To summarize, when the tunnel approached the Fault F1 and the thickness of the resistance body was less than the minimum safety thickness, and then the resistance body of tunnel was broken under groundwater pressure and saturated plastic flow

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soil mixed with breccia and gravel. As a result, groundwater carrying silt, mud, and rocks rushed into the tunnel in a short period, causing water and mud inrush disasters.

3.2.2 Typical Case of Water-Conductive Fault Type Water and Mud Inrush—Yonglian Tunnel of Ji’an-Lianhua Highway (1) Project overview Ji’an-Lianhua Highway is located in the west section of Jiangxi Province of Quanzhou-Nanning expressway, which is the 15th East-West horizontal expressway line of China’s national expressway “7918” network. Yonglian Tunnel (formerly known as Zhongjiashan Tunnel) is designed as a separated tunnel, extending from Yongxin County, Ji’an City to Lianhua County, Pingxiang City. The left line runs 2,486 m from ZK90+349 to ZK92+835, and the right line extends 2,494 m long from YK90+335 to YK92+829, with an average buried depth of 180 m. (2) Geographical overview The tunnel lies in the middle of the Luoxiao Mountains, which is a hilly area. The mountains are rolling, the terrain is undulating. The ridge direction is roughly northsouth. The highest elevation in the territory of the Shimen Mountain is 1,300.5 m, the slope of low mountains ranges from 15° to 30°. Along the tunnel axis from the entrance, the ground elevation gradually increases, with slightly wave-like fluctuations. The tunnel area is in a subtropical monsoon humid climate, with abundant rainfall and four distinct seasons. The average annual temperature is 17.5 °C. The frost-free period is 284 days on average. The average yearly rainfall is 1,600–1,700 mm, and the average annual sunshine is 1,697.4 h. (3) Geological overview The exposed formations in the tunnel site are quartz sandstone, sandstone, powder sandstone, pelitic siltstone of the Upper Devonian Shetianqiao Formation, and limy dolomite, dolomite-limestone, and sand shale of the Lower Carboniferous Datangian Stage. The tunnel area is in the fold system of South China, and there are many fractures in the area, as shown in Figs. 3.16 and 3.17. The fault F5 is 200 m away from the tunnel to the left, parallel to the tunnel axis. Influenced by the fault F5 , many secondary fault zones such as F1 and F2 are developed near the tunnel. The fault F2 intersects the left line from the chainage of ZK91+320 to +385, and the right line from the chainage of YK91+360 to +410, of SSE strike. It intersects the tunnel axis with an angle of 45°, dip direction of E and dip angle of 84°. The fault width is about 50–80 m, and the extending length is 520 m. Most terrain is valley. There are many fissures and open cracks in the fault zone, which are poorly

Fig. 3.16 Geological profile of the Yonglian Tunnel of Ji’an-Lianhua Highway

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Fig. 3.17 Geological layout of the Yonglian Tunnel of Ji’an-Lianhua Highway

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integrated and the rock body is damaged or highly broken. The core extraction rate is 55–65%, RQD is less than 10, and the value of [f a0 ] is 400 kPa.1 ,2 (4) Hydrogeological characteristics There are mainly two types of groundwater in the tunnel area. One is fissure water in the clastic bedrock, as the primary groundwater type. The most water-bearing rocks are quartz sandstone, sandstone, powder sandstone, mud sandstone of the Upper Devonian Shetianqiao Formation. A small part of the formation is the sandy shale of the Lower Carboniferous Datangian Stage. The other water type is karst water, distributed near the tunnel exit. The water-bearing formation is limy dolomite, dolomite-limestone of the Lower Carboniferous Datangian Stage. Regional groundwater is mainly from the atmospheric precipitation. Precipitation seeps into the fault damage zone to supply groundwater, and controlled by the topography and rock fissures, it is stored and transported along with the north-south fault zone, ultimately discharged into the Qinshui River. Tunnel is constructed in fault areas or fault impact zones, where the surrounding rock lithology varies. The formation is severely weathered and swelling-prone when exposed to water. The groundwater is abundant, and the water table is about 150 m above the tunnel vault. (5) Water inflow conditions and characteristics From July 2 to August 19, 2012, a total of 8 large-scale water and mud inrush events happened near the left line entrance, with the inflow volume nearly 5.0 × 104 m3 , and the amount of remaining mud in the tunnel is about 1.7 × 104 m3 . From August 12 to October 25, 2012, seven large-scale water and mud inrushes occurred in the right line, with a volume of about 2.39 × 104 m3 , and the amount of residual mud in the tunnel is about 2.25 × 104 m3 . The inrush details are listed in Tables 3.2 and 3.3 (Li 2015). Fifteen times of water and mud inrushes occurred in the Yonglian Tunnel from July to October 2012, with a total volume of 7.32 × 104 m3 , of which water was 3.36 × 104 m3 and mud was 3.96 × 104 m3 , as shown in Fig. 3.18 (Li 2015). The water and mud inrushes in the tunnel caused large-scale surface collapses, as shown in Fig. 3.19 (Li 2015). The surface depression on the top of the mountain is an irregular oval, about 52 and 33 m in diameter, 1,300 m2 in area, and 14–35 m in depth, which is a severely weathered fault damage zone. (6) Water inflow conditions and cause analysis Tunnel water and mud inrush is closely related to the formation lithology, geological structures, and groundwater. The conditions and causes of the Yonglian Tunnel water and mud inrushes are analyzed as follows. Most of the tunnel surrounding rocks are siltstone, argillaceous sandstone, and shale. They are severely weathered and prone to disintegration, softening and 1 2

RQD refers to rock quality designation. [f a0 ] refers to basic allowable value of bearing capacity.

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Table 3.2 Inrush details of Yonglian Tunnel left line (Li 2015) Date and time

Large-scale water/mud inflow and inrush in the left line Frequency/order

Description

Water/mud volume (residual mud volume)/m3

July 2, 2012, 23:30

First

Water/mud inrush

2,000 (600)

July 3, 2012, 4:20

Second

Water/mud inrush

5,000 (1,200)

July 3, 2012, 10:50

Third

Water/mud inrush

30,000 (3,000)

July 15, 2012, afternoon

Fourth

Mud inrush

1,100 (1,100)

July 24, 2012, 14:30

Fifth

Mud inrush

4,000 (4,000)

August 13, 15, 19, 2012

Sixth–eighth

Mud inrush

4,200 (4,200)

Other times

–

–

3,000 (3,000)

Total

8

–

49,300 (17,000)

Table 3.3 Inrush details of Yonglian Tunnel right line (Li 2015) Date and time

Large-scale water/mud inflow and inrush in the right line Frequency/order Description

August 12, 2012

First

Water/mud volume (residual mud volume)/m3

Water/mud inrush 1,100 (600)

September 19, 2012, 11:00 Second

Water/mud inrush 3,000 (2,100)

September 23, 2012, 16:00 Third

Mud inrush

September 29, 2012

4,200 (4,200)

The surface collapsed on a large scale, and the final sinkhole exhibited as an irregular elliptical shape, with an area of about 1,300 m2 and a depth of 14–35 m

October 1, 2012

Fourth, fifth

Mud inrush

2,200 (2,200)

October 7, 2012

Sixth

Mud inrush

4,900 (4,900)

October 25, 2012

Seventh

Mud inrush

8,500 (8,500)

Total

7

–

23,900 (22,500)

Fig. 3.18 Photos of tunnel water and mud inrush (Li 2015)

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Fig. 3.19 Photos of surface subsidence (Li 2015)

argillization when encountering water, and have hydrophilicity, expansibility and disintegration. In general, the rocks are weak swelling rocks with poor engineering stability. Fault F2 cutting through the tunnel is the main cause for water and mud inrushes. The left line of the tunnel encounters Fault F2 from the chainage of ZK91+310, which is dominated by fault mud and fault breccia. Fault F2 and F5 constitute a complex form of tensile transition, and the rock mass in the faulted zone is highly broken, which is conducive to groundwater storage and transport. The direct source of water and mud inrush is the fissure water in the fault damage zone, which mainly comes from the atmospheric precipitation. Groundwater is directly replenished with sandstone pore water and fissure water on both sides of Fault F2 , especially the formation of the Shetianqiao Formation between Faults F2 and F3 . The formation is tilted towards the inlet, located on the hanging wall of the high-angle inverse fault. It is developed with a certain width of broken zone under tectonic stress, which contains abundant groundwater and continuously supplies Fault F2 in the form of sandstone fissure water. And this is confirmed by the results of the hydrochemistry analysis. Rainfall and surface catchment range in the tunnel area are also two of the fundamental causes for water and mud inrush disasters. Faults F2 and F5 and their broken zones extend to the mountain top surface, forming ditches or depressions under the effect of long-term weathering erosion and water erosion, becoming surface water pooling areas, and many tectonic ditches and valleys converge to form catchment areas. The Plum rain season is rich in precipitation, and the persistent heavy rainfall provides an abundant water supply for the tunnel. To summarize, Fault F2 is filled with soil and mixed with a small amount of breccia, which becomes muddy easily in contact with water. At the same time, many nearby fault zones are overlapped, providing channels for the large groundwater circulation. Once the excavation cuts through the Fault F2 zone during the heavy rainfall season, weak points still exist even with reinforcement in advance. The entire mountain groundwater will flow into the vulnerable zones, increasing the water content in the fault and the plasticity of the mud. This state continues to expand to the weak areas,

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facilitating the pooling of abundant groundwater to the weak locations, forming a vicious circle, and resulting in large-scale water and mud inrush disasters.

3.2.3 Typical Case of Water-Resistant Fault Type Water and Mud Inrush—Qiyueshan Tunnel of Yichang-Wanzhou Railway (1) Project overview Qiyueshan Tunnel of Yichang-Wanzhou Railway is located 23 km northwest of Lichuan City, Hubei Province, and is one of the eight risk level-I tunnels on the Yichang-Wanzhou Line. The tunnel starts from Leyuangou, Yecha town, to the northwest through the Qiyueshan and the Jingzhuyuan platform. The exit is in Xiazhenzui of Baizhanggou. The tunnel extends 10,528 m from the chainage of DK361+255 to DK371+783, with a maximum depth of 670 m. The tunnel is single-sided descent from the entrance to the exit, with a slope of −13‰, −15.3‰, −6‰ (Tian et al. 2006). A parallel pilot pit with a total length of 10,581 m is built 30 m to the left of the tunnel, aligned with the tunnel slope. (2) Geological overview The crossing section of the Qiyueshan Tunnel is divided into the middle mountain area (from inlet to DK364+900), the middle of the valley (from the chainage of DK364+900 to DK365+150), and low/middle mountain areas (from the chainage of DK365+150 to outlet). The three regions correspond to the Qiyueshan tectonic erosion landform, the central landform of the Deshengchang erosion U-type Valley, and the western denudation landform of clastic rock. Among them, the Deshengchang U-type Valley is a narrow-striped spread, with a length of about 68 km, as shown in Figs. 3.20 and 3.21. The formations cut by the Qiyueshan Tunnel are the Lower and Middle Jurassic Shaximiao Formation, Xintiangou Formation, Ziliujing Formation, and Zhenzhuchong Formation; and Triassic Xujiahe Formation, Badong Formation, Jialingjiang Formation, Daye Formation; and Permian Changxing Formation, Wujiaping Formation, and Maokou Formation. The soluble karst section is 4.7 km long, accounting for 45% of the total length of the tunnel, and all soluble rocks are distributed near the tunnel inlet (Tian et al. 2006). The main geological structures around the Qiyueshan Tunnel are the Qiyueshan anticline, Deshengchang trough valley, and Jianzhuxi syncline, as well as other fifteen faults. The primary unfavorable geologies include karst, fault damage zone, natural gas and coal-bearing gas strata, high ground stress and high ground temperature area. The karst stratum in Qiyueshan anticline and the high-pressure water-rich fault F11 in Deshengchang Trough Valley are two major challenges during tunnel construction (Wang and Miao 2010).

Fig. 3.20 Geological profile of the Qiyueshan Tunnel of Yichang-Wanzhou Railway

104 3 Typical Cases and Analysis of Water and Mud Inrush in Tunnels

Fig. 3.21 Geological layout of the Qiyueshan Tunnel of Yichang-Wanzhou Railway

3.2 Typical Cases of Water and Mud Inrush in Fault-Category … 105

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3 Typical Cases and Analysis of Water and Mud Inrush in Tunnels

Fig. 3.22 Diagram of Fault F11 in the Qiyueshan Deshengchang

The Fault F11 near the Qinjiayuanzi consists of several minor faults with a width of 0.2–0.3 m. The central fault zone is from the tunnel chainage of DK365+110 to +340, with a width of 230 m, developed in the junction of soluble rock (limestone, breccia-limestone) and non-soluble rock (shale, marl). The fault cuts through the tunnel vertically, and the surface exposed is between DK365+030 to +145. The length of the fault perpendicular to the tunnel line is about 45 km. The fault strike direction is 35°–45°, and the dip angle is 50°–70°. The width of the fault damage zone is 60–100 m, up to about 150 m locally. It is a branch of the Deshengchang Reverse Fault (Fig. 3.22). (3) Hydrogeological characteristics Three underground rivers are developed in the tunnel area including Dayuquan, Xiaoyuquan, and Deshengchang. Among them, Deshengchang underground river system is located in the karst trough valley on the west side of the Qiyueshan. It is the most extensive groundwater system in the tunnel area. The underground river is about 25 km long and extends to the northeast. At the foot of the Qiyueshan, there are two outlets named Tangfang Xiangshuidong and Dongxikou. The elevation of the Tangfang Xiangshuidong outlet is 900 m; the elevation of the Dongxikou outlet is 890 m; and the outlet flow rates are 4,592.1 and 98.3 L/s, respectively. The inlet of the underground river is in Tianyinqiao, southeast of Moudao, with a flow rate of 168.0–2,581.4 L/s. The primary source of the Deshengchang underground river system is atmospheric precipitation, without external water supply. Atmospheric precipitation infiltration is mainly manifested in two ways: first, the atmospheric precipitation in the karst area seeps and flows through depressions and sinkholes like a planar face; second, atmospheric precipitation in the non-karst area flows on the slopes and sinks into ditches, valleys and streams, transforms into the surface runoff then into the karst area, and directly recharges groundwater through sinkholes and swallet stream inlets. Fault F11 is developed in the Deshengchang Trough Valley, similar to a catchment gallery. Groundwater in the surrounding area flows northwards and eastwards

3.2 Typical Cases of Water and Mud Inrush in Fault-Category …

107

after this convergence, eventually discharging into the underground river outlets in Tangfang Xiangshuidong and Dongxikou, forming a complete groundwater system. The trough valley is spread out in a long and narrow band, about 68 km long, divided into two sections. The section from Xiliushui to Xiangshuidong is about 25 km long, 400–600 m wide. The trough valley is tightly closed and facilitates the Deshengchang underground river. The section from Xiangshuidong to Shiluhe is a horizontal open trough valley, and is the discharge outlet of surface runoff and underground karst spring. The valley can be divided into three karst development zones from the surface vertically downwards: strong karst development zone (depth of 0–60 m), medium karst development zone (depth of 60–100 m), and weak karst development zone (depth of 100 m to the tunnel body). The karst in the buried section is mainly composed of karst fissures and pores, with fewer karst caves, and belongs to weak karst development zone. (4) Water and mud inrush conditions and characteristics During the construction, water and mud inrush hazards occurred in the Fault F11 hanging wall, which is a high-pressure water-rich zone. The collapse disaster takes place in the fault core area and brings severe interference to the construction. Details are provided in Table 3.4 (Wang and Miao 2010). (5) Water inflow conditions and cause analysis First, the fault and its impact zone mainly receive the supply of surface rainfalls. Large fault surface is exposed, with large catchment area and sufficient water supply. The Deshengchang Trough valley is equivalent to a catchment gallery with a large catchment area, and its groundwater recharge source is adequate, mainly from atmospheric rainfall. Surface karsts such as depressions, funnels, and sinkholes in the fault area are developed very well, providing good channels for groundwater recharge. Second, the fault is large-scale, with multi-stage activity and secondary fault development. The central zone of Fault F11 is between DK365+110 to +340, 230 m wide, vertically cutting the tunnel. The fault surface is exposed at DK365+030 to + 145. The length of intersection with the tunnel is about 45 km, with a strike of 35°– 45°, and a dip angle of 50°–70°. The width of the fault damage zone is 60–100 m, locally up to 150 m. Third, the fault is high-pressure and water-rich. In the fault core, fault mud is developed as a relative water-sealing zone, so the high-pressure water-rich zone is formed in the hanging wall of the fault. During the tunnel construction, the measured maximum water inflow rate from the drilling boreholes in the tunnel face was 0.18 × 104 m3 /h, and the water pressure was 2.5 MPa. Fourth, the lithology of the fault is complex and the mechanical properties are poor. The footwall of the fault is in contact with soluble rock, which is a mixture of limestone and mud. Karst is well developed, mostly filling type, and the rock mass is soft and broken. The lithology of the hanging wall is mud-limestone sandwiched by calcium shale and mudstone, and the rock mass is even more fractured. The secondary

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3 Typical Cases and Analysis of Water and Mud Inrush in Tunnels

Table 3.4 Qiyueshan Tunnel water and mud inrush events (Wang and Miao 2010) Chainage

Location

Date

Water/mud inrush situations

Parallel pilot tunnel High-pressure water-rich February 25, 2009 Water inflow and sand zone in fault hanging wall blasting occurred during PDK365+313 pre-excavation drilling, the maximum water flow rate of 2,000 m3 /h; Water inrush occurred when the tunnel face collapsed, with a maximum flow rate approximately of 50,000 m3 /h instantaneously, and stabilized at around 1,500 m3 /h after five minutes. The inrush started with murky water and gradually cleared after two days. The mud blocked the parallel pilot tunnel for about 374 m, with a cumulative total volume of about 10,000 m3 Drainage tunnel PSDK0+083

High-pressure water-rich June 20, 2009 zone in fault hanging wall

Parallel pilot tunnel Fault core PDK365+124

Drill jump was frequent during advance drilling; the initial water inflow reached 4,200 m3 /h, the water was turbid, yellow and black; after three days the rate reduced to 1,000 m3 /h, the water became clear, the cumulative flow out of the broken rock was 1,500 m3 . At the same time, the water inflow of the parallel pilot tunnel face at PDK365+313 was gradually reduced to 300 m3 /h

February 24, 2009 Rock revealed as mud limestone and fault mud, surrounding rock was loose and broken, with mylonitic structure. The water rate was about 30 m3 /h. Tunnel vault collapsed, forming an 8 m × 5 m × 3 m hole

3.2 Typical Cases of Water and Mud Inrush in Fault-Category …

109

faults are significantly developed. The fault damage zone consists of tectonic breccia (calcium, mud cementation), mud-limestone, shale, and fault gouge. The fault zone has diverse lithology and complex composition, belonging to the mylonitic granular structure. Locally, a rounding phenomenon exists for breccia, which is loosely bonded with gravel powder clay or gravel, with weak water conductivity, and scratches are visible on the breccia of breccia limestone. The surrounding rock is of low strength, poor stability, and saturated with water. The engineering conditions are further deteriorated under groundwater immersion. Fifth, the Deshengchang groundwater system is complex, and the connection in the fault zone is good. First, surface depression funnels and springs in the fault zone are very developed. In addition, there is good connectivity between vertical formations and formations developed along tectonic structures, and local open fissures become the main water flow channels. Moreover, due to the influence of the fault core as a water-sealing zone, there is no direct connection between the high-pressure waterrich area and the Deshengchang underground river near the surface of the trough area. Tunnel water inflow predicted by the atmospheric rainfall infiltration method is shown in Table 3.5. Table 3.5 Water inflow prediction in Deshengchang Fault F11 and its impact zone Parameter

Fault F11 and its impact zone

Average annual rainfall/mm

1,131.9

T2 b2+3 Slope runoff zone

Maximum rainfall in years/mm

1,701.9

Conversion factor

2.74

Water convergence area F/km2

1.45

1.96

Runoff coefficient of a slope runoff zone

1

0.8

Rainfall infiltration coefficient α

0.2

0.2

Normal water inflow rate in individual sections/(m3 /d)

899

973

Maximum water inflow rate in individual sections/(m3 /d)

1,352

1,462

Predicted recharge supplied by underground river normal flow/(m3 /d)

9,420

Predicted recharge supplied by underground river maximum flow/(m3 /d)

111,817

Predicted normal water inflow rate in the tunnel Q1 /(m3 /d)

11,292

Predicted maximum water inflow 114,632 rate in the tunnel Q2 /(m3 /d)

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3 Typical Cases and Analysis of Water and Mud Inrush in Tunnels

To summarize, F11 fault zone has a large water catchment area and plenty of water supply, with good vertical hydraulic connectivity. In contrast, the fault core is a watersealing zone, and as such a high-pressure water-rich area is formed horizontally on the upper hanging wall. The lithology is complex in the fault damage zone. In general, the surrounding rock is soft and broken, with poor engineering stability. When the tunnel is under excavation, under the action of high-pressure water, local water inflows carried mud and silt out, causing the fault damage zone to gradually destabilize, which in turn led to water and mud inrush disasters.

3.3 Typical Cases of Water and Mud Inrush in Other-Category Hazard-Causing System Karst and faults are the two main adverse geological types that can lead to water and mud inflow and inrush hazards in tunnels. In addition, the fractured zone caused by the squeezing of intrusive rock and its surrounding rock, tectonic fissures induced by folds, unconformable zones in sedimentary rock formations, and weathered deep grooves, are also the advantageous enrichment space of groundwater. If these water storage areas establish hydraulic connections to the ground surface, they are capable of creating a massive water and mud inrush hazard-causing system. These hazardcausing systems are also frequently encountered in the process of tunnel construction, which should be paid enough attention. This section starts from the typical inrush cases from various hazard-causing systems, and then elaborates the hazard-causing geological conditions, the inrush processes, and the root causes.

3.3.1 Typical Case of Intrusive Contact Type Water and Mud Inrush—Xiangyun Tunnel of Guangtong-Dali Railway (1) Project overview Xiangyun Tunnel of Guangtong-Dali Railway is located in Xiangyun County, Dali Bai Autonomous Prefecture, Yunnan Province, and is a crucial railway project. The railway runs from Xiangyun East Station across a slope, enters Xiangyun tunnel in Pingba Village, passes through Pingba and Dashidong villages to the outlet in the vicinity of Wulipo. The tunnel has a length of 6,940 m and a maximum buried depth of 430 m, which is one of the three Level-I high-risk tunnels (at the chainage of D1K144+455). At 30 m to the right of the tunnel, there is a parallel pilot tunnel with a length of 5,600 m, starting from PDK146+377 (corresponding to the main tunnel chainage D1K146+377), and ending at PDK146+025 (corresponding to the main tunnel chainage D1K146+125). The height difference between the parallel pilot tunnel and the main tunnel is 2 m (Zhang 2016).

3.3 Typical Cases of Water and Mud Inrush in Other-Category …

111

(2) Geographical overview The tunnel area belongs to the monsoon climate of the north subtropical north plateau, with constant temperature in winter and spring and rainy in summer and autumn. The average annual rainfall is 810.8 mm, and the average yearly temperature is 14.7°C. The average temperature is 8.1°C in January and 19.7°C in July, and the hour of sunshine is 2,030.2–2,623.9 h. Vertical zoning of climate is apparent, but the horizontal distribution is complex. The tunnel lies in the junction of the Yunnan-Guizhou Plateau and the Hengduan Mountains. The mountains are the remaining veins of Yunling of the Hengduan Mountains, with an overall north-south trend. The terrain is highly undulating, generally west high and east low. The highest peak is the Wuding Mountain to the north, 3,241 m above the sea level, and the lowest is the Gaofengling riverside to the south, 1,433 m above the sea level. The tunnel passes through the watersheds of the Jinsha River, Yuan River, and Lancang River. The region from Chuxiong to Xiangyun belongs to the Jinsha River System, from Xiangyun to Shangjinchang belongs to the Yuan River System, and from Shangjinchang to Dali is the Lancang River System. The main water systems and mountains along the route mostly have a strike of NW or NNW (Zhang 2016). (3) Geological overview The tunnel is in the oblique and composite tectonic zone between the north-south tectonic area of Sichuan-Yunnan and the 歹-shaped tectonic structure of QinghaiTibet and Yunnan-Myanmar (Li et al. 2017). The east side of the tunnel is the northsouth tectonic system of Sichuan-Yunnan, and the west side is the 歹-shaped tectonic system of Qinghai-Tibet and Yunnan-Myanmar. The tunnel is between the vast fault zones of Er’hai deep fault and Xiangguosi Mount fault (Zhang 2016). Influenced by the above geological structures, the Xiaogou fault, the Chaoyangcun fault, the Shangbeiyi fault, the Er’taipo No. 2 fault, and other fractures are developed in the tunnel area. The Xiaogou fault is a reverse fault with a strike of nearly north-south, and the width of the fault damage zone is 50–70 m. Both the hanging wall and footwall of the fault are basalt of Permian layered tuff and limestone. The fault and the tunnel intersect at the chainage of D1K142+750 with an angle of 65°. The Chaoyangcun fault is also a reverse fault with a strike of 63° and a damage width of 30–150 m. The footwall is Permian basalt, and the hanging wall is a thick limestone of the Carboniferous System. The fault intersects the tunnel at the chainage of D1K146+160, with an angle of 40°. The Shangbeiyi fault is a normal fault with a strike of nearly north-south and a width of 30–100 m. The footwall is limestone of the medium-upper Carboniferous, and the hanging wall is limestone and mud-limestone interbedded shale and sandstone of the lower Devonian System Lianhuaqu Formation. The fault intersects the tunnel at the chainage of D1K146+525, with an angle of 79° (Zhang 2016).

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3 Typical Cases and Analysis of Water and Mud Inrush in Tunnels

The Er’potai No. 2 fault is a regional reverse fault with a strike of 44° and a width of 30–70 m. Both the two hanging walls of the fault are limestone and mudlimestone sandwiched shale and sandstone of the lower Devonian System Lianhuaqu Formation. The fault intersects the tunnel at the chainage of D1K147+500 with an intersection angle of 59°, as shown in Figs. 3.23 and 3.24. The surface of the tunnel is covered with eluvium, alluvial, and silty clay (expansive soil), fine-breccia, and gravel soil of the Quaternary Holocene series. The underlying bedrock is gray-brown, gray-yellow basalt sandwiched tuff and limestone of Permian (P1 β); the light gray, dark gray medium-thick layer microcrystalline limestone of Lower Permian (P1 ); the light gray, gray-white microcrystalline limestone locally interbedded silicon, mud-dolomite (strip and thin-layer) of the Upper Carboniferous (C2 ); the light gray, gray-black limestone (thin to medium-thick layerlike), mudstone interbedded shale and sandstone of the Lower Devonian Lianhuaqu Formation; grey-green, gray-brown gabbro intrusive rock and the fault breccia of the fault damage zone in various periods. (4) Hydrogeological characteristics The groundwater in the tunnel area is mainly bedrock fissure water and karst water locally. The water-bearing bedrock is primarily Permian basalt. The karst water-bearing rock group is limestone of the Lower Permian, limestone of the Medium-Upper Carboniferous, and limestone of the Devonian Lianhuaqu Formation, mainly distributed in sections of D1K144+350~+770, D1K144+980~D1K145+110, D1K145+950~D1K146+265, D1K146+400~+550, and from D1K146+730 to the exit. Tectonic fissures, fault damage zones, and intrusive contact zones are the main storage spaces and drainage channels for groundwater. Especially in the fault damage zones, intrusive rock bodies tend to intrude along faults and joints. When the rock is weathered and broken diabase or gabbro, it is easy to form a water-rich hazardcausing system containing mud and silt. The surface water in the tunnel area is mostly seasonal surface runoff, and a small part is perennial stream water. Groundwater is mainly supplied from atmospheric precipitation, recharged through tectonic fissure seepage, and tectonic fissures and fault damage zone are also suitable storage space and transport channel for groundwater. The edge of the deep ditch valley is usually the dispersed drainage area of groundwater. As a result, springs often appear at the fault zone in ditch valleys. (5) Water and mud inrush conditions and characteristics A water and mud inrush disaster occurred when the parallel pilot tunnel was excavated to PDK146+095, resulting in tunnel blockage and equipment damage. The details are shown in Table 3.6 and Fig. 3.25.

Fig. 3.23 Geological profile of the Xiangyun Tunnel of Guangtong-Dali Railway

3.3 Typical Cases of Water and Mud Inrush in Other-Category … 113

Fig. 3.24 Geological layout of the Xiangyun Tunnel of Guangtong-Dali Railway

114 3 Typical Cases and Analysis of Water and Mud Inrush in Tunnels

3.3 Typical Cases of Water and Mud Inrush in Other-Category …

115

Table 3.6 Water and mud inrush event in Xiangyun Tunnel Date and time

Disaster description

September 30, 2016

Strand water flowed from the left and right abutments on the upper steps, and rates were 12 and 15 L/s. The tunnel face is primarily thin layered carbonaceous shale, interbedded with mudstone, with no seepage from the vault at the beginning. Water seepage occurred and gradually became drops, and then linear dripping

September 30, 2016, 21:30

The linear drip at 1 m on the right side of the vault became strand water flow, the volume increased significantly, and the water was turbid, with mud and silt, and smelly. The right side of the vault had intermittent noises, and the rock began to fall off automatically. Three intermittent smoldering sounds were heard during the evacuation, and large amounts of rock and mud and silt gushed out of the tunnel face

September 30, 2016, 21:45

Water and mud gushed to PDK146+420, with a length of 325 m, inrush followed by a large amount of water inflow, about 850 m3 /h, water was turbid and smelly

October 2, 2016, 10:00

The water inflow rate was 410 m3 /h and stable

October 3, 2016

The gushed mud and silt and rocks piled up; the spray truck was pushed out to PDK146+215 (120 m from the tunnel face) and buried; the maximum diameter of the gushed rock was 2.30 m, it was limestone, gabbro, and silt; and the inflow volume was about 6,000 m3

(6) Water and mud inrush conditions and cause analysis From the tectonic conditions, the surrounding rock in the water and mud inrush section was in the erosion contact zone between gabbro with limestone and carbon shale. Limestone was weakly weathered, and gabbro was strongly weathered, carbonaceous shale was soil-like after completely weathered. On the whole, the stratum has serious differential weathering and is easy to soften when encountering water. In addition, the tunnel was near the fault extrusion damage zone of the Chaoyangcun fault, the folds were seriously crumpled, the rock was fractured with poor stability. From the hydrogeological conditions, the groundwater in the tunnel area was mainly bedrock fissure water. However, from June to September 2016, the Yunnan region was rich in rainfall, groundwater was abundant and easily concentrated in the fault damage zone. In particular, the gabbro along the fault and tectonic fissures was irregularly intruded, making the erosion contact zone a perfect storage space and transport channel for groundwater. Based on the advanced geological forecast results, existing methods cannot accurately determine the geological conditions outside the excavation contour of the tunnel face. As the rock formation is nearly horizontal and layers are thin to medium

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3 Typical Cases and Analysis of Water and Mud Inrush in Tunnels

(a) Surrounding rock at the pilot tunnel face

(c) Inflowed rocks and water

(b) Accumulation of silt at PDK146+195

(d) Flood and sediment at PDK146+400 after inrush.

Fig. 3.25 Photos of water and mud inrush events

thickness ( ωC7 > ωC5 > ωC8 . The type and scale of karst water system, advanced geological prediction, regional karst formations, and vertical karst hydrodynamic zoning have the greatest influences on the evaluation of karst tunnel route selection, with a total weight of 68.5%; followed by the horizontal karst hydrodynamic zoning, precursor information, and monitoring and measurement, the sum of which is 23.3%; and the last is the development degree and scale of karst structural planes and excavation and supports, the sum of which is 8.0%.

4.4.4 Grading Criteria The evaluation and grading of karst tunnel route selection is obtained through the expert ratings and the sum of the weight factors as A = [ a1 a2 · · · ai · · · an ]

(4.4)

T

W = ω1 ω2 · · · ωi · · · ωn

(4.5)

S = A·W

(4.6)

4.5 Engineering Application

169

Table 4.10 Evaluation indicators and grading criteria Influence factors

Level grading Level I: 80 ≤ S ≤ 100

Level II: 50 ≤ S < 80

Level III: 20 ≤ S < 50

Level IV: 0 ≤ S < 20

Type and scale of the karst water system

Large underground river system

Small underground river or Conduit-like karst spring

Karst springs

Dispersed drainage system

Regional karst formations

Regional strong karst formations

Regional medium karst formations

Weak and interlayer karst formations

Non-soluble formations

Vertical karst hydrodynamic zoning

Horizontal runoff Deep slow-flow zone zone

Seasonal variation zone

Vertical seepage zone

Horizontal karst hydrodynamic zoning

Drainage zone (region)

Recharge runoff zone (region)

Recharge zone (region)

Others

The development degree and scale of karst structural planes

Strong development

Medium development

Weak development

Not developed

Advanced geological forecast

Totally unreasonable

Unreasonable

Basically reasonable

Reasonable

Monitor and measurements

Totally unreasonable

Unreasonable

Basically reasonable

Reasonable

Excavation and supports

Totally unreasonable

Unreasonable

Basically reasonable

Reasonable

Precursor information

Strong

Medium

Weak

None

where A and W are the expert scoring vector and the weight vector, and S is the grading value of karst tunnel route selection. As listed in Table 4.10, the expert scoring vector can take corresponding values according to the factor level grading.

4.5 Engineering Application The Qiyueshan Tunnel of Lichuan-Wanzhou Expressway is taken as the example to identify the Deshengchang underground river system. Through determining the water catchment area of the Deshengchang underground river and its spatial relationship with the tunnel, the route selection of the Qiyueshan Tunnel is analyzed and evaluated.

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4 Tunnel Route Selection in Karst Region

4.5.1 Project Overview The Qiyueshan Tunnel of Lichuan-Wanzhou Expressway extends from the Zhujiayuanzi Nanping Township to Shaojiwan Moudao Town, Lichuan City, Hubei Province, and is a separated tunnel. The left line of the tunnel ranges from the chainage of ZK19+005 to ZK22+380, with the total length of 3,375 m and a maximum buried depth of 567 m; and the right line ranges from the chainage of YK19+016 to YK22+402, with the total length of 3,386 m and a maximum buried depth of 543 m. It is a deep-buried extra-long karst tunnel. The tunnel area belongs to the combination of the northwest edge of the SichuanHubei-Hunan-Guizhou uplift fold belt and the East Sichuan fold belt of the Sichuan subsidence fold belt. The north edge is obliquely connected and reconnected with the northwest Dabashan arc structure. The tunnel area exhibits a tectonic corrosiondenudation mid-mountain landform, where karst minimal-landforms such as karst trenches, karst troughs, funnels, and sinkholes are developed. The tunnel crosses the Qiyueshan anticline, and the two flanks of the anticline are asymmetrical. The anticline stratum is dominated by medium-thick layered limestone with interbedded shale and coal. Faults are developed near the core of the anticline and are highly developed karst area. Two faults developed in the tunnel site are the Zhongcao Reverse Fault (F1 ) and the Deshengchang Fault (F2 ). Both faults are narrow in the tunnel body and are basically perpendicular to the tunnel route. Karst is developed in the fault zone, and there are possibly large karst caves. The surface water in the tunnel site area is not much, and the groundwater is extremely abundant, mainly karst water and stored in karst conduits. Groundwater is recharged primarily by atmospheric rainfall, which enters the karst aquifer through surface karst depressions and sinkholes, flows through dissolved fissures and conduits, and is finally discharged in the form of karst springs (or underground rivers). The rock formations that the tunnel crosses in sequence are the Triassic Jialingjiang Formation (T1 j) limestone, Daye Formation (T1 d) limestone and thin shale; Permian Changxing Formation (P3 c) limestone, Wujiaping Formation (P2 w) siliceous shale interbedded with coal seam, Maokou Formation (P1 m) limestone, Wujiaping Formation (P2 w) siliceous shale interbedded with coal seam, Changxing Formation (P3 c) limestone; Triassic Daye Formation (T1 d) thin shale and limestone, and Jialing River Group (T1 j) limestone. Among them, the western flank of the Qiyueshan anticline, i.e., the Triassic Daye-Jialingjiang Formation is a solid karst water-bearing rock. The water-bearing structures are mainly karst conduits and underground rivers. Both sides of the underground river are mainly dissolved fissures and small karst conduits, which are very developed. If the design elevation of the tunnel exit is below the groundwater level or in its seasonal variation zone where there is abundant underground water, the construction would encounter severe water and mud inrush disasters.

4.5 Engineering Application

171

4.5.2 The Development Characteristics of Underground Rivers in the Tunnel Area There are three karst groundwater systems within the impact range of the tunnel (from inlet to outlet): Nanping dispersed drainage karst water system, anticline core karst water system, and Tianyinqiao-Deshengchang-Xiangshuidong underground river system. The first two karst water systems did not form a unified, large-scale underground river system but the Tianyinqiao-Deshengchang-Xiangshuidong underground river system has a significant impact on the tunnel exit area. Horizontal extension survey is carried out to analyze the development characteristics of the underground river so as to determine its scale and direction of extension. The features of karst water in the tunnel area are shown in Fig. 4.3. The Tianyinqiao-Deshengchang-Xiangshuidong underground river system is developed in the west wing of Qiyueshan anticline (i.e., the Lower Triassic Jialingjiang Formation (T1 j)) and gathers the precipitation from the Deshengchang trough valley. There are breccia limestones of the Lower Triassic Jialingjiang Formation Member IV (T1 j4 ) on the west side of the aquifer, and shale of the Lower Triassic Daye Formation Member I (T1 d 1 ) on the east side as water barriers. Groundwater mostly moves northeastward (the direction of the Yangtze River) along the Lower Triassic Jialingjiang Formation (T1 j), and continuously flows down along the boundary between the medium-thick layered limestone of the Lower Triassic Jialingjiang Formation (T1 j) and breccia limestone to form underground river conduits. Due to the erosion of the gravel stream, the contact parts of the breccia limestone of the Lower Triassic Jialingjiang Formation (T1 j) and limestone are cut through, forming multiple concentrated drainage spots (underground river outlets, such as

Fig. 4.3 Karst hydrogeological map of Qiyueshan Tunnel site

172

4 Tunnel Route Selection in Karst Region

(a) Dry season

(b) Rainy season

Fig. 4.4 Photos of exposed underground river in the Xiangshuidong

Xiangshuidong, Dongxikou, Longkong). The flow rate of the Xiangshuidong is 100– 1,000 L/s, as shown in Fig. 4.4. The Deshengchang-Xiangshuidong underground river is the largest karst underground river system in the tunnel site. It is located in the Yulong-Guanyinsi-Deshengchang-Xiangshuidong karst trough valley on the west side of the Qiyueshan anticline. It extends about 30 km from north to south, and 4 km from east to west, originates from the surface watershed of Xiliushui at Yulong Township Wangying Town in the south, runs north-east to Tianyinqiao and turns underground, and continues flowing through Yuhuangmiao, Guanyinsi, Lijiayuanzi, Wutongmiao, Tangjiaba, Deshengchang, and Taojiaxinfangzi, and ultimately gets exposed on the surface in the Xiangshuidong Village, Xiaci Township Moudao Town to the west of the Qiyueshan. The east is bounded by the shale at the bottom of the lower Triassic Daye Formation (T1 d) on the northwest wing of Qiyueshan anticline, and the west is bounded by the surface watershed of the clastic rock of the Middle and Upper Triassic. The catchment area of the system is about 96 km2 , of which the non-carbonate recharge area on the west side of the trough valley is about 20 km2 .

4.5.3 Engineering Analogy Five tunnels that cross the Qiyueshan have been built in the tunnel site. According to the construction time, they are the Qiyueshan Tunnel of Yichang-Wanzhou Railway, the Qiyueshan Tunnel of Shanghai-Chengdu West Expressway, the Yujia Tunnel of Chongqing-Lichuan Railway (Bi et al. 2012; Wu 2015), the Qiyueshan Tunnel of Lichuan-Wanzhou Expressway, and the Qiyueshan Tunnel on Moudao connection line of Lichuan-Wanzhou Expressway. The spatial distribution of the five tunnels is shown in Fig. 4.3, and other details are shown in Table 4.11. The five tunnels mainly pass through the strata in the period of karst development in the Shanyuan Age (elevation of 1,100–1,300 m), where the karst is strongly

Jan, 2006–Jul, 2009

Dec, 2008–Dec, 2010

May, 2013–May, 2015

Qiyueshan Tunnel of Shanghai-Chengdu West Expressway

Yujia Tunnel of Chongqing-Lichuan Railway (Qiyueshan Tunnel)

Qiyueshan Tunnel of Lichuan-Wanzhou Expressway Left: 3,375 Right: 3,386

3,491

Left: 4,075 Right: 4,080

567 543

369

355

670

Dec, 2003–Dec, 2009

Qiyueshan Tunnel of Yichang-Wanzhou Railway

10,528

Maximum buried depth/m

Construction time Length/m

Project

Table 4.11 Details of tunnels in the Qiyueshan area

Inlet:1,137.7 Outlet: 1,084.2

Slope change point of the gable slope 1,427.55

Inlet (left/right): 1,355.45/1,355.18 Outlet (left/right): 1,424.62/1,424.45

Inlet: 1,127.1 Outlet: 975.1

Elevation / m

The tunnel exit passes directly through the Macaodong underground river, and the elevation of the river bottom at the intersection is 1,413.781 m/1,413.769 m (left/right line)

Exposed 61 karst caves, 14 water inflow occurred, maximum inflow rate of 11,530 m3 /h in the rainy season

(continued)

The elevation of the Deshengchang underground river is close to the tunnel elevation

Over 50 caves and Macaodong underground underground rivers river branch was exposed. were exposed The bottom of the underground river was lower than the tunnel floor

15 large caves, and nearly a hundred small karst fissures, conduits, and caves were exposed

187 large karst Deshengchang conduits and caves underground river is 220 m were exposed; 8 above the tunnel extra-large water and mud inrushes occurred

Karst development Spatial relationship with the underground rivers

4.5 Engineering Application 173

347

Oct, 2014–Apr, 2016

Qiyueshan Tunnel on Moudao connection line of Lichuan-Wanzhou Expressway

2,960

Maximum buried depth/m

Construction time Length/m

Project

Table 4.11 (continued)

Inlet: 1,275.9 Outlet: 1,320.3

Elevation / m Revealed 15 karst cave groups, the largest one affecting the tunnel by 62 m

The tunnel elevation is much higher than the Deshengchang underground river elevation

Karst development Spatial relationship with the underground rivers

174 4 Tunnel Route Selection in Karst Region

4.5 Engineering Application

175

Table 4.12 Vertical distribution characteristics of karst cave system (Shen et al. 1996) Layer

Elevation/m

Age and elevation/m

Description

The first layer

>1,500

E’xi Age 1,800–2,000 Taiyuan Age 1,400–1,600

Only a few small-scale karsts, mainly small caves, holes, depressions, and inclined conduits at the bottom of the funnels, at the edges of high-level karst basins or troughs

The second layer

1,100–1,300

Shanyuan Age 1,100–1,300

Strongly developed in the Triassic and some Permian strata, many of which are massive in scale, and horizontal conduits and some caves are often relics of ancient underground rivers

The third layer

800–1,000

Shanpen Age 800–950

Clay, collapsed rocks and a small amount of travertine, limited accumulation

The fourth layer

600–800

Yunpen Age 600–700

Complex conduit system, large scale, with sediments and flow marks in the cave

The fifth layer

< 600

–

Karsts developed during the Qingjiang Age, with different forms in different regions

developed, karst caves are large, and some horizontal conduits and underground rivers are crossed, as shown in Table 4.12 (Shen et al. 1996). Specifically, the top of the Qiyueshan (elevation of 1,700–1,800 m) was formed during the Late-Yanshan Movement in the E’xi Age. Vertical karst conduits such as shafts are developed. The Deshengchang trough valley (elevation of 1,300–12,00 m) and the exit of the Xiangshuidong (elevation of 1,100–900 m) were formed during the early Himalayan movement in the Shanyuan Age. Accompanied by sizeable horizontal karst conduits such as the corrosion troughs, karst caves and underground rivers, funnels, sinkholes, sky windows and other steeply inclined karst forms are developed. As shown in Fig. 4.3, Table 4.11, and Table 4.12, although the five tunnels are in the same geological unit, they belong to different karst water systems.

4.5.3.1

Analysis of Karst Water Systems

The karst water system at the exit of the tunnel is taken as an example. The three tunnels’ exits (Qiyueshan Tunnel of Yichang-Wanzhou Railway, Qiyueshan Tunnel of Lichuan-Wanzhou Expressway, and Qiyueshan Tunnel on Moudao connection line of Lichuan-Wanzhou Expressway) crossing the Qiyueshan Mountains are all in the same karst water system, i.e., the Deshengchang underground river

176

4 Tunnel Route Selection in Karst Region

system (Tianyinqiao-Xiangshuidong underground river system). However, they are in different karst hydrodynamic zones. Specifically, the Qiyueshan Tunnel of YichangWanzhou Railway is located between the lower part of the horizontal runoff zone and the upper part of the deep slow-flow zone. Karst is developed but highly uneven. Karst conduits and caves are developed, filled with water and mud with high pressure, as a result, water and mud inrushes are highly catastrophic. The water inrush during the construction period was less affected by rainfall. The Qiyueshan Tunnel of Lichuan-Wanzhou Expressway is in the seasonal variation zone (upper), with karst development. Influenced by the heavy rain in the tunnel site, the water inflow during the rainy season was relatively large. The Qiyueshan Tunnel on Moudao connection line of Lichuan-Wanzhou Expressway is in a vertical seepage zone with strongly developed karst. Mud-filled or water-free caves are often exposed. There was no water inrush disaster during the construction period, but landslides were prone to occur due to the development of karst. The Qiyueshan Tunnel of Shanghai-Chengdu West Expressway and the exits of the Yujia Tunnel of Chongqing-Lichuan Railway are both in the Macaodong underground river system. The Qiyueshan Tunnel is in the horizontal runoff zone (upper), with karst development. The exit section of the tunnel crosses the underground river and was frequently flooded in the rainy season. The gushed water caused the tunnel to be in a repeatedly pumping-flooding-pumping cycle, which seriously impacted the construction. The Yujia Tunnel is in the seasonal variation zone (upper), with karst development. The influence of karst water is significantly weaker than that of the Qiyueshan Tunnel. Therefore, when tunnels are in the same karst water system but in different karst hydrodynamic zones and if karst disasters occur, the types and hazard severity are also different.

4.5.3.2

Analysis of Tunnel Route Selection

From the construction history, the design and construction sequence of the five tunnels crossing the Qiyueshan is as follows: the Qiyueshan Tunnel of YichangWanzhou Railway, the Qiyueshan Tunnel of Shanghai-Chengdu West Expressway, the Yujia Tunnel of Chongqing-Lichuan Railway, the Qiyueshan Tunnel of LichuanWanzhou Expressway, and the Qiyueshan Tunnel on Moudao connection line of Lichuan-Wanzhou Expressway. Compared with the Qiyueshan Tunnel of the Yichang-Wanzhou Railway, Shanghai-Chengdu West Expressway has raised its elevation, from the lower part of the horizontal runoff zone and the upper part of the deep slow-flow zone to the upper part of the horizontal runoff zone. Compared to the Qiyueshan Tunnel of Shanghai-Chengdu West Expressway, the Yujia Tunnel of Chongqing-Lichuan Railway further raised the route elevation, hence the impact of the karst water disaster was greatly reduced. Affected by route elevation, the Qiyueshan Tunnel of Lichuan-Wanzhou Expressway needs to pass through the Deshengchang underground water system

4.5 Engineering Application

177

where the Qiyueshan Tunnel of Yichang-Wanzhou Railway is located. Compared with the Qiyueshan Tunnel of Yichang-Wanzhou Railway, its route elevation has been significantly raised, from the low level of the runoff area to the high level of the drainage area in the karst water system. The degree of being affected by water disasters is significantly reduced, but it is still within the seasonal variation zone. Affected by the rainfall, water inrush in the rainy season has caused a severe impact on the construction. Compared with the Qiyueshan Tunnel of Lichuan-Wanzhou Expressway, the route elevation of the Qiyueshan Tunnel on the Moudao connection line of LichuanWanzhou Expressway was further raised, from the seasonal variation zone (upper) to the vertical infiltration zone. As a result, the construction was basically unaffected by water disasters. However, the extreme development of karsts was prone to cause landslides and other disasters. Therefore, when the tunnel cannot avoid crossing the large-scale karst water system, raising the route elevation and changing its position in the karst hydrodynamic zone is the best way to reduce the disaster severity and change the type of karst disaster. The construction experience of the five tunnels in the Qiyueshan Mountains provided good references for karst tunnel route selection. In addition to the route elevation, it is necessary to consider the development horizon and scale of karst structures and karst water systems and karst hydrodynamic conditions comprehensively. In areas with solid karst development and large-scale karst water systems, priority should be given to placing the tunnel route in the vertical infiltration zone. It should be noted, however, that it is not the shallower the buried depth, the better. Because the degree of karst development is high in the surface area, and it is prone to landslides and other forms of hazards. The optimal tunnel route in karst area should be at the bottom of the vertical infiltration zone above the water table during the water-rich period. In this condition, the tunnel route is the least affected by karst water, and the degree of karst development on the surface is relatively low.

