Preface

Since the beginning of the twenty-first century，the construction scale and construction technology of underwater tunnels in China have developed rapidly with the construction of a large number of large river-crossing shield tunnels.At present，dozens of large-diameter underwater tunnels have been built in China，including Wuhan Yangtze River Tunnel，Shanghai Yangtze River Tunnel，Nanjing Yangtze River Tunnel，Guangshen Port Shiziyang Tunnel，Wuhan Sanyang Road Yangtze River Tunnel，Wuhan Metro Line 8 River-crossing Tunnel，etc.Slurry shield technology has become the main construction method of underwater large tunnel due to its excellent pressure control mode and safe and efficient advantages.

Due to China's vast territory and different geological conditions，the largediameter underwater slurry shield projects that have been built and are under construction mostly pass through the composite strata of upper soft and lower hard，upper soil and lower rock，which will have a negative impact on the wear and replacement of cutters and the penetration of slurry on the excavation face.In addition，many unpredictable factors such as shallow overburden in the middle of the river and embankment during construction make the construction of large-diameter underwater shield tunnel face great risks，and serious deformation of stratum and instability of excavation face are easy to occur if the control is not good.Underwater tunnels in China are gradually developing towards“long distance”，“large diameter”，“large buried depth”，and“high water pressure”.At the same time，it also brings some urgent problems to be solved，such as initiation and arrival，crossing embankments，shallow overburden construction，crossing high water pressure permeable sandy cobble composite strata in the middle of the river，long distance tunneling and tool replacement，crossing the middle channel.

In order to make the construction personnel of the engineering front line better grasp the new technology of large-diameter underwater shield tunnel construction，based on the scientific research achievements and engineering experience of largediameter underwater shield tunnel construction in the past ten years，and referring to the technical achievements of domestic relevant engineering and technical personnel of scientific research units，the author summarizes and compiles a book based on technical research and theoretical analysis，combined with the relevant typical engineering cases in China，and systematically introduces the new technology used in the construction of large underwater slurry shield under complex conditions.This book clarifies the basic principles，scope of application，construction technology and technical points of key technologies such as the initiation and arrival of shields，crossing shallow overburden in the middle of the river，crossing embankments，and replacing cutters with pressurized cabins，which can be used for reference by engineering technicians，researchers and teachers and students of relevant majors in colleges and universities.

All the contents of this book are compiled and finalized by Professor of Engineering Chen Jian，Deputy Chief Engineer of China Railway Fourteenth Bureau Group Co.，Ltd.，Professor Min Fan Road，Associate Professor of Tunnel and Underground Engineering Institute ofHehai University，and Professor of Engineering Wang Shouhui，Vice General Manager of Qingdao Metro Group Co.，Ltd.after full discussion and consultation.In the process of writing this book，Xu Jingbo，Song Hangbiao，Bai Yuxin，Liu Jie，Du Jiarui，Yu Chaojie，Liu Hai，Wang Yucheng，Lv Huanjie，Wang Sheng，Wang Dengfeng，Xu Zhicheng，graduate students of the Institute of Tunnel and Underground Engineering of Hehai University，participated in the preparation of relevant chapters，data collation，chart drawing and revision，and so on.In the process of writing，this book also quotes some research results of scientific research cooperation units，and refers to some technical data and literature at home and abroad.

The book is jointly funded by the Enterprise Science and Technology R&D Project of China Railway Fourteenth Bureau Group（2017-07），the National Natural Science Foundation of China（51778213）and the Special Fund for Basic Research Services of Central Universities（2016B01214）.

Due to the limited level of the author，there are inevitable deficiencies and errors in the book，please experts and readers to criticize and correct.

Jinan，China　　　　　　　　　　　　　　　　　　　　　Jian Chen

Nanjing，China 　　　　　　　　　　　　　　　　　　　　Fanlu Min

Qingdao，China　　　　　　　　　　　　　　　　　　　　Shouhui Wang