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An Outlook for Researches on the Impact and Control Technology of Shield Construction in Gassy Soils
(1 School of Civil Engineering and Architecture, Anhui University of Science & Technology, Huainan 232001; 2 Department of Civil Engineering, Zhejiang University City College, Hangzhou 310015; 3 General Supervision Station of Construction Engineering Quality and Safety of Hangzhou, Hangzhou 310005; 4 China Railway No.2 Engineering Group Co., Ltd., Chengdu 610031)
Abstract Gassy soils will be inevitably encountered in the shield construction, and shallow gas in gassy soils can have a huge impact on the shield construction process and pose serious hazards to construction workers. After summarizing the types of gassy soils, the pressure of shallow gas, the buried depth and gas composition in various regions of China, it is found that most are dominated by CH4 gas generated by the decomposition of organic matters,with slightly different causes. Based on analysis on existing disaster cases, it illustrates the engineering influence of shallow gas in gassy soils, the impact of controlled gas release, and the influence of matric suction. The results show that gassy soil is a special unsaturated soil, and its shear strength and soil deformation are influenced by the matric suction. At the same time, the uncontrolled or controlled release of shallow gas will cause different degrees of disturbance to the surrounding soils, while the engineering solutions are mostly based on pre-controlled gas release. Some effective measures are presented, which can eliminate the hidden hazards of harmful gas in gassy soils to the construction of subway tunnels.
Abstract：
Gassy soils will be inevitably encountered in the shield construction, and shallow gas in gassy soils can have a huge impact on the shield construction process and pose serious hazards to construction workers. After summarizing the types of gassy soils, the pressure of shallow gas, the buried depth and gas composition in various regions of China, it is found that most are dominated by CH4 gas generated by the decomposition of organic matters,with slightly different causes. Based on analysis on existing disaster cases, it illustrates the engineering influence of shallow gas in gassy soils, the impact of controlled gas release, and the influence of matric suction. The results show that gassy soil is a special unsaturated soil, and its shear strength and soil deformation are influenced by the matric suction. At the same time, the uncontrolled or controlled release of shallow gas will cause different degrees of disturbance to the surrounding soils, while the engineering solutions are mostly based on pre-controlled gas release. Some effective measures are presented, which can eliminate the hidden hazards of harmful gas in gassy soils to the construction of subway tunnels.
DING Zhi1,
2 HE Chenyang1 ZHANG Xiao1 ZHANG Wenhong3 WU Sheng4
.An Outlook for Researches on the Impact and Control Technology of Shield Construction in Gassy Soils[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(5): 9-20
2021, Vol. 58 