4.5.4 Tracer Test Before constructing the Qiyueshan Tunnel of Yichang-Wanzhou Railway, Chen et al. (2003) conducted dynamic observation of the flow at the inlet and outlet of the underground river system (Tianyinqiao-Deshengchang–Xiangshuidong), which is shown in Fig. 4.5. It can be seen from Fig. 4.5 that the flow rate of this underground river system varies greatly, and its response to precipitation is highly sensitive. Thus, the dynamic type of the underground river system is “sudden change due to rainfall”. The underground river has good connectivity, the main conduit appears to be a single line in distribution, and the conduit system is well-developed, in a large scale. In order to further determine the connectivity of groundwater and the surface catchment area, the research team and the design unit carried out multiple tracer

178

4 Tunnel Route Selection in Karst Region

Fig. 4.5 The flow rates at the inlet and outlet of the Deshengchang underground river system (Chen et al. 2003)

tests in the tunnel area (Yu et al. 2017). The tracer was dropped successively at the inlets of Tuanbazi, Niushiqian, and Wangjiaba underground streams and was received at the Xiangshuidong and the discharge tunnel of the Qiyueshan Tunnel of the Yichang-Wanzhou Railway. Some tracer test photos are shown in Fig. 4.6, and the test results are shown in Fig. 4.7 and Table 4.13. As described in Table 4.13, tracers were dropped at the inlets of the Tuanbazi and Niushiqian underground streams. No tracer was received in the Xiangshuidong, and tracer was received in the discharge tunnel. Researchers dropped the tracer at the entrance of the Wangjiaba underground stream and received it at the Xiangshuidong (Fig. 4.7). It can be inferred from the test results: due to the existence and long-term drainage of the discharge tunnel of the Qiyueshan Tunnel of Yichang-Wanzhou Railway, the underground river water was captured. The original Tianyinqiao-Deshengchang-Xiangshuidong underground river system was divided into two subsystems. They are the Tianyinqiao-Tuanbazi-discharge tunnel system in the south and the Wangjiaba-Taojiaxinfangzi-Xiangshuidong underground river system in the north. The watershed between the two underground river systems is between Wutongmiao Niushiqian and Wangjiaba. Therefore, the groundwater upstream of Niushiqian moves to the discharge tunnel, and the water north of Wangjiaba moves to the Xiangshuidong, as shown in Fig. 4.8. Due to the water discharge of the Qiyueshan Tunnel on Yichang-Wanzhou Railway, the water catchment area of Xiangshuidong (the exit of the Qiyueshan Tunnel of Lichuan-Wanzhou Expressway) was greatly reduced, from previously 96 km2 to currently 33 km2 . Therefore, the extent of karst water inrush disasters was reduced. Through field investigation and measurements, the elevations of the inlet and outlet of part of the underground river system are determined, i.e., the “vertical elevation

4.5 Engineering Application

179

(a) Tracer dropping

(b) Tracer reception Fig. 4.6 Photos of tracer tests

Fig. 4.7 Tracer test results from Wangjiaba to Xiangshuidong

180

4 Tunnel Route Selection in Karst Region

Table 4.13 Tracer test results Dropping location

Receiving location

Reception results

Inlet of the Tuanbazi underground stream

Discharge tunnel and Xiangshuidong

No tracer was received in the Xiangshuidong, but was received in the discharge tunnel

Inlet of the Niushiqian underground stream

Discharge tunnel and Xiangshuidong

No tracer was received in the Xiangshuidong, but was received in the discharge tunnel

Inlet of the Wangjiaba underground stream

Xiangshuidong

Tracer was received

Fig. 4.8 Profile of the Tianyinqiao-Deshengchang-Xiangshuidong underground river system

determination” as shown in Table 4.14. The average hydraulic gradient of the underground river is 1.5%. The upstream section of the underground river (TianyinqiaoTaojiaxinfangzi) is developed relatively smoothly, with a hydraulic gradient of less than 0.5%. The downstream section (Taojiaxinfangzi-Xiangshuidong) is much steeper, with a hydraulic gradient greater than 5%. By hydraulic gradient calculation of the downstream section of the underground river, the elevation of the intersection of the underground river and the tunnel is determined, which is about 1,088 m, and the elevation of the tunnel floor at the intersection is between 1,087–1,091.5 m. Since the location of the inflection point cannot be determined accurately, it is inferred that when the tunnel elevation is close to or lower than the underground river conduits of Xiangshuidong, the risk of water inrush is greater. Table 4.14 Elevation of underground stream inlet and outlet Location

Tianyinqiao

Wutongmiao

Wangjiaba

Xiangshuidong

Elevation/m

1,345

1,290

1,290

900

4.5 Engineering Application

181

4.5.5 Geophysical Prospecting and Investigation Inside the Tunnel Due to the significant risk of water inrush in the tunnel, a water discharge tunnel was designed on the left side of the left line exit to perform “water-discharge and pressure-relieve”, in order to ensure safety of tunnel construction and operation. The relative position of the discharge tunnel and the main tunnel is shown in Fig. 4.9. In addition, a variety of geophysical prospecting methods were used for comprehensive detection, combined with the on-site excavation and exposure survey, the spatial relationship between the underground river and the tunnel can be determined, i.e., the “position detection inside the tunnel”. On July 15, 2013, a karst cave was found in front of the tunnel face of the discharge tunnel at the chainage of LK0+468, as shown in Fig. 4.10. In front of the karst cave (behind the working face of the discharge tunnel), there is a large fissure belt filled with mud, which extends upward from the vault and connects with the karst cave. The karst cave is vertical, water seeping down along the walls, and cold wind with water vapor blowing out. The karst cave extends downward for about 10 m, and no boundary could be seen upward. There is a vertical barrier in the middle of the cave, which divides the cave into two connected segments. Dripping water appears on the cave walls and no water at the bottom, indicating that the water level of the

(a) Photo of tunnel exit

(b) Positions of the tunnel and the discharge tunnel Fig. 4.9 Diagram of the relative position of the tunnel and the discharge tunnel

182

4 Tunnel Route Selection in Karst Region

(a) Karst cave exposed

(b) Inside the cave

Fig. 4.10 Karst cave photos at the chainage of LK0+468

underground river system where the tunnel is located is lower than the bottom of the tunnel. It can be inferred that the karst cave in the discharge tunnel is mainly developed vertically, located above the horizontally developed karst, which can prove that the discharge tunnel is above the Deshengchang underground river. To further determine the spatial relationship between the underground river and the tunnel, advanced geological forecasting work was carried out in the discharge tunnel. According to the analysis of the risk of water inrush in the early stage, longdistance TSP detection in the whole tunnel was conducted, medium-distance transient electromagnetic detection and short-distance geological radar detection were carried out in critical sections. The TSP and transient electromagnetic detection results of the tunnel face at the chainage of LK0+090 are shown in Figs. 4.11 and 4.12. TSP detection results show that the S wave reflection is stronger than the P wave reflection in the range of LK0+072 to +67 and LK0+047 to +024, and the Poisson’s ratio increases and the density decrease suddenly in front of the tunnel face. It is estimated that there is a large amount of fissure water and may be water-containing cavities near the section from LK0+047 to +040. The results of transient electromagnetic detection in the tunnel show that there are two low-resistance areas in front of the tunnel face, located on the left side of LK0+045~+037 and LK0+028~+017 segments, respectively, as shown in Fig. 4.12 (a). Due to the relatively low resistivity, it is inferred to be a water-bearing area dominated by fissure water. The resistivity on the right side of the tunnel face is dominated by high resistance. It is concluded that the surrounding rock is relatively intact, and there is no water. The transient electromagnetic detection results of the tunnel floor are as follows. It can be seen from Fig. 4.12 (b) that there is a large area of low resistance in the range of 18~45 m below the floor at the chainage of LK0+090~+130. Due to the low resistivity, it can be inferred that there are water-bearing areas dominated by fissure water. However, the resistivity below 45 m of the floor is mainly dominated by high

4.5 Engineering Application

Dynamic Density Young's -3 modulus/GPa /(g·m )

Poisson's ratio

Vp /Vs

Velocity /(km·s-1)

Chainage

183 LK0+100

5.24

LK0+050

LK0+000

2.32 2.07 1.60 0.35

0.18 2.66 2.55 60

30

Fig. 4.11 Physical parameters of the TSP forecast results

(a) Tunnel face

(b) Tunnel floor

Fig. 4.12 Contour profile of the apparent resistivity

resistance, and hence the surrounding rock gradually becomes complete, indicating that there is no water. According to the comprehensive detection results of TSP and transient electromagnetic method, the groundwater in front of the work face is dominated by fissure water, which may contain corrosion fissure water, and there is a certain risk of water inflow. The water level of the underground river is lower than the bottom of the tunnel. There is no underground river in front of the tunnel face (at the chainage of LK0+090). Moreover, there is no underground river within 80 m below the floor at the chainage of LK0+090~+130 in the discharge tunnel, and only corrosion fissure water.

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4 Tunnel Route Selection in Karst Region

(a) Left sidewall

(b) Right sidewall

Fig. 4.13 Radar detection results of the sidewalls

Geological radar detection was performed on the left and right sidewalls at the chainage of LK0+120~+115 in the discharge tunnel. The detection depth is 30 m, and the detection results are shown in Fig. 4.13. It can be seen from Fig. 4.13 that the left sidewall (at the chainage of LK0+118~+119) in the discharge tunnel had a strong response at a depth of 7~20 m. It is inferred that karst is developed in the surrounding rock with weak structural planes, corrosion fissures, and a high water content. The right sidewall (at the chainage of LK0+116~+118) in the discharge tunnel had a strong signal response at depths of 3~5 m, 12~15 m, and 20~24 m, with low-frequency reflections and discontinuous phase axis. It is inferred that the surrounding rock in this section is affected by weathering, and the corrosion fissures are developed, containing karst fissure water. But there is no large-scale water-filled karst developed on the left and right sidewalls. Based on the field excavation survey, TSP, transient electromagnetic detection, and geological radar detection results, it is inferred that the Deshengchang underground river is located 80 m below the floor of the discharge tunnel (85 m below the bottom of the main tunnel). According to the relationship between the risk of water inrush and the relative position of the tunnel and the underground river, the tunnel position was changed from the intersection with the underground river (inferred during the survey and design period) to above the underground river (determined during the construction period). Then the risk of water inrush was significantly reduced. In addition, the excavation of the discharge tunnel revealed that the surrounding rock was good, with only a small amount of water seeping into the tunnel. It can be inferred that the exit section of the main tunnel has mere risk of water inflow but no severe water inrush risk. Most of the corrosion fissure water is above the water level of the underground river, and the water inflow is mainly affected by surface rainfall.

4.5 Engineering Application

185

Fig. 4.14 Karst cave at ZK22+070

In the later stage of tunnel construction, when the left tunnel was excavated to the chainage of ZK22+070, a karst cave was exposed at the arch foot, as shown in Fig. 4.14. The karst cave is developed obliquely to the upper right and deviates from the tunnel downward obliquely, and spreads out of the tunnel outline. The depth of the cave was measured to be greater than 60 m. No sound of water was heard when throwing stones into the cave. The visible longitudinal length of the cave is about 20 m, and the width is 4.0~5.0 m. The lateral width of the karst cave developed from the arch foot of the tunnel to the inner side of the tunnel is 1.5~2.5 m. Overall, the sidewalls of the cave extend approximately vertically downwards (Zhou 2016). It can be inferred that the vertical karst cave is a karst layer above the underground river. The karst cave may be connected to the underground river system below through karst conduits and fissures, and the underground river system may be located more than 60 m below the tunnel floor. This is consistent with the detection result from the discharge tunnel floor. According to the comprehensive analysis results of geological survey, engineering comparison, tracer test, tunnel inside detection, and excavation description, it is concluded that the underground river is located more than 85 m below the tunnel floor, and the gushed water mainly comes from corrosion fissures and karst conduits. Furthermore, excavation showed that the estimated results were consistent with the actual situation, which proved the correctness of the identification method for underground river.

4.5.6 Evaluation of Karst Tunnel Route Selection After the three-stage underground river identification of “horizontal extension survey - vertical elevation determination - location detection inside the tunnel” at the karst

186

4 Tunnel Route Selection in Karst Region

segment of YK22+000~+300 (ZK21+988~ZK22+280 for the left line) of the Qiyueshan Tunnel of Lichuan-Wanzhou Expressway, the catchment area of the underground river and its spatial relationship with the tunnel were obtained. The evaluation model was adopted for karst tunnel route selection. The results of the geological survey of the underground river system are as follows. 1. Type and scale of karst water system: This section of the tunnel is located in the development area of Deshengchang underground river (from the chainage of YK22+120 to +270). The tracer test results show that the recharge area is greater than 33 km2 . Therefore, the karst water system type is a large underground river system. 2. Regional karst formations: The tunnel section is located at the west foot of the Qiyueshan Mountain, the southwest flank of the Qiyueshan Anticline, with a length of 300 m. The surrounding rock is thick, medium-thick limestone of the Jialingjiang Formation, which belongs to the regional strong karst formation. 3. Vertical karst hydrodynamic zoning: This section is in the seasonal variation zone, which has a lower degree of catastrophability. 4. Horizontal karst hydrodynamic zoning: The tunnel is in the drainage zone (region) of the underground river but 85 m above the underground river. 5. Development degree and scale of karst structural planes: The survey shows that the rock integrity of this section is poor, the karst is developed, and the overall corrosion is severe. Karst caves were exposed in the left tunnel at the chainage of ZK22+070 and the discharge tunnel at the chainage of LK0+468 (outside the scope of evaluation) during the construction. The other exposed karsts were mainly corrosion fissures. 6. Advance geological forecast: The comprehensive advance geological forecasting method was adopted for detection during tunnel excavation, and the method is reasonable. 7. Monitoring and measurement: The monitoring and measurement methods used in the tunnel excavation process are standardized and scientific. 8. Excavation and support: The tunnel excavation and support plans are scientific and reasonable, and the support is timely. 9. Precursor information: The precursor information of the water inrush is not apparent. Expert ratings and evaluation for karst tunnel route selection are shown in Table 4.15. It can be seen from Table 4.15 that during the survey period, the karst tunnel was evaluated as level II based on the engineering geology and hydrogeological conditions. Therefore, a discharge tunnel was designed next to the left tunnel at the exit to carry out “water-discharge and pressure-relieve”, which is shown in Fig. 4.9. During the construction period, a supplementary assessment of the route selection was performed, and the risk of the tunnel crossing the Deshengchang river was determined to be level III. This assessment provided a theoretical basis for tunnel

Construction period

Survey period

S = 46.34, Level III

Supplemental evaluation

0.101 80

0.320 80

Weight

Score

C2

S = 73.92, Level II

Preliminary evaluation C1

80

Score

Factor

C1 0.480

Factor

Weight

Table 4.15 Expert scoring sheet C2

30

0.101

C3

80

0.151

35

0.095

C4

C3

60

0.050

C5

30

0.151

10

0.163

C6

C4

10

0.063

C7

85

0.143

10

0.030

C8

C5

10

0.077

C9

90

0.075

4.5 Engineering Application 187

188

4 Tunnel Route Selection in Karst Region

construction changes. Therefore, it was determined that there would be no largescale water inrush disasters when the tunnel passes through the underground river development area, and only small water inrushes may occur in the rainy season. Then it was decided to stop the construction of the discharge tunnel, and the discharge tunnel segment that had been excavated was used as a drainage channel for the water inrush in the future. Later, the drainage system in the tunnel was improved by guiding the water inflow inside the tunnel to the discharge tunnel through the transverse tunnel and then discharging outside the tunnel. Furthermore, construction plans such as excavation and support were adjusted accordingly and construction costs were saved.

4.6 Summary The extra-large and large-scale water inrushes of karst tunnels occurred mainly because of the tunnel cutting through channels of the underground river system, or caves or conduits with significant water conductivity and catchment capacity. Therefore, when determining tunnel route in karst areas, fully understanding the geological and hydrogeological background of the tunnel area and distinguishing the types of karst water systems are the primary tasks to reduce or avoid significant karst geological disasters during the construction. Different vertical karst hydrodynamic zones where the tunnel is located would result in different probabilities and characteristics of water inrushes. When the tunnel passes through the seasonal variation zone, heavy rainfall will cause the regional groundwater level to rise, leading to pressurized water and mud inrushes. When the tunnel passes through the saturated area, high pressure and large water inrush may occur, especially when there is an underground river system near the tunnel, which is prone to water inrush, causing serious accidents. In summary, the following four conditions should be avoided when determining tunnel route in karst areas: (1) The tunnel passes through the strong karst zone; (2) There is an extensive karst water system in the karst formations; (3) The tunnel crosses the seasonal variation zone or the water saturated zone; and (4) The tunnel passes through karst caves, conduits, corrosion zones, or various karst structural planes. In terms of the route elevation, the optimal route position in the karst area should be at the bottom of the vertical infiltration zone above the water table during the water-rich period. In this condition, the tunnel is least affected by karst water because the karst is relatively not well developed, and the surface is relatively shallow. If it is unavoidable, special study on karst hydrogeology and evaluation of tunnel route should be carried out before construction. The high-risk sections of tunnel karst water inrush and the potential locations of water inrush should be delineated, and water inrush rates and volumes and pressures should be estimated in advance. The appropriate advance geological forecasting plan should be implemented during construction with suitable water inrush warnings and mitigation plans accordingly.

References

189

References Bi Q, He XY, Liu JB (2012) Route selection for Chongqing-Lichuan Railway. High Speed Railway Technol 3(3):57–60 Cao HP, Wang K (2011) Study on geological route selection for railway tunnel engineering in Karst zone. High Speed Railway Technol 2(1):31–36 Chen HF, Xia RY, Liang B (2003) Characteristics of karstification and its influence on the tunnel gushing in Qiyueshan, west of Hubei Province. Carsologica Sinica 4:33–37 Guo CQ, Tian XZ (2011) A comprehensive forecast of water inflow in karst tunnels-Exemplified by the Zhujiayan karst tunnel. Hydrogeol & Eng Geol 38(03):1–8 Han XR (2004) Karst water bursting in tunnel and expert judging system. Carsologica Sinica 3:47–52 Huang X, Li SC, Xu ZH, Lin P, Chen YC, Nie LC, Pan DD, Wang WY (2018). Tunnel route selection and water inrush precontrol analysis for underground river development areas. China J Highw Transp 31(10):101–117, 140 Li CH (2014) Analysis of geological route selection of railway engineering in karst mountain area. Resourc Environ Eng 28(3):300–303 Li SC, Liu B, Nie LC, Liu ZY, Tian MZ, Wang SR, Su MX, Guo Q (2015) Detecting and monitoring of water inrush in tunnels and coal mines using direct current resistivity method: a review. J Rock Mechan Geotechn Eng 7(4):469–478 Li YL (2001) Principles of geomorphology. Peking University Press, Beijing Lin CN (2008) Study on prediction and treatment technology of karst fissure water of Qiue Mountain Tunnel. Chin J Undergr Space Eng 4(4):789–729 Liu G, Yang ZC, Chen WW, Liang SY, Han WF, Song C (2002). Conditions and influencing factors of occurrence of groundwater inflow and invasion into deep-buried tunnel. J Tianjin Ins Urban Constr 3:160–164, 168 Pei JG, Liang MZ, Chen Z (2008) Classification of karst groundwater system and statistics of the main characteristic values in Southwest China karst mountain. Carsologica Sinica 1:6–10 Shen JF, Li YY, Xu RC (1996) Research on karst in Qingjiang River Basin. Geological Publishing House, Beijing Wang CZ (2009) Research on geological prediction ahead for the karst in Maluqing Tunnel (master thesis). Shanghai Jiaotong University, Shanghai Wu F (2015) Case study on safety risk control for tunnels on Chongqing-Lichuan Railway. Tunn Construc 35(7):658–664 Xia RY, Zou SZ, Tang JS, Liang B, Cao JW, Lu HP (2017a) Technical key points of 1: 50,000 hydrogeological and environmental geology surveys in karst areas of South China. Carsologica Sinica 5:599–608 Xu ZH, Li SC, Li LP, Chen J, Shi SS (2011) Construction permit mechanism of karst tunnels based on dynamic assessment and management of risk. Chin J Geotech Eng 33(11):1714–1725 Yang LZ (1985) Distribution of subterranean rivers in south china. Carsologica Sinica 4(1–2):92–99 Yi LX, Xia RY, Tang JS, Shi J, Luo WQ, Chen Z (2015) Dealing with overestimates of underground river discharge in karst areas of southwestern China. Carsologica Sinica 1:72–78 Yu KB, Xu M, Yan JX, Li J (2017) Application of groundwater tracer tests for karst tunnel investigation-taking Qiyueshan Tunnel of Lichuan-Wanzhou Expressway as the example. Geotech Inv Surv 45(10):46–51 Zhou DY (2016) Study on prediction and treatment technology of karst cave in Qiyueshan Tunnel. Railw Construct Techno 8:87–90

Chapter 5

A Dynamic Interval Risk Assessment Method for Water and Mud Inrush During Tunnel Construction

In order to prevent water and mud inrush disasters during tunnel construction, risk assessment and control have gradually become one of the critical technical problems in tunnel construction. Based on the comprehensive interval fuzzy assessment method, a conceptual model for water and mud inrush risk assessment is established in this chapter. The weight factors of disaster risks are studied in depth, and a tunnel construction permit mechanism is proposed based on the interval risk assessment system. The dynamic interval risk assessment method for tunnel water and mud inrush is easy to deploy and is an effective risk control method on the spot, which makes the risk evaluation of tunnel inrush accidents more reasonable and operable and helps to reduce the economic losses, casualties, and project delays caused by disasters during construction. This method has been successfully applied to the Qiyueshan Tunnel of Lichuan-Wanzhou Highway (Wang et al. 2019).

5.1 Risk Assessment Conceptual Model and Index Rating One of the keys to evaluating the risk of tunnel water and mud inrush by fuzzy mathematical theory is to establish a fuzzy comprehensive evaluation model, that is, to determine the main influencing factors of water and mud inrush risk (Zhang et al. 2011). The main influencing factors of water and mud inrush should be comprehensive, and the model can reflect the fuzziness and hierarchy of the risk influencing factors. To this end, a comprehensive evaluation conceptual model of tunnel water and mud inrush risk by in-depth analysis of the risk influencing factors is established in this section. The occurrence and development of tunnel water and mud inrush is a complex process, with many influencing factors, high randomness and high nonlinear relationship between various factors. Based on the existing studies and analyses, we establish

© Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1_5

191

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5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

a fuzzy interval risk assessment conceptual model of tunnel water and mud inrush, including three hierarchies: destination layer, criteria layer, and indicator layer. The first hierarchy is the destination layer, i.e., the risk assessment and rating of water and mud inrush in tunnels (A). The second hierarchy is the criteria layer, including hydrogeological and engineering geological conditions (B1), tunnel construction factors (B2), and dynamic feedback information (B3). The third hierarchy is the indicator layer of water and mud inrush, also known as the evaluation index system, consisting of 13 factors: unfavorable geology (C1), formation lithology (C2), vertical hydrodynamic conditions (C3), lateral hydrodynamic conditions (C4), topography and geomorphology (C5), rock formation occurrence (C6), bedding and interlayer fissures (C7), surrounding rock grading (C8), advance geological prediction (C9), monitoring and measurement (C10), excavation and support (C11), macroscopic precursory information (C12), microcosmic precursory information (C13).

5.1.1 Hydrogeology and Geological Engineering Conditions 1. Unfavorable Geology The large and medium-sized water and mud inrushes encountered in tunnel construction are related to the underground river, water and mud-filled karst cavity, waterbearing fault, karst conduits, erosion zones, and other unfavorable geologies. Based on the severity of the hazard, unfavorable geology can be divided into four levels: strong, medium, weak, and no catastrophability, as listed in Table 5.1. Table 5.1 Grading levels of unfavorable geology Level

Definition

Strong

A large water-bearing structure above the tunnel floor or a large pressure water-bearing structure below the tunnel floor

Medium

A medium water-bearing structure above the tunnel floor or a medium pressure water-bearing structure below the tunnel floor

Weak

A minor water-bearing structure above the tunnel floor or a small pressure water-bearing structure below the tunnel floor

None

No unfavorable geology exists around the tunnel that might cause water and mud inrush

2. Formation Lithology The formation lithology is one of the essential factors to determine the type and scale of tunnel water and mud inrush, and also one of the necessary conditions for karst

5.1 Risk Assessment Conceptual Model and Index Rating

193

development. Based on the solubility of the formation, it can be divided into four levels: regional strong karst formation, regional medium karst formation, weak and interlayer karst formation, and insoluble formation, as explained in Table 5.2. Table 5.2 Grading levels of formation lithology Level

Definition

Regional strong karst formation

Usually refers to the carbonate rock formations with larger thickness and purer lithology

Regional medium karst formation

Usually refers to the impure carbonate rock formations with large thickness and containing mud, carbonaceous rock, siliceous rock

Weak and interlayer karst formation

Usually refers to thin and impure carbonate rock-based formations interbedded with shale and sandstone

Insoluble formation

Insoluble rocks can generally be considered as reliable water barriers or non-karst layers in carbonate rock areas

Regional strong karst formation usually refers to the carbonate rock formations with larger thickness and purer lithology, such as the limestone of the Lower Cambrian Shilongdong Formation (∈ 1sl ), limestone of the Upper Cambrian Sanyoudong Formation (∈ 3s ), limestone of the Middle-Upper Devonian (D2–3 ), limestone of the Permian (P), and limestone of the Lower Triassic (T1 ). Regional medium karst formation usually refers to the impure carbonate rock formations with large thickness and containing mud, carbonaceous rock, siliceous rock, such as limestone of the Seismic Dengying Formation (Zdy ), and limestone of the Ordovician (O). Weak and interlayer karst formation usually refers to the thin and impure carbonate rock-based formations interbedded with shale and sandstone, such as the Middle Cambrian Qinjiamiao Formation (∈ 2q ), and the Lower Cambrian Tianheban Formation (∈ 1t ). Insoluble formations usually refer to formations other than soluble rocks, such as shale, siltstone, and igneous rocks of the Silurian (S). 3. Vertical Hydrodynamic Conditions Groundwater is the material basis of karst water inrush and one of the decisive factors. Groundwater in karst areas has different hazard-causing characteristics when it belongs to different hydrodynamic zones. In the seasonal variation zone and shallow saturated water area, with strong karst development and groundwater activity, groundwater in the form of pore water, fissure water, and karst water has a strong hazard-causing capacity. In the deep saturated zone, also known as the deep slow circulation zone, with reduced activity intensity, groundwater exists in the form of pore water and fissure water. However, due to the high water table, exposing waterbearing fissures or small water and mud-filled karst caves also causes water and mud inrushes. The higher the water table, the larger the water pressure, the greater the

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5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

risk of water and mud inrush. The elevation difference between the water table and the tunnel floor h is used as the evaluation index of water inrush risk. The water table is divided into four levels: h < 10 m, 10 m ≤ h < 30 m, 30 m ≤ h ≤ 60 m, and h > 60 m, as shown in Table 5.3. Table 5.3 Grading levels of water table Level

Definition

h > 60 m

If karst water is exposed, the large amount of instantaneous water flow often causes heavy casualties and property damages

30 m ≤ h ≤ 60 m Medium catastrophability 10 m ≤ h < 30 m

Karst fillings lose stability due to infiltration or a long-time extrusion, thus the hazard-causing capacity is weak

h < 10 m

No risk of water and mud inrush

4. Lateral Hydrodynamic Conditions The lateral hydrodynamic condition is one of the indicators that determine water and mud inrush in the tunnel. If the tunnels are located in different lateral hydrodynamic zones, and the probabilities of large or extra-large water and mud inrush are also different, especially in karst areas. Based on the characteristics of the hydrodynamic field and with comprehensive consideration of the topography and geomorphology, lithology combination characteristics and hydrogeological conditions, the lateral hydrodynamic zone is divided into drainage area (region), recharge runoff area (region), recharge area (region) and other areas (regions), as listed in Table 5.4. The tunnel located in the drainage area (region) and the recharge runoff area (region) is one of the necessary conditions for the occurrence of large-scale karst water inrush. Table 5.4 Classification of lateral karst hydrodynamic zones Classification

Definition

Drainage area (region)

No surface runoff above the groundwater erosion level or in the groundwater exposed area. When drilling boreholes, water head increases with depth. Strong hazard-causing capability

Recharge runoff area (region)

Groundwater concentrated to runoff, no apparent surface runoff; medium hazard-causing capability

Recharge area (region)

In this area, surface water seepage to recharge groundwater, no significant surface runoff. When drilling boreholes, water head decreases with depth; weak hazard-causing capability

Other areas (regions)

Surface runoff zone; no hazard-causing risk

5.1 Risk Assessment Conceptual Model and Index Rating

195

5. Topography and Geomorphology The water catchment capacity usually includes the characteristics of groundwater sources such as depressions, funnels, sinkholes, and trough valleys, especially the surface catchment area of underground karst systems as well as groundwater infiltration recharge and runoff conditions. Surface karst form is a good reflection of underground karst. The amount of water entered (depressions, funnels, sinkholes, and valleys recharged into the underground karst systems) is related to their surface catchment area. Large groundwater input points, such as depressions and the underground extension of underground river inlets, are usually underground river tributaries. Based on the surface karst morphology, the location of underground tributaries can be speculated. The classification of topography and geomorphology is explained in Table 5.5. Table 5.5 Classification of topography and geomorphology Classification

Definition

Large negative terrain

Strong water catchment capacity, underground water in large amount and of high pressure; extremely strong hazard-causing capacity

Medium negative terrain Good water catchment capacity, and strong hazard-causing capacity Small negative terrain

Poor water catchment capacity, and average hazard-causing capacity

No adverse terrain

Low intensity of groundwater activity, and weak hazard-causing capacity

6. Rock Formation Occurrence The occurrence of rock formation is an essential factor determining karst development and groundwater flow. Groundwater recharge, runoff, discharge, infiltration conditions, and karst development degrees are also affected by the occurrence of rock formation. The permeability of rock formations is anisotropic. For example, when groundwater penetrates along the bedding, its permeability is large, and the permeability is small when groundwater permeates vertically. The infiltration in the horizontal rock layers is poor, and hence the karst development is inhibited in solute formations. For the vertical rock formations, the surface water catchment area is small, and the water cycle in the differential karst feedback loop is weak, as a result, the karst is not well developed. The rock formations most conducive to groundwater infiltration and karst development are synclines or anticline flanks with a dip angle of 25° –65°. Based on the existing studies, we divide the dip angle of rock formations into four ranges: 25° ≤ ϕ ≤ 65°, 10° ≤ ϕ < 25° or 65° < ϕ ≤ 80°, 80° < ϕ ≤ 90°, and 0° ≤ ϕ < 10°. 7. Bedding and Interlayer Fissures The development degree and position of the fissures in the surrounding rocks of the tunnel are the key factors to determine the possibility and scale of tunnel water

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and mud inrush. The beddings and interlayer fissures affect groundwater activity and runoff conditions. Generally, the more developed the beddings and interlayer fissures are, the more active the groundwater is. The development degree of karst is high in the medium-thick, thick, and extra-thick limestone formations where fissures are developed. Therefore, when the tunnel passes through such formations, it is easy to cause landslides, water and mud inrushes, and other disasters. The development intensity of beddings and interlayer fissures can be classified into four levels, as shown in Table 5.6. Table 5.6 Development intensity classification of beddings and interlayer fissures Classification

Definition

Strong development

The diameter of the cave in the karst area ≥ 80 cm or the width of the fissure ≥ 60 cm; strong catastrophability

Medium development

The diameter of the cave in the karst area < 80 cm or the width of the fissure is 30 –60 cm; medium catastrophability

Weak development

Rare karst, or the width of the fissure < 30 cm; weak catastrophability

No development

Rare karst, few fissures, no catastrophability

8. Surrounding Rock Grading The mechanical property of the surrounding rock is an essential factor affecting the occurrence of tunnel water and mud inrush. If the surrounding rock has good integrity, high strength, and no adverse structural surfaces, it would have a great capability to resist deformation, and as a result, the deformation due to construction disturbance would be small. Therefore, it is not prone to water and mud inrush disasters. Conversely, the surrounding rock with poor integrity, low strength and adverse structural surfaces has limited ability to resist deformation and construction disturbance. Vulnerable zones such as fault damage zones and filled cavities often cause rock instability or overall extrusion failure due to ground water infiltration. The disturbance of tunnel construction can easily cause water and mud inrushes. In this book, we select the revised basic quality index [BQ] of the surrounding rock as the risk evaluation index, and divided it into four levels, i.e., [BQ] ≤ 250, 250 < [BQ] ≤ 350, 350 < [BQ] ≤ 450, and [BQ] > 450.

5.1.2 Tunnel Construction Factors Construction conditions are the risk factors of water and mud inrush and are the direct factors that lead to disasters. They consist of three aspects: advance geological prediction, monitoring and measurements, and excavation and support, and cover

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197

prediction, monitoring, excavation and support scheme, personnel, equipment, and management, etc. The following conditions may cause tunnel water and mud inrush accidents. For example, failure to carry out the advance geological prediction and monitoring and measurement, unreasonable forecast and monitoring scheme, limited interpretation of data, low accuracy of data analysis, equipment not meeting construction requirements, management issues, vague understanding of geology due to the failure use of prediction and monitoring, and flawed construction programs. 1. Advanced geological prediction The classification criteria for the advanced geological prediction scheme are shown in Table 5.7. Table 5.7 Classification criteria for advanced geological prediction scheme Classification Engineering geological characteristics

Advance geological prediction items

Class I

High probability of extra large-scale water and mud inrush; extreme geophysical prospecting anomaly that is very prone to induce major environmental and geological disasters. For instance, the large-scale, fractured, water-rich, well-conductive faults and sections with well-developed fissures and excellent fissure water storage conditions

➀Geologic sketch; ➁Long-distance prediction: TSP203 (≤100 m); ➂Medium-distance prediction: advance horizontal borehole inspection (30 –60 m, 1 –3 holes), with transient electromagnetic, induced polarization (50 m); ➃Short-distance prediction: ground penetrating radar (15 –30 m), infrared continuous water detection, forward blast holes (5 m, 5 holes) radially arranged along with the vault and sidewalls

Class II

High probability of large-scale water and mud inrush; serious geophysical prospecting anomaly that is likely to induce major environmental geological disasters. For instance, the weak, water-rich, and well-conductive faults, and sections with well-developed fissures and good fissure water storage conditions

➀Geologic sketch; ➁Long-distance prediction: TSP203 (≤100 m) ➂Short-distance prediction: advance horizontal borehole inspection (30 m, 1 –3 holes), forward blast holes (5 m, 3 –5 holes), ground penetrating radar (15 –30 m), ➃Transient electromagnetic or induced polarization (50 m) in key sections

Class III

Possibility of medium and minor-scale water and mud inrush; large geophysical prospecting anomaly; sections with developed fissures and good fissure water storage conditions

➀Geologic sketch; ➁Long-distance prediction: TSP203 (≤150 m); ➂Short-distance prediction: advance horizontal borehole inspection (30 m, 1 –3 holes), forward blast holes (5 m, 3 holes), ground penetrating radar (15 –30 m) for abnormal sections

Class IV

Small possibility of water and mud inrush, with generally developed fissures

➀Geologic sketch; ➁Long-distance prediction: TSP203 (150 m); ➂If necessary, ground penetrating radar (30 m)

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2. Monitoring and measurements The classification criteria for monitoring and measurements are shown in Table 5.8. Table 5.8 Classification criteria for monitoring and measurements Classification

Engineering geological characteristics

Monitoring and measurements items

Class I

High probability of extra large-scale water and mud inrush, significant geophysical prospecting anomaly, and it is very likely to induce major environmental, geological disasters

Geological and support status observation, perimeter displacement and vault settlement monitoring, groundwater level and pore water pressure monitoring, and critical section monitoring

Class II

High probability of large-scale water and mud inrush, significant geophysical prospecting anomaly, and it is likely to induce large environmental, geological disasters

Geological and support status observation, perimeter displacement and vault settlement monitoring, groundwater level and pore water pressure monitoring

Class III

Tunnel entrance section and shallow buried section, surrounding rock fractured section, sections with class-IV and class-V surrounding rock, small and medium-sized water and mud inrush may occur

Geological and support status observation, frequent perimeter displacement and vault settlement monitoring, surface subsidence, and groundwater level monitoring

Class IV

Necessary measurement item; little or no possibility of water and mud inrush, or in a small scale

Geological and support status observation, perimeter displacement, vault settlement monitoring

Note Key section monitoring items include anchor bar stress, initial support, second lining pressure, steel support stress, and concrete stress monitoring, etc.

3. Excavation and support Inappropriate excavation and support scheme and construction method, the low technical level of personnel, old equipment, lack of effective construction management, no timely support and no reinforcement can induce landslides, collapses, mud inrush and other accidents.

5.1.3 Dynamic Feedback of Construction Information The real-time feedback of construction information includes the hydrogeological and geological engineering conditions (directly exposed by the tunnel excavation), adverse geology ahead of the tunnel face (detected by advance geological prediction), water and mud inrush multi-precursor information (by real-time monitoring and

5.2 Fuzzy Evaluation of Water and Mud Inrush Interval Risk

199

measurements), and macroscopic precursory information of some adverse geological conditions. Typical macroscopic precursory information is as follows. Small caves, ruststained fissures and mud fissures appear when approaching to large karst caves and underground rivers. At this time, the air in the tunnel is wet, cold and piercing, the fog is serious, the rock surface is wet, with water droplets attached, and the drilling water is sprayed. As to the fissures and karst caves near the underground river, they often contain river sand and gravel with good roundness. Near the fault damage zone, cracks and small folds (especially drag folds) are developed, the strength of the rock mass is significantly reduced, and fault scratches, mirrors, steps, fault mud, breccia, mylonite, lens, and formation loss or duplication are visible locally. When high-pressure water-rich fillings or fault damage zones are exposed, water spraying from drilling hole is often observed, the water is alternately clear and turbid, and water pressure and volume are unstable. The precursors of water and mud inrushes include visible information and invisible microscopic information. Visible information covers cracks appearing on the lining and surrounding rocks, seepage (spraying) of water and mud, seepage deformation in the form of piping and flowing soil or extrusion of fillings along the pipe wall as a whole. Common microscopic precursors are stress, displacement, temperature and microseism, etc. By analyzing the time history curve, rate curve and acceleration of displacement and stress, the deformation dynamics of surrounding rock can be controlled in real time, which provides guidance for excavation support and prevention of water and mud inrush. Real-time feedback information can be used to update the hydrogeological and engineering geological information and guide geological prediction, monitoring and measurements, excavation support optimization, and design changes. Based on the above analyses, the criteria of the evaluation index for tunnel water and mud inrush are listed in Table 5.9.

5.2 Fuzzy Evaluation of Water and Mud Inrush Interval Risk 5.2.1 Construction of Interval Risk Calculation Model In accordance with the previously constructed conceptual model for tunnel risk fuzzy comprehensive assessment, the Fuzzy Mathematics is introduced to construct the fuzzy comprehensive assessment calculation model for tunnel water and mud inrush risk, on the basis of the nonlinear fuzzy assessment method. The final result vector of the destination layer (A) can be defined as S0 , and the result vector and judgment matrix of the criteria layer (B1, B2, B3) can be defined as M Bi and M Bi-C , respectively. The fuzzy comprehensive evaluation calculation model for water and mud inrush risk in tunnels can be calculated as:

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Table 5.9 Classification criteria of evaluation index for tunnel water and mud inrush Evaluation criteria

Risk level of water and mud inrush I

II

III

IV

Unfavorable Geology C1

Strong

Medium

Weak

Minor or None

Formation Lithology C2

Strong soluble formation

Medium soluble formation

Weak soluble formation and interlayer formation

Insoluble formation

Vertical hydrodynamic conditions C3

h > 60 m

30 m ≤ h ≤ 60 m

10 m ≤ h < 30 m

h < 10 m

Lateral hydrodynamic conditions C4

Drainage area (region)

Recharge runoff area (region)

Recharge area (region)

Others

Topography and geomorphology C5

Large-scale Medium-scale negative terrain negative terrain

Small-scale negative terrain

No adverse terrain

Rock formation occurrence C6

25° ≤ ϕ ≤ 65°

10° ≤ ϕ < 25° or 65° < ϕ ≤ 80°

80° < ϕ ≤ 90°

0° ≤ ϕ < 10°

Beddings and interlayer fissures C7

Strong development

Medium development

Weak development None development

Surrounding rock [BQ] ≤ 250 grading C8

250 < [BQ] ≤ 350

350 < [BQ] ≤ 450

[BQ] > 450

Advance geological prediction C9

Single geophysical prospecting method

A variety of geophysical prospecting methods

Comprehensive geophysical prospecting

Of Geophysical prospecting and drilling combination

Monitoring and measurements C10

Very low frequency

Low frequency

Moderate frequency

High frequency

Excavation and support C11

Totally unreasonable

Unreasonable

Basically reasonable

Reasonable

Macroscopic precursory information C12

Strong differences

Large differences

Minor differences

No differences

Microscopic precursory information C13

Strong differences

Large differences

Minor differences

No differences

S0 = WB · MB

(5.1)

MB = [MB1 , MB2 , MB3 ]T

(5.2)

5.2 Fuzzy Evaluation of Water and Mud Inrush Interval Risk

MBi = Wi · MBi−C

201

(5.3)

⎡

MBi−C

⎤ u i1I u i1II u i1III u i1IV ⎢ u i2I u i2II u i2III u i2IV ⎥ ⎢ ⎥ = [u i jk ]T = ⎢ . .. .. .. ⎥ ⎣ .. . . . ⎦ u inI u inII u inIII u inIV

(5.4)

where W B is the weight matrix of the criteria layer (B); W i = [W i1 , W i2 …, W ij ] is the weight matrix of the indicator layer (C), determined by the analytic hierarchy process; μijk is the membership degree for index Pij belonging to risk grade k and k = I~IV, i = 1~3; and j denotes the criteria layer. When i is 1, j = 1~8; when i is 2, i = 1 ~3; and when i is 3, j = 1 ~2. A definite value is difficult to reflect the uncertainty of the fuzzy evaluation index in the quantification process. Moreover, the value of the evaluation index obtained by the field exploration is usually an interval number, and it is hard to be represented by a definite value. The weight vector expressed as an interval number can more clearly reflect the significance between different indicators. Therefore, interval numbers are introduced into the risk assessment of tunnel water and mud inrush. The resulting vector, judgment matrix, membership degree, and weight vector are represented by interval numbers, expressed in the following equations: S0 = WB =

[[

] [ ] [ ]] [[ s 1 , s 1 , s2 , s 2 , · · · , s4 , s 4

] [ ] [ ]] wB1 , wB1 , wB2 , wB2 , wB3 , wB3

(5.5) (5.6)

[ [ ] ] The operation between interval numbers a, a and b, b meet the following rules: [ ] [ ] [ ] a, a + b, b = a + b, a + b

(5.7)

[ ] [ ] [ ] a, a − b, b = a − b, a − b

(5.8)

[ ] [ { } { }] ] [ a, a · b, b = min a · b, a · b, a · b, a · b , max a · b, a · b, a · b, a · b (5.9) [ ] ] [ ] [ ] [ a, a / b, b = a, a · 1/b, 1/b (5.10)

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5.2.2 Interval Risk Membership Calculation Combined with the conceptual model of fuzzy comprehensive evaluation of tunnel water and mud inrush risk, there are two types of indices used for inrush risk assessment, i.e., quantitative index and qualitative index. The ridge membership function is constructed to calculate the membership degree. Specifically, the membership degree of evaluation index Pij can be calculated in the following forms. 1. Ridge membership function for quantitative index. When the index value belongs to the minimum risk level (level IV) or maximum risk level (level I), the membership function can be calculated as: 1 ( π − 21 sin a2 −a x− 1 ⎪ ⎩ 0 ⎧ ⎪ 0 ( ⎨ π x− = 21 + 21 sin a2 −a 1 ⎪ ⎩ 1

u i jk =

u i jk

⎧ ⎪ ⎨

1 2

a1 +a2 2

a1 +a2 2

)

x ≤ a1 a1 < x ≤ a2 a2 < x

(5.11)

)

x ≤ a1 a1 < x ≤ a2 a2 < x

(5.12)

where (a1 + a2 )/2 is the boundary value of the evaluation index for level I and level 4 ∑ IV, and ∀x ∈ (−∞, +∞), u i jk = 1. k=1

When the index value belongs to other risk levels (level II and level III), the membership function can be written as:

u i jk

⎧ 0 ( ⎪ ⎪ ⎪ 1 1 π ⎪ ⎪ ⎨ 2 + 2 sin a2 −a1 x − = 1 ( ⎪ 1 π 1 ⎪ ⎪ − sin a4 −a3 x − ⎪ ⎪ ⎩2 2 0

x ≤ a1 a1 < x ≤ a2 ) a2 < x ≤ a3 a3 +a4 a3 < x ≤ a4 2 a4 < x a1 +a2 2

)

(5.13)

where (a1 + a2 )/2 and (a3 + a4 )/2 are the boundary values of the evaluation index 4 ∑ for level II and level III, and ∀x ∈ (−∞, +∞), u i jk = 1. k=1

1. Ridge membership function for qualitative index The evaluation indices for tunnel water and mud inrush risk based on practical engineering explorations are mainly descriptive. Thus, the interval value of membership degree can be obtained by transforming the interval value of rank. For convenience, it is assumed that the total range of risk grades for the qualitative indices is [0, 1], and the width of each range is 0.25. Based on the description of the evaluation index, the classification criteria for qualitative indices, and the value interval, the

5.2 Fuzzy Evaluation of Water and Mud Inrush Interval Risk

203

corresponding interval index value can be obtained. Combining the range of risk grades for the qualitative indices and the numerical evaluation index membership interval yields the qualitative evaluation index interval membership function. The ridge membership function is expressed as, ⎧ ⎨

0 x ≤ 0.625 + sin(4π(x − 0.75)) 0.625 < x ≤ 0.875 ⎩ 1 x > 0.875 ⎧ 0 x ≤ 0.375 ⎪ ⎪ ⎨ 1 1 + sin(4π(x − 0.5)) 0.375 < x ≤ 0.625 u I I = 12 12 ⎪ − sin(4π(x − 0.75)) 0.625 < x ≤ 0.875 ⎪ ⎩2 2 0 x > 0.875 ⎧ 0 x ≤ 0.125 ⎪ ⎪ ⎨1 1 + sin(4π(x − 0.25)) 0.125 < x ≤ 0.375 u I I I = 21 21 ⎪ − sin(4π(x − 0.5)) 0.375 < x ≤ 0.625 ⎪ ⎩ 2 2 0 x > 0.625 ⎧ 1 x ≤ 0.125 ⎨ u I V = 21 − 21 sin(4π(x − 0.25)) 0.125 < x ≤ 0.375 ⎩ 0 x > 0.375 uI =

1 2

1 2

(5.14)

(5.15)

(5.16)

(5.17)

Specifically, the value of the qualitative index can be determined by the expert scoring method. The membership degree for qualitative evaluation indices can be calculated according to the above process for the qualitative index.

5.2.3 Interval Factor Weight Analysis In the previous section, the method of determining the interval membership of tunnel inrush risk evaluation is introduced. The interval membership can be obtained, and interval evaluation matrix can be formed using the quantitative and qualitative evaluation index. However, when applying the interval evaluation matrix to the interval fuzzy evaluation of tunnel water and mud risk, it is still necessary to establish a method to calculate the weight vector of evaluation indicators (Zhang et al. 2011). Regarding to interval weight analysis of risk factors for water and mud inrush in tunnel, the judgment matrix of an interval number for an evaluation index can be obtained using the 1 –9 scale (Cao Wengui et al. 2007). Specifically, 1 indicates that the parameter has no prominent influence, 3 indicates a slightly prominent effect, 5 indicates a significant prominent influence, 7 indicates a strong prominent influence, 9 indicates extremely prominent influence, and 2, 4, 6, and 8 represent adjacent values. Therefore, the comparison matrix Fi of the indicator layer (C) can be expressed as,

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5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

Fi = [ f i j ]n×n = [[ f i j , f i j ]]

(5.18)

where j = 1 –n, and n is the number of evaluation indices of the criteria layer (B). Moreover, f i j is the numerical matrix formed by the lower limit of each interval in the comparison matrix, and f i j is the numerical matrix formed by the upper limit of each interval in the comparison matrix. If any i, j, k can meet the following requirements, f i j = 1/ f ji

(5.19)

f i j f jk = f j j f ik

(5.20)

then, Fi is a consistent interval number matrix, f i j and f i j are both quasi-consistent number matrices. Suppose Wiave is the normalized eigenvector of the maximum eigenvalue with positive real part, the weight vector W of Fi can be determined as, Wiave = (

n ∏

f i j )1/n

(5.21)

j=1

Wi j =

Wiave

n ∑

i=1

(5.22)

Wiave

W = [Wi j ]1×n = [[kWi j , mWi j ]]1×n

(5.23)

⎡ ) | n ( n ∑ |∑ √ fi j s k= 1/

(5.24)

j=1

i=1

⎡ ) | n ( n ∑ |∑ √ fi j m= 1/ j=1

(5.25)

i=1

The weight matrix of the criteria layer (B) and the indicator layer (C) can be determined by the above method. The ultimate result vector can be obtained by combining the determined conceptual model and the ridge membership function.

5.2.4 Relative Dominance Analysis of Interval Matrix Combined with the result vector from the analysis in the previous section, the relative dominance analysis method is adopted in this section to determine the final evaluation grade. First, the relative dominance between two different interval number vectors is calculated. Then, the judgment matrix is formed, and the weights of varying interval

5.3 Tunnel Construction Permit Mechanism and Risk Management

205

numbers are determined. Using the maximum weight principle, the final risk level of water and mud inrush in karst tunnels is determined (Zhang Yongjie et al. 2011). Assuming that the result vector for the evaluation of the risk grade is Pi , si = [si , si ] and s j = [s j , s j ] are two of the four interval numbers of Pi , the relative dominance is denoted as, ⎧ 1 − 1/(2 exp(si − s j )) si = si = si , s j ⎪ ⎪ ⎪ ⎨ 1/(2 exp(si − s j )) si = si = si , s j ri j (si ≻ s j ) = ⎪ 1 − 1/(2 exp(I F − 1/2)) IF ⎪ ⎪ ⎩ 1/(2 exp(1/2 − I F)) IF

= s j = s j , si ≥ s j = s j = s j , si ≺ s j ≥ 1/2 < 1/2 (5.26)

where I F = (si − s j )/(si − si + s j − s j ). The judgment matrix of the relative dominance R = [ri j ]4×4 is a fuzzy complementary matrix. With the help of the ranking method for the fuzzy complementary matrix, the weight of each interval number in Pi is obtained as ) ( n ∑ n 1 (5.27) ri j + − 1 Qi = n(n − 1) i=1 2 The grade for the maximum weight of the weight vector Q i (i = 1 – 4) is the final risk level of water and mud inrush.

5.3 Tunnel Construction Permit Mechanism and Risk Management 5.3.1 Construction Permit Mechanism and Risk Management The risk control mechanism during tunnel construction is based on the real-time risk assessment and control. The tunnel construction permit mechanism integrates the information and work outcomes from engineering exploration, design, special research, advance geological prediction, monitoring and measurements, risk assessment, and construction feedback. When the construction permit mechanism is implemented in a tunnel, it helps realize the cooperation among the owner, the supervisor and the construction party, and realize multi-party special research, multi-party data sharing and remote online dynamic control of the construction process. The implementation of the construction permit mechanism can reduce the probability of neglecting risk and overlooked construction, avoid the loss of human and material resources caused by the simple overlay of various equipment, and ensure that construction disasters are predicted and mitigated in a timely and effective manner. The tunnel construction permit mechanism and risk management introduced in this

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5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

section (hereinafter referred to as the construction permit mechanism) can be widely used in tunnel construction. Given the high risk and seriousness of disasters caused by water and mud inrush in karst tunnels, the construction permit mechanism guarantees the safety of tunnel construction and the orderly deployment of construction. At the same time, this mechanism can also provide theoretical support and help to other types of tunnels and engineering risk control work. This section provides a detailed analysis of the tunnel construction permit mechanism.

5.3.2 Implementation Procedures of the Construction Permit Mechanism and Risk Management The generalized construction permit mechanism can be applied not only to the risk control of karst tunnel construction, but also to the risk control in other engineering construction projects. In this section, the construction permit mechanism of a karst tunnel is introduced. The flowchart of the construction permit mechanism is shown in Fig. 5.1. As shown in Fig. 5.1, the tunnel construction permit mechanism mainly includes preliminary assessment, secondary assessment, dynamic assessment, and design revision. First, relevant survey design reports and geological data are collected, a preliminary tunnel risk assessment is carried out, a construction risk assessment report is made, and construction recommendations are proposed. Second, based on the risk assessment report formulated in the first stage, a construction design is carried out, a timely summary is submitted, an electronic database for tunnel risk is established, specific advance geological prediction is formulated with monitoring and measurements, and construction plan, and the secondary assessment of geological risks is conducted. Subsequently, the owner, supervisor, and risk assessment party make specific decisions based on the secondary assessment results. If the specific advance geological forecast, monitoring and measurements and construction plan meet the construction permit conditions, construction can then start as planned. When the plan does not meet the construction permit conditions, it must be revised and a second assessment need to be carried out until the construction permit conditions are met before the construction continues. In the construction process, the construction party needs to upload the latest daily data of tunnel construction on time, summarize and collect information, and regularly report the results of the advance geological prediction, monitoring measurement and geological special research. Third, according to the real-time information obtained in the previous stage, dynamic assessment of tunnel construction risk by sections needs to be performed based on the advance geological prediction, monitoring and measurements, and geological research results, combined with the specific situation of each working section. A tunnel risk assessment report will be developed with specific construction recommendations. When the revised short-term construction risk is the same as the long-term construction risk, the construction party works according to the original plan. When the short-term

5.3 Tunnel Construction Permit Mechanism and Risk Management

Fig. 5.1 Flowchart of construction permit mechanism of karst tunnels

207

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5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

construction risk is different from the long-term construction risk, the construction party shall suspend the construction as soon as possible, and discuss with the owner and the supervisor in time to revise the next plan. Fourth, in view of the above-mentioned inconsistency between short-term and long-term construction risks, professional experts need to be invited at this time together with owners and supervisors to revise the current construction plan and discuss a future plan. Specifically, when the original construction plan still meets the construction permit conditions, the construction unit works normally according to the original plan. When the original construction plan does not meet the construction permit conditions, the construction unit is required to strengthen support and reinforcement measures, monitor more frequently, carry out targeted supplementary geological prediction work, and further optimize the design of the original construction plan until the new plan can meet the construction permit conditions, at which point the normal construction can be resumed. It is worth noting that when the original design (e.g., support) is much higher than the requirements of dynamic construction risk, the support strength and support parameters can be appropriately reduced, or construction method could be changed if necessary. According to the implementation process of the tunnel construction permit mechanism, we can understand the real-time tunnel construction conditions and carry out an accurate and timely risk assessment of the tunnel construction, such as karst tunnel water and mud inrush risk assessment. For specific risk control permit process, refer to the paper “Construction permit mechanism of karst tunnels based on dynamic assessment and management of risk” (Xu Zhenhao et al., 2011).

5.3.3 Principle of Construction Permit Mechanism The specific principles followed by the tunnel construction risk control and permit mechanism are as follows. First, online electronic materials should be presented first, followed by the paper data, and referred to regularly. The advanced geological prediction teams, monitoring and measurement departments, and construction units should submit karst hydrogeological exploration data and dynamic construction data to owners, supervisors, and experts on time. It is recommended that the third-party departments prioritize the real-time online submission of electronic materials and timely formulation of supporting paper materials to the owners and supervisors regularly. The guide to detailed requirements for data sharing and submission shall be formulated. An online sharing platform for information and data throughout the construction process should be established with limited operational rights to all parties in this shared platform, and all parties need to upload data to the sharing platform in time during the preparation phase and construction process. It is reported that many tunnel engineering construction teams have already introduced office automation systems at this stage to promote the use of online risk assessment decision-making. The development

5.4 Case Study of the Qiyueshan Tunnel: Dynamic Evaluation and Control …

209

of electronic data and timely follow-up of paper materials should be prioritized to improve risk control and response efficiency effectively. Second, according to the construction dynamic information, the three-stage evaluation of tunnel construction is carried out. Specifically, based on the construction order, the process is divided into three stages: prior to construction organization design, construction preparation, under construction. First, collect and summarize survey data, carry out preliminary evaluation of engineering geological conditions, and guide the formulation of construction organization design (excavation and support scheme, advance geological prediction measures, monitoring and measurement outline, etc.). Secondly, before carrying out the formal construction operation, carry out the secondary assessment of tunnel construction risk according to the formulated construction organization design in combination with the disaster-forming environment and hazard-causing factors. Then, in the process of tunnel construction, collect information such as tunnel excavation dynamics, advance geological prediction and monitoring measurement, summarize and form phased geological thematic research results, and carry out dynamic evaluation based on the above information results, that is, dynamically revise the tunnel construction risk in the specific section in front of the tunnel face. Finally, based on the risk assessment conclusions, the owners, supervisors, and professional experts should discuss whether to continue or suspend the construction and propose corresponding treatment measures. In short, the principles of tunnel risk control and construction permit mechanism can be summarized as electronic data first, paper data follow-up, real-time construction feedback, and the three-stage assessment.

5.4 Case Study of the Qiyueshan Tunnel: Dynamic Evaluation and Control of Water and Mud Inrush Risk Qiyueshan Tunnel is located in Hubei Province, a typical karst mountainous area in China. The tunnel crosses Qiyueshan Mountains, starting from Nanping Township and ending at Moudao Town, in Lichuan City. It is designed as a separated tunnel with a strike direction of 313°. The left line extends from the chainage of ZK19+005 to ZK22+380, with a total length of 3,375 m and maximum buried depth of 567 m; the right line extends from the chainage of YK19+016 to YK22+402, with a total length of 3,386 m and maximum buried depth of 543 m. The tunnel site area is a tectonic erosion-denudation mid-mountain landform. The surface elevation is 1,100–1,710 m, the terrain is undulating, and an underground watershed is near the chainage of K20+260. The slope angle of the tunnel entrance is 25º and the aspect is 120º; the slope angle of the tunnel exit is 40º and the aspect is 313º. The natural slope angle is generally 20 –40º in the tunnel site area. Karst microlandforms such as ditches, trough valleys, and funnels, sinkholes are well developed. The tunnel site belongs to the combination of the northwest edge of the SichuanHubei-Hunan-Guizhou Uplift fold belt and the East Sichuan fold belt of the Sichuan

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5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

subsidence fold belt. The north edge is obliquely connected and reconnected with the northwest Dabashan arc structure. The tunnel crosses the Qiyueshan anticline. The two wings of the anticline are asymmetric. The occurrence of the southeast wing is 115°∠70°, and the occurrence of the northwest wing is 320°∠60°. The anticline stratum is dominated by medium thick layered limestone, intercalated with shale and coal seams. Faults are developed near the core of the anticline, which is a section with strong karst development. There are two faults developed in the tunnel site area. ➀ Middle trough reverse fault (F1 ), also called Qiyueshan fault, is developed parallel to the mountain range, and it is a compressive fault slightly dipping to the southeast, with a strike of NE and a width of about 20 m. The fault intersects with the tunnel at a large angle at the chainage of YK20+440~+460(ZK20+400~+420). Geophysical exploration shows that the rock mass in this section is an abnormally broken zone, and drilling also shows that the compression structure in this section causes the rock mass to have obvious characteristics of fragmentation and diagenesis. ➁ Deshengchang fault (F2 ), is roughly parallel to the mountain range, and it is developed along the Deshengchang trough, with a strike of about 54°. It intersects with the tunnel at the chainage of YK21+910(ZK21+910), which is about several meters wide. Geophysical exploration shows that this section is obviously broken and abnormal. The two faults are narrow in the tunnel body and basically perpendicular to the route. Karst is developed in the fault zone, and large karst caves may exist, which has a great impact on the construction of the tunnel. There are two groups of joints developed in the tunnel inlet section. ➀ Group 1 joints have a strike of 300° –325°, are nearly vertical, with the surface open for 1 –5 cm and spacing of 1 m. And the extension length is generally greater than 10 m. ➁ Group 2 joins have a strike of 310° –320°∠20° –30° and the extension length of several meters. The middle part of the tunnel is located at the turning end of Qiyueshan anticline, where joints and fissures are extremely developed in all directions, mainly extending along and perpendicular to the structural line. The adverse geology of the tunnel site area is mainly karst. In tunnel areas, karst depressions, funnels, and sinkholes are developed and show a specific trend. Surface karst depressions are scattered from tunnel inlet to the anticline core section, generally with a small scale. The surface water catchment areas are also limited. There is no concentrated scale effect in the lower karst. The karst is mainly in the form of small caves and conduits with poor hydraulic connections. The core of Qiyueshan anticline is the turning point of fault and anticline, where the rock mass is broken, the fissures are developed, and the karst is also relatively developed. The karst depression, sinkhole and funnel are linearly distributed along the middle trough, forming good catchment conditions. From the anticline core to the Deshengchang trough valley, karst exhibits mostly beaded distribution, and the direction is nearly parallel to the tunnel direction. These characteristics show that groundwater is discharged to the Deshengchang trough valley after it is collected through the middle trough and the northwest slope. The Deshengchang trough valley is the main karst conduit in the tunnel area, and the water volume is extremely large. Based on the interval dynamic assessment method described above, the right line of the Qiyueshan Tunnel is chosen as the study area (from the chainage of

5.4 Case Study of the Qiyueshan Tunnel: Dynamic Evaluation and Control …

211

YK19+370~YK20+090). An interval fuzzy comprehensive assessment and management method of water and mud inrush is established. The comprehensive evaluation includes preliminary assessment, secondary assessment, and dynamic assessment.

5.4.1 Preliminary Assessment A total of 13 evaluation indicators are used to assess the section of Qiyueshan Tunnel right line (from chainage of YK19+370~YK20+090). The values of the interval number index of qualitative indicators are determined and then a preliminary fuzzy interval risk assessment is carried out. According to the geological survey conducted before construction, in the section from the chainage of YK19+370~YK20+090, the rock mass integrity is poor, with alternated strong and weak rocks. Corrosion fissures are well developed with good connectivity. This adverse geology presents a high likelihood of water and mud inrush disasters. The surface of this section is partially covered with the Quaternary eluvial deluvial silty clay. The underlying bedrock of the tunnel is the Permian limestone, siliceous limestone (intercalated with coal seam and shale) and Triassic limestone (locally intercalated with thin shale). Specifically, the Lower Triassic Daye Formation (T1 d) consists of yellow-gray shale, organic-rich shale, and thin argillaceous limestone, and the Middle Permian Changxing Formation (P2 c) has a moderately weathered, layered structure of limestone containing biological fossils. The surface water in this section is not developed. As the underground karst fissures are generally well developed and groundwater is relatively abundant, it is mainly stored in the karst conduits in the form of karst water. Groundwater is mainly recharged by atmospheric rainfall, which infiltrates into karst aquifers through surface karst depressions and sinkholes and runs off by corrosion fissures and conduits. Therefore, the rock in this section is a medium-developed karst formation, and the layer-to-layer contact zone is a medium karst development zone. In terms of topography and geomorphology, the karst depressions, folds, and funnels near the tunnel are linearly distributed along the trenches, presenting favorable water-collecting conditions. In addition, many karst depressions exist at the top of the tunnel, mainly of limestone, and are filled with cobblestone silty clay. Based on the engineering and geological conditions, the strength grade of surrounding rock was evaluated to be grade IV as specified by [BQ], the basic quality index. Moreover, in the section of chainage YK19+370~YK20+090, the water table and dip angle of rock formation were measured several times, and the height difference of water table was 24 –37 m and the rock formation dip angle was 22° –27°. The values of interval fuzzy comprehensive evaluation indices are presented in Table 5.10, based on the above geological and hydrogeological analysis. Based on the established ridge membership functions of qualitative and quantitative indicators, the interval membership is calculated, as shown in Table 5.11.

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5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

Table 5.10 Preliminary assessment index values

Assessment index

Values

C1

[0.8, 0.9]

C2

[0.65, 0.8]

C3

[24, 37]

C4

[0.6, 0.7]

C5

[0.6, 0.7]

C6

[22, 27]

C7

[0.65, 0.75]

C8

[360, 400]

Table 5.11 Membership degree of risk indices Assessment index

Grade division I

II

III

IV

C1

[0.794, 1]

[0, 0.206]

0

0

C2

[0.204, 0.794]

[0.206, 0.796]

0

0

C3

0

[0.206, 0.835]

[0.165, 0.794]

0

C4

[0, 0.206]

[0.793, 0.794]

[0, 0.206]

0

C5

[0, 0.206]

[0.793, 0.794]

[0, 0.206]

0

C6

[0.095, 0.794]

[0.206, 0.795]

0

0

C7

[0.024, 0.5]

[0.5, 0.976]

0

0

C8

0

[0, 0.345]

[0.655, 1]

0

Subsequently, according to the 1 –9 scale method, the interval judgment matrix of the secondary hierarchy (the criteria layer B) and the third hierarchy (the indicator layer C) is established, as shown in Tables 5.12, 5.13, 5.14, and 5.15. The weight vector W of the judgment matrix is shown in Table 5.16. Combining the interval membership and weight vector, according to the algorithm of interval number operation, the preliminary result vector of tunnel water and mud inrush risk can be obtained as: S0 = [[0.211 0.768] [0.218 1.034] [0.059 0.299] 0]

Table 5.12 Interval judgment matrix for the criteria layer (B1 –B3)

Assessment index

B1

B1

[1, 1] [1 ] 3,2 [1 1] 6, 3

B2 B3

(5.28)

B2 [1 ] 2,3

B3 [3, 6]

[1, 1] [1 1] 5, 2

[1, 1]

[2, 5]

5.4 Case Study of the Qiyueshan Tunnel: Dynamic Evaluation and Control …

213

Table 5.13 Interval judgment matrix for the indicator layer (C1 –C8) Assessment index

C1

C2

C3

C4

C5

C6

C7

C8

C1

[1, 1] [1 1] 4, 2 [1 1] 4, 2 [1 ] 5,1 [1 1] 6, 3 [1 1] 7, 4 [1 1] 8, 5 [1 1] 7, 2

[2, 4]

[2, 4] [1 ] 2,2

[1, 5] [1 ] 3,2 [1 ] 3,2

[3, 6]

[4, 7]

[5, 8]

[2, 7]

[2, 3]

[2, 4]

[3, 5]

[1, 3]

[2, 3]

[2, 4]

[3, 5]

[1, 3]

[1, 1] [1 1] 4, 2 [1 1] 5, 2 [1 1] 6, 3 [1 1] 6, 2

[2, 4]

[2, 5]

[3, 6]

[1, 1] [1 1] 3, 2 [1 1] 4, 2 [1 ] 2,2

[2, 3]

[2, 4]

[1, 1] [1 1] 3, 2

[2, 3] [1, 1]

[2, 6] [1 ] 2,2 [1 1] 3, 2 [1 1] 4, 2

[2, 3]

[2, 4]

[1, 1]

C2 C3 C4 C5 C6 C7 C8

[1, 1] [1 ] 2,2 [1 ] 2,3 [1 1] 3, 2 [1 1] 4, 2 [1 1] 5, 3 [1 ] 3,1

[1, 1] [1 ] 2,3 [1 1] 3, 2 [1 1] 4, 2 [1 1] 5, 3 [1 ] 3,1

Table 5.14 Interval judgment matrix for the indicator layer (C9 –C11) Assessment index

C9

C9

[1, 1] [1 ] 6,2 [1 ] 6,2

C10 C11

C10 [1 ] 2,6

C11 [1 ] 2,5 [1 ] 3,2

[1, 1] [1 ] 2,3

[1, 1]

Table 5.15 Interval judgment matrix for the indicator layer (C12–C13) Assessment index

C12

C12

[1, 1] [1 ] 4,2

C13

C13 [1 ] 2,4 [1, 1]

Table 5.16 The weight vector of the judgement matrix Assessment index The weight vector WA

[0.381, 0.587], [0.290, 0.482], [0.107, 0.123]

WB1

[0.257, 0.365], [0.109, 0.167], [0.109, 0.167], [0.109, 0.167], [0.121, 0.240], [0.066, 0.080], [0.045, 0.050], [0.030, 0.330], [0.062, 0.100]

WB2

[0.278, 0.636], [0.169, 0.325], [0.205, 0.372]

WB3

[0.428, 0.667], [0.302, 0.544]

Then, the relative dominance of the final result vector can be calculated by the relative dominance analysis and Eqs. (5.26) and (5.27). The final evaluation grade of water and mud inrush in the zone between YK19+370 to YK20+090 can be determined as: Q = [0.170 0.174 0.146 0.083]

(5.29)

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5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

According to the maximum weight principle, the final risk level of the zone between YK19+370 to YK20+090 is Level II. Thus, the Qiyueshan Tunnel is considered as a high-risk tunnel. Therefore, relevant departments should implement this risk control and construction permit mechanism and use advanced geological prediction, monitoring and measurement, and karst hydrogeological exploration to avoid and control the risks that might occur during tunnel construction.

5.4.2 Secondary Assessment The secondary assessment uses the advanced geological prediction, monitoring and measurement, and excavation and support schemes for risk assessment before the tunnel excavation. If the risk assessment is Level I, construction cannot be continued. If the risk assessment is Level III or IV, construction can be resumed. For a tunnel with a risk of Level II, it is necessary to make emergency plans for water and mud inrush and take measures to detect early warning signals before construction. Based on the advance geological prediction results and the preliminary assessment, the final risk assessment of the Qiyueshan Tunnel (YK19+370~YK20+090) is Level II. According to excavation and geophysical prospecting results, geological survey, TSP, and GPR methods were applied, and advanced horizontal drilling was carried out for supplementary exploration. In terms of monitoring and measurement scheme, according to the preliminary risk assessment results, for the section YK19+370~YK20+090 of Qiyueshan Tunnel, rock peripheral displacement, vault subsidence monitoring and other means were adopted, and key sections were selectively monitored according to the excavation exposure and prediction results, with the spacing of monitoring sections set at 10 –20 m. In terms of excavation and support schemes, highly skilled construction personnel were employed, and the construction organization and management were strengthened. Besides, timely support and increased strength were conducted to control the occurrence of risk accidents such as collapse and block falling. Finally, the index of the advance geological prediction scheme, monitoring and measurement scheme and excavation and support scheme were quantified, and the interval number index values were determined as below. The advance geological prediction (C9) was [0.2, 0.3], the monitoring and measurement (C10) was [0.3, 0.5], and excavation and support (C11) was [0.2, 0.4]. Combined with the index values, based on the ridge membership function of qualitative and quantitative indexes established above, the interval membership degree is calculated and the interval judgment matrix and weight vector are determined. Ultimately, the secondary assessment result vector of tunnel water and mud inrush construction risk is obtained. S0 = [[0.081 0.451] [0.083 0.696] [0.075 0.728] [0.002 0.421]] (5.30) Through the relative dominance analysis, the relative dominance of the final result vector can be determined as follow.

5.4 Case Study of the Qiyueshan Tunnel: Dynamic Evaluation and Control …

Q = [0.146 0.156 0.157 0.140]

215

(5.31)

According to the maximum dominance principle, the final risk level of the tunnel section (YK19+370~YK20+090) is Level III for the secondary risk assessment. Thus, the Qiyueshan Tunnel from the chainage of YK19+370 to YK20+090 has a mediumlevel risk. The preliminary risk assessment results showed that the Qiyueshan Tunnel has a level II risk of water and mud inrush disasters for the section of YK19+370 to YK20+090. In view of this, corresponding advance geological prediction, monitoring and measurement scheme and excavation and support scheme were formulated. Afterwards, the secondary assessment results showed that it actually has a level III risk, indicating that current advance geological prediction, monitoring and measurement, and excavation support schemes can ensure safe tunnel construction.

5.4.3 Dynamic Assessment After the preliminary and secondary assessments, the construction permit mechanism was implemented for the Qiyueshan Tunnel. The dynamic evaluation of construction was carried out in real-time. Dynamic update of the karst hydrogeological and engineering geological information was made based on the data obtained by excavation, monitoring and measurements, and the advance geological prospection ahead of the tunnel face, and then the advanced geological forecast, monitoring and measurement, and excavation plans were in turn adjusted accordingly. Afterwards, dynamic assessment and management were used to assess the risk of the modified assessment model. If the risk grade is Level III or IV, construction may continue. A contingency plan for water and mud inrush should be prepared for tunnel sections with the risk level being Level I or II. Moreover, regular inspections of high-risk tunnel sections should be carried out. Furthermore, an exercise to detect early warning signals should be performed before commencing construction of the tunnel. As it is challenging to identify all the adverse geological conditions along the tunnel by geological exploration, the dynamic evaluation in the construction process may be quite different from the secondary assessment results. During the construction process of the Qiyueshan Tunnel, there were many caves, karst fissures zone, mud zone, and rock quality changes in the surrounding rocks. Therefore, it is crucial to make timely updates of hydrogeological and engineering geological information and then conduct a dynamic assessment. Based on the geological and hydrogeological conditions of the Qiyueshan Tunnel from the chainage of YK19+370 to YK20+090, the fuzzy interval dynamic assessment of the tunnel inrush disaster is carried out for three sections, YK19+370~+840, YK19+840~+895, and YK19+895~YK20+090. 1. Section of YK19+370~+840.

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5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

In this section, geological survey, TSP prediction, monitoring measurement, and dynamic risk assessment were performed. Specifically, the TSP method was used for advance geological detection at the working face at the chainage of YK19+730, YK19+766, and YK19+806. According to the TSP survey results and relevant geological data analyses, it is determined that the main formation in the zone of YK19+370~+840 is limestone, with high rock strength and good integrity. Fractures are mainly developed near the section of YK19+740, section of YK19+748~+750 and section of YK19+760. Moreover, in the sections of YK19+766~+770 and YK19+814~+832, the strength and integrity of the surrounding rock are poor, where fissures are well developed. The results of the TSP are shown in Fig. 5.2. Based on the construction factors and risk feedback information, the values of the interval fuzzy comprehensive evaluation indices can be determined, which are presented in Table 5.17. According to the determined index values, calculate the interval membership, determine the interval judgment matrix and weight vector, and finally obtain the result vector of water and mud inrush in the section of YK19+370~+840. S0 = [[0.002, 0.210], [0.122, 1.121], [0.154, 1.057], [0, 0.158]]

(5.32)

Furthermore, through relative dominance analysis, determine the relative dominance of the final result vector according to the relevant formula, as shown below: Q = [0.134, 0.168, 0.169, 0.129]

(5.33)

Based on the principle of maximum dominance, the final risk level of the section (from chainage of YK19+370 to +840) is Level III, which means this section is at a medium risk level in the dynamic construction process. Thus, the tunnel construction can be resumed. 2. Section of YK19+840~+895. In the chainage of YK19+840 to +895, dynamic risk assessment is carried out by means of geological analysis, TSP method, GPR method, high-density electrical method and monitoring measurement. Specifically, the Poisson’s ratio of the surrounding rock is increased in the range of YK19+847~+863, and the negative reflection is enhanced. Rock density showed significant differences in the chainage of YK19+884~+895. Therefore, fissures with abundant water are developed in the surrounding rock in this section. Karst conduits may exist, and the water content is high. Based on the TSP detection method, the GPR method was added to determine the level of karst development in the chainage of YK19+840~+895. The results of the GPR method are shown in Fig. 5.3. In conclusion, the integrity of the surrounding rock is good, but there may be karst conduits in the sections of YK19+850~+866 and YK19+882~+890. In addition, there is a large crack in the left wall of the tunnel in the section of YK19+868~+890, and the groundwater is abundant. Thus, it is believed that water inrush is prone to occur in this section during the rainy season.

5.4 Case Study of the Qiyueshan Tunnel: Dynamic Evaluation and Control …

(a) The reflective surface of P-wave.

(b) 2D results and rock materiality

Fig. 5.2 TSP results for the section of YK19+370~+840

217

218

5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

Table 5.17 Values of evaluation indices for fuzzy interval dynamic assessment Evaluation index

YK19+370~+840

YK19+840~+895

YK19+895~YK20+090

C1

[0.7, 0.8]

[0.8, 0.9]

[0.8, 0.9]

C2

[0.6, 0.7]

[0.75, 0.8]

[0.7, 0.8]

C3

[24, 28]

[30, 37]

[26, 35]

C4

[0.5, 0.55]

[0.6, 0.7]

[0.7, 0.8]

C5

[0.6, 0.65]

[0.6, 0.7]

[0.6, 0.7]

C6

[22, 24]

[22, 27]

[25, 27]

C7

[0.45, 0.55]

[0.7, 0.75]

[0.7, 0.75]

C8

[270, 305]

[305, 340]

[340, 420]

C9

[0.3, 0.4]

[0.3, 0.35]

[0.3, 0.45]

C10

[0.3, 0.5]

[0.45, 0.5]

[0.45, 0.55]

C11

[0.2, 0.4]

[0.6, 0.7]

[0.6, 0.7]

C12

[0.65, 0.75]

[0.75, 0.8]

[0.75, 0.8]

C13

[0.7, 0.8]

[0.75, 0.85]

[0.75, 0.9]

The interval fuzzy comprehensive evaluation indices for this section can be determined according to construction factors and the real-time risk feedback, which are shown in Table 5.17. According to the determined index value, calculate the interval membership, obtain the interval judgment matrix and weight vector, and finally obtain the result vector of dynamic assessment of water and mud inrush construction risk for the section of YK19+840~+895. S0 = [[0.157 0.643] [0.146 0.801] [0.097 0.712] [0.002 0.063]] (5.34) Through the relative dominance analysis, determine the relative dominance of the final result vector according to the relevant formula, as shown below. Q = [0.161 0.164 0.159 0.091]

(5.35)

According to the principle of maximum dominance, the final risk level for the zone (YK19+840~+895) is Level II and therefore represents a high-risk section. Thus, tunnel construction shall be resumed after emergency plans for water and mud inrush are made and warning exercises are carried out. 3. Section of YK19+895~YK20+090. In the section of YK19+895~YK20+090, the geological survey, TSP method, transient electromagnetic method, monitoring and measurement method have been carried out successively to carry out dynamic risk assessment. Specifically, the TSP method was applied for section of YK19+895~YK20+005 and the transient electromagnetic method for section of YK20+012~+082, with detection results shown

5.4 Case Study of the Qiyueshan Tunnel: Dynamic Evaluation and Control …

219

Fig. 5.3 Ground penetrating radar detection results of section of YK19+840~+895 (a) The reflective surface of P-wave. (b) 2D results and rock materiality

in Fig. 5.4. According to the TSP detection results, the strength and integrity of the surrounding rock are poor, and the fissures are developed in the sections of YK19+920~+927, YK19+944~+952, and YK19+976~+988. Karst caves and waterbearing structures may exist in these sections. Moreover, two low-resistivity regions

220

5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

are found in the sections of YK20+030~+034 and YK20+047~+057. And the resistivity on both sides for the section of YK20+064~+072 is relatively low, which indicates a high probability of water-bearing structures. According to the construction factors and the obtained risk dynamic feedback information, the values of the interval fuzzy comprehensive evaluation indices are presented in Table 5.17. With the determined index values, calculate the interval membership, obtain the interval judgment matrix and weight vector, and then obtain the dynamic assessment result vector of water and mud inrush construction risk for the section of YK19+895~YK20+090.

Fig. 5.4 TEM results of YK20+012~+082

5.5 Summary

221

S0 = [[0.145 0.646] [0.126 1.066] [0.093 0.506] [0 0.030]]

(5.36)

Determine the relative dominance of the result vector through the relative dominance analysis and the final evaluation grade can be determined as: Q = [0.162 0.169 0.154 0.114]

(5.37)

According to the principle of maximum dominance, the final risk level of the section (YK19+895~YK20+090) is Level II, which means that the Qiyueshan Tunnel at the chainage of YK19+895~YK20+090 still has a high-level risk. Therefore, emergency plans for water and mud inrush should be made, and warning exercises should be carried out before construction. In summary, the risk level for the section of YK19+370~YK20+090 in the Qiyueshan Tunnel is level II for the preliminary assessment and level III for the secondary assessment. After the hydrogeological and engineering geological information is updated, a dynamic assessment is carried out. And the updated assessment results are as follows: the section of YK19+370~+840 has a risk of Level III, and sections of YK19+840~+895 and YK19+895~YK20+090 have a risk of Level II. Clearly, the dynamic assessment result shows a greater risk than the secondary assessment. The reason is that excavation survey and geological detections find that the section of YK19+370~YK20+090 belongs to the typical fissure-type water inrush section. The inrush channel is mainly karst conduits that are developed along with the rock layers and locally crossing through layers. A good water connection exists between the karst fissures in layers. Groundwater shares strong connectivity with the surface, and the water inflow shows seasonal characteristics. On consecutive sunny days, there is little water for water inflow. But the water inflow surges after a few hours of heavy rainfall, and the flow rate is proportional to the rainfall and precipitation time. In the preliminary evaluation, the fracture characteristics, water inflow and rainfall characteristics of this section were not taken into consideration, thus resulting in evaluation errors. In the late construction process, the area encountered several water inrush disasters in the storm season, and the tunnel was flooded and forced to shut down nearly 10 times. The pictures of water inflow are shown in Fig. 5.5.

5.5 Summary Based on the interval fuzzy comprehensive evaluation method, this chapter establishes the conceptual model of tunnel water and mud inrush risk evaluation, deeply studies the weight of water and mud inrush disaster risk factors, and puts forward the construction permit mechanism based on the interval evaluation system of risk evaluation. Finally, an interval risk assessment method of water and mud inrush in the course of karst tunnel construction was established and successfully applied to the Qiyueshan Tunnel. The dynamic construction risk assessment includes preliminary assessment, secondary assessment, dynamic assessment, and design revision.

222

5 A Dynamic Interval Risk Assessment Method for Water and Mud Inrush …

Fig. 5.5 Water inrushes at YK19+740 and YK19+853 in the Qiyueshan Tunnel

1. A systematic analysis of influencing factors in the tunnel site area was carried out. These factors include unfavorable geology, formation lithology, vertical hydrodynamic conditions, lateral hydrodynamic conditions, topography and geomorphology, rock formation occurrence, bedding and interlayer fissures, surrounding rock grading and so on. Prior to the construction plan, a preliminary assessment of hydrogeological and engineering geological conditions was carried out. 2. Based on the risk results of the preliminary assessment, a practical construction organization design was formulated, including an advance geological forecasting scheme, monitoring and measurement scheme, and excavation support scheme. Subsequently, the secondary assessment was performed considering both hydrogeological and engineering geological conditions and construction factors. 3. Based on the results of the secondary assessment risk, considering the geological features of the tunnel excavation section and the advance geological prediction results, the geological factors were dynamically feedback. Taking hydrogeological and engineering geological conditions, construction factors, and risk feedback information into account, the first dynamic assessment and design optimization were carried out. For the surrounding rock section with increased risk in dynamic assessment, the construction unit was required to strengthen support measures and monitoring and measurement, carry out targeted supplementary

References

223

work of advance geological prediction, and further optimize the design of the construction scheme. For the sections with lowered risk, unnecessary support and reinforcement measures can be reduced accordingly for economic reasons. 4. According to the optimized scheme, the dynamic evaluation was carried out until the new construction plan can meet the construction permit conditions. Then, the subsequent construction cycle continues when the evaluation result is reduced to Level III or IV. In summary, the dynamic risk assessment method of water and mud inrush is easy to deploy and operate in the construction site and is an effective method for tunnel risk control, which can reduce the casualties and economic losses caused by disasters such as water and mud inrush in tunnels.

References Cao WG, Zhang YJ, Yang QJ (2007) Study on interval nonlinear fuzzy judgment method of rock mass classification. Chin J Rock Mechan Eng (03):620–625. Wang XT, Li SC, Xu ZH, Li XZ, Lin P, Lin CJ (2019) An interval risk assessment method and management of water inflow and inrush in course of karst tunnel excavation. Tunn Undergr Space Technol (92):1–15. Xu ZH, Li SC, Li LP, Chen J, Shi SS (2011a) Construction permit mechanism of karst tunnels based on dynamic assessment and management of risk. Chin J Geotech Eng 33(11):1714–1725 Zhang YJ, Cao WG, Zhao MH, Zhao H (2011) Interval fuzzy judgment method for roadbed stability in karst area. Chin J Geotech Eng 33(1):38–44

Chapter 6

Assessment Method of the Resistance Body Against Water and Mud Inrush in Tunnels

This chapter draws on the rock mass quality evaluation and classification methods through analyzing the sources and the resistance bodies of water and mud inrush disasters, and selects 11 main influencing factors (including adverse geology, hydrodynamic conditions, water supply conditions, hydraulic connectivity, the thickness of resistance body, rock quality and integrity, joint state, rock strength, ground stress, rock mass permeability, strike direction and dip angle of rock strata) in terms of adverse geology, hydrodynamic conditions, the thickness of resistance body, and surrounding rock characteristics as the evaluation indices. An assessment method for the resistance body against water and mud inrush in tunnels is proposed (the RBAM method, formerly called the PSAM method), the classification and scoring system of each influencing factor is established, and the implementation process of the assessment is illustrated. Finally, the verification of a typical water and mud inrush disaster project carried out in the Yesanguan Tunnel of the Yichang-Wanzhou Railway proved the scientificity and practicality of the assessment method (Huang Xin et al. 2018).

6.1 Influencing Factors of the Resistance Body Stability The source of the water and mud inrush disaster (Ds ) in the tunnel is the primary geological factor for the occurrence of water and mud inrush in the tunnel. The resistance body (Rb ) is the last barrier for water or mud to penetrate into the tunnel. The occurrence of water and mud inrush disasters during tunnel construction depends on the interaction between the disaster source and the resistance body. Only by clarifying the respective influencing factors (influencing factors of the disaster source and that of the resistance body), can we use quantitative or semi-quantitative analysis methods to make a scientific and reasonable assessment of the resistance body stability.

© Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1_6

225

226

6 Assessment Method of the Resistance …

6.1.1 Influencing Factors of the Disaster Source The main factors affecting the disaster source (Ds ) of water and mud inrush are as follows. 1. Unfavorable geology (U g ) During the construction of the tunnel, various unfavorable geological conditions were encountered, forming karst category, fault category, and other category of water and mud inrush hazard-causing systems. The type and scale of these unfavorable geological conditions largely determine the hazard-causing scale of water and mud inrush in the tunnel. 2. Hydrodynamic conditions (H d ) (i)

Hydraulic pressure characteristics (H p ). Groundwater is the primary disaster source for water and mud inrush in tunnels and is also one of the decisive factors. Under the same hydrogeological conditions, the higher the groundwater level, the greater the water pressure, the greater the security threat against the resistance body, the higher the probability of water and mud inrush, and the greater the damage once a water and mud inrush disaster occurs. (ii) Water recharge conditions (W r ). Water recharge conditions include groundwater replenishment method and recharge volume. Water recharge conditions and the groundwater connectivity will change the water pressure characteristics of groundwater to a large extent, thereby affecting the evaluation of the resistance body stability. Negative topography such as depressions, funnels, sinkholes, and troughs are all important input points of the groundwater system, and the input water volume is related to the surface catchment area of each input point. Large-scale groundwater input points, such as depressions and underground extensions of underground river entrances, are generally the channels of underground higher-level tributaries. (iii) Hydraulic connectivity (H c ). Hydraulic connectivity is mainly reflected in the development of corrosion fissures in the tunnel site area, and it covers the connectivity with karst depressions and sinkholes, the dip angle of rock strata and the development status of bedding fissures, the vertical continuity of the rock strata, the fault connection between the tunnel and the surface, and the development status of the structural fissures, etc. Hydraulic connectivity affects the pressure of groundwater, that is, the size of the head loss (the effective height of the head). The better the connectivity of groundwater, the smaller the head loss, the more unfavorable it is to the stability of the resistance body for water and mud inrush.

6.1 Influencing Factors of the Resistance Body Stability

227

6.1.2 Influencing Factors of the Resistance Body The main factors that affect the property of the resistance body (Rb ) against water and mud inrush are as follows. 1. Resistance body thickness (Rt ) The resistance body is the last barrier to prevent the occurrence of water and mud inrush disasters. It is the object of action when the energy accumulated in the disaster source is released, and it is the breakthrough point for the water and mud inrush channel to finally penetrate. The failure of the resistance body is a dynamic damage process induced jointly by the movement of the disaster source water body and the construction disturbance in the tunnel. Traditionally, the safe thickness of the resistance body usually consists of three parts: relaxation zone thickness (D1 ), transition zone thickness and fissure zone thickness (D2 ) (Gan Kunrong et al. 2007; Li Liping et al. 2010; Guo Jiaqi 2011). Thereof, the thickness of the relaxation zone is mainly affected by the excavation disturbance and is related to the grade of the surrounding rock. The fissure zone usually develops around the karst structures (Criss et al., 2008), and its thickness is mainly affected by the stratum lithology and rock strata thickness. When the relaxation zone and the fissure zone penetrate each other, that is, when the thickness of the resistance body d ≤ D1 +D2 , the resistance body will undergo delayed or direct damage, which will induce water and mud inrush disaster accidents. In addition, the practical experience of a large number of engineering cases shows that when the thickness of the resistance body exceeds twice the thickness of the tunnel diameter, usually no water and mud inrush disaster will occur, which will be referred to as the relative safe thickness D3 later. This book defines the thickness of D1 +D2 as the critical thickness, and the thickness of D1 +D2 +D3 as the safe thickness. 2. Surrounding rock characteristics (S r ) (i)

Rock mass quality and integrity (Ri ). The quality and integrity of the rock mass is an important factor that affects the resistance assessment for karst tunnels. Surrounding rock with good integrity, high strength, and no disadvantageous structural surfaces has strong anti-deformation ability, small construction disturbance deformation, and strong resistance against water and mud inrush disasters. The surrounding rock has poor integrity, low strength, and development of unfavorable structural surfaces, resulting in weak resistance against deformation, and large deformation caused by construction disturbance. In particular, weak zones (bodies) such as the fault fracture zones and filled karst caves often experience seepage instability or overall extrusion damage under the action of groundwater. A slightly improper construction will cause water and mud inrush disasters. (ii) Joint state (J s ). The greater the opening degree of the joints in the surrounding rock, the straighter the joints without filling, the severer the weathering of the rock

228

6 Assessment Method of the Resistance …

(iii)

(iv)

(v)

(vi)

and the more broken the surrounding rock, the more unfavorable it is to the stability of the surrounding rock. Consequently, the smoother the movement of groundwater in the joints, the more abundant the groundwater replenishment source when water and mud inrush occurs, and the more serious the disaster will be. Rock strength (Rc ). The greater the rock strength, the stronger the ability of the surrounding rock to maintain the original structure under the unloading of the tunnel excavation. Therefore, the expansion ability of intermittent joints in the surrounding rock is reduced, and it is not easy to form cracks penetrating through the resistance body, thereby improving the self-stability and the resistance capacity against water inrush. Ground stress (Gs ). Tunnel excavation will change the distribution characteristics of the initial stress field, and the initial state of the stress field determines the secondary distribution of the stress field to a certain extent. When the stress and seepage are coupled, the initial ground stress affects the change of the seepage field through the secondary distribution of the tunnel construction stress, which in turn affects the water and mud inrush process. Rock mass permeability (K). The permeability of rock mass is one of the important factors affecting the flow and migration of groundwater. The stronger the permeability of the rock mass, the faster the flow and migration speed of groundwater under suitable replenishment conditions, the stronger the weakening effect on the unfavorable structural surface of the rock mass, and the less conducive to the stability of the resistance body. Strike and dip angle of rock stratum (Ψ ). The angle between the strike of the rock strata and the axis of the tunnel, as well as the tunnel excavation along the inclination or against the inclination, all have a certain influence on the stability of the surrounding rock. When the direction of tunnel excavation is opposite to the inclination of the rock strata, the smaller the angle between the direction of the rock strata and the tunnel, and the smaller the dip angle of the rock strata, the less conducive to the stability of the resistance body.

6.2 Establishment of the Resistance Body Assessment Method Water and mud inrush is essentially a phenomenon that groundwater, cohesive soil, sand, etc., flow into the tunnel under the influence of the excavation of tunnels and underground engineering. The influencing factors are numerous and complex. Therefore, it is very difficult to carry out an accurate assessment on the resistance against

6.2 Establishment of the Resistance Body Assessment Method

229

water and mud inrush. We analyze the disaster source Ds and the resistance body Rb of the water and mud inrush disaster, and conduct investigations on the following four aspects: unfavorable geology U g , hydrodynamic conditions H d , resistance body thickness Rt and surrounding rock characteristics S r , so as to formulate the assessment method for the resistance body stability. Among them, the hydrodynamic conditions include hydraulic pressure characteristics H p , water recharge conditions W r and hydraulic connectivity H c ; surrounding rock characteristics include rock quality and integrity Ri , joint state J s , rock strength Rc , and it is subjected to the influence of ground stress Gs, rock mass permeability K and strata strike and dip angle Ψ , as shown in Fig. 6.1. The classification method of each influencing factor index for surrounding rock characteristics comprehensively draws on the related methods of rock mass quality evaluation and classification, such as RQD classification method (Deere et al. 1967), BQ classification method (GB 50218–1994), RMR classification method (Bieniawski 1978) and NGI (Q system) classification (Barton et al. 1981; Barton 2002). At the same time, the close integration with the engineering characteristics of the tunnel water and mud inrush disasters ensures that the classification method for the influencing factors of surrounding rock characteristics has strong scientificity and applicability. Based on the statistics and analysis of a large number of engineering cases and the analytic hierarchy process (Gu Yilei et al. 2005; Li Liping et al. 2010; Li Liping et al. 2011; Xu Zhenhao et al. 2011; Li et al. 2013a, b; Zhou Zongqing et al. 2013), the resistance assessment focuses on a total of 11 influencing factors including the resistance body thickness Rt , hydraulic pressure H p , unfavorable geology U g , rock quality and integrity Ri , joint state J s , water recharge W r , hydraulic connection H c , rock strength Rc , ground stress Gs , rock mass permeability K, and strata strike and dip angle Ψ , all of which are comprehensively scored, with a highest score of 500. According to the different effects of various factors on the resistance assessment, the scores of each factor are assigned, and the assigned scores are shown in Table 6.1. It can be seen from Table 6.1 that the thickness of the resistance body, hydraulic pressure characteristics, unfavorable geology, rock mass quality and integrity have the greatest influence on the resistance body, accounting for 76%, which are the main influencing factors; Followed by the state of surrounding rock joints, water recharge conditions, hydraulic connectivity and rock strength, accounting for 24%, which are secondary influencing factors; finally, the strata strike and dip angle, ground stress, and rock mass permeability are the correction factors. The total score Q of the resistance body is calculated according to formula (6.1), Q = Q Rt + Q Uw + Q Ug + Q Sr

(6.1)

The score of hydrodynamic conditions is calculated according to formula (6.2), Q Hd = Q Hp + Q Wr + Q Hc

(6.2)

The score of surrounding rock characteristics is calculated according to formula (6.3),

230

6 Assessment Method of the Resistance …

Fig. 6.1 Index system of factors affecting the resistance body. The data in the brackets is scores; ground stress Gs , rock mass permeability K, strata strike and dip angle Ψ are correction factors, scored by positive value; the total score is calculated according to formulas (6.1)–(6.5)

Table 6.1 Scores assigned to factors affecting the resistance body Influencing factors

Rt

Hp

Ug

Ri

Js

Wr

Hc

Rc

Gs

K

Ψ

Scores

125

100

90

65

40

30

30

20

10

10

10

Q Sr = Q Ri + Q Js + Q Rc − Q G s − Q K − Q ϕ

(6.3)

where Q Rt is the score of the resistance body thickness Rt , and the meanings of other symbols are analogized. The score Q Ri of Ri is determined by the rock quality index RQD and the integrity index J n , as shown in formula (6.4), Q Ri = RQD /Jn

(6.4)

6.3 Grading and Scoring of Factors Affecting the Resistance Body Stability

231

Table 6.2 Grading and scoring of resistance body Grades

I

II

III

IV

Status of the resistance body

Safe

Basically safe

Delayed failure

Directly failure

Scores

(400, 500]

(250, 400]

(100, 250]

[0, 100]

where Q Js is determined by the joint closure condition J c , the joint roughness J r and the joint filling property J f , as shown in formula (6.5), Q Js = Jc · Jr /J f

(6.5)

The resistance assessment grades for water and mud inrush in karst tunnels are divided into grades I to IV, as shown in Table 6.2. Grade I means that the resistance body is in an ideally safe state and has sufficient resistance against water and mud inrush. Grade II means that the resistance body is in a basically safe state. During the construction process, attention shall be paid to controlling the excavation step and providing timely support. Grade III indicates that the resistance body may undergo delayed damage. In the delayed damage stage, affected by water pressure, groundwater seepage and construction disturbance, the resistance body will undergo progressive damage, which will eventually induce water and mud inrush disasters. Of course, with timely treatment, such as grouting reinforcement, water release and pressure reduction, and blockage of groundwater supply channels, the occurrence of water and mud inrush disasters can still be prevented. Grade IV means that the resistance body will be directly destroyed, broken and collapsed, and water and mud inrush disasters will occur consequently.

6.3 Grading and Scoring of Factors Affecting the Resistance Body Stability According to the impact degree of various factors on water and mud inrush disasters, the influencing factors of the disaster sources and the resistance body (a total of 11 factors) for tunnel water and mud inrush are graded and the scored.

6.3.1 Grading and Scoring of Factors Affecting Disaster Sources 1. Unfavorable geology U g According to the degree of catastrophability, the unfavorable geology U g is divided into 4 grades and scored accordingly, as listed in Table 6.3.

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6 Assessment Method of the Resistance …

Table 6.3 Grading and scoring of unfavorable geology (U g ) Grading of catastrophability Description of unfavorable geology

Scores

High

Water-rich faults, water-conducting faults, large-scale water-storage faults, karst caves and karst penetration fissures, subterranean streams, water-bearing fracture zones formed by igneous rock intrusion, large karst trenches, karst troughs, abandoned mines, etc.

[0, 30]

Medium

Water-storage faults, fault fracture zone, well-developed (30,60] surface karst ditches, solution grooves and corrosion fractures, wide corrosion fractures and karst conduits, medium water-filled closed karst caves, contact zones between soluble rock and non-soluble rock, nonconformable contact zone, etc.

Weak

Water-blocking faults, corrosion fractures, karst conduits, small closed karst caves, etc.

None

No unfavorable geology that might cause water and mud 90 inrush near the tunnel

(60,90)

Table 6.4 Grading and scoring of water pressure (H p ) Waterhead height H/m

≥60

200

Good integrity, with few or no joints

Integrated, extremely thick layered

1.0

1

(100, 200]

1 set of joints

Block, thick layered

1.2

1–2

(60, 100]

1 set of joints with other disordered joints

Block

1.4

2

(40, 60]

2 sets of joints

Fractured block, medium-thick layered

1.6

2–3

(20, 40]

2 sets of joints with other disordered joints

Medium and thin layered

1.8

3

(6, 200]

3 sets of joints

Fractured block

2.0

≥4

≤6

4 or more sets of joints, with randomly distributed joints of strong development

Fractured

3.0

Unordered

–

–

Granular, crushed

4.0

Table 6.12 Joint closure (J c ) and scores Joint closure status

Completely closed

Shear dislocation ≤ 10 cm

Non-contact

Scores

5

4

3

Table 6.13 Joint roughness (J r ) and scores Joint roughness

Discontinuous

Rough or wavy joints

Smoothly wavy or straight joints

Scores

8

7

6

Note: When J c is described as non-contact joint surface, J r is 6

5. Ground stress Gs According to the scores of ground stress, the initial ground stress can be divided into four grades: extra-high stress, high stress, medium stress and low stress, and scored accordingly, as shown in Table 6.16.

236

6 Assessment Method of the Resistance …

Table 6.14 Filling property of joints (J f ) and reduction coefficient Filling property

Reduction coefficient

Joint surfaces are in close contact, and the filling is impermeable

1.0

Without soft mineral cover, sand, and no clay disintegrated rock, etc.

1.2

With silty or sandy clay cover, and a small amount of non-softening clay 1.4 fine particles Fragmented rock, and softening clay mineral cover of low friction

1.6

Fragmented rock, and expansive clay filling

1.8

Thick continuous clay layer (non-softening, softening, expansive clay)

[1.6, 2.0]

Table 6.15 Grading and scoring of intact rock strength (Rc ) Point loading strength /MPa

> 10

(4, 10]

(2, 4]

[1, 2]

–

–

–

Uniaxial compressive strength > /MPa 250

(100, 250] (50, 100] (25, 50] (5, 25] (1, 5] [0, 1]

Scores

16

20

10

6

4

2

0

Table 6.16 Grading and scoring of ground stress (Gs ) Initial ground stress

Extra-high

High

Medium

Low

δ = Rc /σ max

7

Scores

[6, 10]

[3, 6)

[1, 3)

0

Table 6.17 Grading and scoring of rock permeability (K) Status of tunnel effluent

Dry

Wet

Water seeping or dripping

Frequent water seeping or linear running water

Water inflow

Volume of water inflow /(L/(min•10 m))

0

(0, 10]

(10, 25]

(25, 125]

>125

Scores

0

(0, 2)

(2, 5]

(5, 8]

(8, 10]

6. Rock permeability K According to the status of tunnel effluent and volume of water inflow, the rock permeability can be divided into 5 grades and scored accordingly, as shown in Table 6.17.

6.4 Implementation Procedure of the Resistance Body Assessment

237

Table 6.18 Grading and scoring of rock strata strike and dip angle (Ψ ) Bedding strike

Vertical to tunnel axis

Parallel to tunnel axis

Strike unconsidered

Excavation along the dip angle

Excavation against the dip angle

Dip angle /(°)

(45, 90]

(20, 45]

(45, 90]

(20, 45]

(20, 45]

(45, 90]

[0, 20]

Scores

0

(0, 3)

[3, 5)

[5, 7)

[3, 7)

[7, 10]

[5, 7)

7. Rock strata strike and dip angle Ψ The scores of rock strata strike and dip angle can be determined by analyzing the relationship between the rock strata strike and tunnel axis and excavation direction, as shown in Table 6.18.

6.4 Implementation Procedure of the Resistance Body Assessment The implementation procedure of the resistance body assessment of water and mud inrush in karst tunnels is shown in Fig. 6.2. 1. Firstly, determine the thickness of the relaxation zone D1 , the thickness of fractured zone D2 and the relative safety thickness D3 ; and D1 and D2 can be measured by geophysical exploration and drilling or obtained by referring to Tables 6.8 and 6.9. 2. Preliminary assessment is conducted according to the thickness of the resistance body d. If d ≤ D1 +D2 , the resistance body will encounter delayed failure or direct failure; If d > D1 +D2 +D3 , the resistance body will keep in a safe or basically safe state; If D1 +D2 < d ≤ D1 +D2 +D3 , further scoring evaluation shall be conducted to the resistance body. 3. Further scoring evaluation is carried out as follows. All factors affecting the resistance body such as thickness of the resistance body, hydrodynamic conditions, unfavorable geology and surrounding rock characteristics are further graded and scored according to Formula (6.1) and Table 6.1, so as to finally determine the state of the resistance body. The evaluation result is safe, basically safe, delayed failure or direct failure.

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6 Assessment Method of the Resistance …

Fig. 6.2 Implementation procedure of the resistance body assessment

6.5 Engineering Verification 1. Project overview Yesanguan Tunnel of Yichang-Wanzhou Railway is located between Wankou River and Zhijing River in Yesanguan Town, Badong County, Enshi Prefecture. The starting

6.5 Engineering Verification

239

and ending chainages are DK116+205~DK130+038, with a total length of 13,833 m and a maximum buried depth of 684 m. It is the longest tunnel on the YichangWanzhou Railway (Sun Mingbiao, 2010). The tunnel passes through the area where soluble rock strata is widely distributed, and there are strong karst development and complex hydrogeological conditions and geological structures, and hence it is an important control project of Yichang-Wanzhou Railway. The tunnel passes through Triassic Daye Formation, Triassic Jialingjiang Formation, Permian, Carboniferous, Devonian and Silurian strata, of which clastic rock stratum accounts for 37% of the tunnel, limestone stratum accounts for 63% of the tunnel, and 6 karst conduit flows are developed in the tunnel site. Among them, No. 3 underground river has the greatest impact on the tunnel. It is distributed in a belt shape and crosses obliquely above the tunnel. The elevation of the discharge datum level is 1,050 m, 220 m higher than the tunnel. The underground river has strong hydraulic connection with the tunnel through karst fissures, faults and other channels. A total of 12 faults are developed in the tunnel site, of which the F18 fault cuts through and connects with No. 3 underground river, which has a significant risk of water and mud inrush. The tunnel passes through the contact zone between clastic rock and limestone for many times, resulting in a high construction risk (Sun Mingbiao, 2010; Ma Dong, 2012). The geological section diagram of Yesanguan Tunnel of Yichang-Wanzhou Railway is shown in Fig. 6.3. 2. Water and mud inrush description On August 5, 2007, the exit end of Yesanguan Tunnel Line I of Yichang-Wanzhou Railway was excavated to the chainage of DK124+602, and a major water seepage disaster of large-scale collapse, mud and rock inrush suddenly occurred, as shown in Fig. 6.4. Under the action of high water pressure, the groundwater transmits pressure along with the concealed broken rock mass, fracturing the complete surrounding rock of the tunnel free face, resulting in the large-scale collapse of the tunnel cavern, penetrating the karst conduits above the tunnel, and seizing the No. 3 underground river. The instantaneous water inflow reached 15 × 104 m3 /h, with a total of 5.4 × 104 m3 sediment and block stone gushing out, filling the tunnel by about 400 m, causing huge economic losses and casualties (Zhang Mei et al. 2010).

Fig. 6.3 Geological section diagram of Yesanguan Tunnel of Yichang-Wanzhou Railway

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6 Assessment Method of the Resistance …

(a) Sediments and rock blocks gushing out

(b) Distortion and disassembly of several equipment

Fig. 6.4 Photos of water and mud inrush occurring in No. 602 karst cave of Yesanguan Tunnel

3. Influencing factor analysis (i)

(ii)

(iii)

(iv)

Resistance body thickness Rt . When drilling ahead to lock the boundary of the solution cavity in front of the discharge tunnel, it is found that there is a broken limestone area with a thickness of 1.2–1.9 m near the solution cavity side of the rock wall in front of the discharge tunnel. Therefore, the thickness of the fractured zone D2 can be taken as 2 m; the surrounding rock is of Class II, so the thickness of the relaxation zone D1 is 1 m. The section of the main tunnel is horseshoe type, 7.16 m wide and 9.46 m high, so the safe thickness D3 is 7.5 m. Therefore, the preliminary evaluation shows that when d ≤ 3 m, the resistance body will experience direct damage or delayed damage; when d > 10.5 m, the resistance body is safe or basically safe; when 3 m < d ≤ 10.5 m, further scoring evaluation is required. Unfavorable geology U g . The karst cavity is developed from the chainage of DK124+583 to +610, with a longitudinal length of 27 m along the tunnel. The karst cavity crosses the tunnel. The main karst cavity is located at 40 m to the left and 100–250 m to the upper left of line I at the chainage of DK124+580~+640. It is connected with the ground upward and gradually pinched out to the right, developing into a wide tensile fracture. The fillings are limestone block stones, sand pebbles, silt and water. The “602 karst cavity” water and mud inrush breach is on the left sidewall at the chainage of DK124+602~+605, with a total volume of water inflow of 2, 600 × 104 m3 . Hydraulic pressure H p . Before the water inrush, the measured water pressure in the karst cave at DK124+602 is 1.0 MPa. After the inrush, the water pressure in the karst cave is generally about 0.1 MPa, and the fracture water pressure in the surrounding rock mass is 0.3–0.9 MPa (Sun Mingbiao, 2010). Water recharge condition W r .

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The tunnel is located in the limestone section of the contact zone between limestone and mudstone, which belongs to the transition zone from limestone aquifer to mudstone non-aquifer. The karst fissure water in the limestone section is developed and rich in groundwater. Its groundwater is in the same hydrogeological unit as the No. 3 underground river of Yesanguan Tunnel. The tracer test results show that there is an obvious hydraulic connection between the water inrush point of the tunnel and the surface water of Shuidongping karst depression and No. 3 underground river, indicating that the surface water of Shuidongping karst depression, No. 3 underground river and the karst aquifer of Permian Qixia-Maokou Formation are the main water sources of water inrush (Wu Li et al., 2009). (v) Hydraulic connectivity H c . Vertical karst such as sinkhole, karst funnel and depression are very developed in this section. The groundwater recharge and runoff conditions are good, and the karst water can be easily introduced into the tunnel through the fault fractured zone. (vi) Rock quality and integrity Ri . The tunnel passes through the limestone of Qixia-Maokou Formation of Lower Permian and limestone containing chert nodule and asphaltene stratum. It is thick layered and the core is relatively complete, with RQD = 70%. The surrounding rock of this section is classified as grade II, and J n = 1.2. (vii) Joint state J s . Karst fractures are developed in this section, and the fracture development direction intersects the tunnel nearly vertically or at a large angle, crossing line I and line II. The fractures are basically developed along the strike of the rock stratum, the main joints are closed or shear dislocation occurs, the occurrence of joints is rough or wavy, and occasional fractures are mixed with mud or carbonaceous limestone particles. (viii) Rock strength Rc . As mentioned above, the surrounding rock that the tunnel passes through at the chainage of DK124+550~+650 is of good integrity and belongs to class II. The collapse accumulation body of tunnel surrounding rock is dark gray limestone block of Qixia Formation, and the uniaxial compressive strength of the rock block is 90–110 MPa. (ix) Rock permeability K. According to the geological data, the tunnel section at the DK124+550~+650 is located in the deep slow flow zone of groundwater, with weak karst development. Water effluent state is mainly in the form of fissure seepage and dripping, and the water flow dynamics is relatively stable. The actual construction reveals that there are multiple water inflow points near the tunnel face (Ma Dong, 2012), and the water inflow has a large volume. (x) Ground stress Gs . The buried depth of the tunnel at the chainage of DK124+602 karst cave is 520 m, and δ > 7. It belongs to low stress area. (xi) Rock stratum strike and dip Ψ .

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6 Assessment Method of the Resistance …

This section is located in the west wing of Shimaba anticline. The tunnel is excavated against the inclination, and the dip angle of rock stratum is 10°–45°.

4. Resistance evaluation results and analysis According to the above analysis on the influencing factors of Yesanguan Tunnel, the corresponding scores for each influencing factor are shown in Table 6.19. Next, the impact of three main categories of influencing factors (i.e., the hydrodynamic conditions, unfavorable geology and surrounding rock characteristics) on the resistance evaluation is analyzed, mainly considering the following two aspects: the scoring values of its contribution and the percentage of the scoring value in the total scores of various types of factors. The greater the scoring values, the stronger role this factor plays in the resistance; a smaller percentage value usually indicates that this factor plays a weak role in the resistance and hence shall be primarily considered in construction reinforcement measures. Figure 6.5 shows the scores and percentage values of main categories of influencing factors in the resistance evaluation of Yesanguan Tunnel. Table 6.19 Scoring of factors affecting the resistance body in Yesanguan Tunnel Influencing factors

Hp

Ug

Ri

Js

Wr

Hc

Rc

Gs

K

Ψ

Scores

20

30

35

28

10

10

12

0

9

6

Fig. 6.5 Scores and percentages of hydrodynamic condition, unfavorable geology and surrounding rock characteristics

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According to the analysis in Fig. 6.5, the scores of surrounding rock characteristic S r is the greatest, indicating that the surrounding rock in this section plays an important role in the stability of the resistance body; the percentage value of the hydrodynamic condition H d is only 25%, which is an obviously “weak” factor. To strengthen the safety of the resistance body, hydrodynamic conditions shall be firstly considered, that is to take the imitative to prevent and control water and mud inrush via water release, pressure reduction and supply channel blockage. According to the scoring values of various factors in Table 6.19, the resistance evaluation score Q can be obtained from Eq. (6.1): Q = Q Rt + 130

(6.6)

When d ∈ (D1 +D2 , D1 +D2 +D3 ], that is, 3 < d ≤ 10.5, the relationship curve between the resistance evaluation scores and the thickness of resistance body is shown in Fig. 6.6. The resistance evaluation score here is calculated according to the linear relationship with the thickness of the resistance body, i.e., Q Rt = 125 × (d − 3)/7.5

(6.7)

By analyzing the Q-d relationship curve when “P = 1.0 MPa” in Fig. 6.6, it can be obtained that: when the thickness of resistance body d > 10 m, the resistance evaluation grade is II, indicating a basically safe state; when the thickness of resistance body 3 m < d ≤ 10 m, the resistance evaluation grade is III, indicating a delayed failure state; when the thickness of resistance body d ≤ 3 m, the resistance evaluation grade is III or IV, indicating a delayed failure or a direct failure state. When water and mud inrush occurred in the actual engineering construction of Yesanguan Tunnel, the thickness of the “602 solution cavity” is 7.5 m, which is

Fig. 6.6 Relationship curve between the resistance evaluation scores Q and the thickness of resistance body d (Q-d)

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6 Assessment Method of the Resistance …

less than 10 m, the required thickness of resistance body to reach the resistance evaluation of Grade II (hereinafter referred to as the minimum thickness of resistance body). Moreover, this water and mud inrush is induced by the progressive damage of the resistance body, which firstly expands and penetrates and then experiences progressive damage under the dual action of high water pressure and excavation disturbance. That is to say, it is a delayed water and mud inrush case. 5. Discussion If water release and pressure reduction were conducted to the “602 solution cavity” before the disaster, with the water pressure inside the cavity reduced to less than 0.1 MPa, then the subsequent Q-d relationship curve can be shown in Fig. 6.6 (with P < 0.1 MPa). Obviously, the current thickness of resistance body d ≥ 6.5 m and the resistance evaluation grade is Grade II, indicating a basically safe state. That is to say, when the tunnel face is excavated with the thickness of the resistance body being 7.5 m, water and mud inrush will not occur. With further proactive prevention and control measures such as blocking the groundwater supply channel, grouting to strengthen the surrounding rock and improving the adverse geological body, the minimum thickness of the resistance body that would experience failure will gradually decrease, as shown in Fig. 6.7. After taking proactive prevention and control measures such as water release and pressure reduction and blocking groundwater supply channel, the sum of scoring values of hydrodynamic conditions, unfavorable geology and surrounding rock characteristics reach 210, and the minimum thickness of the resistance body is about 5.5 m, which is less than the actual thickness of the resistance body when the water inrush occurred. Of course, with further improvement of the unfavorable geological conditions, the minimum thickness of the resistance body can be further reduced.

Fig. 6.7 Comparison of minimum thickness of resistance body under proactive prevention and control measures A represents no intervention measures; B represents reducing pressure by drainage; C represents blocking supply channel; D represents improving unfavorable geology; “10, 130” represents under the working condition A, the minimum thickness of resistance body is 10 m and the total scores of hydrodynamic conditions, unfavorable geology and surrounding rock is 130; and analogy in other cases

6.6 Summary

245

As for the treatment of Yesanguan Tunnel water and mud inrush, such technologies as “high-level water release adit to reduce water pressure, grouting and plugging to consolidate the colluvium of broken rock blocks, and advance support by pipe-shed” were implemented (Zhang Mei et al. 2010), which are consistent with the abovementioned proactive prevention and control measures of “water release and pressure reduction, blocking groundwater supply channels”. And this avoids the recurrence of water and mud inrush disasters in the later treatment process. During the construction of similar karst tunnels with a risk of water and mud inrush, the above measures can also be used to control and reduce the risk level, avoid the occurrence of water and mud inrush disaster and ensure the safety of tunnel construction.

6.6 Summary In this chapter, focusing on the disaster source and the resistance body of water and mud inrush, we summarized 11 influencing factors of water and mud inrush in tunnel from four aspects: hydrodynamic conditions, unfavorable geology, the thickness of the resistance body and surrounding rock characteristics, established the resistance evaluation method of water and mud inrush in tunnels, and developed a rapid identification method of water and mud inrush that is suitable for engineering site. This method makes up for the deficiencies that the existing risk assessment of water and mud inrush fails to describe the characteristics of surrounding rock and the influence of the resistance body thickness, and that the traditional minimum safe thickness calculation method does not comprehensively consider important influencing factors such as hazard-inducing environment and surrounding rock characteristics. Therefore, we have constructed the index system of influencing factors for water and mud inrush resistance evaluation: the thickness of the resistance body, hydraulic pressure characteristics, unfavorable geology and rock mass quality and integrity are the main influencing factors, accounting for 76%; the joint state in surrounding rock, water recharge conditions, hydraulic connectivity and rock strength are the secondary influencing factors, accounting for 24%; the strike and dip angle of rock stratum, ground stress and rock permeability are the correction factors. On this basis, we put forward the grading method and scoring system of various influencing factors, formed the grading and scoring query table, ensured the scientificity and practicability of the resistance evaluation method, and realized the rapid query and resistance evaluation at the project site. Finally, the resistance evaluation method of water and mud inrush in the tunnel is verified, and the water and mud inrush accident of “602 solution cavity” in Yesanguan Tunnel of Yichang-Wanzhou Railway as the engineering case is analyzed in detail. The results showed that hydrodynamic condition is the “weak” factor for the safety of the resistance body in this case and that the thickness of the resistance body when inrush occurred is less than the calculated minimum thickness of the resistance body, which is a delayed water and mud inrush case. The engineering case analysis proves that the resistance evaluation method is scientific and practical.

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References Barton N, Loset F, Lien R, Lunde J (1981) Application of Q-system in design decisions concerning dimensions and appropriate support for underground installations. International Conference on Sub-surface Space, Rock Store. Stockholm, 553–561 Barton N (2002) Some new Q-value correlations to assist in site characterization and tunnel design. Int J Rock Mech Min Sci 39(2):185–216 Bieniawski ZT (1978) Determining rock mass deformability: experience from case histories. Int J Rock Mechanics Mining Sci Geomechan Abstr 15(5):237–247 Criss EM, Criss RE, Osburn GR (2008) Effects of stress on cave passage shape in karst terranes. Rock Mech Rock Eng 41(3):499–505 Deere DU, Hendron AJ, Pation FD, Cording EJ (1967) Design of surface and near surface construction in rock. Failure and breakage of rock, Proceedings of the 8th US Symposium on Rock Mechanics, New York, 237–302 Gan KR, Yang Y, Li JS (2007) Analysis on karst water inflow mechanisms and determination of thickness of safe rock walls: case study on a tunnel. Tunn Constr 27(3):13–16 Gu YL, Li XH, Zhao Y, Ren S (2005) Analysis of forming reason of mud breakout in Tong-Yu Tunnel. Rock Soil Mechan 6:920–923 Guo JQ (2011) Study on against-inrush thickness and waterburst mechanism of karst tunnel (Ph.D. Thesis). Beijing Jiaotong University, Beijing. Huang X, Lin P, Xu ZH, Li SC, Pan DD, Gao B, Li ZF (2018) Prevention structure assessment method against water and mud inrush in karst tunnels and its application. J Central South Univ (Science and Technology) 49(10):2533–2544 Li LP, Li SC, Zhang QS (2010) Study of mechanism of water inrush induced by hydraulic fracturing in karst tunnels. Rock Soil Mechan 31(2):523–528 Li LP, Li SC, Chen J, Li JL, Xu ZH, Shi SS (2011) Construction license mechanism and its application based on karst water inrush risk evaluation. Chin J Rock Mechan Eng 30(7):1345– 1355 Li SC, Zhou ZQ, Li LP, Shi SS, Xu ZH (2013a) Risk evaluation theory and method of water inrush in karst tunnels and its applications. Chin J Rock Mechan Eng 32(9):1858–1867 Li SC, Zhou ZQ, Li LP, Xu ZH, Zhang QY, Shi SS (2013b) Risk assessment of water inrush in karst tunnels based on attribute synthetic evaluation system. Tunn Undergr Space Technol 38:50–58 Ma D (2012) Study on impact mechanism of deep buried karst to tunnel safety and the treatment technique (Ph.D. Thesis). Beijing Jiaotong University, Beijing Sun MB (2010) 602 Karst cave treatment in Yesanguan Tunnel on Yichang-Wanzhou Railway. Mod Tunn Technol 47(1):91–98 Wu L, Wan JW, Chen G, Zhao L, (2009) Cause of the “8.5” water burst incident at Yesanguan Tunnel along the Yi-Wan Railway. Carsologica Sinica 28(2):212–218 Xu ZH, Li SC, Li LP, Chen J, Shi SS (2011) Construction permit mechanism of karst tunnels based on dynamic assessment and management of risk. Chin J Geotech Eng 33(11):1714–1725 Zhou ZQ, Li SC, Li LP, Shi SS, Song SG, Wang K (2013) Attribute recognition model of fatalness assessment of water inrush in karst tunnels and its application. Rock Soil Mechan 34(3):818–826 Zhang M, Zhang MQ, Sun GQ (2010) Technology for treating burst port of filling solution cavity with high-pressure and rich water of Yesanguan Tunnel on Yichang-Wanzhou Railway. J Railw Eng Soc 27(3):81–86

Chapter 7

Recognition Methods for Hazard-Causing Systems of Water and Mud Inrush in Tunnels

Many technologies exist in recognizing hazard-causing systems of water and mud inrush in tunnels. Each recognition technology has its own principles. The scope of application, recognition advantages, and recognition distance among all technologies are different, and each is of certain limitations. For example, geological survey techniques mainly provide qualitative description, and have poor performances in quantitative analysis. Geophysical prospecting results offer multiple solutions, and drilling technology is limited to a “one-hole view”. The tunnel water and mud inrush hazard-causing systems are complex and diverse; therefore, a single recognition method bears low accuracy and is prone to miss or misjudge the location, scale, and type of hazard-causing systems. On the other hand, if several recognition technologies are used at the same time but not optimized, resources can be wasted, and the best recognition result may not be achieved. By fully understanding the geological environment associated with hazard-causing systems and using different recognition methods reasonably, engineers can more accurately obtain the type, scale, and location of such systems and ensure the safe construction of tunnels. In this chapter, we develop a comprehensive recognition method for tunnel water and mud inrush hazard-causing systems based on geological characteristics, geophysical response characteristics, and drilling borehole exposed features. It is an accurate and efficient method that integrates geological, geophysical prospecting, and drilling recognition components. This chapter introduces the implementation process, implementation principles and hazard-causing system characteristics of this comprehensive recognition method, and engineering application analysis is carried out taking the identification process of the high-risk karst section of the Qiyueshan Tunnel on Lichuan-Wanzhou Expressway as an example (Huang et al. 2020).

© Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1_7

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7.1 Implementation of the Recognition Method for Water and Mud Inrush Hazard-Causing System The recognition method of tunnel water and mud inrush hazard-causing system is an integrated combination of geological recognition, geophysical prospecting recognition, and drilling recognition. Based on the geological characteristics, geophysical response characteristics and drilling exposure characteristics of the hazard-causing system, this recognition method follows the basic principles “geology first, monitoring throughout, geophysical prospecting and drilling collaboration, complementation and verification, integration and dynamic feedback”. This method can maximize advantages of geological, geophysical prospecting, and drilling recognition methods to improve the accuracy of recognizing hazard-causing systems. It should be noted that the recognition method of the water and mud inrush hazard-causing system mentioned in this chapter is mainly carried out during the construction period, especially the geophysical prospecting and drilling recognition methods.

7.1.1 Implementation Process The implementation flow chart of the recognition method for tunnel water and mud inrush hazard-causing systems is shown in Fig. 7.1. 1. Geological recognition. First, relevant engineering and hydrogeological data (if possible, learning from tunnels already built in the tunnel area, combining additional detection methods such as outside-of-the-tunnel geological survey, withinthe-tunnel geology sketch, and tracer test) are collected to analyze the geological structure, formation lithology, strata combination, geographic and geomorphic conditions, groundwater level, and the dip direction and angle of the formation. And then the surface basin distribution, tectonic types, and groundwater storage, movement, recharge and discharge information are obtained. The type of water and mud inrush hazard-causing system and its development laws are estimated. Second, researchers should conduct geological sketch method for the entire tunnel to analyze the geological changes in the excavation process and identify the precursor geological information of the water and mud inrush. Geological recognition provides preliminary data for geophysical prospecting and drilling, guides the selection of detection methods and the implementation of drilling schemes, and solves the issue of multiple solutions for geophysical prospecting. 2. Geophysical prospecting recognition. Geological sketch and TSP detection method should run through the entire construction process. When a geological sketch finds the precursor of possible water and mud inrush, or TSP detection shows abnormal bodies in front of the tunnel face, the transient electromagnetic method should be conducted to detect whether it is a water-containing structure and its distribution and location. In the case of a water-bearing body, further

7.1 Implementation of the Recognition Method for Water and Mud Inrush …

249

Fig. 7.1 The flow chart of the tunnel water and mud inrush hazard-causing system recognition

detection should be carried out by ground penetrating radar, resistivity method, and high-density electric method to locate the water-bearing body and determine its scale. The geophysical recognition can identify the location, scale, and water containing characteristics of the geological bodies, which will compare with the drilling results and guide the formulation of drilling plan. The features of commonly used detection methods and the corresponding recognition of adverse geology are shown in Table 7.1. 3. Drilling recognition. Through geological and geophysical recognition, the approximate location of the adverse geological body is determined, then boreholes are drilled to expose the geology body. The location, scale and water bearing characteristics of the hazard-causing system are identified according to the properties of rock powder, flushing fluid, and the water inflow of the borehole, as well as the drill speed, failure energy, and abnormal phenomena such as

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Table 7.1 Commonly used geophysical prospecting methods and their characteristics Geophysical prospecting method

Detection Time distance (h) (m)

Sensitivity to adverse geology

TSP

120 ~ 150 2

Quantitative judgment for vertical and transverse wave velocity, elastic modulus, Poisson ratio, and other rock mechanical properties

Typical adverse geological recognition Water-free Water-free Water-bearing faults and karst faults and their karsts damage zones √ √ √

√

√

Sensitive to water-bearing and water-conductive structures

×

×

Sensitive to water-bearing and water-conductive formations. The low resistivity area reflects the water-bearing structure

×

×

Sensitive to water and mud conductive structures

×

×

20 ~ 30 Ground penetrating radar

0.5 ~ 1 Sensitive to water-bearing and water-conductive geology, caves without filling and caves filled with water and mud

Transient 60 ~ 80 electromagnetics

1.5

Resistivity method

30

1

High-density electricity

Related to 1 ~ 2 the number and distance of electrodes

√

√

√

√

7.1 Implementation of the Recognition Method for Water and Mud Inrush …

251

stuck, jump and collapse. As a supplementary detection means, drilling recognition and geophysical methods confirm each other and work together to reduce the multiplicity of geophysical exploration results, and improve recognition accuracy.

7.1.2 Implementation Principles The recognition method of tunnel water and mud inrush hazard-causing system follows the principle of “geology first, monitoring throughout, geophysical and drilling collaboration, complementation and verification, integration and dynamic feedback”. “Geology first, monitoring throughout” refers to the procedure that researchers and practitioners first carry out geological recognition before the tunnel construction, to understand the geological situation of the tunnel site entirely, preliminary determine the type and distribution of hazard-causing systems, and improve the accuracy of hazard-causing system identification. During tunnel construction, the precursor geological features and abnormal geological phenomena provide basis for formulating geophysical and drilling implementation plans. Geological recognition results provide important prior information and reference for the geophysical exploration and interpretation. In addition, drilling exposure can achieve the most intuitive judgment and geological recognition of the characteristics of hazard-causing systems. This principle highlights the importance of geological recognition. “Geophysical and drilling collaboration, complementation and verification” means that based on geological recognition, the optimized geophysical detection method is used to determine the distribution and water-bearing characteristics of the hazard-causing system, and the drilling plan is then formulated to determine the drilling positions and depth parameters. Thus, geophysical detection as the guidance to drilling, and drilling as a supplement to geophysical detection, the two systems cooperate and complement each other to identify hazard-causing systems accurately. “Integration and dynamic feedback” refers to the organic combination of geological analysis, geophysical prospecting, and drilling recognition. The geological analysis preliminarily assesses the hazard-causing system and its distribution, disaster precursor information supplements and feeds back the preliminary results. Geophysical detection and drilling constitute a targeted interpretation based on the prior knowledge and timely feedback to improve and revise the geological analysis. Excavation and exposure verification analysis results can enrich the statistical database of the developmental characteristics of hazard-causing systems and accumulate experience in geological analysis, geophysical detection, and drilling recognition.

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7.2 Typical Hazard-causing System Characteristics Under certain geological conditions, tunnel water and mud inrush hazard-causing systems often show unique geophysical response characteristics in the surrounding rock lithology, water-bearing property and filling conditions. In addition, drilling exposure will also show abnormal features. Therefore, it is of great significance to study the development law, geophysical response characteristics, and drilling exposure characteristics of hazard-causing systems, so as to determine their type, location, and scale and ensure safe and rapid tunnel construction.

7.2.1 Geological Recognition 1. Geological features of fault-category hazard-causing systems Fault-category hazard-causing systems can be identified according to the following geological features. First, the existence of faults makes the surface exhibit unique geomorphological forms, such as fault cliffs, fault triangles, faulted ridges, the contact zone of plain and mountain cross-cutting mountain ridges, string beaded lakes or depressions, ribbon distribution of spring water, faulted water systems, and rivers. These geomorphological features allow faults to be identified on the surface. Second, it can be determined according to some unique geological phenomena produced during fault development. Those phenomena can be a discontinuity of tectonic lines, the existence of fault rocks, duplication or deletion of adjacent formations, the presence of magma activity and mineralization, sudden changes in lithic facies and thickness, and the strengthened tectonics caused by fault activities, such as the appearance of the lens body, rapidly changed, variable, and steep rock formation occurrence, the emergence of highly jointed, cleavable and even foliated narrow bands, the surge of small folds, and the appearance of crushing and various scratches, steps, drag folds or folds. In addition, the following geological phenomena can occur when the tunnel is constructed near a fault. (1) The number of joint sets in the surrounding rock increases significantly, for example, 6 ~ 12 sets. (2) An inverse joint or a small broom-shaped structure composed of arc-shaped joints appear in the surrounding rock. (3) The strength of the surrounding rock is significantly weakened, and there are phenomena such as rust dyeing, crushing rock, and cataclastic rock. (4) In the lower plate of a water-rich fault, the wetting and softening of shale and mudstone, which acts as a water barrier, is significant, e.g., water dripping, scattering and spraying.

7.2 Typical Hazard-causing System Characteristics

253

2. The characteristics of karst-category hazard-causing systems In karst areas, the probability of encountering karst-category water and mud inrush is high. The water and mud inrush disasters occurring in the same region or the same geological unit are usually similar in type. Therefore, the disaster characteristics of previously built tunnels can serve as a reference for the later construction. In addition, tracer tests can be used to analyze karst water connectivity and estimate the volume of water inflow. Besides, the analysis of karst development and disaster precursor information also contributes to the recognition of water and mud inrush hazard-causing systems. (1) Tracer test When carrying out the hydrogeological survey in the tunnel site area, tracer test can be used to estimate the karst groundwater connectivity. The underground flow is proved to be connected between the tracer dropping and receiving points if the fluorescent dye can be detected at the receiving point. The flow rate when the tracer is received is the maximum rate of underground flow, and the flow rate corresponding to the peak of the tracer curve is the average speed of underground flow. The singlepeak tracer curve with better symmetry indicates that the karst passage is relatively simple and has no karst pool development. If the tracer curve is a single asymmetric peak, and the peak drop is slow, it indicates that the karst channel has such structures of karst pool, underground lake, etc. The tracer curve of several independent peaks demonstrates multiple parallel karst conduits in the groundwater passage. Tracer test can obtain the following relevant parameters: tracer recovery quality M 0 , tracer average retention time t, volume V of underground water passage system, underground water passage cross-sectional area A, groundwater crossing channel average diameter D, average tracer migration speed v, which can be expressed as (Zhang et al. 2015): 

∞

M0 =

C(t)Q(t)dt

(7.1)

0

∞ t = 0∞

tC(t)Q(t)dt

C(t)Q(t)dt  t V = Qdt

(7.2)

0

(7.3)

0

A= D=2

V x √

(7.4) A π

(7.5)

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∞

x C(t)Q(t)dt v = 0 ∞ t 0 C(t)Q(t)dt

(7.6)

where C(t) is the monitoring tracer concentration, Q(t) is the flow rate at monitoring point, t is the monitoring time, and x is the distance between the tracer dropping point and receiving point. (2) Water inflow rate forecast Areas with significant forecast water inflows tend to be more prone to water and mud inrush disasters. Therefore, the estimates of water inflow are helpful to make a macro-judgment on the location and scale of the water and mud inrush hazardcausing system. At present, the methods of predicting the tunnel water inflow and their characteristics are shown in Table 7.2 (Zhu and Li 2000). Underground runoff coefficient method, underground runoff depth method, precipitation infiltration method, depression infiltration volume method, and well/spring recharge method are suitable for the construction areas of simple groundwater formation and can only predict macro behaviors generally. Thus, they are more likely to be used for the initial tunnel water inflow prediction, namely the pregeological survey stage of tunnel construction. Groundwater dynamics is a method to predict the water inflow and needs the relevant survey and test data of the tunnel area. The isotope tritium method is suitable for groundwater flow prediction over a short distance. The numerical analysis method has been applied more and more frequently because of its fast calculation and practicality. The key to predicting water inflow is to establish a correct geological or seepage model. (3) Karst development feature recognition Factors such as formation lithology, the dip direction and angle of formation, formation combination, geological structure, topographical features, and groundwater mobility are essential in karst development (Xu et al. 2011a, 2011b). Their geological recognition characteristics are shown in Table 7.3. (4) Geological information of disaster precursors In the tunnel excavation process, when the tunnel face is near the adverse geology, some obvious information can exist indicating that water and mud inflow or inrush is about to occur. This information is called the disaster precursor geological information. Based on precursor information in karst tunnels, experts can predict large karst cave water bodies and underground rivers, issue disaster warnings, and optimize detection methods to guide construction plan revision. The precursor geological information of extensive karst hazard-causing systems includes the following aspects (Guo et al. 2013; Xu et al. 2011b). (1) Cracks and fissures near the tunnel face contain rust stain, clay or mud, and even mud fillings are squeezed out. (2) Rock formations are wet and softened decidedly, and there are water droplets attached or seepage and water leakage.

7.2 Typical Hazard-causing System Characteristics

255

Table 7.2 Commonly used water inflow prediction methods and their characteristics Prediction method

Basic principle

Application

Method characteristics

Underground runoff coefficient method

The product of the underground runoff coefficient and the water catchment area of the tunnel

Cross-ridge tunnel, passing through one or more surface water basin areas, karst regions

Macro, simple and effective. It is based on dry season water flow, and the calculated water inflow in dry seasons is closer to the actual water inflow, but it is significantly lower than the actual in rainy seasons

Underground runoff depth method

The product of underground runoff depth, tunnel catchment area, and conversion coefficient

Cross-ridge tunnel, passing rough one or more surface water basin areas, karst regions

Macro and approximate predictions, influenced by runoff depth, evaporation volume, and surface retention depth

Precipitation infiltration method

The product of multi-year average precipitation, tunnel catchment area, precipitation infiltration coefficient, and conversion coefficient

Karst tunnel, shallow buried cross-ridge tunnel

Macro and general predictions. As multi-year average rainfall, precipitation seepage coefficient, catchment area, and other parameters change significantly, there is deviation in results

Depression infiltration volume method

The product of depression water catchment area and precipitation

The situation in which Simple principle, macro rain in the depression and general prediction area goes directly into of tunnel water inflow the tunnel

Well/spring recharge method

The sum of all spring flows within the impact range of the tunnel

Fountains are the primary source of supply for the tunnel water inflow

Groundwater dynamics method

Based on the principle Homogeneous of groundwater formation seepage flow mechanics

Simple principle, macro and general prediction of tunnel water inflow Permeability coefficient is obtained by pumping tests. For non-homogenous formations, an error can be significant, which can only be used as a reference (continued)

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Table 7.2 (continued) Prediction method

Basic principle

Hydrogeological comparison method

Analogy of a Large statistics of previously built tunnel water inflow in the that shares the same tunnel area hydrogeological conditions

Application

Method characteristics Simple principle, practical, but low accuracy

Isotope tritium method

Determine the tritium content in the water samples of upstream and downstream, calculate the speed of groundwater and the water inflow rate according to time differences

Mountain tunnels, cross-ridge tunnels

Tunnels pass through water-bearing bodies, and require specific water yield or crack rate

Numerical analysis method

The traditional mathematical analysis method has been applied with the development of computer technology

Water inflow calculation of complex and simple boundaries, complex constitutive models, and complex conditions

No need for many assumptions, suitable for multi-filed coupling, can solve two-dimensional and three-dimensional problems, need calibrated calculation model

(3) Water seeping out or flowing along the cracks on the tunnel face. The water flow contains mainly rock debris, as well as fine sand, silty fine sand, and sticky gravel. Water gradually becomes turbid from clear or alternates between clear and turbid. (4) The number of small karst caves has increased, often accompanied by water flow, river sand or pebbles, or the appearance of water flow scouring trace. (5) The water inflow in drilling or blast holes is significantly increased, the duration is long, and contains sediment or small gravel. As a result, the water quality changes in turbidity. (6) Cool wind blows, or sound of water flows out of the borehole. (7) When the tunnel is approaching to the karst conduits, the non-fault fracture zone shows the phenomenon of inward dipping or small faults are inclined inward. In addition, because of the water-conductive karst column, the surrounding rock formation is moist or muddy and often shows loose, darkening, and other oxidation phenomena. (8) Karst fissures and caves near underground rivers often contain fillings such as river sand and well-rounded gravel. The existence of underground rivers according to the karst forms exposed by underground rivers on the surface can be determined, such as striped depressions, beaded depressions, erosion funnels,

The permeability of rock formations is anisotropic, which affects groundwater recharge, runoff, discharge and infiltration conditions: small vertical permeability leads to poor infiltration; permeability along the layer is large, but the surface water catchment area is small, and the corrosion effect is poor

Pure and thick rock has sparse and wide native fissures, The dense pure soluble formation has strong with strong permeability karst development and significant in scale; the more mud or other impurities in the soluble rocks, the thinner the rock layer, the weaker the karst development degree

Layer thickness and composition

(continued)

25° ≤ ϕ ≤ 65°, most conducive to karst development; 10° ≤ ϕ < 25°, 65° < ϕ ≤ 80°, conducive to karst development; 80° < ϕ ≤ 90°, slightly conductive to karst development; 0° ≤ ϕ < 10°, unconducive to karst development

Taking limestone as an example: micro-particles > fine particles > medium grain, oolitic structure and hidden crystal-fine crystal structure of limestone dissolves faster, and the relative solubility of rock with uneven grain composition is larger than that of rock with even grains

The smaller the grain, the larger the relative solubility

Characteristics The solubility decreases in the order of halogen salt formations (e.g., halite, sylvite), sulfate formations (e.g., plaster, mirabilite) and carbonate formations (e.g., limestone, dolomite, silicone limestone, mud limestone), and the karst development decreases in the same order

Rock structure

Principle The greater the solubility, the faster the erosion speed, and the better the karst development

Chemical composition

Dip direction and angle of rock formation

Formation lithology

Recognition factor

Table 7.3 Karst development characteristics

7.2 Typical Hazard-causing System Characteristics 257

The karst development of the fold core is more vital than that of the flank, the core is easy to develop caves filled with gravel and karst water. The karst is developed well in an anticline dipping end, syncline deflection starting end, and fold turning point. In extensional fault, karst is developed seriously, but in compressional fault, karst development is relatively weak. In rare cases, strong karstification occurs. In shear faults, karst extends significantly in depth, along the dense tension-shear fault zone, some large-scale karst caves and corridors are developed The larger the surface water catchment area, the deeper the development of surface ditches and trough valleys, the easier it is for water to seep down and promote the development of deep karst cavities

It dominates the development process of karst, and controls the direction and scale of karst development

Surface topography, catchment area, and other infiltration conditions and water supply

Geological structure

Topography

(continued)

Large karsts are easy to be developed in the contact zone between soluble and insoluble layers, especially close to the soluble layer. When the two rock formations alternate, the degree of karst development decreases gradually with the increase of the number of non-karst layers

The spatial relationship between karst and non-karst varies, and the water runoff conditions are different, which affects karst development

Characteristics

Principle

Recognition factor

Formation combination

Table 7.3 (continued)

258 7 Recognition Methods for Hazard-Causing Systems of Water and Mud …

Sulfide orebody is easily oxidized, and the resulting sulfate ions enhance the erosion of carbonate rocks

Sulfide Orebody

Karst development is strong near the oxidation zone of the sulfide orebody

It can provide enough CO2 to dilute the concentration In groundwater active movement area, karst of CaCO3 in water and increases the corrosion capacity development is strong; in groundwater slow movement area, karst development is weak; in in groundwater groundwater stagnation area, no karst develops

Characteristics

Principle

Recognition factor

Groundwater mobility

Table 7.3 (continued)

7.2 Typical Hazard-causing System Characteristics 259

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and sinkholes. In addition, tracer tests can be used to study the connectivity of underground river and its spatial relationship with the tunnel. (9) Moreover, when the working face is close to karst cave and other extensive karst water-bearing bodies, the wall normally becomes reddish and sweaty, and there will be foggy, water whistle, and temperature reduction phenomena.

7.2.2 Geophysical Prospecting Recognition 1. TSP seismic wave recognition (1) Principle of measurement A small amount of explosive is detonated in the sidewall behind the tunnel face to generate seismic waves, which travel in the form of spherical waves. When encountering the structural surface or various adverse geological interfaces, some signals are reflected and received and converted by the receiving sensors. The time from the detonation to the reflection signal received is proportional to the distance of the reflective surface. Thus, the nature of the relevant interface can be obtained, and the intersection angle with tunnel axis as well as the distance from the measuring point to the receiving point can be calculated. Figure 7.2 shows a diagram of the principles of the TSP measurement system. The geomechanical parameters of the surrounding rock in front of the tunnel face can be obtained by the relevant equations, such as P wave velocity V P , S wave velocity Vs, Poisson’s ratio μ, and Yang’s modulus E. First, P wave velocity of the seismic waves can be calculated by the distance from the direct wave to the sensor. Vp =

L1 T1

(7.7)

where L 1 is the distance between the hypocenter and the sensor, and T 1 is the time the direct waves take to reach the sensor.

Fig. 7.2 Diagram of the principles of the TSP measurement system

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261

According to the measured P wave velocity and reflected wave propagation time, the distance between the reflection interface and the receiving sensor can be calculated by below formula, i.e., the space location of the hazard-causing system. T2 =

L2 + L3 2L 2 + L 1 = Vp Vp

(7.8)

where T 2 is the time the reflected waves take to reach the sensor, L 2 is the distance between the blast holes and the reflection surface, and L 3 is the distance between the sensor and the reflection surface. Poisson ratio, Yang’s modulus and other parameters of the surrounding rock can be obtained by Formulas, 7.9 and 7.10 : V P2 − 2VS2 2(V P2 − VS2 )  2 2 2 3V P − 4VS E = ρVS V P2 − VS2 μ=

(7.9)

(7.10)

where V S is the speed at which shear waves travel and ρ is the density of the rock. (2) Recognition features According to the seismic wave reflection characteristics, the type of hazardcausing system and filling properties can be predicted (Sun et al. 2008; Xu et al. 2008), as shown in Table 7.4. 2. Ground penetrating radar recognition (1) Principles of detection The ground penetrating radar transmits high-frequency short-pulse electromagnetic waves to the front of the working face by the transmitting antenna. When different medium interfaces are encountered, the reflection occurs due to electrical differences received by the receiving antenna, and the signal is converted and stored. After the signal is processed, the type, position, scale, and distribution of the geological body can be estimated according to the electromagnetic wave propagation time, energy amplitude, and waveform. The larger the electrical difference between various media, the stronger the reflected signals. The ground penetrating radar detection diagram is shown in Fig. 7.3. The reflection characteristics of different media are different. Electromagnetic waves travel through rock bodies and reflect on the contact surface of two media with different relative dielectric constants. The amount of reflected wave energy depends on the reflection coefficient R, which can be expressed as √ √ ε1 − ε2 R=√ √ ε1 + ε2

(7.11)

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Table 7.4 Seismic wave recognition characteristics of hazard-causing systems Category

Recognition features

Fault damage zone

P wave reflection is strong, and if the rock formation is water-rich, the S wave reflection is also strong. Depth offset starts with strong negative reflection, ends with strong positive reflection. The reflection area’s positive and negative reflection layers are complex, mainly negative reflection. The single reflection zone is narrow, and the elongation is low. The P and S wave velocities decrease overall but change frequently

Corrosion fissure water

The reflection of the S waves is stronger than the P wave. The S waves’ negative reflection energy is stronger than its positive reflection energy and contains apparent negative reflection surfaces. The P wave velocity is in the high-speed zone, and the S wave velocity is in the low-speed zone. The ratio between the P and S wave increases, or the Poisson’s ratio suddenly increases

Mud/rock filled karst cave The P waves reflection is strong. When the filling rock particle size and content is large, the depth offset graph has more positive and negative reflection layers and is cluttered, mainly negative reflection. The single reflection zone is narrow, and the elongation is low. Conversely, the positive and negative reflection layer is limited, mainly negative reflection. The single reflection zone is wide, and the elongation is great. The P and S wave velocity decreases generally, its frequency of change decreases with increasing particle size in the cave and increases with the content of the block rocks in the filling Soft mud-filled karst cave The P wave reflection is very strong. The depth offset starts with strong negative reflection and ends with strong positive reflection. In the reflection area, the positive and negative reflection layers are less, mixed, mainly negative reflection. The single reflection zone is wide, and the elongation is great. The P and S wave velocities decrease, and the wave velocity inside the filling does not change significantly Water-filled karst cave

The reflection of the P and S waves is stronger, but the S wave reflection is stronger than the P waves. The depth offset starts with strong negative reflections and ends with positive reflections. The negative reflection zone (S waves) has greater bandwidth and energy than the positive zone. In the reflection area, positive and negative reflection layers are limited, mainly negative reflection. The single reflection zone is wide, and the elongation is great. Both P and S wave velocities decrease significantly, and the wave velocity inside the filling does not change significantly

Fig. 7.3 Diagram of ground penetrating radar detection

7.2 Typical Hazard-causing System Characteristics Table 7.5 Relative dielectric constants for common materials

263

Material

Relative dielectric Material constant

Relative dielectric constant

Air

1

6.4

Concrete

Dry sand

3~5

Silty clay 6.0

Granite

4~8

Shale

5 ~ 15

Limestone 4 ~ 8

Wet sand

20 ~ 30

Sandstone

Water

81

6

where ε1 and ε2 are the relative dielectric constants of the media. As can be seen from Eq. (7.11), the larger the difference between the relative dielectric constants of the two media, the greater the reflection coefficient, the more obvious the reflection. The relative dielectric constants of the typical media are shown in Table 7.5 (Gao et al. 2009; Liu et al. 2009). Specifically, the relative dielectric constant of air is 1, the relative dielectric constant of water is 81, and other media have values somewhere in between and are much smaller than that of water. As a result, radar waves produce strong reflections when they encounter the interface between the water body and the surrounding rock. Their instantaneous amplitude is also stronger than other positions. Therefore, ground penetrating radar can better identify the water-bearing structure in surrounding rocks. The propagation speed v of electromagnetic waves in the medium can be calculated from the relative dielectric constant, C v=√ ε

(7.12)

where C is the speed at which electromagnetic waves travel in a vacuum and ε is the relative dielectric constant of the medium. The position of the reflector can be determined by the calculated electromagnetic wave velocity and the measured travel time of the reflected wave, which can be calculated as √ 4h 2 + x 2 (7.13) t= v where t is the return time of the reflected wave (ns), h is reflector depth (m), x is the distance between the transmitting antenna and the receiving antenna (m), and v is the radar pulse speed (m/ns). (2) Recognition features The ground penetrating radar method can recognize different hazard-causing systems according to the characteristics of electromagnetic wave reflection frequency, intensity, and phase. The detailed recognition characteristics are listed in Table 7.6.

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Table 7.6 Ground penetrating radar recognition characteristics of hazard-causing systems Category

Recognition method

Fault and fault damage zone

If the phase is not continuous, the reflection intensity is significant, and the primary frequency is low, it is a damaged water-bearing geobody. If the phase is dislocated, the reflection intensity increases, but the phase and primary frequency remain unchanged, it is a damage zone that does not contain water

Water-bearing body and cave

The interface is a low-frequency strong reflector; reflected wave phase and incident wave phase are opposite; the subsequent signal energy decay faster; high-frequency waves are absorbed; the primary frequency is reduced; the reflection intensity is low

Dry cave

The primary frequency remains constant, and the reflection intensity increases. If the cave boundary is within the measuring range, both starting and ending parts have hyperbolic reflections. In subsequent signals of the starting boundary, the reflection wave phase is abnormal

Water passing-through fissures Dislocated phase, low-frequency and intense reflection; straight line or deviated line distribution along the crack axial direction; hyperbolic distribution at a certain angle with the fissures

3. Transient electromagnetic recognition (1) Principles of detection This method uses an ungrounded loop to emit a pulsed magnetic field into the front of the working face. When the current in the emission loop is disconnected, a secondary eddy current field will be excited in the medium to maintain the magnetic field generated before the current is disconnected (i.e., the primary field). The size and attenuation characteristics of the secondary eddy current are related to the electrical distribution of the surrounding medium. The changing characteristics of the secondary eddy current over time in the primary field can be intermittently observed. After processing the data, the electricity, scale, and form of the geobody can be obtained (Bu et al. 2017; Guo et al. 2006; Li et al. 2015; Shi et al. 2017). Figure 7.4 shows the principles of the transient electromagnetic method. (2) Recognition features The transient electromagnetic method is sensitive to low resistance body. The water-bearing body that can cause significant water and mud inrush disasters has relatively low resistivity compared with the surrounding rocks. As a result, the approximate range and relative position of the low-resistance body can be located by checking the apparent resistivity section contour plot, which further determines the distribution of water-bearing structures.

7.2 Typical Hazard-causing System Characteristics

265

Fig. 7.4 Diagram of the principles of the transient electromagnetic method

Fig. 7.5 Diagram of the resistivity method at a tunnel face

4. Tunnel face resistivity method forward detection recognition (1) Principles of detection The resistivity method is based on electrical differences between different geological media, and it measures the electrical field distribution of the subject to achieve geological exploration (Bu et al. 2017; Li et al. 2011; Nie 2014; Shi et al. 2017). Figure 7.5 shows the schematic diagram of the resistivity forward detection method at a tunnel face. (2) Recognition features The resistivity method determines whether the rock body in front of the tunnel face is a water-bearing or water-conductive structure by its resistivity distribution. For instance, the low-resistance distribution area in a 3D image represents a water-bearing or water-conductive structure. 5. High-density electrical method recognition (1) Principle of detection The high-density electrical measurement system is based on the difference of electrical parameters between the surrounding rock and the water-bearing geological structures (Deng 2007). According to the distribution of the surrounding rock conducting electrical current under an applied electrical field, the geological conditions of different resistivity within the detection range are inferred. As shown in Fig. 7.6, a certain number of electrodes are first set on the measuring line, direct current is supplied automatically via A, B electrodes by a specific sequence, and

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Fig. 7.6 Diagram of a high-density electrical measurement system

then the potential difference between the two electrodes with measuring electrodes (M and N) can be measured. Afterwards, the apparent resistivity profile can be calculated, and then the resistivity section of the surrounding rock is calculated by inverse calculation. Therefore, the water-containing system according to the apparent resistivity difference can be recognized. The apparent resistivity ρs can be solved by: ρs = k

U I

(7.14)

where I is the current input to the ground, U is the potential difference between the two measuring electrodes, and k is the device coefficient, which varies with the measuring device. (2) Recognition features High-density electrical method can effectively recognize the water-bearing structure or water-conductive channel and other adverse geological conditions. Its primary judgment basis is as below. On the resistivity inversion profile, the water-bearing system shows low resistance; the complete surrounding rock shows high resistance; the unfilled caves, fissures, and other adverse geological features are characterized by high resistance, but low resistance when filled with low-resistance bodies such as water and mud; soft and weak layers, weak rock masses, and leakage channels mainly exhibit low resistance.

7.2 Typical Hazard-causing System Characteristics

267

7.2.3 Drilling Recognition Drilling is the most direct and effective method to obtain the geological information of the tunnel surrounding rock and ahead of the tunnel face. Depending on the drilling depth, pre-excavation drilling can be divided into three categories: longdistance (80 ~ 120 m), medium-distance (30 ~ 60 m), and short-distance (3 ~ 8 m). Long and medium-distance drilling requires large drilling rigs. Depending on the drilling speed, drilling rigs can be divided into fast, medium, and slow rigs (Liu et al. 2007). For example, the RDP-150C drilling rig is a fast-drilling rig with a speed of 10 ~ 15 m/h; the MKD-5S and ZYG-150B are medium-speed drilling rigs with a speed of 5 ~ 7 m/h. The rate of a slow-speed drilling rig is 1 ~ 3 m/h, such as HGY-300D, JD-30, LF-100, MGY-60B, MK-3, MK-5, XY-2, XY-150, XY-2P, XY2PC, YQ-100, and ZD-60. The faster the drilling speed, the shorter time it takes, the smaller the impact on construction. Short-distance pre-excavation drilling is usually carried out by air drill. For example, when deepening drilling holes, air drilling can be carried out simultaneously as blast holes are arranged, with short construction time and convenient operation. Targeted drilling can also be carried out in water-bearing structure exposed by geophysical detection so as to verify the detection results. Drilling can be divided into impact drilling and core drilling depending on whether coring is included. Core samples can help directly identify the surrounding rock lithology, weathering degree, crack development, and mud filling conditions, as well as whether there are traces of flushing. However, because of time-consuming and high technical requirements, core drilling is only used under extraordinary complex geology and in cases where there is a significant risk of water and mud inrush. Therefore, tunnel construction mainly uses impact drilling, which helps determine the adverse geological conditions ahead of the tunnel face by the drilling speed, destructive energy, rock debris, water characteristics, and other abnormal conditions during drilling. Generally, high drilling speed with low destructive energy indicate that the rock mass is soft and fractured. If the drilling speed accelerates sharply and the destructive energy is significantly reduced, it may encounter karst filling or a weak interlayer. The changes in drilling speed and destructive energy frequently indicate that the rock mass is alternating between hard and soft. The slow drilling speed and high destructive energy suggest that the rock strength is becoming greater. Conversely, slow speed and low destructive energy without large changes indicate that the rock mass is relatively soft and homogenous. Near the fault zone, if the drilling time is shortened, the speed is faster, and the flushed liquid is dirty and contains mud, the fault is often interbedded with a soil layer. Drilling anomalies can help determine the existence of hazard-causing systems and surrounding rock conditions (Zhang 2008). Drill string stuck indicates that the surrounding rock is crushed, containing large fissures or a fractured zone filled with gravel; drill string jump means that the surrounding rock has a weak interlayer, usually a damage zone or a cave filled with mud, clay, or sand. Drill collapse indicates that the surrounding rock is broken with low strength, and joints and fissures are well

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developed, causing it hard to form a borehole. This is because jointed fissures are generally developed in soil, mud, debris rock, and other weak rock formations, filled caves, or fault damage zones. The lithology and strength of the surrounding rock can be estimated by the color of drilling fluid, and size, shape and composition of the returning particles during the drilling process (Zhang 2008; Zhao 2014). In general, the flushed liquid from gray sandstone and limestone is milky white; from fuchsia mudstone and mud-sand stone is turbid and yellow–brown; and from filled caves or damage zone is turbid and yellow-grey. The large and flaky particles illustrate that the rock strength is low and brittle, mostly with clay cementation. On the other hand, if the particles are small and gravelly, the rock strength is great, mostly with calcium cementation. The pressure and connectivity of the water-bearing geobody ahead of the tunnel face can be determined based on the amount of water out of the borehole, the water pressure, and the turbidity of the water quality. If there is a sudden advancement in drilling speed, water sprays out from the drilling hole with high pressure, larger volume, and long duration, it indicates that the hazard-causing system is under high water pressure and has extensive groundwater static reserves. If the water from the hole is turbid or stops intermittently and is mixed with sediment or small gravel, it indicates that the adverse geology may be a large-scale karst system, such as waterand sediment-filled caves or underground rivers. Once exposed, it is prone to cause large-scale water inflow or mud inrush disasters.

7.3 Engineering Application 7.3.1 Project Overview The project overview is described in Sect. 3.1.1. Engineering application was carried out in the zone between YK19+835~YK20+080 in the right line of the Qiyueshan Tunnel. Geological recognition can preliminarily determine the type of hazard-causing system and the possible water inflow conditions. The whole-process geologic sketch and TSP detection were used to identify water-bearing structures in the construction process. The transient electromagnetic, ground penetrating radar, induced polarization, and high-density electric methods were used as supplementary recognition methods, and drilling exposure helped to verify the detection results.

7.3.2 Geological Recognition The tunnel area is located in the overlap of the northwestern edge of the SichuanHubei-Hunan-Guizhou uplift fold belt and the east Sichuan fold belt of the Sichuan subsidence fold belt. The northern margin and the northwest Dabashan arc structure

7.3 Engineering Application

269

are obliquely connected and reconnected, and the geological structure is complex. The tunnel runs across the Qiyueshan Anticline, with asymmetric wings. The formation is mainly medium-thick limestone, containing some shale and coal seams. Two faults are developed in this area, namely the Qiyueshan Fault and the Deshengchang Fault. Both faults are narrow near the tunnel area and are approximately perpendicular to the tunnel. As a result, karst is developed in the fault zones and may contain large caves. Two tunnels were built in this area, namely the Qiyueshan Tunnel of Yichang-Wanzhou Railway and the Qiyueshan Tunnel of Shanghai-Chengdu West Expressway. During tunnel construction, karst-caused disasters occurred frequently, which brought severe obstacles to the excavation. Specifically, the tunnel construction on Yichang-Wanzhou Railway encountered 10 faults and 3 underground rivers, exposed 187 karst conduits or caves, 8 large-scale water and mud inrush accidents, which seriously delayed the construction. The terrain of the tunnel site area is wave shaped. There is an underground watershed near the chainage of K20+260. From the tunnel inlet to the Qiyueshan Anticline core, the surface is scattered with ditches, trough valleys, funnels, sinkholes, and karst depressions. They are small scales and have limited surface catchment areas. The lower karst has not formed a concentrated scale effect, and is developed in little caves and conduits with poor hydraulic connections. As shown in Fig. 7.7, karst funnels and depressions are developed 64 m to the right of the chainage of YK19+919 and 15 m to the right of the chainage of YK20+005 on the surface. The tunnel area is a subtropical continental monsoon climate, with abundant rainfall and concentrated precipitation. Precipitation seeps into the rock formation through karst depressions, providing a perfect water supply for karst development. The entrance section of the Qiyueshan Tunnel is on the east flank of the Qiyueshan Anticline, bounded by the Triassic Daye Formation shale. It belongs to the Nanping dispersed drainage karst water system, involving Wulongsi karst water subsystem and Daluonianfangwan karst water subsystem. And it is located in the watershed part of the two karst subsystems. The karst hydrogeological conditions are relatively

(a) 64 m to the right of YK19+919 Fig. 7.7 Tunnel surface erosion funnels

(b) 15 m to the right of YK20+005

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favorable to tunnel construction. These dispersed drainage karst water subsystems are characterized by: (1) Karst water system is generally small in scale; and the catchment area is generally a few square kilometers. For example, the catchment area of the Wulongsi karst water subsystem is about 4 km2 , and the Daluonianfangwan karst water subsystem is about 9 km2 . (2) Karst water-containing medium is mainly corrosion fissures and small karst conduits, which do not form an extensive karst underground river system. A relatively smooth short-ranged karst conduit is developed locally, such as the Daluonianfangwan karst water subsystem. (3) The flow rate of these karst water systems is generally a few to dozens of liters per second, occasionally in the rainy season can reach several hundred liters per second. Groundwater dynamics are relatively stable, and rainfall lag time is generally two to three days. The tunnel passes through moderately weathered limestone mixed with shale of the Triassic Daye Formation and limestone of the Permian Changxing Formation. The Daye Formation limestone is a very strong karst water-bearing rock, the Changxing Formation limestone is a medium-level karst water-bearing rock, and the Daye Formation shale is a non-karst rock, which acts as a water barrier. Karsts are developed along the contact zone between shale and limestone on both sides. The rock formation inclination is 70° ~ 80° (high dip), and it is a steeply inclined filling fissure type hazard-causing system, which is common but easily overlooked and has high catastrophability (Xu et al. 2011c). Corrosion fissures and small karst conduits dominate the karst development.

7.3.3 Geophysical Recognition 1. TSP recognition TSP pre-excavation geological forecast was carried out at the tunnel face of YK19+895 in the Qiyueshan Tunnel, with a detection range from YK19+895 to YK20+0005, a total of 110 m. The detection results are shown in Fig. 7.8. In the chainage of YK19+920~+935, seismic waves start with a strong negative reflection and end with a strong positive reflection, with a wide reflection zone and good elongation. In this zone, P wave velocity increases, S wave velocity decreases, V P /V S increases, Poisson ratio increases, and the density decreases. Therefore, it is inferred that karst fissures are developed, and there may be caves or water-bearing structures in the surrounding rock mass. At chainage of YK19+925, during the tunnel construction process, water inrush occurred at about 3 m above the tunnel floor at the right arch. The water column diameter was about 40 cm, and the height of water head was 0.3 m ~ 2 m. It was a karst conduit with an on-site measured depth of more than 3 m, as shown in Fig. 7.9.

7.3 Engineering Application

271

Fig. 7.8 TSP detection results

Fig. 7.9 Water inflow from the tunnel floor at the chainage of YK19+925

At the chainage of YK19+930, an elliptical cave was discovered on the sidewall of the transverse cross-section, 13.6 m away from the tunnel axis. The sidewall is next to the cave, which causes seasonal water inflow, waterfall-like during the water-rich period. The cave is about 2 m wide and has water dripping down from the top, as shown in Fig. 7.10. 2. Ground penetrating radar recognition According to the geological sketch results, several small karst conduits were exposed on the left sidewall of the Qiyueshan Tunnel right line. To evaluate the groundwater connectivity and provide a reference for the treatment plan, ground penetrating radar was used in the range of YK19+850~+890. The results are shown in Fig. 7.11.

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(a) cave without water inflow

(b) karst cave water inflow

Fig. 7.10 Karst cave at the chainage of YK19+930

Fig. 7.11 Ground penetrating radar detection results

(1) The radar signal within 1 ~ 2.5 m of the left sidewall in the chainage of YYK19+868~+890 and YK19+882~+890 is strong. It is speculated that the internal water-conducting structure and karst pipeline are contained, and fissure connectivity is good. In the heavy rain season, rainwater breaks through the channel, causing water inflows. (2) The radar signal is abnormal within 6 ~ 15 m on the left sidewall in the chainage of YK19+868~+890, which indicates that there may be a large fissure containing water and mud. The depth of the fissure increases towards the direction of larger chainage. For example, in the zone of YK19+868~+874, the depth is 6 ~ 7 m; in YK19+874~+878, the depth is 6 ~ 10 m; in YK19+878~+880, the depth is 8 ~ 12 m; in YK19+880~+885, the depth is 8 ~ 15 m, and in YK19+885~+890 the depth is 7 ~ 12 m.

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Fig. 7.12 Measuring line arrangement of high-density electrical detection

(3) The water content is high within 17 ~ 23 m of the left sidewall in the zone of YK19+852~+883, and mud is observed at some locations. 3. High-density electrical method recognition In order to further explore groundwater conductive channels, high-density electrical detection method was applied on the left sidewall and the floor of the tunnel right line at the entrance (from chainage of YK19+835 to +998), as shown in Fig. 7.12. The inverse resistivity section of the geobody within the detection range is shown in Fig. 7.13, and the results are as follows. (1) The inversion image of Line 1 shows a low resistance anomaly area (1.5 ~ 6.0 m of the sidewall in the chainage of YK19+965~+971 and 1 ~ 4.5 m of the sidewall in the chainage of YK19+988~+998), hence it is inferred that there is a water-bearing structure or a mud-filled structure. (2) The inversion image of Line 2 shows a relatively low resistivity anomaly area (2 ~ 5 m of the sidewall at the chainage of YK19+847~+853), inferring the presence of water-bearing or mud-filled bodies in the range of the left sidewall. A low resistivity anomaly area also appears within 6 ~ 21 m of the sidewall at the chainage of YK19+865~+883. This narrow zone has an angle of about 45° with the tunnel axis, inferred as a water-bearing body or a water-conductive channel. A flat low resistivity anomaly area exists within 6 ~ 12 m of the sidewall at the chainage of YK19+887~+905 along the tunnel axis, inferred as a water-bearing body or a mud-filled structure. In addition, there is a relatively low resistivity anomaly within 1 ~ 7 m of the sidewall at the chainage of YK19+917~+923. It is inferred as a water-bearing body or a mud-filled structure, which corresponds to the cave location exposed by the transverse passage. (3) On the inversion images of Line 3 and Line 4, low resistivity abnormal areas appear in the chainage of YK19+892~+908 the tunnel floor and the exact location of Line 2, inferring that there is a water-bearing body or a water-conductive channel 1 ~ 10 m below the floor, and it is tilting downwards.

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(a) data processing result diagram of Line 1

(b) data processing result diagram of Line 2

(c) data processing result diagram of Line 3

(d) data processing result diagram of Line 4

Fig. 7.13 High-density electrical detection results

Several water inflow events occurred on the right line of the Qiyueshan Tunnel (at the chainages of YK19+852.9, YK19+862, YK19+888, YK19+920, and YK19+925), causing the tunnel to be flooded several times (see Fig. 7.14). As a result, construction was forced to stop, resulting in schedule delays and increasing cost of drainage and treatment. Furthermore, the water inflow position at the chainage of YK19+852.9 corresponds to the location predicted by the high-density electrical detection method,

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as shown in Fig. 7.15. Therefore, the detection results can provide the basis for the treatment planning. After excavation, a small karst conduit was exposed in the chainage of YK19+862 at the left sidewall, about 1 m from the upper section, filled with a small amount of mud and without water, as shown in Fig. 7.16 (a). However, after the rainfall, a large amount of water flowed out of the karst conduit, causing water accumulation in the tunnel, as shown in Fig. 7.16 (b). Therefore, ground penetrating radar and high-density electric detection method have effectively identified the location of the inflow channel, which provides an essential basis for the later management. There is a small karst conduit about 25 cm in diameter above the vault at the chainage of YK19+888, with dripping and scattered karst fissure water from the

Fig. 7.14 Photo of a flooded tunnel after water inflow

Fig. 7.15 Water inflow at the chainage of YK19+852.9

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(a) No water before the rain

(b)Water inflow after the rain

Fig. 7.16 Water inflow at YK19+862 left sidewall

(a) Scattering water gushing at vault

(b) Water inflow at the arch foot

Fig. 7.17 Water inflow at the chainage of YK19+888

vault, as shown in Fig. 7.17 (a). Strands of water appear on the left sidewall, 1.7 m above the bottom of the arch leveling layer, and the water hole has a diameter of about 12 cm. A water inflow event occurred at about 1 m above the left arch foot, and the water hole is about 15 cm in diameter, as shown in Fig. 7.17 (b). The exposed water inflow positions correspond to the detected anomaly areas, which verifies the correctness of the detection results. A large, developed corrosion fissure was found at the outlet of the left arch foot in the chainage of YK19+920, with a water outlet area of 5 m2 and a long-term inflow of about 7.2 m3 /h, which can reach 36 m3 /h in the event of external rainfall. The detection results show that the karst fissure develops along the YK19+892~+908 the left side of the tunnel floor to the YK19+917~+923 the sidewall, and ultimately is exposed at the arch foot of YK19+920. According to the detection results, grouting reinforcement was conducted to seal the fissure. Drilling holes reveal no apparent water-bearing structure, only filled fissures at the chainage of YK19+965~+971; water-bearing structure at YK19+988~+998 developed close to the sidewall; water inflow occurred at left arch foot in the chainage of YK19+991 in the rainy season with a rate of about 3.6 m3 /h. Water inflow stopped after grouting treatment. 4. Transient electromagnetic method identification

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The geological sketch results show a water seepage phenomenon near the tunnel working face at the chainage of YK20+002. A transient electromagnetic detection was carried out in this section, with a detection range covering the chainage of YK20+012~+082 and a detection depth of 80 m. The apparent resistivity contour is shown in Fig. 7.18, which reflects the change of the apparent resistivity at different depths ahead of tunnel face. The distribution of water-bearing structures ahead the tunnel face is determined by identifying the low-resistivity areas in the figure. The detection results are as follows. There are low resistivity areas on the right side in the chainage of YK20+030~+034, right side in the chainage of YK20+047~+057, the right and left sides in the chainage of YK20+064~+072. The low resistivity indicates water channels such as water-conductive fissures and water-bearing or mud-filled bodies in these areas.

Fig. 7.18 Apparent resistivity contour of a section

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Fig. 7.19 Resistivity method detection results

5. Advance detection and recognition using the resistivity method at a working face Advance detection and recognition using the resistivity method was carried out at the tunnel face of the Qiyueshan Tunnel in the chainage of YK20+002, with a detection range of 30 m, covering the chainage of YK20+002~+032. The resistivity detection results are shown in Fig. 7.19. The resistivity detection results are analyzed as follows. (1) Section of YK20+002~+012: A low resistivity area appears on the left and right sides of the tunnel face in the 3D inversion image, with a resistivity of about 50 Ωm, inferring that it may contain bound water or a mud-filled structure. The abnormal body on the right is within 2 ~ 7 m from the center of the tunnel face to the right, and the left abnormal body is within 5 ~ 10 m to the left. (2) Section of YK20+026~+034: In the 3D inversion image, a low resistivity area appears on the right sidewall of the tunnel face, with a resistivity of approximately 100 Ωm, inferred as a water-containing body or a mud-filled structure, located 6 ~ 8 m to the right of the center of the tunnel face. When the tunnel was excavated, the mud-filled cave was exposed on the left and right sides of the tunnel face at the chainage of YK20+007, as shown in Fig. 7.20 (a). During the rainy season, water inflows in the section of YK20+001.5~+007.5 were severe. As a result of the geological sketch, there was a noticeable stream flow at the spandrel, either from a corrosion fissure or a corrosion conduit, as shown in Fig. 7.21 (a). Based on the geological sketch and geophysical detection results, sidewall drilling revealed the water inflow, as shown in Fig. 7.21 (b). With surface rainfall, the amount of water flowing from the borehole surged sharply, and the water inflow on the left sidewall was scattered. The surrounding rock exposed at YK20+032 contained mud interlayer, partially watery, as shown in Fig. 7.20 (b). After the rain on May 19th and 20th, 2014, water inflow occurred at YK20+036, together with the inflows at YK19+877, YK19+888,

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(a) a mud-filled cave

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(b) a mud-filled interlayer

Fig. 7.20 Photos of excavation revealed structures

(a) Strand water inflow at the spandrel

(b) Water inflows from boreholes in the sidewall

Fig. 7.21 Water inflow at YK20+001.5~YK20+007.5 section during rainy season

and YK19+920, resulting in tunnel flooding for over 300 m behind the tunnel face, with a maximum depth of 5.1 m, containing a large amount of silt. In addition, no water-bearing structure was found during the excavation of YK20+047~+055 and YK20+068~+072 sections, but excavation revealed mud-filled corrosion cracks and mud mixed layers. Geological recognition, geophysical recognition, and drilling verification accurately determined the type, scale, and location of the hazard-causing structure and provided a helpful guide for water inrush management, which allowed the builders to finally seal the inrush channels to ensure tunnel construction and operation safety.

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7.4 Summary In view of the tunnel water and mud inrush disasters, we have developed a comprehensive recognition method for hazard-causing systems based on a large number of engineering practices, taking the Qiyueshan Tunnel of Lichuan-Wanzhou Expressway as a case study. The method integrates geological recognition, geophysical recognition, and drilling verification. Geological recognition provides preliminary information and guides the implementation and interpretation of geophysical detection; geophysical recognition guides the drilling design. Geological recognition, geophysical recognition, and drilling recognition have seamlessly integrated together and provided mutual verifications, with dynamic feedback and accuracy. Using this integrated recognition method, we can examine the geological characteristics and precursor information, geophysical response characteristics, and drilling exposure characteristics to determine the type, location, scale, and water-bearing features of the hazard-causing systems. The effective combination of various detection methods can improve the accuracy of identifying hazard-causing systems, provide safety guidance for tunnel construction, and provide essential references for similar projects.

References Bu L, Li SC, Shi SS, Li LP, Zhao Y, Zhou ZQ, Nie LC, Sun HF (2017) Application of the comprehensive forecast system for water-bearing structures in a karst tunnel: a case study. Bull Eng Geol Env 78(1):357–373 Deng CW (2007) The principle and application of highdensity electrical method technique. J Shaoguan Univ 28(6):65–67 Gao Y, Zhang QS, Yuan XS, Xu ZH, Liu B (2009) Application of geological radar to geological forecast in karst tunnel. J Shandong Univ 39(4):82–86 Guo C, Liu BZ, Bai DH (2006) Prediction of water disasters ahead of tunneling in coal mine using continuous detection by UW TEM. Seismolog Geol 3:456–462 Guo RJ, Ding JF, Liao YK (2013) On the application of comprehensive geological forecasting techniques to karst tunnels. Mod Tunn Technol 50(5):158–163 Huang X, Xu ZH, Lin P, Liu B, Nie LC, Liu TH, Su MX (2020) Identification method of water and mud inrush hazard-causing structures in tunnel and its application. J B Sci Eng 28(1):103–122 Li SC, Liu B, Li SC, Zhang QS, Nie LC, Li LP, Xu ZH, Zhong SH (2011) Study of advanced detection for tunnel water-bearing geological structures with induced polarization method. Chin J Rock Mechan Eng 30(7):1297–1309 Li SC, Liu B, Nie LC, Liu ZY, Tian MZ, Wang SR, Su MX, Guo Q (2015) Detecting and monitoring of water inrush in tunnels and coal mines using direct current resistivity method: a review. J Rock Mech Geotech Eng 7(4):469–478 Liu B, Li SC, Li SC, Zhang QS, Xue YG, Zhong SH (2009) Study of application of complex signal analysis to predicting karst-fractured ground water with GPR. Rock Soil Mech 30(7):2191–2196 Liu ZW, Zhang MQ, Wang SR (2007) Prediction and treatment technology of disaster in karst tunnel. Science Press, Beijing Nie LC (2014) Quantitative identification theory and its application of advanced geological prediction for water-bearing structure using induced polarization in tunnel construction period (Ph D Thesis). Shandong Univ, Jinan

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Sun KG, Li SC, Zhang QS, Xue YG, Li SC, Xu ZH (2008) Application of the TSP geological forecast method of a mountain tunnel in a karst zone. J Shandong Univ 38(1):74–79 Shi SS, Bu L, Li SC, Xiong ZM, Xie XK, Li LP, Zhou ZQ, Xu ZH, Ma D (2017) Application of comprehensive prediction method of water inrush hazards induced by unfavourable geological body in high risk karst tunnel: a case study. Geomat Nat Haz Risk 8(2):1–17 Xu ZH, Li SC, Li LP, Chen J, Shi SS (2011a) Construction permit mechanism of karst tunnels based on dynamic assessment and management of risk. Chin J Geotech Eng 33(11):1714–1725 Xu ZH, Li SC, Li LP, Hou JG, Sui B, Shi SS (2011b) Risk assessment of water or mud inrush of karst tunnels based on analytic hierarchy process. Rock Soil Mech 32(6):1757–1766 Xu ZH, Li SC, Li LP, Chen J, Zhang ZG, Shi SS (2011c) Cause, disaster prevention and controlling of a typical kind of water inrush and lining fracturing in karst tunnels. Chin J Rock Mechan Eng 30(7):1396–1404 Xu ZH, Li SC, Zhang QS, Liu B, Zhang X, Ge YH (2008). Reflection characteristic of seismic wave in TSP advance geological prediction. Chin J Undergr Space Eng (4):640–644 Zhang QX (2008) Advance drilling construction technology in Qiyueshan Tunnel. Railway Stand Des 5:81–83 Zhang ZQ, Zhang Q, Ban YY, Hu YJ (2015) Quantitative analysis of karst conduit and its hydraulic parameters based on tracer test. Yangtze River 11:80–83 Zhao PY (2014) Highway tunnel ahead geological study of advanced drilling geological prediction in mountain tunnel on the Shitian Highway in Gansu Province (Master Thesis). Chang’an University, Xi’an Zhu DL, Li QF (2000) Method to predict discharge rate of tunnel. Geotech Inv Surv (4):18–22

Chapter 8

Dynamic Management and Analysis Platform for Tunnel Water and Mud Inrush Cases

There are various types of hazard-causing systems for water and mud inrush in tunnels, with a large number of hazard cases, and the disaster-generating environment and catastrophe evolution mechanism are also extremely complex. Different types of hazard-causing systems have different geological identification characteristics. By studying the type of hazard-causing systems, geological features, and water and mud inrush characteristics in many typical cases, it can provide reference for the prediction and prevention of water and mud inrush disasters of the same type of hazard-causing system. However, there is currently no comprehensive database for statistical analysis of water and mud inrush cases, where researchers in this field can consult each other and obtain reference information. Therefore, collecting typical cases of water and mud inrush in tunnels and establishing a dynamic management and analysis platform for cases are of great significance and value for both the firstline tunnel construction personnel and the theoretical researchers of water and mud inrush. With the help of computer and internet technology, the Dynamic Management and Analysis Platform for Tunnel Water and Mud Inrush Cases (hereinafter referred to as the case management and analysis platform) has been established. The platform can sort and classify the typical cases that have been collected, and users can add, review and modify the case base according to different user rights, thus realizing the dynamic management of the case base. In addition, the platform is also embedded with a module for water and mud inrush case analysis, which can conduct in-depth analysis in terms of risk assessment, water inrush prediction, resistance evaluation, disaster analysis and treatment measures recommendations. Finally, through the continuous enrichment and improvement by the construction, design, supervision and scientific research personnel, it can provide a platform of network learning, technical exchange and expert question answering for relevant researchers in the field of tunnel water and mud inrush. The platform not only summarizes many tunnel water and mud inrush cases, but also makes in-depth analysis from the disaster mechanism, and proposes corresponding suggestions on the prediction and treatment of tunnel water and mud

© Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1_8

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inrush disasters, so as to provide experience guidance for the prevention and control of tunnel water and mud inrush disasters in the future.

8.1 Design Objectives and Requirements of the Case Management and Analysis Platform 8.1.1 Design Objectives of the Platform In view of the specific need of tunnel water and mud inrush disaster prevention and control, combined with the current advanced computer software and hardware technology and calculation and analysis algorithm, the dynamic management and analysis platform of tunnel water and mud inrush cases with high efficiency, intelligence and strong operability is developed. The platform realizes the collection, classification, retrieval, feedback and analysis of tunnel water and mud inrush cases, and disseminates the latest trends of tunnel water and mud inrush disasters, helps to make accurate and professional judgments and decisions on cases, provides certain guidance for tunnel safety construction, and reduces the risk of tunnel water and mud inrush disasters.

8.1.2 General Requirements for Platform Design 1. Overall performance design requirements (1) Practicability. The platform shall solve practical problems, so as to meet the need of users, fully realizing the core function of the platform with consideration of its auxiliary functions. (2) Stability. The platform adopts a perfect development framework, which can ensure the stable operation of the platform. Under normal circumstances, it can support no less than 500 concurrent visits, and the overall response of the platform is controlled within 3 s. (3) Security and confidentiality mechanism. The platform shall have a perfect network and information security and authentication system, and a strict and flexible access control mechanism to ensure the security of internal data and user data. (4) The back-end server of the platform shall have a certain amount of data storage and management ability, which can support the storage and management of more than 4 TB of total data and more than 60 GB of spatial data. It should have a good database structure design, which helps realize the rapid retrieval of data.

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(5) The data exchange of the platform shall fully consider the application status of the platform, and it should completely meet the existing data exchange system standards. 2. Platform reliability design requirements Platform reliability refers to the reliability level of the platform in the process of operation. Generally speaking, the reliability of the platform is expressed by the mean time between failures, that is, the average value of the correct operation time of the platform. The correct operation of the platform is judged by the following four criteria: (1) The program is not destroyed or stopped by the bug; (2) The results do not include the error caused by the bug; (3) The execution time does not exceed a certain limit; (4) The program runs in the allowable field (Ding 2010). The reliability design requirements of the platform are as follows: (1) The reliability of the server system. The business acceptance application server is the core of the entire platform. All business processing in the platform depends on the host. Once the host fails, the entire platform cannot be accessed or even paralyzed. It should be ensured that when a server fails, the platform can still work normally. (2) The reliability of the platform software. In addition to the reliability of the back-end server, the reliability design of the management platform is also very important. It is required that any command run by the front-end can get a correct and timely response to ensure that the platform logic is reasonable and the operation is normal. (3) Perfect data backup and recovery mechanism. Data is the core of the entire platform. The system must not only ensure the security of case data, but also ensure the security of user information. The security of the data must comply with the standard, and the updated data must be backed up in real time. After a failure, there is a recovery mechanism to restore the data. 3. Operating performance design requirements The operating performance of the platform mainly refers to the data capacity of the platform, the number of concurrent users, and the speed of computer processing services. In addition to ensuring the performance requirements of the initial stage, corresponding technical measures shall be taken to ensure that the platform can exert its best performance during operation, so that after the data volume and the business scale increases, the performance of the platform remains optimal. The design requirements for platform operating performance are as follows. (1) Network system. The network system is a direct channel for data circulation and command transmission, which has the greatest impact on the performance of the system. In order to ensure the normal operation of the platform, high-backplane switches and routers are used in the center of the platform, and the internal LAN uses a 10 Mb/100 Mb information exchange network.

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(2) Server system. The server system will affect data access and request operations. The performance design of the server system shall take notice of the following condition. The host of the data server should be a dual-computer system, and it shall be fully considered whether the CPU of a single host can meet the needs of the platform for processing data and command exchange; in order to meet the needs of fast storage and command processing of large amounts of data, the storage system of the host is designed to adopt optical I/O storage. (3) Front-end application system. The front-end application system mainly uses a multi-layer computing system, and the application terminal is often only connected to the application platform. Therefore, the performance of the front-end application system has an important impact on the entire platform. The logical rationality and functional design of the front-end is an important part of improving system performance. 4. Scalability design requirements The Dynamic Management and Analysis Platform for Tunnel Water and Mud Inrush Cases has great economic and social benefits, and the scalability of the platform is one of the important indicators for evaluating its value. In order to ensure that the platform has good scalability, the following should be paid attention to when designing the platform. (1) In the architecture design of the platform, a scalable architecture is adopted for design. (2) It is necessary to fully consider the scalability of the front-end system functions to ensure that the services of the platform can be upgraded and developed as demand increases.

8.2 System Development Procedure On the basis of case data, the system has established user authentication, case retrieval, case submission, case analysis, and case review modules, which can realize dynamic management of tunnel water and mud inrush case data. Figure 8.1 shows the system development procedure. 1. Demand analysis (1) The platform is a Web version of the application management system. The user group is mainly engaged in tunnel design, construction, and management, as well as research in water and mud inrush disasters. The relevant personnel should have a certain foundation in computer operation. (2) The terminal supported by the system is determined according to the number of users supported by the database, and the number of concurrent operation users supported by the system should be more than 500.

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Fig. 8.1 Flow chart of management system development

(3) The data transmission speed should be fast, and a small amount of data records should realize various operations and conversion transmissions in a short time. When business requirements change, the system can respond to and maintain the consistency of code and table data in a timely manner, without changing the operating environment and operating methods. (4) The security of user information and case data shall be highly ensured, while the system should be maintainable and expandable.

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2. Module Design (1) Authentication login. The system automatically verifies the account and password entered by the user and provides a registration channel. (2) Data downloading. Provide a channel to download cases for users who have logged in. (3) Case submission. According to the case submission process, users can submit cases as required after logging in. (4) Case review. According to the requirements of the review, the reviewing experts put forward their comments and feedback to the author, and the platform will release them in time after the author’s corrections and improvements. (5) Case analysis. The platform conducts case analysis through algorithms, carries out risk assessment, water inflow prediction, resistance evaluation, and disaster analysis, then proposes corresponding recommendations of disaster treatment measures and expert evaluation results, etc., and finally provides users with corresponding interface services. 3. Interface Design The human-machine interface adopts the Web technology—Browser/Server structure system. The final user interface is unified as a browser, and the application system is all on the server side. Module interface. Each module relies on Level, UserName, PassWord to communicate, and the function control of each sub-module gives the corresponding operation authority according to the user level of the user judgment platform.

8.3 Platform Composition and Architecture 8.3.1 Platform Composition The dynamic management and analysis platform for tunnel water and mud inrush cases is a set of intelligent interactive system for dynamic management and analysis of tunnel water and mud inrush disaster cases. The platform adopts advanced network programming technology and network architecture. It is a case network management and analysis platform with simple operation, easy maintenance, safe data transmission, good interactivity, and intelligent analysis functions. Dynamic management and analysis platform for tunnel water and mud inrush disasters is mainly composed of user authentication login module, case retrieval and display module, case submission module, case analysis module, and case study module. Each module can transmit data and commands to each other while realizing different functions. The composition of the dynamic management and analysis platform for tunnel water and mud inrush cases is shown in Fig. 8.2.

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Fig. 8.2 The composition of the dynamic management and analysis platform for tunnel water and mud inrush cases

8.3.2 B/S Architecture The B/S architecture is the browser and server architecture model, which is the change and improvement of the C/S architecture with the development of Internet technology. Under the B/S architecture, the user interface is implemented through the browser, and very few transaction logic is implemented in the browser, and the main transaction logic is implemented in the server (Huang 2012). The B/S architecture model unifies the client, concentrates the core part of the system function implementation on the server, and simplifies the development, maintenance and use of the system. The browser interacts with the database through the Web Server, which can greatly reduce the load on the client computer and reduce the cost of system maintenance and upgrades. Figure 8.3 is a schematic diagram of the B/S architecture. The B/S architecture has the following advantages.

Fig. 8.3 Schematic diagram of B/S architecture

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(1) Convenience. With the B/S architecture, users can operate anywhere without installing any special software. As long as there is a machine with Internet access, users can visit the platform, realizing zero maintenance of the client (Huang 2012). (2) Security. The B/S system only open HTTP protocol and port, and database only allows one server to access. (3) Scalability. System expansion is one of the most expensive parts of the software life cycle. B/S allows individual components to be replaced and can achieve seamless system upgrades. (4) Reusability. The B/S can be based on the.Net platform architecture, reducing the cost of system maintenance and upgrades, and is conducive to protecting user resources. The secondary development is quick, and business functions can be expanded by adding web pages. (5) High performance. All users of the B/S structure can connect to the database through the JDBC connection pool, and users do not need to maintain a connection to the database.

8.4 Main Functions of the System The Dynamic Management and Analysis Platform for Tunnel Water and Mud Inrush Cases realizes dynamic management and intelligent analysis of water and mud inrush cases. Based on a large number of water and mud inrush cases and related data, combined with the author’s years of research results on water and mud inrush disasters, the platform divides the cases into 3 categories and 11 types, and conducts dynamic management. Meanwhile, based on the intelligent analysis algorithm, the platform provides users with a case analysis system, which can provide a reference for the prevention and control of tunnel water and mud inrush under similar geological conditions. The platform adopts a single-type architecture, namely the B/S architecture, selects C# and SQL2008 as the development language, based on the.Net framework, and reasonably uses SQL Server data storage and cache to realize dynamic management, analysis, review, and data sharing of water and mud inrush cases. The platform provides integrated image data of water and mud inrush disaster cases, encourages users to share experiences, provides case materials, and archives them in the system’s case library after the expert review. In response to the needs of the platform, an operation interface that is user-friendly, simple in process, and highly interactive is designed. Figure 8.4 is the home page of the platform. The system is divided into different modules based on different functions, which are convenient for users to understand and operate, mainly including user authentication login, disaster news, image & video, latest cases, typical cases, case classification, case analysis, case discussion, expert comments, popular articles, and other modules. Users can directly access the content or use the functions under this module by clicking. The content of the homepage is updated in real-time to

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ensure the timeliness and reliability of the information. With a navigation window, users can access more information and functions provided by the system, such as submission instructions, and expert team introduction. The system is scalable, and the functional modules will continue to be improved as demand increases, and strive to provide a more complete platform for the study of tunnel water and mud disasters.

8.4.1 User Authentication Login Generally speaking, each application system has an independent user information management function, and the format, naming, and storage methods of user information are also diverse. Based on the basic principles of unified user management, the platform provides a unified authentication method and authentication strategy for all users to identify the legitimacy of user identities. The platform grants different permissions based on the identity of the visitors, which are mainly divided into tourists, ordinary users, and expert users. (1) Visitors do not need to be authenticated to access the platform. They can browse the latest and typical case information on the homepage, obtain real-time disaster news, and browse all the case content and video materials that have been approved. In addition, visitors can click on the “hazard-causing system” module in the navigation module of the platform homepage to view the definition of the hazard-causing system, the classification of the hazard-causing system, the characteristics of the occurrence, and the identification method. In this way, it is expected that readers will have a deeper understanding of the classification basis and identification method of the hazard-causing system. (2) For users who have not yet registered, the system provides a registration channel, and users only need to fill in the corresponding information to complete the registration. When the user fills in the relevant information for registration, the platform first checks the validity of the filled user name, and matches the user name with the registered user names in the database. If the user name already exists, the platform will remind the user to re-enter it; if the user name is qualified, the system will check the information format filled in by the user and check whether the required fields are completely filled in. When an ordinary user logs in, the platform must authenticate the user name and password. If the authentication fails, the system will inform the user of related error information. After the authentication succeeds, the user can enter the platform homepage. After logging in, the user can view and download all approved cases, complete user information in the “Basic Information” interface of the “Personal Center”, view the submitted cases in “My Uploads”, check the recently downloaded cases in “My Downloads”, check other users’ comments and supplements on the case in “My Comments”, and check the latest progress of case review and comments in “My Updates”. In addition, users can upload water and mud inrush cases in the “Case Submission” module, and view the

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8 Dynamic Management and Analysis Platform for Tunnel Water …

Fig. 8.4 The homepage of the platform

8.4 Main Functions of the System

293

review progress and expert comments in the “Personal Center” module after uploading the case. Meanwhile, the system will promptly send the case review message to the user through the mailbox registered during the user registration. If the user forgets the password, he can retrieve his login password through the password retrieval module. (3) The expert user login system also adopts the form of account and password, and the authentication method is the same as that of ordinary users. There are two ways to become an expert user. One is that the platform assigns an account and password to the expert, and the other is that ordinary users can apply to become expert users after submitting a certain number of manuscripts. In addition to all the rights and functions of ordinary users, expert users also have the right to review cases.

8.4.2 Case Display, Retrieval, and Download The homepage of the platform provides dynamic display modules of typical cases, latest cases, and case classification. Users can directly access the detailed content of the case through the link of each case displayed. In the module of latest case, users can obtain the latest water and mud inrush cases and the latest progress in the research on water and mud inrush disasters. In the module of typical case, users can look through the 3 categories and 11 types of water and mud inrush typical cases, including the engineering overview, physical geography overview, geological background, karst water system characteristics, water inrush characteristics and other information to understand the processes and causes of different types of water and mud inrush disasters. In the module of case classification, users can view cases according to the types of water and mud inrush disasters. For example, under the “corrosion fissure type”, users can view all the cases of corrosion fissure type of water and mud inrush in the case library. The platform also provides a complete search function to facilitate user inquiries. Case retrieval is mainly divided into type retrieval, case name retrieval, keyword retrieval, author retrieval and other methods. After the retrieval is completed, the user can browse the detailed content and comment information of the case online. The platform provides download channel of the case, and users can download the case to the local in PDF format by clicking “download now”.

8.4.3 Case Submission After logging in, the user can submit the water and mud inrush disaster case to the case management analysis platform in the form of a manuscript in the “Case Submission” module. In the module of case submission, the user needs to read the “Instructions” provided by the platform in detail, and modify the manuscript

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according to the sample format. After the manuscript meets the requirements, the user fills in the relevant information of the case according to the prompts, including the title, abstract, keywords, and case documents, etc. After filling in, the user can click “Confirm upload” to complete the case submission. The case management analysis platform has strong real-time and interactivity. After the case is submitted successfully, the system will automatically generate the serial number and classify it as a manuscript to be reviewed. The platform transfers the manuscripts to be reviewed to the expert review system, which will be reviewed by the experts according to the requirements of the platform and the specific circumstances of the case. Users can view the review progress of the manuscript and expert revision opinions in the “Personal Center”, and the review progress will be promptly reported to the author in the form of short messages and emails.

8.4.4 Case Review Cases submitted by users to the system need to be reviewed by experts before they can be archived and displayed in the system. The case management analysis platform provides a case review module for review experts to review manuscripts and communicate with case authors to achieve real-time interaction. Expert users can view the cases that need to be reviewed in the “personal center” after logging in. The review expert must read the content of the case in detail to see if it meets the platform’s collection standards. The expert’s decision on the manuscript includes three options: “accept”, “revise” and “reject”. Accepted cases are directly included into the platform case management database for users to read and download. For cases that need to be revised, experts need to propose comments and submit the comments to the review system. The system will feed back the expert comments to the author through the mailbox. The author revises the case based on the comments of experts, and submits the revised manuscript to the platform again for review. After the experts have reviewed the revised version and decided it is acceptable, the case will be accepted into the platform case database. Case authors can view expert review comments and the review progress of the submitted cases in “My Uploads”.

8.4.5 Case Comment The platform provides a communication platform for researchers of water and mud inrush disasters. If you have any questions or comments, you can leave messages, comment in real time, and communicate with each other. After the user successfully logs in to the platform, he can comment and supplement the case under the case he is viewing and there is no word limit. After the comment is completed, click “Submit Comment”. The user can also view other users’ comments on the case. In addition, the author of the case can also view case comments and supplements in the “Personal

8.4 Main Functions of the System

295

Center”. In this way, the content of the case is enriched and it can provide reference for the same type of projects. Meanwhile, the latest and hottest comments of the case will be displayed on the homepage of the platform for users to communicate and grasp the updated case.

8.4.6 Case Analysis The platform has established an effective case analysis module based on the types of water and mud inrush disasters, disaster-generating environment and catastrophic evolution mechanism, which mainly include risk assessment, water inflow prediction, resistance evaluation, disaster analysis and treatment recommendations and expert judgment. The platform has important engineering value and guiding significance for ensuring the safe construction of the tunnel. 1. Risk assessment Risk assessment is a basic function of the case analysis module in the dynamic management and analysis platform of tunnel water and mud inrush cases. The function of the risk assessment module is to help experts, scholars and onsite construction personnel in this field to quickly and accurately estimate the construction risk level of water and mud inrush in front of the tunnel, so as to realize the dynamic assessment of the construction risk of water and mud inrush in the tunnel, and provide construction suggestions. The detailed tunnel water and mud inrush risk assessment conceptual model is divided into three levels: The first-level evaluation index is the target layer, which reflects the risk assessment and grade division of tunnel water and mud inrush; The second-level evaluation index is the criteria layer, including hydrogeological and engineering geological conditions, tunnel construction factors and construction dynamic feedback information; The third-level evaluation index is the tunnel water and mud inrush risk index layer, which consists of adverse geology, stratum lithology, vertical hydrodynamic conditions, lateral hydrodynamic conditions, topography and landforms, rock formations, bedding and interlayer fissures, and surrounding rock levels, advance geological forecast, monitoring measurement, excavation support, macro-precursor information and micro-precursor information indicators. So far, an indicator system of factors affecting the risk of water inrush and mud inrush has been constructed. When conducting risk assessment, it is necessary to determine the index interval value according to the specific geological information and construction information, to calculate the membership degree of the evaluation index, and construct a weight matrix to obtain the weight interval. It is also necessary to establish a fuzzy comprehensive evaluation calculation model for the tunnel water and mud inrush risk to obtain the result vector and dominance of the evaluation index.

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Click the risk assessment module on the system homepage, and the system will automatically jump to the risk assessment page. Enter the relevant information in sequence according to the risk assessment procedures, and then the risk assessment can be carried out. The basic process of applying the risk assessment module to carry out dynamic assessment of the risk of water and mud inrush tunnel construction is as follows. (1) Click on the module homepage to start the dynamic evaluation of construction risks. The system will prompt to enter the tunnel name, evaluation mileage, evaluation unit and time, and users select in turn for preliminary evaluation, secondary evaluation, and dynamic evaluation. (2) When conducting a preliminary assessment, first follow the system prompts and enter the evaluation index values of the selected section, including adverse geology, stratum lithology, vertical hydrodynamic conditions, lateral hydrodynamic conditions, topography and landforms, occurrence of rock formations, bedding and interlayer fissures, surrounding rock grades, etc.; Then select the membership function, and calculate the degree of membership according to the selected function; Finally, perform the weight analysis, and input the expert evaluation weight scores of the criteria layer and the index layer according to the prompts, that is, to complete the input judgment matrix, and the system will automatically calculate the weight vector, then click “Next”. (3) According to the obtained membership degree and weight vector, the system automatically calculates the result vector and dominance degree. According to the principle of maximum dominance, a preliminary assessment of the risk level is performed. Click “Next” to enter the secondary evaluation. (4) When conducting the secondary evaluation, follow the prompts to supplement the evaluation index value of the selected section, including advanced geological forecast, monitoring measurement, excavation and support, and then calculate the degree of membership according to the index value; combined with the weight score and weight vector obtained in the preliminary evaluation, the system automatically calculates the secondary evaluation result vector and dominance. Click “Analyze” to obtain the risk level of the secondary assessment, and click “Next” to enter the dynamic assessment. (5) When conducting dynamic evaluation, enter the section mileage of the tunnel according to the prompts, and perform dynamic evaluation on each mileage respectively. The process is as follows: follow the prompts to enter all the evaluation index values of the selected section, including adverse geology, stratum lithology, vertical hydrodynamic conditions, lateral hydrodynamic conditions, topography and landforms, occurrence of rock formations, beddings and interlayer fissures, surrounding rock levels, advance geological prediction, monitoring and measurement, excavation and support, macro-precursor information and micro-precursor information; combining the weight vector obtained in the above evaluation, the system automatically calculates the dynamic evaluation result vector and

8.4 Main Functions of the System

297

dominance of the section, click “Analyze” to obtain the dynamic evaluation risk level, and then conduct the dynamic evaluation of all sections in turn. With the aid of the risk assessment module, based on the above-mentioned tunnel water and mud construction risk interval assessment process and construction permit mechanism, the dynamic assessment of the tunnel water and mud inrush construction risk interval can finally be realized. 2. Water inflow prediction Water inflow prediction is an important part of the evaluation of tunnel water and mud inrush, and it is very important in the tunnel water inrush and mud inrush analysis platform. The function of the water inflow prediction module is to evaluate the water inflow of the tunnel under the premise of relatively accurate engineering geology and hydrogeological data, and give more realistic results such as water inflow volume, water inflow state and water head pressure and so on, and provide a basis for design and construction. Water inflow refers to the total amount of water that enters tunnels and underground spaces from surface water and groundwater during a precipitation process or a draining period. The amount of water inflow is mainly estimated by the rainfall infiltration method and the groundwater draining method. Among them, the dynamic reserve is estimated by the rainfall infiltration method, and the static reserve is estimated by the groundwater draining method. In the process of water and mud inrush, the water volume composition is different in different periods. The vertical hydrodynamic zoning of the tunnel is different, and the composition of the water inflow source, the dynamics and characteristics of the water inflow are also different. In general, water inflow is generally composed of one or two of static reserves and dynamic reserves (dynamic reserves during dry periods and dynamic reserves during flood periods). The static reserves are often related to the thickness of the aquifer and the structural characteristics of the water-containing medium (or the duration of draining). The dynamic reserves are often related to the rainfall in a precipitation process (usually 2 days) and the dynamics of natural water points (underground rivers, karst springs, etc.). If water inrush in the tunnel causes the ground to collapse or breaks through the water-conducting fault and causes surface water to intrude, the amount of water inflow in the tunnel shall consider the inflow of surface water. According to the volume of water inflow, it can be divided into four levels, namely, small water inflow (10,000 m3 /d). The module is composed of three parts: the first part is to determine the composition and state of water inrush sources according to the groundwater level and vertical hydrodynamic zoning; the second part is to give corresponding prediction formulas and parameters according to different water sources to predict the extreme value of water inflow; the third part is to give corresponding water pressure estimation formulas and parameters based on the groundwater level and different water-bearing media, and estimate the head pressure at the water gushing point.

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When using this module, the user needs to provide local rainfall (extreme value), groundwater level (elevation) or natural water point exit elevation in the tunnel area, water catchment area, tunnel floor elevation, and other survey data such as engineering geology (regional stratum lithology combination and geological structure) and hydrogeology (groundwater system). It shall be noted that the prediction of water inflow is not just a matter of substituting a few data into formula calculations. The selection of parameters requires the wisdom and experience of geologists. The water inflow estimated by this module can be used for learning and communication among practitioners and as a reference for water inflow prediction in actual engineering. 3. Resistance evaluation The resistance evaluation is an important function in the case analysis module of the Dynamic Management and Analysis Platform for Tunnel Water and Mud Inrush Cases. This module can be used to quickly evaluate the stability of the resistance body against water and mud inrush in the tunnel. The basic principle of resistance evaluation is to construct an index system of influencing factors for water and mud inrush evaluation, which mainly covers 4 aspects, i.e., the hydrodynamic conditions, adverse geology, resistance body thickness and surrounding rock characteristics. Among them, resistance body thickness, water pressure characteristics, adverse geology, rock mass quality and integrity are the main influencing factors; surrounding rock joint state, water supply conditions, hydraulic connectivity, and rock strength are secondary influencing factors; rock strata strike and dip angle, ground stress, and rock mass permeability are correction factors. By determining the classification method and system of influencing factors, a classification and scoring table of influencing factors suitable for quick inquiries and judgments on the project site is formed. Through the resistance evaluation process, the rapid evaluation of the resistance body stability and the possibility of water and mud inrush can be realized. Click on the resistance evaluation module on the system homepage, and the system will automatically jump to the resistance evaluation page. Follow the resistance evaluation process to input the relevant information in turn for the resistance evaluation. The basic process of applying the resistance evaluation module to carry out the resistance evaluation of tunnel water and mud inrush is as follows: (1) Click “Start Evaluation” on the module homepage, and the system enters the interface of the tunnel basic information and parameter. Follow the prompts and enter the tunnel name, target mileage, section size (height and width), relaxation zone thickness, fracture zone thickness, actual thickness of the resistance body and other information in sequence. Among them, the thickness of the relaxation zone and the thickness of the fracture zone can also be selected according to the drop-down menu. After the input (or selection) is completed, click the “OK” button, and the critical thickness and safety thickness values will be displayed below. The critical thickness is equal to

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299

the sum of the thickness of the relaxation zone and the thickness of the fracture zone, and the safe thickness is equal to the sum of the critical thickness and the relative safe thickness. (2) Click “Preliminary evaluation” and the preliminary evaluation result interface will pop up. There are three possible results of the preliminary evaluation, and the evaluation logic is as follows: If the thickness of the resistance body is less than or equal to the critical thickness, the results will be “the resistance body of the XX tunnel at the XX mileage will experience delayed damage or direct damage, and the tunnel is prone to water and mud inrush disasters”. If the thickness of the resistance body is greater than the safe thickness, the result will be “the resistance body of the XX tunnel at the XX mileage is in a safe or basically safe state, and no water and mud inrush will occur in the tunnel”. If the thickness of the resistance body is greater than the critical thickness and no greater than the safe thickness, the results will be “further score evaluation is needed”. If the preliminary evaluation shows the first two conditions of results, the evaluation process is over, and users can exit by clicking “Finish”. If the preliminary evaluation shows the third type of results, further score evaluation is required. Click the “Score evaluation” button, and the software will enter the score evaluation page. (3) On the score evaluation page, there are 10 factor indicators, namely, water pressure characteristics, adverse geology, rock mass quality and integrity, joint state, water supply conditions, hydraulic connectivity, rock strength, rock strata strike and dip, ground stress, and rock mass permeability. Users can select the status of the factor according to the drop-down menu of each factor index. After selecting the status, click “OK” to display the corresponding score value. Take the water pressure characteristic factor as an example, the drop-down menu has the following four options: (1) Water head height: H < 10 m, or water pressure value: p < 0.1 MPa; (2) Water head height: 10 m ≤ H < 30 m, or water pressure value: 0.1 MPa ≤ p < 0.3 MPa; (3) Water head height: 30 m ≤ H < 60 m, or water pressure value: 0.3 MPa ≤ p < 0.6 MPa; (4) Water head height: H ≥ 60 m, or water pressure value: p ≥ 0.6 MPa. The corresponding score values are 90, 65, 35, and 10, respectively. The score value of the option is set according to the middle value of the corresponding score interval in Table 6.4. The options of other factors and their corresponding scores are similar, so we won’t go into details. Among them, there are multiple selection boxes for the two factors of rock mass quality and integrity, and joint state. After the selection is completed, it is necessary to calculate the score value according to formula (6.4) and formula (6.5). The score value of the above factors can also be manually input according to the actual situation, directly enter the score value in the score value box corresponding to a factor, and then click “OK”. (4) After the scoring is completed, click on “Score evaluation”. If there is an option that has not been selected properly or the score value is not input, the software will remind users to determine the score value of the factor. After

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the score values of each factor are selected or input, the software calculates the total score according to the formula. According to the total score range, the evaluation results may fall into the following four ranges: (1) If 400 < Q ≤ 500, the system displays the resistance evaluation grade of the XX tunnel at XX mileage is Class I, indicating a safe state; (2) If 250 < Q ≤ 400, the system displays the resistance evaluation grade of the XX tunnel at XX mileage is Class II, indicating a basically safe state; (3) If 100 < Q ≤ 250, the system displays the resistance evaluation grade of the XX tunnel at XX mileage is Class III, indicating a delayed failure state; (4) If 0 ≤ Q ≤ 100, the system displays the resistance evaluation grade of the XX tunnel at XX mileage is Class IV, indicating a direct failure state. (5) After the score evaluation result is given, the evaluation process is over, click “Finish” to exit. 4. Disaster analysis and treatment measure recommendation The module of disaster analysis and treatment measure recommendation mainly realizes the rapid analysis of the tunnel water and mud inrush situation and the preliminary treatment plan design, which embodies the modular, standardized and normalized water and mud inrush disaster treatment. This module has three parts: case display of disaster treatment, analysis of water and mud inrush disaster, and recommendations for treatment of water and mud inrush disaster. The display of disaster treatment cases is an extension of the display function of water and mud inrush cases. The system includes text and video data of treatment methods, treatment techniques, treatment processes and treatment effects of a large number of tunnel water and mud inrush disaster cases. Users can learn and use for reference by referring to relevant cases. This module also includes the principles of treatment of water and mud inrush disasters in tunnels. The water and mud inrush disaster analysis function works in the following way: The system learns a large number of water and mud inrush disaster cases through deep learning, and automatically searches for the water and mud inrush disaster keywords provided by the user according to the tunnel water and mud inrush situation provided by the user. Then the case of water and mud inrush disaster, such as the cause, type, and scale of the disaster, are analyzed. Through the analysis of the results, the user has a further understanding of the tunnel water and mud inrush situation. The function of water and mud inrush disaster treatment recommendation is to provide appropriate treatment suggestions for tunnel water and mud inrush situations. This module collects a large number of water and mud inrush cases and their treatment techniques, and establishes treatment methods for different types of water and mud inrush disasters through deep learning. Finally, based on the analysis of the water and mud inrush case provided by the user, it automatically gives corresponding treatment recommendations. Since each tunnel water and mud inrush case has its particularity, the user can flexibly choose the corresponding treatment method according to the treatment suggestions and the actual water and mud inrush project situation.

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For major water and mud inrush disasters or when the treatment suggestions automatically given by the system cannot meet the needs, users can enter the expert evaluation module for further analysis. 5. Expert evaluation Expert evaluation is an important extension of dynamic management of water and mud inrush cases and the case analysis module of the analysis platform. The function of expert evaluation module is to analyze the water and mud inrush disasters provided by users through online experts so as to provide decision support, which is pertinent, authoritative and interactive. For large-scale water and mud inrush disasters, water and mud inrush disasters caused by special geological conditions, or those with controversial geological origin, users need to further study and analyze the case situations. Through the expert evaluation module, users input the engineering geology and hydrogeology of the tunnel and the general situation of water and mud inrush into the system, and upload relevant images and text data into the system. Online experts will conduct real-time analysis of the disaster situation, determine the cause of the disaster, and provide disaster treatment suggestions and construction decisions. The expert evaluation module has an expert selection function, and consulting users can choose experts in the system to make an appointment for communication. For cases without expert response, the system can also recommend relevant experts to the case and users. Experts provide consulting services according to their own wishes.

8.5 Summary In order to realize the statistical analysis of numerous tunnel water and mud inrush cases, a dynamic management and analysis platform for tunnel water and mud inrush cases was established with the help of computer and Internet technology. This platform can not only dynamically manage and analyze the existing tunnel water and mud inrush cases, but also encourage researchers in the field of water and mud inrush disasters to add and update cases. At present, this platform has collected more than 300 cases of water and mud inrush in tunnels at home and abroad, which can realize the functions of case retrieval, download, submission, review and comment. The platform is also embedded with a tunnel water and mud inrush case analysis module to realize analysis functions such as tunnel water and mud inrush risk assessment, water inflow prediction, resistance evaluation, disaster analysis and treatment measure recommendations, and expert evaluation. It provides a platform for network learning, communication and expert evaluation for the study of tunnel water and mud inrush disasters, and realizes real-time sharing and intelligent automatic analysis of tunnel water and mud inrush cases.

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References Ding C (2010) The design and implefmentation of golf swing coach system based on OpenCV. Master thesis, Huazhong University of Science & Technology, Wuhan Huang J (2012) The design and application of the online monitoring system for sunshine drugs. Med Equipment 25(2):25–27

Appendix 1

Karst Category

© Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1

303

YK16+042

YK16+040

YK16+076~+050

YK16+098~+050

YK16+086~+022

YK16+086~K15+985

9/30/2009

10/14/2009

5/23/2010

5/24/2010

7/16/2010

7/24/2010

Jijiapo Tunnel

1-1

Chainage

Time

Tunnel

Serial No

The accumulated water in the tunnel was about 18,000 m3 ; after water inrush, water inflow rate was about 40 m3 /h

Water inflow lasted for about 160 min, flooding the tunnel for over 480 m, with a total volume of 15,000 m3

The total water inflow was about 120 m3 /h and then decreased to about 50 m3 /h. Until June 6, the total volume of water inflow and mud inrush reached 25,000 m3 and 2,000 m3 , respectively

Water inflow carried a large amount of yellow-white clay. The initial water inflow was about 100 m3 /h and increased to 300 m3 /h after about 2 h and then declined to about 60 m3 /h

The initial water inflow was 350 m3 /h and reduced to 200 m3 /h on October 15 and 100 m3 /h on 16

Stranded pressure water inflow carried a large amount of yellow-white sediment, and the initial water inflow was about 100 m3 /h and reduced to 70 m3 /h on October 2

Water and mud inrush description

Corrosion fissure type

(continued)

(Xu Zhenhao et al., 2011c)

Type of References hazard-causing system

304 Appendix 1: Karst Category

12/24/2014

Moudao Connection line of Qiyueshan Tunnel

Maoxian Tunnel

1-5

1-6

GK3+265

DK116+205~DK130+038

D8K132+314

8/5/2007

Yesanguan Tunnel

1-4

PDK255+978

8/20/2016

1/21/2006

Malujing Tunnel

1-3

K35+040

YD8K132+312

6/8/2007

Tianchi Tunnel

1-2

Chainage

7/15/2016

Time

Tunnel

Serial No

(continued)

Karst cave type

Karst cave type

Stranded water flowed out from the right arch waist, with a large area of water spraying on the vault

Water inrush occurred on the tunnel face at the Corrosion bottom of the middle line, and the water inrush fissure type flow was 310 m3 /h

A small amount of mud inrush at the karst cavity, 1,000 m3 of mud and stone gushed out

Instantaneous water inflow reached 15.1 × 104 Karst cave m3 /h, the volume of sediment and rock blocks type gushed out was 5.4 × 104 m3 , filling the tunnel for nearly 400 m, with a total water inflow of 26 million m3

Water and mud inrush lasted for about 2 h and then water inflow rate decreased to 300 m3 /h, with a maximum rate of 30 × 104 m3 /h

(continued)

(Zhang Zhenguo, 2016)

(Zhou Lun, 2017)

(Sun Mingbiao, 2010; Zhang Mei et al., 2010; Wu Li et al., 2009)

(Yang Bing, 2011)

(Chen Zhenxi and Cheng Xiang, 2008; Huang Jie, 2009)

Type of References hazard-causing system

Clean water flowed out along the bottom of the Corrosion crack at the lower right part of the tunnel face, fissure type with an average flow rate of about 17.2 L/s. Water and mud inrush occurred 8 times successively, and the total amount of water and mud inrush reached 16 × 104 m3

Water and mud inrush description

Appendix 1: Karst Category 305

2/22/2004

Unknown

Huayingshan Tunnel

Pishuang’ao Tunnel

Tongyu Tunnel

Jianshanzi Tunnel

1-8

1-9

1-10

1-11

6/2001

4~7/1998

3/1999~ 8/2000

Hejiazhai Tunnel

1-7

Time

Tunnel

Serial No

(continued)

YK19+759

K21+780

RK63+400

RK63+094~102

Karst cave type

Sudden water inflow occurred when the tunnel Pipe and face encountered the lower karst breccia, with a underground water inflow of 600 m3 /d river type

Water inflow suddenly occurred at the large karst cave on the right side of this section, which brought out a large amount of sediment and formed violent debris flow

The slotted ditch emitted water upward to form a water column of 20~30 cm high

Pipe and underground A fountain of over 2 m gushed upward from the river type tunnel bottom, a large amount of sediment and gravel gushed out

Water inflow occurred several times in the solution joint at tunnel bottom

Water inflow range of the tunnel face was 22 m, and the maximum water inflow of the tunnel face was 2,127 m3 /h

YK34+669

RK63+020

Sudden high-pressure water inrush at the tunnel Pipe and face carrying yellow sediment, and the underground maximum water inflow was 1,676 m3 /h river type

(continued)

(Luo Zhaohui and Li Yong, 2001)

(Ding Hao et al., 2005)

(Yang Man et al., 2007)

(Liu Jianguo and Liu Yili, 2003; Jiang Yun and Wang Lansheng, 2002)

(Qing Sanhui and Huang Runqiu, 2006)

Type of References hazard-causing system

Large water inflow occurred 22 times, carrying Karst cave a large amount of silt. Water inflow was 1~10 type × 104 m3 /d and sand inflow was 500~8,000 m3

Water and mud inrush description

YK34+518

D2K1+430~D2K2+620

Chainage

306 Appendix 1: Karst Category

Tunnel

Gaojiaping Tunnel

Yanziyan Tunnel

Shangpilin Tunnel

Dasangyuan Tunnel

Tanchang Tunnel

Tiefengshan No. 2 Tunnel

Serial No

1-12

1-13

1-14

1-15

1-16

1-17

(continued)

9/24/2004

2/23~ 28/2008

9/10/2006

Unknown

Unknown

11/14/2014

Time

YK26+170

YK27+235

DK354+460~490

YK45+110

Unknown

The middle of the tunnel face collapsed forward as much as 17 m, with a water inflow of 5 × 104 m3 /d. The water inflow of the right tunnel face was 3.7 × 104 m3 /d

Pipe and underground river type

Filling karst cave was revealed, karst water and Karst cave mud inrush occurred many times, a total of type 3,000 m3 sludge was removed

(continued)

(Wang Quansheng et al., 2006)

(Zhao Wei and Ma Gui, 2008; Zhou Sen, 2008)

(He Junxian, 2008)

Karst cave was revealed, a total of 144 m3 debris flow like materials filled the entire advance pilot

Karst cave type

(Zou Ruinong, 2016)

Karst category (Mo Yangchun, 2009)

Karst cave was revealed, water and mud inrush Karst cave occurred type

Initial support of the vault collapsed, with a collapse volume of 300 m3 . Carbonaceous mudstone filled the collapsed cavity, with severe surface water seepage

(Tian Qingchao et al., 2016)

Type of References hazard-causing system

Karst pipes were revealed and water inflow was Pipe and 2,500 m3 /d underground river type

Water inflow occurred on the left and right sides of the tunnel face, with the maximum flow of 12,000 m3 /d. The flow at the right water inflow spot declined from 1,000 m3 /d to 300 m3 /d

YK19+833

ZK45+995

Water and mud inrush description

Chainage

Appendix 1: Karst Category 307

Tunnel

Changtan Tunnel

Doumo Tunnel

Daliang Tunnel

Pingdong Tunnel

Serial No

1-18

1-19

1-20

1-21

(continued)

5/15~ 6/19/2012

4/23/2013

7/13/2012

Unknown

Time

Water inflow crashed the tunnel face and caused collapse in front of the tunnel face, with water inflow volume of 6 × 104 m3 /d

YK26+155

ZK98+044

DK332+266,+237

D1K842+697

D1K842+893

Karst cave type

Large strands of water inflow occurred at the reserved cavern of fire-fighting facilities, and the water inflow was about 20,000 m3 /d

Water inflow occurred suddenly and then decayed gradually, accompanied by sand and gravel gushing out

Pipe and underground river type

Karst cave type

(continued)

(Shi Ming, 2013)

(Bi Huanjun, 2015; Zhang Minqing et al., 2015)

(Xing Shaochuan, 2014)

(Wang Jue and Wang Hao, 2010)

Type of References hazard-causing system

Pipe and underground Flow plastic cohesive soil was ejected from the river type Karst cave left and right sides of the tunnel face, and the type spraying distance was up to 15 m

Tunnel floor bulged under water pressure, with the water inflow of 760 m3 /h

Water inflow occurred when drilling ahead, carrying a small amount of silt; 3 strands of water gushed upward to 3 m, with the water inflow of 4,000 m3 /d

Water inrush occurred when the left line was excavated to ZK26+167, with water inrush volume of 7 × 104 m3 /d

ZK26+167

YK19+638

Water and mud inrush description

Chainage

308 Appendix 1: Karst Category

ZK38+770~820

YK39+397

YK39+391

11/9/2008

4/18/2009

10/17/2009

Jigongling Tunnel

Pingkan Tunnel

1-23

1-24

11/19/2016

12/4/2009

ZK38+790

12/21/2007

Pingyang Tunnel

Z4K32+793

ZK19+509

Inrush mud and the associated air flow pushed the transport vehicle at the second lining platform for about 50 m, and the amount of rock and mud inrush was about 7,000 m3

Karst cave type

Water inflow occurred in the advance blast Corrosion hole, in the form of spraying water, carrying fissure type sediment, and the total water inflow was 35~45 L/s

The amount of mud inrush was about 5 × 104 m3 , with an impact range of about 455 m

Maximum water inflow reached 5 × 104 m3 /d, and 10,000 m3 of yellow sand and silty yellow mud gushed out

The thickness of inrush silt deposition was about 2 m, distributing for over 100 m along the tunnel, and the total amount of water and mud inrush was about 105 × 104 m3

(continued)

(Zhang Boyu, 2018)

(Li Shucai et al., 2014b)

(Su Chang et al., 2012)

Type of References hazard-causing system

A stream of muddy water flowed out at the arch Karst cave foot of the lower right tunnel face, and the type volume of water and mud inflow was about 5 × 104 m3

Large strands of water inflow occurred in the reserved cavern of vault power distribution facilities, and the water inflow was about 20,000 m3 /d

ZK98+027

1-22

Water and mud inrush description

Chainage

Time

Tunnel

Serial No

(continued)

Appendix 1: Karst Category 309

Unknown

10/24/2013

Chaoyang Tunnel

Yangmeipu Tunnel

Nanshanzhai Tunnel

Yangling Tunnel

1-26

1-27

1-28

1-29

Unknown

6/10/2018

Unknown

Xulingguan Tunnel

1-25

Time

Tunnel

Serial No

(continued)

K3+731

Unknown

ZK15+567

PDK170+674

K43+000

K43+066

Chainage

A large amount of brown soft plastic silty clay in semi-humid state slipped into the tunnel, forming more than 300 m3 of mud inrush and collapse

A large amount of silt seeped out from the funnel, resulting in the collapse of the tunnel face at the top of the tunnel, with a collapse height of 60 m

Soft plastic flow or plastic yellow clay constantly gushed out of the large karst cave, and a small amount of dot like water drops existed at the vault of the tunnel face

(Li Ping, 2009)

/

Karst cave type

(continued)

(Yu Liyuan et al., 2016)

Karst category (Sun Xishou and Liu Shilong, 2011)

Karst cave type

At the tunnel face 1893 m away from the exit of Karst cave the pilot tunnel (PDK 170+674), instantaneous type water and mud inrush occurred suddenly, with the water inrush height about 2.5 m higher than the bottom plate and lasting for about 1 h

(Zhao Ping et al., 2010)

Type of References hazard-causing system

Two streams of water gushed out, one from the Karst cave fissure on the left side of the external solution type cavity and another from one solution hole on the left roof of the internal solution cavity, with a stable flow of about 4.0 L/s

Water and mud inrush description

310 Appendix 1: Karst Category

K42+462

Daluliangzi Tunnel

1-33

K44+090

5/11/2004

7/2007

Shijialiang Tunnel

1-32

ZK112+744

K38+664

Unknown

Wulongshan Tunnel

1-31

K128+843

Chainage

3/26/2004

8/6/2009

Dingshang Tunnel

1-30

Time

Tunnel

Serial No

(continued)

Karst cave type

Karst cave type

The water inflow of the tunnel face reached 3,500 m3 /h. The sudden water accumulation depth in the whole tunnel was 0.3 m. After about 2.5 h, the water inflow basically stabilized at about 200 m3 /h

Water inrush occurred in the boreholes at right side of the vault in varying degrees, with a water inflow of 360 m3 /h and a small amount of sediment

Karst cave type

(continued)

(Liu Xiaogang, 2010; Nan Xiaoyu, 2007 )

(Chen Yangyong et al., 2009)

(Cao Jianping, 2006)

(Tian Jun and Yang Xianzhang, 2011)

Type of References hazard-causing system

A large amount of water seepage began to Karst cave appear at the lining construction joint. After the type rainstorm on July 16, the maximum water inflow of the whole karst cave was 8,700 m3 /h

The clay in the karst cave continuously flowed into the tunnel. At the same time, many cracks appeared on the surface, with a maximum width of about 25 cm

A large amount of mud flushed out, and the mud and gravel were piled up to the vault height of the tunnel face. The total amount of mud was about 3,000 m3

Water and mud inrush description

Appendix 1: Karst Category 311

Tunnel

Yingzuiyan Tunnel

Xiatangkou No. 1 Tunnel

Shanggu Tunnel

Longtan Tunnel

Serial No

1-34

1-35

1-36

1-37

(continued)

ZK72+177.8

2/24/2007

On the right arch foot of a step, there were serval strands of muddy water, followed by water inrush and mud inflow. The mud inflow volume was 1,800 m3 /h, and the instantaneous flow was 0.34 m3 /h

Karst cave type

(continued)

(Liu Qin et al., 2013)

(Li Xuedong et al., 2008)

The peak water flow reached about 7.0 × 104 m3 /d

LK29+700

Many strands of muddy water flowed out of the Karst cave right arch, and the debris flow flowed out from type the tunnel face downward. The instantaneous water inrush and mud inflow reached 0.34 m3 /s, which belonged to intermittent mud inflow, with a distance of nearly 42 m

(Guo Yaolin et al., 2013; Cao Xiaoyong, 2013)

The peak water inflow reached about 4.2 × 104 Corrosion fissure type m3 /d

LK29+220

ZK72+167~+202

(Xu Hongwu, 2010)

(Wu Fazhan, 2008; Zhao Xiangyang, 2010)

Type of References hazard-causing system

A large amount of water inrush occurred on the Karst cave right side of the vault in the left line, with a type large amount of sediment in the water flow. The peak flow of water inrush was estimated to be 2,500~3,000 m3 /h

Water and mud inrush description

The water was surging out from the fracture of Karst cave the second lining, and its maximum water flow type reached 26.46 m3 /s

YK23+187.5~199.5

ZK39+822~+845

Chainage

11/8/2006

6/24/2011

5/23~ 24/2007

6/11/2007

Time

312 Appendix 1: Karst Category

Tunnel

Masangshao Tunnel

Wulong Tunnel

Dazhiping Tunnel

Serial No

1-38

1-39

1-40

(continued)

ZK72+184

ZK72+163

5/9/2009

7/3/2009

9/29/2006

5/13/2002

PDK132+990

DK193+185~+210

DK966+842~DK968+142

ZK72+175

3/28/2007

10/31/2013

Chainage

Time

Pipe and underground river type

A large amount of soft plastic sludge gushed out, and the water inflow in half an hour reached 10 × 104 m3 , mud inflow of about 7,000 m3

Karst cave type

(continued)

(Xie Xianguang, 2009)

(Zhang Xiaohua and Liu Qingwen, 2005)

(Dai Peiyi and Bai Minglu, 2015)

Type of References hazard-causing system

On May 13, the first water inrush had a volume Pipe and of 30 × 10 4 m3 /d, and then 4 more water underground inrush accidents occurred, with water inrush of river type 200 × 104 m3 /d, 140 × 104 m3 /d, 718 × 104 m3 /d, and 21 × 104 m3 /d

The total drainage in the tunnel was 694,289.9 m3 . The maximum water output of the monitoring section (D1K966+710~ D1K966+890) reached 2,673.6 m3 /d

A large-scale mud inrush occurred once in about 30 min, the estimated water flow was 60 m3 /h, the total mud inflow was about 7,000 m3

Two strands of muddy water at the arch foot of a step, which caused the slipping of the arch foot and induced the karst water and mud inrush

Intermittent mud inrush occurred from the tunnel face downward, covering the tunnel by nearly 60 m

Water and mud inrush description

Appendix 1: Karst Category 313

Tunnel

Lazhidong Tunnel

Renfang Tunnel of China Academy of Engineering Physics

Diversion Tunnel of Damo Power Station

Baguashan Tunnel

Serial No

1-41

1-42

1-43

1-44

(continued)

Upper heading DK132+340

1+620

10/22/1996

1/3/2006

1+601

No. 1 and No. 2 shelters

10/18/1996

4~8/2002

DK174+610

IIDK132+914

4/30/2008

7/1/2005

Chainage

Time

Karst cave type

The water entrained with mud and slag Karst cave continuously flowed out from the exploratory type hole, with a total water inflow of about 15,000 m3 and the volume of inrush breccia gravel was about 1,800 m3

Huge water inflow in the tunnel, with a water inflow of about 30,000 m3 /d and debris flow

Strand-like water inrush on the vault of the Karst cave tunnel face. The vault at the section of 1+601~ type 1+610 collapsed, forming a deep groove with a depth of 0.5 m and a width of about 1.5 m

(continued)

(Wang Shuanglong, 2009)

(Zheng Maoyuan et al., 1998)

(Wang Yun, 2012)

(Zhang Zonggang, 2006; Hou Xiaojun, 2008)

Type of References hazard-causing system

The maximum short-time water inrush of No. 2 Corrosion and No. 1 shelters were 6,800 m3 /d and 5,200 fissure type m3 /d, respectively, and the water inrush was accompanied by serious mud and sand inrush

The karst cave group filled with soft plastic clay was exposed, and mud inrush suddenly occurred, filling the 45 m long excavation space in the tunnel

The height of sediment inflow at the tunnel face was about 3 m, the sediment inflow was about 3,000 m3 , and the water volume stabilized at 300 m3 /h

Water and mud inrush description

314 Appendix 1: Karst Category

Tunnel

Geleshan Tunnel

Xinzhai Tunnel

Xiangshan Tunnel

Dajing Tunnel

Serial No

1-45

1-46

1-47

1-48

(continued)

YDK24+158

7/23/2009

K438+800

K438+850

YDK24+136

7/30/2009

Unknown

YDK24+098

DK365+740

5/12/2000

4/12/2008

PK1+791

PDK3+484

Chainage

7/9/1999

7/2/2002

Time

(continued)

(Chen Mantian et al., 2010)

Karst category (Liu Chengyu and Liu Zhaowei, 2014)

A large amount of underground water inflow on Karst cave the vault and the left and right sidewalls, with type the maximum water inflow of 1,800 m3 /h

The initial collapse volume of the left initial support was about 600 m3 , the water inflow was about 800 m3 /h, and the total water inflow was about 50 × 104 m3

The single-hole water output of pre-exploratory hole was about 500 m3 /h, and the measured water pressure was 1.4 MPa

Water inflow was 850 m3 /h, water pressure reached 1.1~1.5 MPa; On June 5, water inflow was about 1,000 m3 /h and then stabilized at 450~500 m3 /h

The water inflow had reached 12,000 m3 /d, and the maximum total water output in the tunnel had reached 55,200 m3 /d

(Yuan Zhenxiu and Li Yanjun, 2004)

Karst category (Zhou Xungao, 2006)

Type of References hazard-causing system

Yellowish brown mud water flowed out from Corrosion the pre-exploratory borehole in the middle and fissure type lower part of the tunnel face, and the maximum peak value reached 21 × 104 m3 /d

Sudden water inrush occurred on the left side of the tunnel face, with a water inflow of 300 m3 /h and yellow sediment mixed in the water

Water and mud inrush description

Appendix 1: Karst Category 315

Tunnel

Guiyang Metro Line 1

Zhongba Tunnel

Youfangping Tunnel

Motianling Tunnel

Huama Tunnel

Tonghai Tunnel

Serial No

1-49

1-50

1-51

1-52

1-53

1-54

(continued)

PDK29+203

PDK29+310

12/23/2007

DK302+926

ZK43+090~+125

ZK42+785~+800

DK387+512

D9K55+218

ZDK19+200

Chainage

8/22/2007

1/5/2011

4/21/2007

Unknown

7/14/2012

8/18/2014

Time

Corrosion fissure type

Karst cave type

(Luo Yuhu et al., 2011)

(Yu Qingfeng et al., 2015)

(Liu Quan et al., 2014)

Water inflow rate at the left arch waist and working face of pilot tunnel was about 60 L/s

Water and sand inrush occurred suddenly, with maximum water inflow of 2 × 104 m3 /d

Corrosion fissure type

(continued)

(Sun Jinyu et al., 2011)

Water inflow suddenly occurred at a drilling Karst category (Wu Shiyan, hole at the right arch waist, and the water 2012; Zhou spraying distance reached 12 m. The maximum Quan, 2014) water inflow was 35,000 m3 /d

Large-scale water inrush occurred 9 times in the left line, and the water inrush in the full section of the left sidewall and the foot of both sidewalls was the largest in scale, with a total water inflow of 72,000 m3

Clay seepage and sediment gushing out Pipe and occurred onto the karst pipelines, with water underground inrush of 400 m3 /h and ejection distance of 4 m river type

The water was jetted out in strands along the tunnel face direction, with the maximum spraying horizontal distance of nearly 8.0 m and the maximum water pressure of 0.8 MPa

(Chen Fada et al., 2016)

Type of References hazard-causing system

The peak water inflow reached 700 m3 /min, the Pipe and whole section was submerged by about 4 m, underground with the water inflow of about 18,000 m3 river type

Water and mud inrush description

316 Appendix 1: Karst Category

9/10/2002

5/25/2009

Qipanshi Tunnel

Tianbaling Tunnel

Yuanliangshan Tunnel

Zijingshan Tunnel

1-56

1-57

1-58

1-59

7/12/2010

8/6/2009

5/25/2009

ZK221+960

DK354+879~+920

Unknown

H3DK0+891

ZK212+884

PDK35+770

6/26/2007

Munaoshan Tunnel

DK29+174

12/23/2007

1-55

Chainage

Time

Tunnel

Serial No

(continued)

Karst cave type

Karst cave type

Hidden river flowed into the tunnel with a flow Pipe and of about 5,000 m3 /h underground river type

No. 3 karst cave was exposed, blasting mud inrush occurred on the tunnel face, causing the hard plastic-soft plastic clay to fill the lower pilot adit of 244 m3 instantly

(Sun Jinyu et al., 2011)

(continued)

(Shi Shaoshuai et al., 2012)

(Hui Guoting 2005; Zhang Minqing and Liu Zhaowei, 2005)

(Guo Lian, 2011)

(Sun Weiliang, 2010)

Karst pipe type (Huang Xueliang, 2015)

Corrosion fissure type

Type of References hazard-causing system

Strands of water inflow had a maximum rate of Karst cave 2,000 m3 /d and tunnel face was seriously type flooded

Water inflow at the left lower part of the working face reached 260 m3 /min and water flow stabilized around 7~10 m3 /min at 19:00

Sudden water and mud inflow occurred, with large quantities of yellow mud gushing out from the tunnel face

Maximum water inflow exceeded 12 × 104 m3 /d, stone inrush reached over 1,000 m3 , and the total drainage was over 400 × 104 m3

Water inrush (stable water inflow) was 2.2 × 104 m3 /d, with ponding water depth exceeding 1m

Water and mud inrush description

Appendix 1: Karst Category 317

11/12/2001

Unknown

Tongren Tunnel

Pingtu Tunnel

Lvliangshan Tunnel

Shuikou No. 3 Tunnel

Shilin Tunnel Unknown

Qingping Tunnel

1-61

1-62

1-63

1-64

1-65

1-66

Unknown

11/24/2005

6/26/2006

4/11/2001

Pengshui Tunnel

1-60

Time

Tunnel

Serial No

(continued)

Yk43+611

DK658+981~+ 976

DK57+641

DK57+633.8

Shaft 1# 05+80

DK1905+098

DK539+734

DIIK238+911

Chainage

Karst cave type

Large streams of water flowed out of the tunnel, with a water inflow of 6 m3 /min (of which the sediment content was about 25%)

Karst cave type

A large amount of red clay gushed from the Karst cave arch on the right side of the face. The type longitudinal length of mud gushing was about 10 m, and the volume of mud inflow was about 680 m3

Strands of muddy water flowed out, the instantaneous water inrush and mud inflow reached about 0.34 m3 /s, and the total amount of intermittent debris flow was about 1,200 m3

(continued)

(Tang Haozhi and Xu Chengjin, 2010)

(Lin Zhiping, 2016)

(Zhang Zhaofeng, 2008)

(Chen Zhigao, 2009)

Corrosion fissure type

Water inflow reached 4,000~8,000 m3 /d

(Wang Aicong et al., 2002)

(Zhang Yi, 2007; Lei Shengxiang et al., 2003)

(Yang Kai, 2010)

Karst cave type

Pipe and underground river type

Type of References hazard-causing system

The silt filled the tunnel section about 100 m Karst cave long, and a funnel-shaped cavity was formed at type the vault

Water inrush carried a large amount of strand sludge into the tunnel, and 500 m3 soft sliding mass was accumulated at the entrance of the tunnel face

Extra-large water inrush occurred suddenly, measured flow rate reached 8,750 m3 /h

Water and mud inrush description

318 Appendix 1: Karst Category

Tunnel

Laozhuang Tunnel

Liujiayu Tunnel

Kedong Tunnel

Baiyanjiao Tunnel

Qiyueshan Tunnel of Liwan Expressway

Qiyueshan Tunnel of Yiwan Railway

Serial No

1-67

1-68

1-69

1-70

1-71

1-72

(continued)

PDK361+582.5

PDK361+597

PDK361+873.5

4/28/2004

5/31/2004

ZK19+752.9~ZK20+150

D1K640+145~+473

Zk72+678

Yk27+280

Zk45+200

Chainage

3/24/2004

2014

6/30/2017

Unknown

Unknown

Unknown

Time

Pipe and underground river type

Karst cave type

Corrosion fissure type

Water inrush occurred suddenly, water inflow of a single hole reached 60 m3 /h

Advance horizontal drilling coring showed that there was a filling-type karst cave at DK361+614, filled with soft-flow plastic clay

Water inflow in the advance drilling hole, and Karst cave the tunnel filled with silt. The water inflow was type up to 300 m3 /h, and then 30 m3 /h

During the tunnel construction in 2014, water inflow occurred in many places and forced to stop work for nearly 10 times. The maximum water inflow was 8.7 × 104 m3 /d

The water injection point suddenly appeared at Pipe and the left arch waist, and the maximum water underground inflow at the outlet of the mileage tunnel river type reached 13.9 × 104 m3 /d

There was muddy water gushing out from the left vault, with a water inflow of 1,000 m3 /h

(continued)

(Tian Siming et al., 2006)

(Li Shucai, 2015)

(Zou Chen et al., 2018)

Type of References hazard-causing system

A karst pipe was found at the base of the tunnel, Pipe and and there was water flow in the karst cavity underground river type

A karst pipeline intersecting with the tunnel was developed, and the diameters of the inlet and outlet of the pipeline were 1.5 m and 1.8 m, respectively

Water and mud inrush description

Appendix 1: Karst Category 319

Tunnel

Guanjiao Tunnel

Serial No

1-73

(continued)

No. 2 shaft

No. 4 shaft

No. 5 shaft

No. 6 shaft

Unknown

Unknown

9/19/2010

DK362+277

2/17/2005

No. 3 shaft

PDK362+144

10/10/2004

7/31/2008

DK362+060

10/15/2004

Unknown

Chainage

Time

Water inflow inside the tunnel, the water level in the tunnel was up to transverse passage at DYK296+110

Water inflow at the tunnel face, with high water pressure and long spraying distance, water inflow volume of about 1.5 × 104 m3 /d

Water discharge at the tunnel portal before and after shaft flooding was 8,500 m3 /d and 30,000 m3 /d

The average water volume at the shaft was 15,000~20,000 m3 /d

No large water inrush occurred

Water inrush flow was 100 m3 /h, the outflow from the solution cavity was mainly block stone and a small amount of cohesive soil, with a volume of about 500 m3

Water inrush occurred suddenly at the advance borehole, with the water inrush of about 800 m3 /h

When a 5-m-long deepening drill was used for advance detection, a 4-m-long water flow was emitted from the exploratory hole

Water and mud inrush description

Corrosion fissure type

(continued)

(Tan Zhongsheng et al., 2017; Qian Fulin, 2014)

Type of References hazard-causing system

320 Appendix 1: Karst Category

Meihuashan Tunnel

Dazhushan Tunnel

Xindabashan Tunnel

Dabashan Tunnel

1-75

1-76

1-77

1-78

Unknown

YDK434+477

1/17/2007

Unknown

PDK434+492

Syncline

Unknown

Transverse tunnel work area parallel adit construction to 2,200 m away

Chainage

10/25/2006

8/5/2009

Unknown

Wumengshan 5/13/2009 No. 2 Tunnel

1-74

Time

Tunnel

Serial No

(continued)

Maximum water inflow reached 15 × 104 m3 /d, causing the interruption of tunnel construction for 3 months

Filling materials in the vault karst cave collapsed, with a collapse height of 6 m. The plastic clay gushed out of the cave again, mixed with a small amount of thin rock

Filling materials collapsed at the vault after excavation of pilot tunnel, a small amount of water seepage inside the karst cave

Maximum water inflow of pilot tunnel reached 12,180 m3 /h and 5,600 m3 /h for the second mud inrush and water inflow

Huge water inflow of karst cave, hidden river was intercepted by building a water blocking wall

Underground river was exposed by construction, water inflow of hidden river reached 14 × 104 m3 /d

Water and mud inrush description

Karst cave type

Karst cave type

Karst cave type

Karst cave type Pipe and underground river type

Karst cave type Pipe and underground river type

(continued)

(Han Xingrui, 2004)

(Zhong Chaoquan, 2008)

(Zhang Jinfu and Wen wenzhao, 2018)

(Han Xingrui, 2004)

(Fang Jinsong, 2014)

Type of References hazard-causing system

Appendix 1: Karst Category 321

Unknown

Nanling Tunnel

Shengjingguan Tunnel

Xiakou Tunnel

Meiziguan Tunnel

Loushanguan Unknown Tunnel

1-80

1-81

1-82

1-83

1-84

K80+210~+270

Unknown

XJK0+093

11/28/2011

Unknown

XJK0+101

Unknown

DK1936+269

DK1936+967

DK1937+010

K27+227~+248

Chainage

8/7/2011

Unknown

Unknown

Zhongliangshan Tunnel

1-79

Time

Tunnel

Serial No

(continued)

Several water inflow occurred on the arch ring of the upper step, the total water inflow was more than 30 L/S, and linear water gushed out from the vault and the arch waist

The stable water inflow was 0.45~0.75 m3 /s, pouring water flooded the tunnel, and the maximum water inflow was 2.61 m3 /s

Mud inrush occurred at the upper left of the working face, with a mud inrush volume of 1,200 m3 . On December 5, the mud inrush volume was about 4,500 m3

Water inflow occurred in the blast hole, with a spraying distance of about 4 m and a water inflow volume of about 64 m3 /h

Serious water seepage at the tunnel construction joint, the sidewall arch waist and the wall corner

Water and mud inrush mostly concentrated in the exit section, occurring 16 times, and the total water inflow exceeded 22,000 m3 /d

Corrosion fissure type

Karst cave type

Karst cave type

Corrosion fissure type

Corrosion fissure type Karst cave type

(continued)

(Mo Yangchun, 2009)

(Li Shucai et al., 2013)

(Mo Yangchun, 2009)

(Tan Yujun and Chen Xiaochun, 1990)

(Zhang Fangzheng, 2013)

Type of References hazard-causing system

Water inflow on the sidewall of the tunnel face, Corrosion the total water inflow was about 84 m3 /h, and fissure type the water inflow pressure was stable at about 2 MPa

Water and mud inrush description

322 Appendix 1: Karst Category

Unknown

Unknown

Xinpai Tunnel

Dadushan Tunnel

Lishuwan Tunnel

1-86

1-87

1-88

Unknown

Unknown

Yanjiaozhai Tunnel

1-85

Time

Tunnel

Serial No

(continued)

Karst cave type

Type of References hazard-causing system

Sudden water inflow occurred in the lower part of tunnel face, water inflow was about 3,500 m3 /d Water spraying, measured water inflow was 8,000~10,000 m3 /d and water pressure was 0.5~1.0 MPa

YK4+095

YK4+025

(continued)

(Yu Jixin, 2005)

Karst category (Xing Shaochuan, 2014)

Strands of water inflow, measured water inflow Karst cave was 5~20 L/s (the sediment content was about type 25%)

Sudden water inflow occurred above the vault, lasting for over one month, flooding the tunnel for 100 m

Water and mud inrush volume during Karst category construction reached 10,000 m3 /d, water and mud inrush volume during operation was 2,112 m3 /d in dry seasons and 16,235 m3 /d in rainy seasons

Sudden water and mud inrush occurred in the karst cave of the tunnel floor, flooding the tunnel, seriously affecting construction progress

Water and mud inrush description

YK4+195

No. 1 Transverse tunnel parallel adit PDK855+973

Unknown

Unknown

Chainage

Appendix 1: Karst Category 323

Water inrush occurred at the fissures of the vault, with water inrush of 200 m3 /h Karst cave was exposed, water inrush reached 2,000 m3 /h and the total volume of mud was about 6,000 m3 Water inrush of the blasting hole was 200~300 m3 /h and the total volume of mud was about 1,000 m3 Water inrush flooded the pilot tunnel for over 50 m, and water inrush reached 3,000 m3 /h

ZK69+532

CK9+543

CK9+539

DK3+733

DK3+728

Yangjiaonao Tunnel

Yudong No. 1 1/2015 Tunnel

Changdangzi Tunnel

1-91

1-92

1-93

Unknown

6/15/2009

5/28/2007

Sailimuhu Tunnel

+925

ZK151+685

Left line excavated 15 m, right line excavated 12 m

Corrosion fissure type Pipe and underground river type

Karst cave type

A large amount of soft plastic clay mixed with Karst cave gravel gushed out of the karst cave, and the type water content of the gushed material was large, and the total amount of mud reached 7,800 m3

The upper bedrock on the left side of the tunnel Corrosion face was developed with dissolution fissures, fissure type resulting in different degrees of karst collapse and house cracking on the surface

(continued)

(Rong Kai et al., 2010)

(Xiong Chengyu and Zhang Qiang, 2017)

(Tian Jun and Yang Xianzhang, 2011b)

(Zhao Yong, 2008)

(Zhang Zhidao and Bai Jicheng, 1998)

Type of References hazard-causing system

Strands of water inflow, maximum water inflow Corrosion was 245 m3 /h fissure type

Pipe water inflow occurred suddenly, mixed with gravel and pebble, and the water inflow was 1.5~2.0 m high and 415 m long

1-90

+853

+595

581+585

Unknown

Jiazhuqing Tunnel

Water and mud inrush description

1-89

Chainage

Time

Tunnel

Serial No

(continued)

324 Appendix 1: Karst Category

Unknown

Unknown

Yunwushan Tunnel

Baojiashan Extra-long Tunnel

Jinkuidi Tunnel

Dayahe Tunnel

Tuojiashan Tunnel

1-95

1-96

1-97

1-98

1-99

K37+199

LK68+730

9+593

YK157+400~+414

7/20/2018

9/20/2011

YK158+000~+010

DK245+260

DK247+785

DK194+039~DK193+980

Chainage

6/28~ 7/3/2018

Unknown

1/11/2006

Baiyangping Tunnel

1-94

Time

Tunnel

Serial No

(continued)

A large amount of flow plastic clay gushed out of the face and collapse occurred

Water inflow occurred at the tunnel face, the water was linear and drop-like

The water seepage first occurred at the top of vault, and the mud inrush volume was about 1,200 m3

Water and sand inflow occurred at the bottom of the side foundation and the central ditch. The water inrush was about 100 m3 /h and the total amount of sand was about 80 m3

Corrosion fissure type

Corrosion fissure type

Karst cave type

(continued)

(Liu Xiufeng, 2007; Li Jianjun et al. 2005)

(Feng Weiqiang and Liu Chaosheng, 2009)

(Zhao Fahui and Zhou Rui, 2013)

(Yang Jian et al., 2010)

Water inflow was 100~200 m3 /h and the Karst cave amount of silt and sand inflow was estimated to type be 300 m3

(Guo Feng, 2007) (Xue Bin and Zhang Minqing, 2009)

Corrosion fissure type

Type of References hazard-causing system

Water inflow occurred, but TSP indicated the Corrosion underground water was not developed. There fissure type was certain deviation between water inflow and geophysical prospecting results

Water inrush accident happened in the tunnel, with water inrush of 150 m3 /h

Water and mud inrush description

Appendix 1: Karst Category 325

Unknown

7/13/2012

Unknown

Foling Tunnel

Chalinding Tunnel

Gangwu Tunnel

Qingyantou Tunnel

Dahuashan Tunnel

1-101

1-102

1-103

1-104

1-105

3/12/2018

6/21/2012

Unknown

Pingguan Tunnel

1-100

Time

Tunnel

Serial No

(continued)

ZK23+909

YK33+763.8

D1K871+805

LK124+520~LK124+630

LK124+573.5

K13+618 of left line

Unknown

Chainage

Karst cave type

Corrosion fissure type; Karst cave type

Sudden water inflow occurred in the tunnel face, water was clear and strand-like, initial water inflow was 450 m3 /h and water inflow still reached 129.6 m3 /h on March 29

A large amount of mud water gushed out, average water depth reached 1.2 m, water inflow was 1,200~1,600 m3 and volume of water and mud inrush for the second time was nearly 4,580 m3

Corrosion fissure type

Karst cave type

(continued)

(Li Ruizhe, 2018)

(Luo Wei et al., 2018)

(Mao Bangyan et al., 2016)

(Zou Huanhua, 2016)

(Wang Hu and Shen Yupeng, 2014)

Karst category (Mo Yangchun, 2009)

Type of References hazard-causing system

Sudden water inflow occurred in the transverse Karst cave tunnel, with water inflow of 5.7 × 104 m3 /h type and a total volume of 3.4 × 105 m3

Filling materials in the solution cavity under the road surface was gradually hollowed out under the long-term scouring of groundwater, resulting in water and mud inrush on the road surface of the left-line tunnel

Strong water inflow occurred at the lower left part of the upper step, with an estimated water inflow of 30,000 m3 , and karst caves and cavities existed

Water and mud inrush during construction reached 108,600 m3 /d, the intermittent water and mud inrush was 75,000 m3 /d and that for dry seasons was only 200 m3 /d

Water and mud inrush description

326 Appendix 1: Karst Category

Tunnel

Hexiba Tunnel

Yujialing Tunnel

Huling Tunnel

Shanggaoshan Tunnel

Micangshan Tunnel

Serial No

1-106

1-107

1-108

1-109

1-110

(continued)

1/17/2015

8/23/2015

10/2008

9/1/2011

6/3~4/2014

Time

K41+720

DK490+373

YK153+020~031

ZK153+100

DK114+570

YK5+660

Chainage

Karst cave type Corrosion fissure type

Corrosion fissure type Pipe and underground river type

Corrosion fissure type Karst cave type

(Fang Zhenhua et al., 2017)

(continued)

A large amount of groundwater flowed into the Karst category (Cao Fang tunnel through the advance blasting holes of et al., 2017) the working face, with an initial flow of 300 m3 /h; after 5 days, the water inflow was reduced to 120~150 m3 /h and the accumulated water inflow was 33,642 m3 /d

Water inflow at karst cave entrance, initial water inflow was 226.8 m3 /h, after karst cave exposed, water inflow continued, with a water inflow of 130~415 m3 /h

with the spraying height of 3~4 m, and water seepage occurred in the construction joint

(Kang Chen, 2018)

(Zhang Chi, 2017)

(Zhao Xianlun and Tao Lichun, 2018)

Type of References hazard-causing system

Sudden water inflow occurred in the tunnel face Corrosion fissure type Water spraying occurred in the cable trench,

The spraying distance of water column at the left arch foot and the arch waist was 7 m, and a large amount of sediment was mixed in the water. The water inflow was about 685 m3 /d

Interstitial water was jetted out from the top and both sidewalls, mixed with a large amount of sand and gravel, with a water inflow of 7,000 m3 /d

Water and mud inrush description

Appendix 1: Karst Category 327

Tunnel

Bailongshan Tunnel

Guangzhou Metro Line 2

Qingshan Tunnel

Serial No

1-111

1-112

1-113

(continued)

3DK320+710

DK320+803

6/2000

ZDK18+226

DK27+900

Chainage

4/1/1999

9/5/2000

4/16/1999

Time

Karst cave type Corrosion fissure type

Turbid water carrying sediment gushed from the drainage holes, and the measured water inflow was as high as 2,690 m3 /h (continued)

(Yao Yunxiao, 2004)

(Feng Shuomou, 2002)

Karst category (Yang Guorong and Fu Tengxuan, 2003)

Type of References hazard-causing system

Water inflow was mixed with a large amount of Corrosion sediment and small stones, with measured fissure type water inflow of 1,559 m3 /h

Sudden water inflow occurred at the tunnel floor, after one hour and eight minutes, water inflow level reached 4.71 m high and had a total volume of 138.38 m3

Small streams of rapid water suddenly gushed out from the left sidewall, and then became large streams of water, with a flow of up to 10,000 m3 /d

Water and mud inrush description

328 Appendix 1: Karst Category

Rainy season in 2014

6/5/2000

Zhujiayan Tunnel

Juyun Tunnel 5/22/2006

11/2002

Bibanpo Tunnel

Xianrenxi Tunnel

Yinshan Tunnel

Dahongtian Tunnel

Sandu Tunnel 4/5/2011

1-114

1-115

1-116

1-117

1-118

1-119

1-120

11/2003

Unknown

Time

Tunnel

Serial No

(continued)

DK135+508

K74+500~+650

K72+900~K73+350

DK124+420~+405

DK124+368~+355

DK124+425~+396

K971+015~+025

K1+512

YK52+164

D1K978+704~D1K981+640

PDK978+460~PDK980+380

Chainage

(Cai Dezhi, 2009)

(Liu Guangshi and Ding Xiumei, 2018)

(Li Limin and Yin Li, 2004)

(Zhu Mingjie, 2007)

(continued)

(Bai Jun, 2013)

Karst category (Zhu Chunlin et al., 2010)

Karst cave type

Corrosion fissure type Karst cave type

Karst category (Li Qiang et al., 2007)

Corrosion fissure type

Corrosion fissure type Karst cave type

Type of References hazard-causing system

Strand-like water inflow, with water pressure of Corrosion 1.55 MPa and water inflow of 2,000 m3 /h fissure type

Water inflow occurred at the tunnel wall and roof, with water inrush of 520 m3 /d and 1,000 m3 /d, respectively, in the form of water spraying and rain-like

Water gushed out from the lining construction joints, weak pores and drainage pipes, and the accumulated water in the tunnel was over 1 m deep in only 20 min

The water gushed out in an arc shape, with a water inflow of 120 t/d

Sudden karst water inflow occurred in the left upper part of the working face, with a water inflow of 1,500 m3 /h

Fissures were well developed in the surrounding rock ahead, and water inflow occurred

Most of the water inflow came from the dissolution fissure, carrying a large amount of sediment. In 2014, the maximum water inflow of the tunnel reached 19.27 × 104 m3 /d in rainy seasons

Water and mud inrush description

Appendix 1: Karst Category 329

DK1076+860

DK567+100

2/22/2012

Xinlongfeng Tunnel

Jialiangshan Tunnel

Xitieche No. 2 Tunnel

Xiao gaoshan 11/15/2012 Tunnel

1-123

1-124

1-125

Unknown

10/2~ 7/2011

DK567+240

DK567+162

DK567+106

A large amount of strand water gushed out, with a water inflow of 800~1,000 m3 /h, and the solution cavity was filled with mainly yellow mud

K142+568

Karst cave type

Maximum water inflow in the left side of upper Pipe and step was 1,100 m3 /h and that in the right side of underground river type lower step was 7,130 m3 /h, with water inflow carrying a large amount of sediment

Water inflow occurred at the vault, the water Corrosion inflow was 130 m3 /h and 275 m3 /h on February fissure type 23

Water inflow from the fissures, with a water inflow of 600~800 m3 /h

Water and mud inrush occurred on the arch Pipe and line, with a water inflow of 690 m3 /h. The underground water inflow reached 1,100 m3 /h from October river type 10 to 13

(continued)

(Zhang Huigang et al., 2016)

(Sun Lei, 2013)

(Yan Lilai, 2013)

(Wang Jialiang et al., 2012)

(Gu Chongjian, 2014)

Type of References hazard-causing system

The yellow and black water flowed out of the Karst cave blasting hole, with a water spraying distance of type about 4 m and a maximum water inflow of 75 m3 /h

Water and mud inrush description

K142+643

DK926+780~+790

DK188+747

1-122

7/10/2013

Zhongfu Tunnel

Chainage

1-121

Time

Tunnel

Serial No

(continued)

330 Appendix 1: Karst Category

Sanquan Tunnel

Guangshan No. 1 Tunnel

Jinyunshan Tunnel

Xinxiakouba Tunnel

Shagou Tunnel

1-127

1-128

1-129

1-130

1-131

Unknown

6/18/2013

12/21/2011

2/24/2016

Unknown

Yanling No. 2 9/6/2013 Tunnel

1-126

Time

Tunnel

Serial No

(continued)

K157+711

LDK0+580

Unknown

K24+971

K7+000~130

K9+675

Chainage

Karst cave Corrosion fissure type

(Chi Yanbin et al., 2017)

Karst category (Ou’yang Na and Zheng Jianxin, 2015)

Type of References hazard-causing system

A large amount of flowing plastic sludge gushed out from the vault of the tunnel face, with a sludge volume of 3,000 m3

A large amount of soft and hard plastic cohesive soil mixed with a small amount of stones gushed from the tunnel face, with the mud inrush volume of about 3,000 m3

Karst cave type

Karst cave type Corrosion fissure type

A large amount of sand and mud mixture Karst cave gushed out from the karst cave, and it gradually type became continuous mud inrush

(continued)

(Chen Jianjun, 2013)

(Fan Yongqiang, 2014)

(Zhang Tai, 2015)

Water inflow was about 100 m3 /h and increased Karst category (Liu Zemin and to 150 m3 /h on February 25 Lv Tingwen, 2017)

Water inflow at water inflow spot reached 112 m3 /h, two karst caves exposed at K7+095 and K7+125 in the left tunnel, acting as the main water inflow spots

Large water inflow occurred at the arch waist and vault interlayer on both sides of tunnel face, with water carrying large quantities of yellow mud

Water and mud inrush description

Appendix 1: Karst Category 331

Guanhu6/5/2011 chong Tunnel

Xianrendong Tunnel

Shangjiawan Tunnel

Dayakou Power Station Tunnel

1-133

1-134

1-135

1-136

No. 4 branch tunnel 0+175

ZK64+920

4/20/2014

Unknown

ZK64+918

DK12+132

YK129+435

ZK129+506

ZK40+697

Chainage

5/31/2013

7/28/2011

11/18/2009

Guanxi Tunnel

1-132

Time

Tunnel

Serial No

(continued)

Sudden water inflow at the lower corner of the right tunnel, with water inflow of about 373.32 m3 /h

The spraying distance of water inrush was 5 m, and the water carried a large amount of fine sediment

Water inflow occurred at the left shoulder of the tunnel face, with water pressure of 2 MPa and water inflow of about 200 m3 /h

A large amount of soft plastic yellow mud gushed out from the tunnel face. On July 29, the mud inrush volume reached 5,900 m3 , and the mud was mixed with limestone blocks

(Yuan Yongcai et al., 2017)

(continued)

Karst category (Yang Xiaodong et al., 2014)

Karst cave type

Karst cave type Corrosion fissure type

(Feng Pan, 2014)

(Li Qing et al., 2012)

Water inflow of left line was 10 × 104 m3 and reached 12.5 × 104 m3 on June 19; right line had a water inflow of 15 × 104 m3 and the water inflow carried a large amount of sediment and pebble

Karst cave type

(Long Hong et al., 2012)

Type of References hazard-causing system

A large amount of mud and stone gushed out Karst cave from the tunnel face, with a mud inrush volume type of about 3,000 m3 . The gushed materials buried the upper step for 50 m, and the height of the accumulated materials reached 3.3 m

Water and mud inrush description

332 Appendix 1: Karst Category

Unknown

6/17/2007

Shiruguan Tunnel

Maochang Tunnel

No. 5 tailrace Unknown tunnel of Goupitan Hydropower Station

5/24/2014

Diversion Tunnel of Jinyuan Hydropower Station

Daba Tunnel

Qiyueshan Tunnel of Hurongxi Expressway

1-137

1-138

1-139

1-140

1-141

1-142

3+255

3+252

3+240

Chainage

11/23/2017

YK329+893

ZK329+967

YK86+140~YK86+200

K0+320~+355

No. 4 branch tunnel 11+316

First half of DK40+430~+460 2009

Time

Tunnel

Serial No

(continued)

Karst cave type

(Sun Jianguo, 2016)

The outlet flow rate of Macaodong underground river was 1.58 m3 /s, flooding the subterranean drainage outlet of Yangliutang-Jiaohuadong. The observation was not feasible and the flow was estimated 1.6~1.7 m3 /s

Huge water inflow and rapid water flow, maximum water inflow was 4.14 m3 /s, lasting for 4 to 5 days and then gradually decreased

Water inflow was 30~35 m3 /h and maximum water inflow reached 100 m3 /h

Karst conduit and underground river type

Karst cave type

Karst cave type Corrosion fissure type

(continued)

(Li Shucai, 2015)

(Li Shucai et al., 2018)

(Zhu Xinyuan et al., 2010)

Flow plastic clay flowed out, and then sand and Karst category (Wu Xingliang gravel. A large amount of water gushed out, and Gao Fenfei, with water ponding depth of 2.0 m and the 2018) volume of inrush materials of over 2,000 m3

Karst water and mud inrush, with a volume of over 2,000 m3 /h

(Chen Chunlei, 2014)

Type of References hazard-causing system

A large karst cave was exposed at the left vault, Karst cave with strong water inflow, which was mixed type with a large amount of sand and gravel

Water and mud inrush description

Appendix 1: Karst Category 333

Tunnel

Yanglin Tunnel

Qiyaoshan Tunnel

Xiema Tunnel

A highway tunnel in Guizhou

Niandong Tunnel

Jiudingshan Tunnel

Serial No

1-143

1-144

1-145

1-146

1-147

1-148

(continued)

7/27/2017

9/2019

Unknown

11/6/2015

6/12/2018

11/26/2017

Time

ZK281+942

ZK91+081~ZK91+086

YK21+125

YK9+011

ZK20+962

K19+903

Chainage

Karst conduit and underground river type

(Song Shiwen, 2020)

Type of References hazard-causing system

Karst cave type

Karst cave type

Karst cave type

The intermittent water inrush occurred 10 Karst cave times, each water inrush time was about 10~ type 20 min, the maximum water inflow was 28,000 m3 . The total volume of water inflow was 50,760 m3

Water and mud inrush occurred 6 times. The accumulated siltation during construction was about 24,500 m3

The initial water flow at the right tunnel face was 320 m3 /h. The water was turbid and there was a certain water pressure. The water flow from September to November was 180 m3 /h

Mud inrush occurred at the upper step, the inrush mud was yellow and of high viscosity; the rate of mud inrush was 500 m3 /h

(continued)

(Chen Junwu et al., 2020)

(Zhu Weining, 2020)

(Chen Hao et al., 2022)

(Hu Mingjian, 2018)

The first water and mud inrush lasted for Karst category (Yu Jian, 2020) 80 min, and the inrush volume was about 10,000 m3 . The second inrush lasted for 40 min, and the inrush volume was about 8,000 m3

A large water inflow occurred on the outside of the right arch foot of the upper steps, with a water inflow of about 120,000 m3 ; and water flow was 2,900 m3 /h on November 27

Water and mud inrush description

334 Appendix 1: Karst Category

Tunnel

A tunnel in the Eastern Yunnan Plateau

Tianbacun Tunnel

Naqing Tunnel

Yanjiao Tunnel

Serial No

1-149

1-150

1-151

1-152

(continued)

11/12/2016~ 12/3/2016

8/29/2017, 8/31/2017, 9/2/2017

Unknown

6/30/2011

Time

Pipe and underground river type

A karst cave was revealed, with water inflow of Karst cave 1,312 m3 /d, and mud and sand inflow of 100 type m3 /d The karst cave was about 1.5 m high and 1 m wide, with water inflow of 1,400 m3 /d and mud and sand inflow of about 120 m3 /d The karst cave was about 1.5 m high and 1 m wide. Water inflow was mixed with black silt and pebble. Water inflow was 1,800 m3 /d. Mud and sand inflow were about 180 m3 /d

DK32+379

DK32+360

Mud sprayed through the drilling hole, with the Karst cave spraying distance of about 30 m. Finally, there type was a torrent flowing out of the tunnel, with a rate of about 0.5 m/s. The first inrush amount was 3 × 104 m3 , the second inrush amount was 2 × 104 m3

(continued)

(Zhou Guanxue et al., 2019)

(Xu Kaiqi, 2019)

(Yuan Yi, 2021)

(Xu Mo et al., 2015)

Type of References hazard-causing system

The water inflow at the tunnel face exceeded Corrosion 10,000 m3 /d, and the water inflow at tunnel exit fissure type was 36,000 m3 /d

Over 7 water inflow spots on the right wall, with an estimated water inflow of 300~500 m3 /h

Water and mud inrush description

DK32+396

ZK24+405

DyK59+298~ DyK59+192

K9+838.673

Chainage

Appendix 1: Karst Category 335

Tunnel

Jinyunshan Tunnel

Teke Tunnel

Diversion Tunnel of Ganhe Pumping Station

Shangganping Tunnel

Dejiang Tunnel

Serial No

1-153

1-154

1-155

1-156

1-157

(continued)

Unknown

Unknown

Unknown

6/19/2017

12/21/2011~ 12/27/2011

Time

ZK10+428

K41+128

No. 2 branch tunnel 2+483.5 m

H2DK0+877

Corrosion fissure type

Karst cave type

Water inflow occurred at advanced drilling on the tunnel face, with water flow of about 300 m3 /h, and water inflow pressure of about 1.8 MPa

Mud inrush occurred outwards from the karst cave at the tunnel face vault, with the volume of inrush mud of about 1,500 m3

(Wang Changchun, 2022)

(continued)

Karst category (He Qiao, 2020)

Karst cave type

(Zhang Tianming, 2013)

(Chen Guoqiang, 2020)

(Cai Yongxiang, 2014)

Type of References hazard-causing system

Water inflow occurred at the middle and lower Pipe and part of the tunnel face, water column diameter underground was about 20 cm, with the jetting length of river type 15 m; total water inflow was 2,000 m3 /h. In the later stage, the water inflow exceeded 5,000 m3 /h

Stranded water inflow occurred in the drilling holes, with a jetting distance of about 5 m. Measured water inflow at No. 2 transverse tunnel was about 23,784 m3 /d

Large mud inrush occurred 5 times at the tunnel face, with a total mud volume of about 1,800 m3

There were 4 karst caves in the tunnel face. Water inflow was 2,300 m3 /d at 2# karst cave, 500 m3 /d at 4# karst cave. The amount of mud and sand inflow from 2# and 4# caves was about 380 m3 /d

DK32+353

K4+183

Water and mud inrush description

Chainage

336 Appendix 1: Karst Category

Xinjie Tunnel 5/14/2019

A tunnel on GuilinLiucheng highway

Yangcangyan Unknown No. 2 Tunnel

Auxiliary tunnel of Jinping Hydropower Station

1-159

1-160

1-161

7/25/2004

Unknown

AK1+117

YK137+157

ZK91+093~ZK91+063

ZK48+448~ZK48+450

YK10+401

Unknown

1-158

Chainage

Time

Tunnel

Serial No

(continued)

Karst cave type

Two strands of water inrush occurred near the Corrosion vault of the tunnel face left sidewall, with water fissure type pressure of about 1~2 MPa. The water inrush range of one borehole was 16 m, and the flow rate was about 0.15 m/s. The other flow rate was about 0.05 m/s, and the range was about 6 m. The initial water inrush was mixed with a small amount of travertine, clay, sand and other debris

The water seepage on the tunnel face suddenly Corrosion increased, and the water inflow was 8,000 m3 /d fissure type

(continued)

(Li Fufa, 2006)

(Ji Xiao, 2017)

(Zheng Yingjun, 2021)

(Zeng Fanxiong and Song Yingzhang, 2022)

Type of References hazard-causing system

A small-scale mud inrush occurred on the Karst cave tunnel face vault, and a few hours later, the mud type inrush occurred again, with a mud volume of 2,000 m3 and a water volume of 2.4 × 104 m3

Yellow mud inrush occurred at the left vault, and the mud poured into the tunnel with a longitudinal length of 43 m, with a total volume of about 2,000 m3

Water inflow occurred when the drilling was 9.8 m, with water inrush of about 350 m3 / h and water pressure of about 2.0 MPa

Water and mud inrush description

Appendix 1: Karst Category 337

Serial No

(continued)

Tunnel

Chainage

BK1+137

BK14+888

AK14+762

BK2+637

Time

9/15/2004

1/8/2005

3/30/2005

4/20/2005

The maximum water inrush was about 15.6 m/s. Then the water inrush decayed rapidly, and the flow rate was only about 1 m3 /s after 24 h. In the process of continuous water inrush, there were a lot of brown consolidated sand and gravel

The initial flow was about 7 m3 /s, and the average flow velocity was about 1.3 m/s. A small amount of travertine, sand and other debris were entrained in the water inrush. Subsequently, the flow velocity and flow rate basically decreased steadily. In the later stage, the flow velocity was about 0.8 m/s, and the flow rate was about 2.5 m3 /s, and the flow rate was basically stable for a long time

At the initial stage, a small amount of rock debris was mixed within the water inrush, with a flow of about 0.2 m/s and a water pressure of about 4.7 MPa

The maximum instantaneous water inrush flow rate was 7.4 m3 /s, the range of water inrush spot was about 15~18 m, and the water pressure was about 1~2 MPa. The initial water inrush was mixed with a small amount of travertine, clay, sand and other debris

Water and mud inrush description

(continued)

Type of References hazard-causing system

338 Appendix 1: Karst Category

D5K355+613

7/26/2016

Kakiziyuan Tunnel

1-164

8/16/2020

D5K355+489

6/15/2016~ 7/8/2016

Xiao’an Tunnel

1-163

D3K83+420

ZK26+188

Unknown

Yingpanshan Tunnel

Chainage

1-162

Time

Tunnel

Serial No

(continued)

The maximum water inflow at the entrance Pipe and reached 1.88 × 106 m3 /d, and the arched waist underground river type and vault had a linear water inflow, and the water inflow reached a peak value of 970,000 m3 on August 17

Water inrush occurred in the karst cave on the right, and the tunnel was flooded by nearly 1 km in less than 4 h, with a maximum water inrush of about 4,900 m3 /h

Mud inrush occurred in the karst cave, the mud Karst cave inrush section was nearly 700 m, and the mud type inrush volume was 100,000 m3

(Wang Zihang et al., 2022)

(Xu Huairen, 2022)

(Gao Xianlei, 2022)

Type of References hazard-causing system

The main tunnel and the inclined shaft in the 2# Karst cave inclined shaft working area were all flooded. type The water flow at the entrance of the inclined shaft was 1,500 m3 /h, and the water in the inclined shaft and the main tunnel was about 260,000 m3

Water and mud inrush description

Appendix 1: Karst Category 339

340

Appendix 1: Karst Category

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Appendix 2

Fault Category

© Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1

347

9/19/2003

Dafengyakou Tunnel

Sanyang Tunnel 5/25/2008

Henglutou Tunnel

Shibanling Tunnel

Galongla Tunnel

2-1

2-2

2-3

2-4

2-5

10/20/2009

Unknown

4/19/2005

Time

Tunnel

Serial No

K48+860

K14+030

YK17+070

ZK150+411

K255+281~K255+285

Chainage

Waterconductive fault type

Water-resistant fault type

Type of hazard-causing system

(Li Jiangxu, 2009; Cai Junhua, 2009)

(Liu Renyang, 2006)

References

Sudden water inflow occurred in the tunnel face, water pressure was estimated to be 2 MPa initially, and water inflow was as high as 300~400 m3 /h

(continued)

Water-rich fault (Wang type Jianliang, 2013)

Serious water seepage in the tunnel face, a Water-rich fault (Ye Zhen, large amount of groundwater gushed out from type 2006) the fissures, with water inflow of about 3,500 m3 /d

Water inflow occurred in the tunnel face of the Water-rich fault (Zhou Tao and right line, with huge water pressure and type Wang Guoxin, spraying distance of about 10 m in the initial 2006) stage, and water inflow was about 0.05 m3 /s

Water spraying occurred from the blasting holes of tunnel face, with the distance of 6~ 8 m and water inflow of about 11 × 104 m3 /h

Water inflow from the arch gushed out with a large amount of mud and stones, the total volume of water and sediment was 214 × 104 m3 and 11 × 104 m3

Water and mud inrush description

348 Appendix 2: Fault Category

Tunnel

Yangpeng Tunnel

Xiapu Tunnel

Dapingshan Tunnel

Serial No

2-6

2-7

2-8

(continued)

RK78+055~+085

10/27/2000

Unknown

YK48+836~+925

ZK45+058~+977

YK43+135~+170

Unknown

RK78+030~+028.5

10/21/2000

Unknown

LK77+850~+870

Chainage

1/30/2000

Time

(Zhang Dong and Yong Quanmao, 2000; Li Weimin, 2002; Li Yingshun, 2001)

References

Water-rich fault (Chen Liping, type 2009)

Waterconductive fault type

Type of hazard-causing system

Water inflow lasted for 24 days, the volume of water inrush was 9,267 m3

water inrush was 9,882 m3

(continued)

Water inflow lasted for 20 days, the volume of Water-rich fault (Zuo water inrush was 2,079 m3 type Changqun et al., 2014) Water inflow lasted for 23 days, the volume of

Rich tectonic fissure water in the tunnel body, with maximum water inflow of over 2,000 m3 /d

The volume of inrush sludge reached 4,000 m3 and water inflow maintained a rate of 800~ 1,200 m3 /d

The water was jetted out and brown, with a rate of 20,000~25,000 m3 /d and gradually decreased after about 90 min and ultimately stabilized around 4,000~6,000 m3 /d

Water inflow continued for over 40 days, with a rate of about 600~800 m3 /d; mud, sand and gravel were mixed in the water

Water and mud inrush description

Appendix 2: Fault Category 349

9/17/2012

3/23/2005

Kangjialou Tunnel

Cangling Tunnel

Feixianguan Tunnel

2-10

2-11

2-12

9/20/2015

11/22/2013

9/28/2013

Panling Tunnel

2-9

Time

Tunnel

Serial No

(continued)

K23+708

K101+558 K101+549

ZK71+215

K72+625

Chainage

Water-resistant fault type

Type of hazard-causing system

Water mixed with gravels rushed out in large Water-barrier quantities, with a water depth of 15~20 cm, fault type maximum water inflow of 15.2 × 104 m3 /d and cumulative water volume of 933 × 104 m3

Water inrush occurred in the lower right Watercorner, with a water inflow of 800 m3 /d. conductive Without sediment, the water inflow gradually fault type declined, with the spraying distance gradually decreasing to 0

The water flowed out in the form of rain, and a Watersmall amount of falling blocks appeared on conductive the right side of the vault. The water fault type accompanied with a large amount of strongly weathered sandstone and shale fragments suddenly gushed out, the volume of mud inrush was about 400 m3

The water and mud inrush volume of the face was about 6,000 m3 , and the water mixed with block stone, gravel, fault breccia and fault gouge, etc. gushed out, with a rate of about 20,000 m3 /d

A large area of flowing water in the left rock layer and the middle fault, and the seepage was about 50 m3 /min

Water and mud inrush description

(continued)

(Chen Qixue et al., 2016)

(Li Zhong and Yang Weixun, 2007; Wang Qi et al., 2006)

(Sun Chensheng, 2013; Wei Jie, 2015)

(Huang Jin et al., 2015; Hu Xinhong et al., 2016)

References

350 Appendix 2: Fault Category

Tunnel

Hanlingjie Tunnel

Jingyuankou Tunnel

Liupanshan Tunnel

Serial No

2-13

2-14

2-15

(continued)

No. 3 shaft

DK91+284

DK91+284

6/2/2014

6/7/2014

YK9+238

K88+597

Chainage

5/21/2014

Unknown

7/14/2012

Time

Type of hazard-causing system

References

Water inrush occurred in the tunnel face, the accumulation length of mud inrush was 250 m, the volume of mud inrush and water inflow was about 4,600 m3 and 3 × 104 m3 , respectively

A large amount of debris flow gushed out from the right side of the vault, accompanied by a large amount of mud water. The volume of debris flow and water inflow was about 1,500 m3 and 2 × 104 m3 , respectively

Black water mixed with fault breccia gushed from the tunnel face, and debris flow accumulated in front of the face, reaching about 300 m3 , with water inflow of 7,000~ 8,000 m3 /d

Groundwater was jetted out from the top of the tunnel face, and large water inrush and mud inflow collapse occurred at the upper right of the tunnel face. The initial water inflow was 200 m3 /h

(continued)

Water-rich fault (Li Shougang, type 2015)

Water-rich fault (Lin Lihua, type 2007; Qiu Xiaojing, 2007)

Water inrush occurred in the main vault, water Water-rich fault (Fang Jianhua, gushed out in a waterfall shape. The water was type 2013) yellow and carried mud. The total amount of water inrush was about 3.6 × 104 m3

Water and mud inrush description

Appendix 2: Fault Category 351

Zhucangdong Tunnel

Lingjiao Tunnel 10/19/2011

Maozhanling Tunnel

2-17

2-18

2-19

11/1/2009

Unknown

Unknown

Nibashan (Daxiangling) Tunnel

2-16

Time

Tunnel

Serial No

(continued) Type of hazard-causing system

LK76+358

(Zhang Jia, 2016; Guo Wenguang, 2012; Li Sensen, 2013)

(Kang Jie, 2013)

(Li Jianjun, 2010)

References

(continued)

Large water inflow occurred in the borehole of Water-rich fault (Jin Wenliang, tunnel floor, the water was reddish brown, type 2012) containing a large amount of sediment and jetted out, with a maximum spraying distance of 15.0 m and water inflow of 6,900 m3 /d

Mud inrush occurred in the tunnel face, with a Water-rich fault volume of over 1.5 × 104 m3 . Afterwards, type water inflow and mud inrush occurred again and continued for 17 min, with a volume of about 0.5 × 104 m3

Water inrush occurred in the right arch waist, the accumulated water volume in 10 days was 1,600 m3

YK61+982~+995

EK18+215

Water inrush occurred in 4 places of the tunnel Waterface, with the total water inrush of about 10 conductive m3 /min and maximum spraying distance of fault type about 2 m

The blasting hole was full of water, and one Fault category hour later, a large water inflow occurred at the arch foot on the left side of the tunnel face. Daily water inflow reached 17,000 m3 . The highest water level was 1.98 m

Water and mud inrush description

ZK61+058~+068

Unknown

Chainage

352 Appendix 2: Fault Category

Unknown

Tianchengshan Tunnel

Lianhuashan No. 1 Tunnel

Xindayaoshan No. 1 Tunnel

2-21

2-22

2-23

1/8/2008

11/20/2015

9/6/2004

Xiaopiliu Tunnel

2-20

Time

Tunnel

Serial No

(continued)

DK1911+398

ZK190+637

YK22+136

K201+510

Chainage

There was a large amount of clear water emerging from the left arch and left sidewall of the tunnel, with a flow of about 400 m3 /h

There were strands of water, accompanied by the continuous falling of strongly weathered surrounding rocks, causing water and mud inrush. The amount of falling and mud inrush was about 500 m3

Mud inrush occurred at the arch waist on the left side of tunnel face for 3 times, with the mud volume of about 450 m3 , 1,800 m3 and 14,000 m3 , respectively; mud gushed out in the form of quicksand

Slag falling occurred on the left side of the vault of the tunnel face, followed by mud inflow, with a mud volume of about 30 m3 ; after stabilization, the total volume of mud was about 432 m3 , and the accumulation was soft plastic loess mixed with stone

Water and mud inrush description

(Ma Huaipeng et al., 2014)

(Fu Lixin and Xiong Jianjun, 2008)

References

(continued)

Water-rich fault (Wang Guoji type and Wang Gongzhong, 2010; Gong Junwei et al., 2009)

Water-rich fault (Lin Xiaoqing type and Pi Liang, 2016)

Waterconductive fault type

Fault category

Type of hazard-causing system

Appendix 2: Fault Category 353

Tunnel

Zoumaling Tunnel

Baolin Diversion Tunnel

Zhengyang Tunnel

Xingyi No. 2 Tunnel

Wuzhishan Tunnel

Serial No

2-24

2-25

2-26

2-27

2-28

(continued)

10/17/2004

Unknown

Unknown

K28+880

K92+180~+215

K90+900~+930

YK31+390~365

Unknown

K47+194

7/21/2004

7/14/2018

K47+013.5

Chainage

5/28/2004

Time

The maximum water inflow of the tunnel was about 11,000 m3 /d, which flowed out in the form of rainstorm or multiple streams

Karst and fissure water flowed out in the form of rain or inrush current, and the surrounding rock falls and collapses occurred at the vault. The total length of water inrush section was 65 m

Geological disasters such as landslides and mud inflow occurred many times during construction

About 450 m away from the tunnel face, a water conductive fault was encountered, causing major water and mud inrush, and the silt depth was 3~4 m

The maximum water inflow was 14,000 m3 /d, and the average daily water volume in September was 12,395.6 m3

A large water inflow occurred at the junction of the two groups of strata, with a maximum flow of 11,884.3 m3 /d, and then rapidly decreased and basically stabilized at 4,320~ 5,184 m3 /d

Water and mud inrush description

Fault category

Fault category

Fault category

Waterconductive fault type

Fault category

Type of hazard-causing system

(continued)

(Li Yanghong et al., 2009)

(Wan Youqing, 2011)

(Gao Panke et al., 2012)

/

(Kang Xiaobing et al., 2006)

References

354 Appendix 2: Fault Category

Tunnel

Xinwanshansi Tunnel

Tianzhushan Tunnel

Cimushan Tunnel

Bieyancao Tunnel

Serial No

2-29

2-30

2-31

2-32

(continued)

K31+390~+638

2/2005

5/30/2004

Unknown

5/31/2013

DK406+680~+710

K1+499~+557

K1+230~+250

0 km+543

DK150+934

K29+542

8/6/2005

7/9/2006

Chainage

Time

The right sidewall changed from the original dripping water to strand water inflow, and cracks appeared on the concrete surface. The maximum water inflow was 2,100 m3 /h

References

Fault category

Fault category

(continued)

(Zhang Minqing et al., 2006)

(Chen Zhiping et al., 2011)

(Liu Fang, 2015)

Water-rich fault (Li Weihong, type 2010)

Type of hazard-causing system

It was mainly located in the coal bearing strata Fault category of Xujiahe Formation. Affected by the F2 Huangshan fault, water inflow occurred in these two sections

Large-scale mud and water inrush occurred at the working face. A large amount of water rushed out of the tunnel with sediment. In a short time, the range of 186 m behind the working face was filled with sediment. The surging body was in flow plastic shape, with high water content

The initial water inflow of the face reached 3,000 m3 /d, and then decreased to about 500 m3 /d, without sediment and other substances

The maximum water inflow of the tunnel was about 35,000 m3 /d, which flowed out in the form of rainstorm or multiple streams

Huge water inrush suddenly appeared on the tunnel face and caused landslides. The water inflow suddenly increased to 3,800 m3 /h and then gradually stabilized at 800 m3 /h

Water and mud inrush description

Appendix 2: Fault Category 355

Tunnel

Jiupu Tunnel

Diversion Tunnel of Dafa Hydropower Station

Serial No

2-33

2-34

(continued)

Unknown

Type of hazard-causing system

Extra-large water inflow in this section, with initial water inflow of 5,280 m3 /h Permeable fissure water inflow in this section, with water inflow of 2,180 m3 /h The water inflow at the lower left corner of the face was 2,079 m3 /h, and the water inflow carried a large amount of debris and sediment deposition Fissure water was exposed during excavation, mainly in drop and linear flow, and local water inflow was in strands

Diversion 4+805~832 Diversion 5+120~6+093

Diversion 6+093~8+283.66

Fault category

Water inrush occurred at the right arch foot, Fault category and the maximum water inrush was 320 m3 /h; After about 2 h, the initial support of the excavated section at the rear was deformed and cracked, and the maximum width of the crack was 8 cm

A large water inrush occurred, the water depth in the tunnel was about 1.8 m, forming a huge debris flow, and the sudden discharge time lasted about 40 min. Since then, the original outlet of Miaoping underground river had been completely cut off and replaced by the tunnel water inrush discharge channel

Water and mud inrush description

Diversion 4+361~366

DK29+424

DK406+422

9/11/2004

8/2010

Chainage

Time

(continued)

(Kong Bin, 2009)

(Zhang Mei et al., 2011; Xie Tao, 2012; Li Xiang and Liu Zhanfeng, 2014)

References

356 Appendix 2: Fault Category

Gaogaishan Tunnel

Dananshan Tunnel

2-37

2-38

Unknown

Sand and water inflow occurred on the left side of the tunnel face Mud and water inflow in the right pilot adit, with mud gushing out for about 50 m; mud inrush and water inflow occurred 2 times, with accumulated volume of mud inflow of about 4,000 m3

DK262+411

Water and mud inrush occurred at the arch, with a water flow of about 600 m3 /h. High-pressure water accompanied by breccia and filling materials rushed out, forming a 50-m long accumulation body in front of the face, completely covering the tunnel face

Sudden collapse and water inflow at the vault, maximum water inflow was about 1,000 m3 /h and declined to 300 m3 /h when it was 19 in the afternoon and stabilized around 100 m3 /h after 3 days

Sudden water inflow at the tunnel face. The water gushed from the blasting hole at the lower left side of the tunnel face. Then the water inflow continuously increased, and the water inrush spot increased from 1 to 4. On November 13, the water inflow basically stopped

Water and mud inrush description

DK262+388

YDK472+234

DK129+393

Kekeqiaoke No. 3/23/2007 3 Tunnel

2-36

9/9/2011

DK175+807

11/7/1999

Xinluona Tunnel

Chainage

2-35

Time

Tunnel

Serial No

(continued)

Fault category

Fault category

Water-resistant fault type

Fault category

Type of hazard-causing system

(continued)

(Pu Xiaoping and Wang Quansheng, 2009)

(Wang Chansheng, 2015)

(Zhang Qiusheng and Jing Xueya, 2007)

(Li Zhong et al., 2001)

References

Appendix 2: Fault Category 357

Lenglongling Diversion Tunnel

Diversion Tunnel of Baoxing Hydropower Station (Huaneng)

Xianghe Tunnel Unknown

2-40

2-41

2-42

K1+186

D1K79+352

Chainage

D1K151+460

07~08/2007 (Reroute) 0+310~ (Reroute) 0+316.5

5/13/2000

Unknown

Xinzhai No. 2 Tunnel

2-39

Time

Tunnel

Serial No

(continued)

Fault category

Type of hazard-causing system

(Fan Hengxiu and Xu Guangmin, 2005)

(Wei Xiuli, 2009)

References

(continued)

(Hou Dongsai, 2017)

Water-rich fault (Yi Guohua, type 2008)

A large amount of water flowed out of the Fault category advance exploratory hole of the tunnel face, carrying sediment and other particles. When the water inrush occurred, the tunnel face presented surface water flow. The maximum length of accumulated water in the tunnel was 110 m, the maximum depth of accumulated water was 2.05 m, and the maximum peak value of water inflow was 1,300 m3

Mud and water inrush occurred for 4 times, with a total volume of about 3 × 104 m3

There was a small hole of 20~30 cm at the Fault category right arch foot, from which coal chips flowed out; and there was a hole of about 1 m3 behind the hole. The ballast gushed out for over 500 m, with a volume of 4,500~5,000 m3

Sudden debris flow occurred, the length of mud inrush in the tunnel was over 70 m, of which the length of mud inrush at the top of the whole section was over 50 m, and the amount of mud inrush was over 3,000 m3

Water and mud inrush description

358 Appendix 2: Fault Category

DK2081+097

DK95+435~+735

Qingyunshan Tunnel

Beilingshan Tunnel

Pingling Tunnel 2/10/2008

Dongqinling Tunnel

2-45

2-46

2-47

Unknown

1/20/2014

Unknown

ZK46+963

DK502+230

K160+274

2-44

Unknown

Tiezhaizi No. 1 Tunnel

Chainage

2-43

Time

Tunnel

Serial No

(continued) Type of hazard-causing system

(Fang Renying, 2009)

References

After excavation, water gushed out in curtain Fault category shape from the F5 fault and its influence zone, the section of DK95+435~DK95+735

(continued)

(Gao Hongtao, 2004)

(Han Hailiang, 2010)

Water-rich fault (Chen Lei, type 2017)

Water-rich fault (Jin Kunxue, type 2014)

Five times of water and mud inrush occurred Waterin the cracks at the vault, resulting in the conductive 668-m excavated section being silted up by fault type brownish yellow silty clay, silt, silty fine sand with breccia and gravels, etc., with a sediment of 32,000 m3

The maximum water inflow of the face was 180 m3 /h, and the water flow was yellowish brown and turbid. The amount of mud and stone generated was up to 1,000 m3 and gushed out to 70 m away from the tunnel face

The peak water inflow reached 2,300 m3 /h, and then it basically remained between 850~ 1,000 m3 /h, and then the water inflow attenuated to 450~500 m3 /h

Water and mud inrush occurred many times on Fault category the left upper part of the vault, and a large amount of gravel and sediment flowed into the tunnel, with a mud inflow volume of about 3,000 m3

Water and mud inrush description

Appendix 2: Fault Category 359

Unknown

YK2390+046 YK2390+030

Changliangshan 5/1998 Tunnel

Unknown

2/28/2011

Huinongshan Tunnel

Wuqiaoling Tunnel

2-50

2-51

K3+140

ZK3+970.4~+980.8

ZK3+980.8

4/1/2006

11/16/2006

11/22/2006

1994+213 of F9 fault

2-49

4/11/1985

Dayaoshan Tunnel

Chainage

2-48

Time

Tunnel

Serial No

(continued)

Fault category

Type of hazard-causing system

(Xin Mingao, 2007)

(Zeng Weidong and Li Haiqing, 2008; Yang Xiuwen, 2007)

(Wang Rucheng, 1989; Deng Yiming and Yu Liangji, 1996)

References

3,000 m3 /d to 6,313 m3 /d (continued)

The water inflow was kept at about 3,000 m3 /d Water-rich fault (Li Shengjie type et al., 2013) The water inflow increased gradually from

The maximum spraying distance of Fault category groundwater flow reached 2.3 m, and the water inflow was 400~600 m3 /d, and the water inflow of No. 5 shaft body lasted for more than 2,300 m3 /d

Collapse and mud inrush of 50 m3 occurred, and then the collapsed face gushed out about 2,000 m3 of earth rock flow at a time, with a gushing distance of 80 m

Water inrush mixed with large quantities of sediment from the vault, with water inflow of 1.15 × 104 m3 /d and maximum water inflow of 3.33 × 104 m3 /d

Gray mud with breccia and gravels flowed out, Water-resistant mud inrush was 170 m away, and mud inrush fault type volume was about 5,000 m3

Water inrush occurred when excavating to section of 1994+213, with a water inflow of 2,000 m3 /d initially and then 4,000 m3 /d

Water and mud inrush description

360 Appendix 2: Fault Category

Tunnel

Beitianshan Tunnel

Yanmenguan Tunnel

Maoba No. 1 Tunnel

Dawushan Tunnel

Serial No

2-52

2-53

2-54

2-55

(continued)

8/2012

2/2007~ 9/2009

11/2011

K18+427

ZK297+624 etc

DK118+645~+740 etc

Fault category

The total volume of debris flow was about 13,000 m3 , and the water inflow was about 300 m3 /h

Fault category

There were 32 large-scale water inrush Waterdisasters in the tunnel, with a maximum water conductive inflow of 26,400 m3 /d fault type

The underground water in the tunnel area was mainly fissure water, and the maximum water inflow of the tunnel was 29,800 m3 /d

DzK114+777 of parallel adit Mud and water inrush occurred at the arch line, the pilot adit was submerged by water for 200 m, and the accumulation length of the outflow was 100 m

1/31/2008

There was pressure-bearing strand water gushing at the left arch waist, and the water inflow increased to 7,991 m3 /d, driving the scattered and broken surrounding rock to pour down

Type of hazard-causing system

DzK114+780 of parallel adit The fluid fault breccia mixed with fault gouge Fault category gushed out, with a water inflow of 50 m3 /h and a total of about 800 m3 ballast was poured out

YK2390+021

3/6/2011

Water and mud inrush description

10/27/2007

Chainage

Time

(continued)

(Zong Yijiang et al., 2016)

(Guan Yitao et al., 2010)

(Xu Dacheng, 2014)

(Wen Wenzhao, 2009)

References

Appendix 2: Fault Category 361

Songnan Tunnel Unknown

Nanling Tunnel

Qiyueshan Tunnel of YichangWanzhou Railway

2-57

2-58

2-59

DK1936+269

12/1980~ 7/1981 PDK365+313

DK1936+967

10/1980

2/25/2009

DK1937+010

Unknown

DK334+733

Chainage

9/1980

1/14/2010

Baiyun Tunnel

2-56

Time

Tunnel

Serial No

(continued) Type of hazard-causing system

References

Fault category

Fault category

The tunnel face collapsed and water inrush Water-resistant occurred, and the instantaneous maximum fault type flow was about 5.0 × 104 m3 /h, and stabilized at about 0.15 × 104 m3 /h after 5 min, with the cumulative amount of about 1.0 × 104 m3

The maximum water inrush was 300 t/h, and the total volume of mud inrush was 5,200 m3

The maximum water inrush was 150 t/h, and the total volume of mud inrush was 1,500 m3

The maximum water inrush was 150 t/h, and the total volume of mud inrush was 1,000 m3

Water inrush occurred in many places and times during construction. The maximum water inflow was over 200 m3 /h

(continued)

(Wang Wei and Miao Dehai, 2010)

(Li Chengyuan, 1994; Tan Yujun, 1990)

(Chen Liangwang, 2002)

Water and mud inrush occurred on the left side Water-rich fault (Zhang of the arch, with a mud inrush volume of about type Minqing et al., 200 m3 . During desilting, large-scale mud and 2012) water inrush occurred, with mud inrush volume of about 2,000 m3 and water inrush of about 300 m3 /h

Water and mud inrush description

362 Appendix 2: Fault Category

K2+738

Affected by fs3 fault, the joints and fissures of surrounding rock were developed, and the water inflow was 1.85 × 104 m3 /d

(Li Suqing and Li Chunjie, 1998)

(continued)

Water-rich fault (Li Limin, type 2015)

Water inrush occurred in this section, with the maximum water inrush of 356 m3 /h and the stable flow of 40 m3 /h

DK74+202~+162

Jiaoxihe Section 9/16/2013 of Qinling Tunnel

Water inrush occurred in this section, with the maximum water inrush of 320 m3 /h and the stable flow of 90 m3 /h

DK78+153~+190

2-63

Unknown

(Wu Guanzhou et al., 2012)

References

The water flowed out in the form of rain, Water-rich fault (Wang Xiaoxu partially in the form of strands and flows, with type et al., 2013) the maximum water inflow pressure of 3 MPa and the maximum water inflow of 3 × 104 m3 /d, daily average water inflow 2 × 104 m3 /d Water inrush occurred in this section, with the Water-barrier maximum water inrush of 280 m3 /h and the fault type stable flow of 125 m3 /h

Qinling Tunnel

2-62

Type of hazard-causing system

Water inrush and collapse occurred, Fault category groundwater flow increased from 23 L/s to 66.7 L/s, inducing the collapse of surrounding rock in the tunnel to form a large-scale sudden debris flow, and the length of debris flow deposits exceeded 400 m

Water and mud inrush description

DK79+110~DK78+380

YK29+816 etc

Xinwuji Tunnel

2-61

10/2011

Unknown

No. 3 belt 8/5/2009 conveyor tunnel of Dagangshan Hydropower Station

Chainage

2-60

Time

Tunnel

Serial No

(continued)

Appendix 2: Fault Category 363

Unknown

9/1~3/2005

Yanying’an Tunnel

Diversion Tunnel of Nanyahe (Shimian)

Dabeiling Tunnel

Shenghongqing Tunnel

2-66

2-67

2-68

Unknown

1/4/2016

DK105+990~DK106+970

K049+935~K050+112

Unknown

DK87+998

DK172+818

4/6/2017

2-65

DK172+824

Chainage

12/30/2016

Zangga Tunnel

2-64

Time

Tunnel

Serial No

(continued)

Waterconductive fault type

Type of hazard-causing system

(Zhang Jiankun, 2018)

References

Water inrush occurred at the joint of secondary Waterlining circumferential construction conductive fault type

Tunnel passing through the F2 fault and water Waterinflow suddenly occurred, with water inflow of conductive 26 m3 /h fault type

(continued)

(Cao Xiaopin, 2006)

(Bi Jianxun et al., 2004)

The groundwater spraying speed reached Water-rich fault (Ma Deqin, 150 m/s, the water inflow was 400 L/s, and the type 1981) discharged sediment filled the pilot tunnel and construction adit. After half a year, the water inflow stabilized at 5~15 L/s

The accumulated water inflow of the face Water-rich fault (Zhang reached 47.9 × 104 m3 , with intermittent sand type Zhaolong, 2018) inflow, and the sand inflow from January 4 to 5 was about 2,650 m3

Materials gushed out were mainly fault breccia and gouge, with mud inflow volume of 8,000 m3 and measured water inflow of 432 m3 /h

There was water and mud inrush at the left arch waist, materials gushed out were mainly water mixed with structural breccia and block stones. The volume of mud inrush was 2,100 m3

Water and mud inrush description

364 Appendix 2: Fault Category

Tunnel

Sipujian Tunnel

Jinzhushan Tunnel

Mingyueshan Extra-long Tunnel

Huangshaling Extra-long Tunnel

Serial No

2-69

2-70

2-71

2-72

(continued)

YK5+398

1/18/2006

ZK104+910~ZK105+310

YK5+379

1/5/2006

Unknown

K5+573

K64+664

DK156+330

Chainage

Unknown

3/13/2010

2/13/1998

Time

Fault category

Waterconductive fault type

Fault category

Type of hazard-causing system

(Chen Guihong et al., 2007; Qin Renpei et al., 2007)

(Li Yongjiang et al., 2011)

(Yang Yugang and Chao Gengqi, 2002)

References

(continued)

There was a large amount of water inflow at Water-rich fault (Liu Qisheng, the lower right side, with a water inflow of type 2012) about 4,885 m3 /d, and the total water inflow of this section was 9,600 m3 /d

Water inrush occurred on the right side of the arch, with a flow of 33 m3 /min, and the water flowed out with marl and gravel. Since then, the water inflow had been stable at about 110 m3 /min for a long time

There was a large water seepage at the arch on the right side of the tunnel face, followed by water and mud inrush, and a large number of gravel blocks were washed out, with a water flow of about 5 m3 /min

Water and mud inrush occurred above the tunnel vault, a large amount of mud flowed into the tunnel, burying the tunnel for more than 150 m

There were linear and strand water inrush on the vault of the tunnel face, and the maximum water inflow was 11,000 m3 /d

The fault was exposed by excavation. On February 14, the water inflow reached 6,000 m3 /d, and then gradually stabilized at 2,000 m3 /d

Water and mud inrush description

Appendix 2: Fault Category 365

8/12~ 10/25/2012

Diversion Tunnel of Longjinxi

YK91+360~+410

Yonglian Tunnel 7/2/~ 8/19/2012

2-76

2-77

ZK91+320~+385

Palong No. 2 Tunnel

2-75

0+950 of No. 3 Adit 3+551 of No. 2 Adit 7+925 of No. 3 Adit

12/16/2012

4/10/2013

K4101+814

DK17+495

5/22/2012

10/19/2014

Tangcun Tunnel Unknown

2-74

K1+13

Yakexiaxueshan 4/29/2010 Tunnel

Chainage

2-73

Time

Tunnel

Serial No

(continued)

The water inflow of No. 3 adit reached 438.54 m3 /h, with water depth inside the tunnel of about 1.7 m

The water flow of No. 2 adit work area at the entrance was 135~175 m3 /h

The water inflow of No. 3 adit reached 140 m3 /h

Waterconductive fault type

There were 8 large-scale water and mud inrush Waterdisasters, with a water and mud inrush volume conductive of nearly 5.0 × 104 m3 , residual mud in the fault type tunnel exceeded 1.7 × 104 m3 There were 7 large-scale water and mud inrush disasters, with a water and mud inrush volume of about 2.39 × 104 m3 , residual mud in the tunnel was about 2.25 × 104 m3

(Wang Yang et al., 2013)

References

(continued)

(Hao Yong, 2017)

(Li Shucai, 2015)

(Wang Mengwei and Xu Feng, 2017)

Water-rich fault (Zhang Fei and type Zhang Hu, 2013)

Waterconductive fault type

Type of hazard-causing system

Sudden water inrush at the right lower part led Waterto water accumulation within 80 m behind the conductive tunnel face, with a depth of 1.3 m fault type

The maximum water inflow of the tunnel face was 12,500 m3 /d, and after that, the water inflow was maintained at 1,000 m3 /d

The peak water inflow of the tunnel reached about 32 m3 /h

Water and mud inrush description

366 Appendix 2: Fault Category

Caijiazhai Tunnel

Denghuozhai Tunnel

Diversion Tunnel of Huangjialing

Diversion Tunnel of Donghu Power Station

Diversion Unknown Tunnel of Jinwo Hydropower Station

2-79

2-80

2-81

2-82

12/16/2012

Unknown

5/7~ 13/2012

11/10/2013

7+363

8+776 of No. 2 Adit

K209+830

YK22+136

ZDK47+252

3+062 of No. 2 Adit upstream

10/18/2013

2-78

Chainage

Time

Tunnel

Serial No

(continued)

Fault category

(Mao Jin, 2017)

The water inflow at the vault was 2,000~2,700 Fault category m3 /h, and a large amount of mud mixed with stone flowed out from the tunnel face

(continued)

(Sun Jinfu, 2017)

Sudden water inrush in the tunnel, the adit and Water-rich fault (Shao its control section were submerged after 5 h, type Zhengquan and with a total drainage of 135,600 m3 Guo Qingchun, 2014)

Under the action of water, a large number of broken rock blocks gushed out, with a water inflow of 150 m3 /h, and the tunnel face was filled with debris flow like collapse bodies

Water-rich fault (Tang type Lianquan et al., 2013)

450 m3 quicksand mud gushed from the arch waist; On May 8, another 1,800 m3 mud gushed out; On May 13, mud inrush occurred in the tunnel face, with a total volume of 14,000 m3

(Ning Yuansi, 2017)

References

Fault category

Type of hazard-causing system

Brownish yellow clay mixed with a small amount of limestone fragments gushed from the tunnel face, and the mud inflow in the tunnel was 1,600 m3

The flow in the No. 2 adit upstream work area reached 675 m3 /h in the initial 5 h, and the mud inrush volume reached 1,000 m3 on April 1

Water and mud inrush description

Appendix 2: Fault Category 367

Tunnel

Nanchong Tunnel

Dongzhouxincheng Tunnel

Longyanjiangshan Tunnel

Sanqingshan Tunnel

Serial No

2-83

2-84

2-85

2-86

(continued)

9/30/2012

Unknown

Unknown

5/12/2013

Time

DK430+211

K3+370~500

K0+735

DK1133+394

Chainage

Fault category

Type of hazard-causing system

Water-rich fault (Su Xingju, type 2009)

(Pan Changhong et al., 2017)

(Zhang Huiling and Fan Shengming, 2017)

References

(continued)

The initial flow of the tunnel face was 150 Water-rich fault (Li Xiaoyong, m3 /h, the flow of the water outlet on October 1 type 2017) was 188 m3 /h, and 6,500 m3 /d on October 8

The water gushing on the tunnel face lasted for 10 min, mixed with a large amount of sediment to form a violent debris flow

The average water inflow of the right tunnel Fault category was 178.09 m3 /h and 61.38 m3 /h for the left tunnel, and the water inflow was accompanied by a large amount of fine sand

There were two strands of water at the tunnel face, and the water flow gradually increased, and then there was mud and water inflow, covering the tunnel for 160 m. The survey found that the surface collapsed to form a circular pit with a diameter of about 22 m

Water and mud inrush description

368 Appendix 2: Fault Category

6/18/2019~ 8/4/2019

Zheduoshan Tunnel

Dengloushan Tunnel

Jiufeng Tunnel

A tunnel in Xinjiang

2-87

2-88

2-89

2-90

Unknown

9/1/2018

3/11/2021

Time

Tunnel

Serial No

(continued)

82+184.7~82+177

B0+883

2XJK0+697

K1+035

Chainage

Type of hazard-causing system

Several water seepages and strands of water inflow, and the overall water inflow was 31,200 m3 /d

Fault category

Fault category

The daily water volume was about 2,000 m3 , the mud flowed to 91 m away from the tunnel face, and the surface water level decreased significantly

(continued)

(Li Xiaobing, 2022)

(Zhao Xiaofeng, 2021)

Water-rich fault (Chen Minghui type et al., 2021)

(He Yushan and Guo Shoujing, 2021)

References

Water inrush happened at the left side of the arch waist of the tunnel face, the predicted initial peak water inflow was about 1,500 m3 /h, after the pumping and drainage, water inflow was about 400 m3 /h

Water and mud inrush occurred 2 times, Water-rich fault flooding the tunnel by 200 m for the first time, type with the amount of mud inrush of about 13,500 m3 . A funnel-shaped pit with a diameter of about 30 m and a depth of about 15 m was formed on the surface. The second inrush flooded outwards from the tunnel portal for nearly 200 m, forming a collapse cavity with a surface diameter of about 40 m and a depth of about 19 m. The collapse cavity had a volume of about 16,700 m2 and the surface subsidence area was about 962 m2

Water and mud inrush description

Appendix 2: Fault Category 369

Tunnel

Gantasi Tunnel

Xiangyun Tunnel

Shixia Tunnel

Dongtianshan Tunnel

Hongtu Tunnel

Serial No

2-91

2-92

2-93

2-94

2-95

(continued)

Unknown

7/9/2017

Unknown

8/18/2014

Unknown

Time

ZK94+351

ZK9+186

ZK31+595

PDK143+074

V1K108+263.4

Chainage

There were several spots along both sides of the black fracture zone that sprayed water outward

(continued)

Water-rich fault (Xu Feng, type 2022)

Water-rich fault (Huang Jiefang type et al., 2021)

The average water inflow was 117,000 m3 /d on that day. The maximum water inflow was 175,000 m3 /d

(Wu Jingang et al., 2019)

(Hou Dongsai, 2017)

Fault category

Fault category

The initial debris flow was about 150 m3 , and the water inflow was about 200 m3 /h. Water and mud inrush occurred again on the tunnel face on September 1, and the debris flow was about 2,300 m3

(Gao Weiwei, 2017)

References

With a relatively large volume and accompanied by a large amount of gravel and muddy fillings, the water flowed into the tunnel. The mud inrush volume was about 1,000 m3 , and the continuous water flow was about 1,200 m3 /d

Fault category

Type of hazard-causing system

Small-scale water and mud inflow occurred first, the water inflow was about 20 m3 /h, and the mud inflow was about 6 m3 /h. Later, the tunnel face collapsed, soil and stone gushed out 60 m away, with a volume of 600 m3

Water and mud inrush description

370 Appendix 2: Fault Category

5/14/2020

Huajiaopo Tunnel

Xinping Tunnel

2-97

2-98

Unknown

7/19/2018

Dazhongshan Tunnel

2-96

Time

Tunnel

Serial No

(continued)

Unknown

D1K78+933

Unknown

Chainage

Type of hazard-causing system

References

Fault category

A total of 28 times of water inrush and inflow Water-resistant occurred in the tunnel, and the mud inrush fault type amounted to about 64,000 m3 . The single maximum inrush and inflow volume was up to 10,000 m3 , and the maximum water inflow was up to 1,175 m3 /h

The second inflow occurred on the tunnel face on June 1, the mixture of water and mud sand had a flow rate of about 80~166 L/s, the water was black and accompanied by a lot of soil

The water output from the tunnel face was about 25~30 m3 /min, mixed with a large amount of sediment. The mud inrush body was 3.5 m in thickness, 300 m in length and had a volume of about 5,250 m3

(continued)

(Li Ping, 2022)

(Lin Ke, 2022)

The water inflow on the tunnel face suddenly Water-rich fault (Guo Gaofeng increased, and the maximum pumping volume type et al., 2022) was about 330 m3 per hour. During the construction period, the water inflow continued to increase, and the maximum amount of water pumped per hour was about 330 m3

Water and mud inrush description

Appendix 2: Fault Category 371

Tunnel

Bijiashan Tunnel

Baolin Tunnel

Serial No

2-99

2-100

(continued)

247+395

ZK274+649

Unknown

6/11/2018

YK274+610

Chainage

Unknown

Time

References

(Zhan Kangwu and Xu Meng, 2020)

Water-rich fault (Han Jinsong, type 2018)

Type of hazard-causing system

Water and mud inrush occurred 3 times, with a Watertotal amount of 8,100 m3 loose slag body. The conductive first water inrush volume was about 5,200 m3 , fault type and the second mud inflow volume was about 1,500 m3 . Six people missed after a third water and mud inrush

The bedrock fracture water was extremely developed and flowed out in strands in several places. A large amount of muddy water was ejected when the advance detection hole was set up

The mud inrush occurred on the right side of the vault of the tunnel face, with a volume of about 1,500 m3 . During the emergency treatment, a small mud inrush occurred again, with a volume of about 600 m3

Water and mud inrush description

372 Appendix 2: Fault Category

Appendix 2: Fault Category

373

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Appendix 3

Other Category

© Science Press 2023 S. Li et al., Hazard-causing System and Assessment of Water and Mud Inrush in Tunnel, https://doi.org/10.1007/978-981-19-9523-1

379

2/2006

Unknown

Qinglong Tunnel

Deli Tunnel

Shuangfeng Tunnel

Ganquan Tunnel

Yaozhai Tunnel 2/12/2011

Baofuling Tunnel

Nanshan Tunnel

3-1

3-2

3-3

3-4

3-5

3-6

3-7

Unknown

Unknown

2/1/2007

7/7/2012

Time

Serial No Tunnel

Water inflow in the right vault was 29 m3 /h, in the form of linear water Water inflow at the vault was 24 m3 /h, in the form of dropping water

k2+185~+225 k2+260~+320

(continued)

(Sun Yulin and Wu Shiyou, 2006)

Structural fissure type

Water inflow in the left vault was 35 m3 /h, in the form of linear water

(Hu Wenxue and Yang Yan, 2013)

k2+140~+160

Unconformable contact type

(Chen Zhiqiang and Yue Hua, 2011)

(Jia Changzhi, 2013)

(Xu Feng and Zhu Bin, 2016)

(Xu Tao, 2007)

(Chen Qian, 2008)

Large-scale water and mud inrush occurred, with a mud volume of 10,000 m3

Water inrush and mud inflow inside the tunnel Special for 222.5 m condition type

Intrusive contact type

Intrusive contact type

Unconformable contact type

Type of References hazard-causing system

Large-area water spraying and partial stranded Structural flow, with water inflow of 2,880 m3 /d fissure type

K35+680~+700

ZK47+067

Unknown

Large quantities of mud and water mixture gushed out suddenly from the tunnel face and arch, with a flow rate of about 2,000 m3 /h

Water inflow of the arch and sidewall was about 5,000 m3 /d

DK150+137 DK466+608

Stranded water inflow occurred in the middle of tunnel face and blocks fell off

Rock fissure water inflow occurred in the tunnel face, with calculated water inflow of 31,104 m3 /d

Water and mud inrush description

DK150+133

ZK84+828

Chainage

380 Appendix 3: Other Category

5/11/2010

12/12/2015

Dayahe Tunnel

Baotashan Tunnel

Dongtoushan Tunnel

Hushan Tunnel

Cao’an Tunnel

Huayoushan Tunnel

Zhongtianshan Tunnel

3-10

3-11

3-12

3-13

3-14

3-15

3-16

10/6/2011

Unknown

Unknown

9/13/2012

Unknown

Tiezhaizi No. 1 9/15/2009 Tunnel

3-9

3/25/2014

Guantian Tunnel

Time

3-8

Serial No Tunnel

(continued)

DyK154+901

DK28+700

DIK752+869~890

K24+445

YK37+915

XK0+283 of No. 3 inclined shaft

LK68+730

YK161+315

Right line K52+265

Chainage

Structural fissure type

Structural fissure type

Structural fissure type

Structural fissure type

Structural fissure type

Structural fissure type

Large water inflow occurred in the tunnel face Structural when drilling, flooding the tunnel for 930 m fissure type

Large quantities of water inflow in the left Structural side of arch, accompanied with a large amount fissure type of mud and pebble, mud inrush was in a state of flow plastic

Water inflow inside the tunnel reached 7,000 m3 /d

Water inrush of the right-line tunnel face at the exit was 120 m3 /h

Water inflow occurred in tunnel face, water was jetted out, with a flow of 25,000~30,000 m3 /d

(continued)

(Zhao Jianyu, 2013)

(Li Shoufeng, 2012)

(Song Lunjie, 1999)

(Zhao Xiaorong, 2013)

(Che Ligang et al., 2017)

(Liu Jinhui, 2015)

(Feng Weiqiang and Liu Chaosheng, 2009)

(Pei Shulin, 2014)

(Chen Daqi, 2015)

Type of References hazard-causing system

Water inrush at the top of tunnel face was 400 Structural m3 /h and maintained at 210 m3 /h after 4 h fissure type

Linear water drops appeared in the tunnel face, and then became stranded water

Sudden water inrush and collapse in the left spandrel, with a water inflow of about 37 L/s

Water sprayed out from the fissures, with a water inflow of 25,900 m3 /d

Water and mud inrush description

Appendix 3: Other Category 381

Unknown

Fu’an Tunnel

Heluoshan Tunnel

Nanshan Tunnel

Weijiashan Tunnel

Yangdongtan No. 2 Tunnel

Xiushan Tunnel Unknown

Daliang Tunnel 3/30/2013

3-17

3-18

3-19

3-20

3-21

3-22

3-23

1/10/2011

Unknown

4/~9/2003

12/21/2007

Time

Serial No Tunnel

(continued)

DK332+266

PDK34+570

YK194+046

K100+636

K4+760

X3 K0+152.5 of No. 3 inclined shaft

Unknown

Chainage

Structural fissure type

Structural fissure type

Water inrush occurred in the right side of arch Structural waist, with the maximum instantaneous flow fissure type of 2,300 m3 /h

Yellow mud and water gushed out with a large Structural amount of sandy and breccia dolomite, with a fissure type water inflow of about 8,000 m3 /d

Large-scale collapse and mud inrush occurred Structural in the tunnel face, the collapse body was fissure type yellowish brown mud, rushing out 30 m away from the tunnel portal

Water inflow was inform of spraying, strand Structural and linear water, with a maximum rate of 29.3 fissure type m3 /h

(continued)

(Bi Huanjun, 2015)

(Lu Jixia and Liu Xiangyang, 2009; Luo Ningning, 2011)

(Wu Ping et al., 2013)

(Xu Qiang, 2014)

(Wang Zhongwei, 2013)

(Zhou Guolong, 2009)

(Sun Yuchen, 2012)

Type of References hazard-causing system

Sandstone fractures were relatively developed, Structural and a large amount of water inflow occurred fissure type in the tunnel, with a maximum rate of 19,346 m3 /d

Sudden water inflow at the arch foot, with a flow rate of 290 m3 /h

Water inrush occurred around the water-rich fissure dense zone. Maximum water inflow of the tunnel face was about 8,805.12 m3 /d

Water and mud inrush description

382 Appendix 3: Other Category

Shilin Tunnel

Gangcheng Tunnel

Jijiacun Tunnel

Bairenyan Tunnel

Humaling Tunnel

Taoshuping Tunnel

Baosen Tunnel

3-24

3-25

3-26

3-27

3-28

3-29

3-30

Serial No Tunnel

(continued)

4/29/2015

11/4/2014

9/25/2011

Unknown

Unknown

Unknown

Mud inrush, water inflow

DK230+950

DK4+973

Unknown

K218+581

LK106+851

Special condition type

Special condition type

Special condition type

Special condition type

Stranded water flow, with a flow rate of 1,500 m3 /d, completely weathered quartz sandstone gushed out

Differential weathering type

Stranded water appeared in the sidewall, Special mixed with a small amount of quicksand, with condition type water inflow of 5 m3 /h and total sand volume of 5,000 m3

Water and sand inflow occurred above the arch, the sand accumulation body was 40 m away from the tunnel face, with a volume of 5,000 m3

Mud inrush occurred in the tunnel face, with soil volume of about 50 m3

(continued)

(Wu Tiexiang, 2016)

(Zhang Minqing et al., 2016)

(Zhang Baoyong, 2015)

(Shi Xianhuo, 2011)

(Wang Wanping et al., 2015)

Ma Huaipeng, 2009)

(Yuan Chuanfeng, 2013)

Type of References hazard-causing system

Mud inrush occurred in the tunnel face, with a Special distance of 33 m and a volume of 3,000 m3 condition type

Linear water was discharged from the arch, and large quantities of sediment gushed out, with a volume of about 120 m3

YK14+260~267 DK349+409

Collapse, accompanied with mud inrush Mud inrush, water inflow

YK14+175~191

Water inflow in form of pipe, with a rate of about 300 m3 /h and turbid water

Water and mud inrush description

YK14+194~205

DK332+237

7/31/2013

Unknown

Chainage

Time

Appendix 3: Other Category 383

11/16/2005

Qingshui Tunnel

Qinyu Tunnel

Baofeng Tunnel Unknown

Jiulongjiang Tunnel

A Tunnel of Nanpinglongyan Railway

Lianhuashan Tunnel

3-31

3-32

3-33

3-34

3-35

3-36

Unknown

4/29/2015

6/25/2014

7/10/2006

Time

Serial No Tunnel

(continued)

DK179+767

DK230+950

Unknown

Unknown

DK127+427

DK442+660~+668

Chainage

Differential weathering type

Differential weathering type

Differential weathering type

Mud inflow occurred on the tunnel face. The gushing materials were completely weathered granite and diabase, intercalated with strongly—weakly weathered rock blocks. The total amount of gushing materials was about 1,350 m3

Intrusivecontact type, Differential weathering type

Large strands of water flow appeared at the Differential right arch foot, with a flow rate of 1,500 m3 /d, weathering type the completely weathered silty mudstone gushed out along with the underground water from the arch waist

Water and sand inrush occurred, with sand volume of 150 m3 and water volume of 1,500 m3

Tunnel face collapsed, with severe water and mud inrush, forming funnel-shaped collapse on the surface

(continued)

(Qu Bo, 2013)

(Tang Zhaokui, 2016)

(He Zhiqiang and Jin Zuoliang, 2015)

(Deng Qihua, 2016)

(Liao Shuzhi, 2007)

(Mu Yonggang, 2008)

Type of References hazard-causing system

Two streams of concentrated water flowed out Differential of the face, with a flow rate of about 20 m3 /h weathering type

Mud inflow and collapse occurred in the tunnel face

Water and mud inrush description

384 Appendix 3: Other Category

3/16/2009

Liangshan Tunnel

Pusagang Tunnel

Water Intake Tunnel of Changshu Power Plant

Dongkoudui Tunnel

Hengchajibailu No. 1 Tunnel

3-37

3-38

3-39

3-40

3-41

6/16/2010

Unknown

Unknown

Unknown

Time

Serial No Tunnel

(continued)

DK90+850

Tunnel entrance and No. 1 inclined shaft

Unknown

K173+109

DK96+505

Chainage

Special condition type

The mud inflow lasted for 1 h, the mud was in Special flow shape, and the slumped mud was about condition type 450 m3

Many strands of water were jetted out, the water was yellow and turbid, with the water inflow of about 700 m3 /d

The confined water carried quicksand into the Special tunnel, causing water inrush and sand gushing condition type

Water inflow occurred 5 times, with maximum Special spraying distance of over 30 m, and water condition type inflow of 200~180 m3 /h

(continued)

(Du Ping, 2014)

(Wang Hao, 2011)

(Wu Peipei et al., 2016)

(Fu Lixin et al., 2011)

(Wu Peirong, 2015)

Type of References hazard-causing system

Sudden water inflow and mud inrush, with Differential mud volume of 2,000 m3 and the accumulated weathering type mud volume reached 8,000 m3 on March 19

Water and mud inrush description

Appendix 3: Other Category 385

Baihe Tunnel

Liulangshan Tunnel

Diversion Tunnel of Mantan Power Station

Urban Cable Tunnel

A Tunnel of Nanjing Metro Line 2

Jingxi Tunnel

Beilingshan Tunnel

3-42

3-43

3-44

3-45

3-46

3-47

3-48

Serial No Tunnel

(continued)

1/20/2014

3/19/2016

11/26/2006

5/2000

Unknown

Unknown

Unknown

Time

ZK46+963~+965

DK93+715

K20+070~+075

K0+57.8

Unknown

DK34+485

Structural fissure type

Special condition type

Intrusive contact type Mud inrush occurred at the arch waist, with Structural water inrush of 180 m3 /h and debris of 650 m3 fissure type

Confined water flowed out at the left arch corner, with a water inrush of 2,800 m3 /h

A large amount of muddy soil with rich water Special content gushed out in front of the vault, and condition type the upper step was submerged

The sewage washed the sand and gravel layer Special to form a channel and flowed into the tunnel in condition type large quantities, with the water inflow reaching 100 m3 /h

Mud and water inrush occurred for 7 times, with a cumulative mud inrush volume of 13,000 m3 and a maximum mud inrush volume of 5,400 m3

(continued)

(Hu Qinglin, 2017)

(Zhao Changwei, 2018)

(Deng Jijie and Zhang Zhicheng, 2007)

( Li Shu, 2008)

(Song Hongshui, 2015)

(Shi Lei, 2013)

(Mao Huarong, 2007)

Type of References hazard-causing system

The seepage of the tunnel face at the arch part Special became severe and blocks fell off, then water condition type inrush and mud inflow occurred, and the arch wall collapsed

Water seepage and water dripping/ The yellow water flowed from the 30-cm circular spraying hole, and the single hole flow reached 100 m3 /h

K127+242

Water and mud inrush description

K127+104

Chainage

386 Appendix 3: Other Category

6/26/2013

4/1/2018

Xinlian Tunnel

Xiaozhongdian Tunnel

Diversion Tunnel of Datang Linzhou Thermal Motor Project

Extra-long Tunnel of HanjiangWeihe Diversion Project

3-49

3-50

3-51

3-52

7/9/2015

Unknown

Time

Serial No Tunnel

(continued)

The fissure water flowed out, and the water flow was 260~300 m3 /h

DK727+510~+480

K68+995

K3+402

Structural fissure type

Strand, surface water and linear water dripping, with the maximum water inflow of about 8,000 m3 /d

Structural fissure type

Water inrush and mud inflow occurred at the Special top of the tunnel, with a mud volume of about condition type 45 m3 , mixed with a large number of broken stones, and a total of 2,566 m3 of silt and broken stones was cleared

(continued)

(Li Yubo, 2018)

(Fang Liang et al., 2017)

(Wang Pan et al., 2018)

(Chen Xu et al., 2018)

Type of References hazard-causing system

There was rain-like dripping at the arch, and a Structural small amount of sediment was mixed in the fissure type water. On April 3, the volume of water and sand inflow was 900 m3 and water flow rate was 130 m3 /h

Concentrated stranded water flowed out at the right arch waist with a flow of about 620 m3

PDK726+963

YK32+531

Strands of water flowed out of the vault and left sidewall, the water was clear and had a flow rate of about 360 m3 /h

Water and mud inrush description

PDK727+508

Chainage

Appendix 3: Other Category 387

Unknown

10/24/1998

Unknown

Xizhai Tunnel

Xinyongchun Tunnel

Yezhuping Tunnel

Baofuling Tunnel

3-55

3-56

3-57

3-58

Unknown

Unknown

ZSK39+576

Pimiao Interval Unknown Tunnel of Qingdao Metro Line 2

3-54

K35+680

K2+287

N8+058

Unknown

10/2014

Qiaoyuan Tunnel

3-53

Chainage

Time

Serial No Tunnel

(continued)

Special condition type

Large-area water spraying and local stranded water flow, with a flow rate of 2,880 m3 /d

Large quantities of water flowed out of the right arch waist and right vault, accompanied with collapse and block falling off, and daily maximum water inflow reached 8,000 m3

Sudden large-scale water inflow occurred, with a maximum flow of 80 m3 /min and long-term water inflow maintained at 25~35 m3 /min

Differential weathering type, Structural fissure type

Structural fissure type

Structural fissure type

Large quantities of mud and water gushed out Special from the tunnel, causing water and mud inflow condition type disaster

(continued)

(Chen Qian, 2008)

(Zhang Hao and Cui Yongjie, 2018)

(Fu Ziren et al., 2004)

(Ji Tianlin and Liu Gaofei, 2002)

(Zhang Lianzhen, 2017)

(Wang Bowen, 2018)

Type of References hazard-causing system

Strand-like water inflow appeared at the vault, Special then a large number of sand particles mixed condition type with a small amount of water continuously gushed from the water inflow point, and the material gushed out changed from sand to sand-water mixture

The water inflow at tunnel entrance and exit was 43.2 m3 /d and 5.0 m3 /d, respectively

Water and mud inrush description

388 Appendix 3: Other Category

Unknown

12/8/2006

Yufengshan Tunnel

Shamaoshan Tunnel

Yangkou Tunnel

Diversion Tunnel of Qinglong Power Station

Shizizhai Tunnel

3-60

3-61

3-62

3-63

3-64

6/27/2010

Unknown

Unknown

Xinqilin Tunnel 6/21/2006

Time

3-59

Serial No Tunnel

(continued)

Right line K43+194

Strand-like water inflow, with a flow rate of 4,000 m3 /d

Stranded water inflow mixed with large quantities of sediment, water was turbid, causing large-area collapse of tunnel face

Water seepage was aggravated, forming a large area of water pouring and strand-like water flow, with a water inflow of 2,950 m3 /d

ZK61+290

(Diversion) 8+229~+227

Severe water seepage appeared at the arch of tunnel face and sidewalls

Sudden water gushing from the tunnel face occurred, the water column was in jet shape, with the flow rate of 55 m3 /h

A large amount of groundwater gushed out of the tunnel face of the upper pilot adit along the sandstone joint surface and fissures in large strands, and the maximum flow was 1,000 m3 /h

Sudden water inflow occurred at the tunnel entrance, with a flow of 12,000 m3 /d

Water and mud inrush description

ZK61+300

ZK27+629

LK15+195~235

DZK209+390

Chainage

Structural fissure type

Structural fissure type

Differential weathering type, Structural fissure type

Structural fissure type

Structural fissure type

Structural fissure type

(continued)

(Song Bo, 2011)

(Peng Qiang and Gao Jun, 2010)

(Hei Fusheng, 2009)

(Huang He, 2009)

(Feng Zhentu, 2009)

(Li Zhiwen and Wanglixin, 2008)

Type of References hazard-causing system

Appendix 3: Other Category 389

12/2/2009

High line No. 1 Unknown Tunnel on the right bank of Guandi Hydropower Station

4/8/2010

4/22/2011

Paiqian No. 2 Tunnel

Liweizhai Tunnel

Zhongyang Tunnel

Fubaoshan Tunnel

3-65

3-66

3-67

3-68

3-69

8/12/2013

Time

Serial No Tunnel

(continued)

DK257+578

ZK158+567

K23+133

K0+576

DK125+163

Chainage

The actual maximum water inflow reached 51,700 m3 /d. At 6:00 p.m. on April 30, a strand of water gushed from the left-line arch waist, and the water inflow reached 30,000 m3 /d

Large water inflow suddenly occurred at tunnel floor, with water carrying large quantities of sediment, and maximum spraying distance of water inflow was 6.5 m

Structural fissure type

Structural fissure type

Large quantities of water gushed from the Structural arch of tunnel face, carrying a large amount of fissure type sediment and block stone, with a volume of 150 m3

A large range of water inrush at the vault, and Structural the water came from the mountain confluence fissure type and passed through the cracks and leaked down from the tunnel top

(continued)

(Deng Minggao, 2014)

(Zhong Hongquan, 2014)

(Xu Yongxing, 2014)

(Wang Lixin, 2013)

(Wei Jianjian, 2012)

Type of References hazard-causing system

Strong water and sand inflow occurred on the Unconright side of tunnel face, with a flow rate of 50 formable m3 /h; on December 6, the volume of sand contact type inflow was 3,000 m3

Water and mud inrush description

390 Appendix 3: Other Category

Unknown

Kuibalu Tunnel Unknown

Unknown

4/3/2014

Highway Tunnel of Changheba Hydropower Station

Huajiaoqing Tunnel

Tongsheng Tunnel

Yanglin Tunnel 7/20/2016

Qiandiao No. 3 Tunnel

3-70

3-71

3-72

3-73

3-74

3-75

5/16/2016

Time

Serial No Tunnel

(continued)

K77+820~+827

ZK14+190

A large amount of water inrush occurred in the Structural right sidewall, with a water inflow of 300 m3 /h fissure type

A large amount of water mixed with sediment Special gushed from the tunnel face, and the water condition type inflow and mud inrush amount reached 4,000 m3 . The total amount of water and mud inrush was 12,000 m3

Secondary water and mud inrush occurred, with a water inflow of about 7.4 × 104 m 3

ZK114+395

Special condition type

Structural fissure type

Structural fissure type

(continued)

(Deng Yong, 2017)

(Bao Jiaohe, 2017)

(Wang Zhangqiong et al., 2017)

(Bai Guoquan, 2016)

(Wei Gaozhi, 2015)

(Wang Xiaoming et al., 2014)

Type of References hazard-causing system

Water inrush started from the bottom of tunnel Structural face collapse, and the water inflow reached fissure type 136 m3 /h

The water inflow of tunnel face was about 1,000 m3 /d, and the accumulated volume of mud inrush was about 1,300 m3

The water inflow was in the form of water column and maintained a flow of about 500 m3 /h, and the water inflow pressure was greater than 0.4 MPa

Large fissure water gushed from the tunnel face, with a water inflow of 37 L/s

Water and mud inrush description

ZK114+377

K40+113

YK4+570

BK1+491

Chainage

Appendix 3: Other Category 391

7/16/2011

Tianheshan Tunnel

Liangfutai Tunnel

Yanggongkeng Tunnel

Gaoyangpo Tunnel

Qinling Tunnel of HanjiangWeihe Diversion Project

3-76

3-77

3-78

3-79

3-80

10/23/2011

Unknown

4/1/2012

10/18/2011

Time

Serial No Tunnel

(continued)

K26+760~+810

DK13+747

ZK55+931.5

Mud inrush and water inflow occurred at the vault. The gray black and light-yellow rock debris mixed with gravel gushed out of the crack. The mud inrush and water inflow was about 100 m3 /h

A water inflow spring was exposed at the inverted arch, with a flow rate of 60 m3 /d

A large amount of mud gushed from the left arch line above the tunnel face, and the peak water inflow was 1,200 m3 /h

A large amount of gray white silty fine sand gushed out from the tunnel face, causing the face to collapse. After that, collapsed body with a volume of 1,000 m3 was removed

Water inflow was 5,700 m3 /d; on October 28 2012, water inflow of right line reached 5,622 m3 /d and left line had a water inflow of 6,838 m3 /d on November 27

No. 2 inclined shaft

DK12+126

Stranded water inflow, with a flow of 2,200 m3 /d; on September 30, water inflow reached 7,500 m3 /d

Water and mud inrush description

No. 1 inclined shaft

Chainage

Unconformable contact type

Special condition type

Differential weathering type

Special condition type

Structural fissure type

(continued)

(Li Limin, 2014)

(Zhang Guangwu, 2017)

(Zhou Zhenyu and Wei Ganying, 2013)

(Qi Weihua, 2013)

(Sun Chensheng, 2017)

Type of References hazard-causing system

392 Appendix 3: Other Category

4/14/2012

Diversion Tunnel of Shidou Reservoir

Yilu Tunnel

Shigushan Tunnel

Gaoligongshan Tunnel

3-81

3-82

3-83

3-84 D1K224+200~+230

PDZK221+481

8/27/2019

YK12+198

YK174+988

(Diversion) 0+760

Chainage

11/2/2018

2/23/2011

Unknown

Time

Serial No Tunnel

(continued)

Structural fissure type

Structural fissure type

The rock mass in front of the TBM cutterhead Special in the form of mud and sand flowed out condition type continuously, and the amount of slag was about 100 m3

Previously, the maximum water inflow was Structural 200 m3 /h, resulting in a collapse of about fissure type 20 m in diameter in the channel directly above the tunnel, and all the streams entered the collapse pit. On November 3, a total of 26,000 m3 mud inrush submerged the excavation section for over 700 m and trapped the TBM. The mountains on both sides of the surface collapse pit collapsed, forming a 28 m × 42 m bell mouth

Water inrush occurred at the right arch waist, with a flow of 60 m3 /h; water inflow of the tunnel face reached 500 m3 /h at 20:00 on February 24

Stranded water flow, with average water inflow of 1,200 m3 /d

(continued)

(Yang Zhiyong, 2022)

(Jia Jianbo et al., 2021)

(Chen Zhongrong, 2012)

(Lin Feng, 2018)

(Xiao Yunxue, 2014)

Type of References hazard-causing system

Large quantities of water flowed out of the Other category borehole, with water spraying distance of 2 m and water inflow of tunnel face reached 131 m3 /h

Water and mud inrush description

Appendix 3: Other Category 393

Daxingxiang Tunnel

Junchang Tunnel

3-87

3-88

9/11/2013

12/2/2018

6/11/2013

Banshan Tunnel

3-86

CK7+838

K45+200

DK218+871.2

Unknown

220+855~220+835

Unknown

11/26/2019

226+010

Unknown

Anshi Tunnel

Chainage

Time

3-85

Serial No Tunnel

(continued)

Special condition type

Special condition type

Stranded water inflow happened at the upper Differentialstep tunnel face. The maximum water inrush weathering was 1,280 m3 /h, the accumulated water inrush type volume was 250,000 m3 , the volume of silted mud and sand was about 2,500 m3

Water inflow happened at tunnel face, the amount of water was not large, with broken stone falling down; the accumulated amount of inrush mud was about 1,500 m3 , and the water volume was about 130,000 m3

Water and mud inrush occurred on the left Structural side of the arch of the upper step, with a mud fissure type volume of about 4,000 m3 and a water volume of about 5,000 m3 during the day and night

Two accidents of water and mud inrush occurred. The first mud inrush volume was about 3,000 m3 , the second mud inrush volume was about 1,200 m3 , and the water inflow was about 800 m3 /h

Water inflow happened at the joint dense area, presented as partial stranded water

(continued)

(Chen Weizhong et al., 2019)

(Yu Zhenhai, 2021)

(Tang Yao, 2021)

(Chen Dejin, 2021)

–

Type of References hazard-causing system

Collapse cavity occurred during excavation, Structural accompanied by stranded water inflow, with a fissure type rate of about 240 m3 /h

Water and mud inrush description

394 Appendix 3: Other Category

Guling Tunnel

Hongdoushan Tunnel

Cushishan Tunnel

3-89

3-90

3-91

Serial No Tunnel

(continued)

CK7+835

DK7+939

5/1/2015

10/23/2015

2/1/2016

8/17/2018 11/14/2018

K100+490

PKD121+661

ZK28+448

DK7+963

9/13/2014

5/2018

Chainage

Time

Structural fissure type

A large amount of water-bearing mud inflow appeared at upper step tunnel face. The volume of mud inrush was about 300 m3 . Later, the water inflow was basically stable, with a large flow rate and clear water

Structural fissure type

(continued)

(Cai Pingbo, 2017)

(Quan Fei et al., 2021)

(Wang Shuyong, 2019)

Type of References hazard-causing system

Water and mud inrush occurred 2 times. The Special estimated total collapse volume was 800 m3 , condition type and the water inflow at the collapsed body was about 14,160 m3 /d

Several water inrush and inflow happened at the left section of the tunnel face, the water inflow area was about 18 m2 , and the water inflow was 13,200 m3 /d~18,000 m3 /d

A mixture of mud and water containing debris inflow gushed out intermittently from the arch part of the tunnel face, with a mud volume of about 3,000 m3

The accumulated water inflow volume was 10 × 104 m3 . The volume of silted mud and sand was about 1,000 m3

Water inflow occurred at the top position of the center line of the tunnel face. The amount of mud inrush was 2,900 m3 , and the maximum water inflow was about 150 m3 /h

Water and mud inrush description

Appendix 3: Other Category 395

LK100+310

LK100+308

RK100+261

7/28/2014

8/6/2014

9/13/2014

Wangbei’ao Tunnel

3-93

DLII30+738

LK100+370 RK100+383

Unknown

Shizishan 1# Tunnel

3-92

Chainage

6/23/2014

Time

Serial No Tunnel

(continued)

Water inflow occurred at several spots of the upper step, and the water inflow was 288 m3 /d. The collapse area was located between the vault and the inner arch foot of the upper step. The tunnel face collapsed volume was about 26 m3

The middle of the upper step collapsed with water inflow, the water flow was about 259.2 m3 /d, and the collapsed volume of tunnel face was about 20 m3

Water inflow and collapse occurred, and a large water inflow zone was formed within the arc length of about 4 m at the top of the tunnel, and the water flow was about 345.6 m3 /d

Disasters such as water inflow and partial collapse of the vault occurred, and the water inflow was 363 m3 /d and 288 m3 /d respectively

Structural fissure type

(continued)

(Zhou Songchuan, 2017)

(Wang Guowo, 2021)

Type of References hazard-causing system

Mud and water inflow appeared at the upper Special step, with the volume of mud inflow being condition type 3,120 m3 and that of water inflow being 4,250 m3 . The seepage from the cavity was 80~90 m3 /h

Water and mud inrush description

396 Appendix 3: Other Category

ZDK25+343

ZK11+866

Zhongjiashan Tunnel

Jingganglu5/2019 Shazikou tunnel of Qingdao Metro Line 4

A tunnel in Yunnan Province

3-96

3-97

3-98

7/3/2020

12/19/2012

12/25/2019

Tabaiyi Tunnel

3-95 YK92+093

K63+035~K63+050

DK418+344

Unknown

Guanyinyan Tunnel

3-94

Chainage

Time

Serial No Tunnel

(continued)

Special condition type

The mud inrush volume was about 4,500 m3 and the mud inrush length was about 50 m

Special condition type

The collapsed and inflow material were about Special 1,500 m3 . Directly above the tunnel, there was condition type a funnel-shaped collapse pit with a diameter of 15 m and a depth of 10 m

The amount of water and mud inrush in the tunnel was about 11,679 m3 , including 7,723 m3 of water and sediment inflow outside the collapse pit

Water inflow occurred at the inner side of the Special tunnel face, with a water flow of 228 m3 /h. condition type The water inflow mixed with a small amount of gray-white clay, hard sandstone blocks and a small amount of gravel; later the water gradually became clear, and the water inflow rate was about 329 m3 /h

Structural fissure type

(continued)

(Hu Qiang, 2021)

(Qiu Wenge et al., 2021)

(Xiao Yongping, 2015)

(Ding Yanfang, 2020)

(Guo Qingjun, 2020)

Type of References hazard-causing system

Water and mud inrush occurred at the tunnel face. The water flow was about 1,080 m3 /h, and a large amount of mud and sand was mixed with, and the mud inrush amounted to 1,000 m3

Water and mud inrush description

Appendix 3: Other Category 397

K100+490

K2+692.5

K2+706.9

K2+738

Qinling Tunnel 2/20/2013 of HanjiangWeihe Water Transfer Project

6/15/2013

9/17/2013

Cushishan Tunnel

3-100

3-101

2/1/2016

YK41+857.1

Chainage

Pingtian Tunnel Unknown

Time

3-99

Serial No Tunnel

(continued)

Small water seepage became concentrated water inflow from the lower part of left sidewall of the tunnel face, with a water flow of about 45 m3 /h and the maximum water flow of about 1,000 m3 /h

Water inflow occurred at the bottom of the left sidewall and the bottom of the tunnel face. The initial water inflow was about 9,800 m3 /d, and then the maximum water inflow increased to about 23,600 m3 /d

A large water inflow occurred at the upper part of the middle of the tunnel face. It was estimated that the initial water inflow was about 11,000 m3 /d, and the minimum water inflow was about 4,800 m3 /d

Structural fissure type

A large amount of mud and water gushed out Differentialfrom the right side of the arch waist of the weathering upper step, with a mud volume of about 400 type m3 and a mud transport distance of more than 50 m

(continued)

(Guo Xi and Chai Junrui, 2019)

(Chen Yufei, 2017)

(Wu Weiran, 2022)

Type of References hazard-causing system

The fissure water firstly flowed out in strands, Structural then, the sand and gravel in the rock layer also fissure type flowed out, and a large amount of soft and weak mud-filled materials was trapped in the water, forming mud inrush, with a total volume of 3,000 m3

Water and mud inrush description

398 Appendix 3: Other Category

Xianglushan Tunnel

0+504.0

0+502~0+504

12/6/2020

12/7/2020

K80+982

8/8/2012

3-104

K80+978

7/26/2012

Changlashan Tunnel

3-103

K6+045—K6+047

K80+970

Unknown

Feishuiyan 3 # Tunnel

3-102

Chainage

7/20/2012

Time

Serial No Tunnel

(continued)

Unconformable contact type

The water inrush occurred between the left arch to the vault, and the water inflow was about 60 m3 /h, then increased to 110 m3 /h. In the evening, water inflow increased again, the water level rose sharply

The left vault has water seepage, accompanied Special by continuous falling blocks to form a condition type collapse cavity

The fragmentation degree of surrounding rock in front of the tunnel face began to increase, and the water inflow was estimated to be as high as 13,000 m3 /d

The water inflow of the left sidewall increased gradually, and the erosion damage degree to the left surrounding rock of the tunnel increased significantly, resulting in collapse

Water inflow occurred at the left sidewall of the tunnel, and the average daily water inflow was 2,000~2,500 m3 /d

–

(continued)

(Han Haijun and Xu Chongbang, 2013)

(Liu Junjie, 2011)

Type of References hazard-causing system

There was fissure water on the right side of Structural the vault, accompanied by collapse and falling fissure type block. The initial flow rate was about 0.6~1.0 m3 /min

Water and mud inrush description

Appendix 3: Other Category 399

3-106

3-105

CX33+152.2

8/25/2022

DLI114+043~+042

CX33+066.4

5/20/2022

7/26/2022~ 8/1/2022

CX33+058.0

5/9/2022

Changyucun Tunnel

CX32+963.0

0+493~0+501

8/15/2022

3/25/2022

Unknown

12/11/2020

CX32+843.7

Chainage

Time

Fengtun Tunnel 12/18/2021

Serial No Tunnel

(continued)

Special condition type

–

–

(continued)

Type of References hazard-causing system

On July 26, the tunnel face collapsed; On July Special 31, water inflow occurred at the tunnel face condition type when excavating wall for grouting at tunnel face; A small mud inflow occurred on August 1

The water inflow increased to 31,000 m3 /d, the surface reservoir water level was declining continuously

The water inflow in the drilling hole increased suddenly, with a water flow of 26,000 m3 /d

There were several stranded water at the tunnel face

Water inflow occurred at tunnel face in the form of rain

A few small strands of water inflow occurred at vault

The water seepage from the right arch waist scoured and flowed out of the middle left of the tunnel face

The water inflow on the tunnel face increased and the water level rose. In the afternoon, the mud and water inrush increased further, and the sediment rose out of the water surface and moved towards the tunnel portal

Water and mud inrush description

400 Appendix 3: Other Category

9/26/2019

12/5/2019

Songqinggang Tunnel

Wangjiazhai Tunnel

Ningchan Tunnel

Namicun No. 2 Tunnel on China-Laos Railway

Dabieshan Tunnel

3-107

3-108

3-109

3-110

3-111

K22+073

YK2+614

Chainage

YK19+670~YK19+703

Unknown

12/28/2017

10/23/2009

Unknown

12/22/2017

10/17/2017~ YK37+500 10/18/2017

Time

Serial No Tunnel

(continued)

Structural fissure type

Special condition type

A large amount of water inflow occurred at the fissure, the daily water inflow was 1,080 m3 , forcing on-site construction to stop

A large amount of mudstone and sandstone fragments flowed out with water in debris flow, the average daily water inflow was 3,500 m3 /d, and the maximum water inflow was 7,874 m3 /d Structural fissure type

Water inrush occurred at the left arch foot of Special the tunnel face, and the daily water inflow was condition type about 6,200 m3 /d

Mud inrush occurred 2 times, with a total volume of about 8,000 m3 , resulting in a mud inrush cavity with a diameter of about 25 m and a depth of about 15 m on the surface

(continued)

(Chen Yucheng et al., 2011)

(Fan Xuefei et al., 2020)

(Zhang Danfeng et al., 2020)

–

(Weng Huobin, 2022)

Type of References hazard-causing system

Water and mud inrush occurred on the tunnel Special face, causing a total of 11,570 m3 of sediment condition type in front of and the upper part of the tunnel face flowing into the tunnel

The amount of mud and stone inflow was about 620 m3 and water inflow was about 3, 000 m3 /d

Water and mud inrush description

Appendix 3: Other Category 401

K42+142

K42+142

Bojiwan Tunnel 4/21/2020

5/11/2020

1.16 km away from the tunnel exit

3-113

7/15/2021

Shijingshan Tunnel

ZK20+000~ZK20+010, and The surrounding rock of the tunnel face had YK20+040~YK20+050 obvious stratification, and the water inflow in the fracture zone and interlayer continued

2/28/2010

A large amount of silty loess flowed out from the tunnel face. The mud inrush area in the tunnel was about 35 m, and the mud inrush volume was about 1,000 m3 . The surface formed a collapse pit with a diameter of about 10 m and a depth of about 20 m

Sudden stranded water occurred on the right side of the vault of the tunnel face, followed by mud inflow, and a large cavity was formed

When the tunnel passed through Jida Reservoir, it encountered a weathered deep trough of water-rich granite. Improper engineering measures led to the collapse of right-line tunnel face and flooding, which rushed into the left-line tunnel and drowned the working staff

The surrounding rock was stratified, and the water inflow in the fracture zone and interlayer continued, and the daily water inflow reached 1,200~1,500 m3

YK20+000~YK20+030

1/23/2010

Water and mud inrush description

Chainage

Time

3-112

Serial No Tunnel

(continued)

Special condition type

Differentialweathering type

(continued)

(Li Chengyu, 2022)

–

Type of References hazard-causing system

402 Appendix 3: Other Category

Ao’zailing Tunnel

Yangbajing No. Unknown 1 Tunnel

Yan’an RoadZhongshan Road Interval Tunnel

3-115

3-116

3-117

9/25/2015

Unknown

No. 2 shaft of Unknown Dongzhimen— Beixinqiao Interval Tunnel on Capital Airport Line

Time

3-114

Serial No Tunnel

(continued)

YDK23+603

K3787+397~K3787+415

YK53+723, YK53+665

A large amount of silt appeared on the vault and sidewall in front of the tunnel face and large rocks poured out. The mud volume was estimated to be 270 m3 on site

The primary support near the tunnel face collapsed, and the tunnel face could not be excavated for construction. The cumulative amount of debris flow in the cave was about 41,200 m3

Water inrush with a large water volume occurred 2 times, with high water pressure and sufficient water volume. The maximum water spraying distance was 15 m

Special condition type

Special condition type

Structural fissure type

Water inrush occurred 3 times during the Special construction of the horizontal passage of the condition type shaft. The third inrush was at the 28.5 m away from the horizontal passage. The inrush volume of pebbles and medium-coarse sand was about 40 m3 , and the water inrush volume was 1,000~1,500 m3

1st floor transverse passage K0+022, K0+024, K0+028.5

(Sun Wenjin, 2022)

(Huang Qigui et al., 2022)

(Wu Shaowei and Xiongjunjie, 2022)

(He Shangxiu et al., 2022)

Type of References hazard-causing system

Water and mud inrush description

Chainage

Appendix 3: Other Category 403

404

Appendix 3: Other Category

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