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Surrounding Rock Stress in the Failure Process of a Tunnel Buried in an Inclined Soft/Hard Interbed Stratum
(1 School of Civil Engineering, Chongqing University, Chongqing 400045; 2 Key Laboratory of New Technology for Construction of Cities in Mountain Area, Ministry of Education, Chongqing 400045; 3 Department of Civil Engineering and Architecture, Chongqing Jiaotong University, Chongqing 400074; 4 Shanxi Transportation Research Institute, Taiyuan 030006)
Abstract Based on the Yajiang tunnel on the Nanchuan-Fuling expressway in Chongqing, a model test for the fail? ure process of a tunnel buried in an inclined soft/hard interbed stratum was performed. The results indicate the tunnel′s failure begins from the soft stratum around the left sidewall. The failure process can be divided into five stages according to the failure characteristics, and the surrounding rock′s failure leads to the unloading effect of the surrounding rock stress. A numerical model of the Yajiang tunnel was also established by finite element software, and the numerical calculation results show that the extreme value of the surrounding rock′s maximum principal stress always occurs at the left haunch, which is different from where failure first happens. According to the stress distribution along the vault route, the third principal stress is the highest one. The surrounding rock stress varies in a shock? ing way as a result of different stratum properties caused by the soft/hard interbed stratum. At the first stage of the failure process, the scope of the pressure arch is about 1.35 times the tunnel′s excavated span.
Abstract：
Based on the Yajiang tunnel on the Nanchuan-Fuling expressway in Chongqing, a model test for the fail? ure process of a tunnel buried in an inclined soft/hard interbed stratum was performed. The results indicate the tunnel′s failure begins from the soft stratum around the left sidewall. The failure process can be divided into five stages according to the failure characteristics, and the surrounding rock′s failure leads to the unloading effect of the surrounding rock stress. A numerical model of the Yajiang tunnel was also established by finite element software, and the numerical calculation results show that the extreme value of the surrounding rock′s maximum principal stress always occurs at the left haunch, which is different from where failure first happens. According to the stress distribution along the vault route, the third principal stress is the highest one. The surrounding rock stress varies in a shock? ing way as a result of different stratum properties caused by the soft/hard interbed stratum. At the first stage of the failure process, the scope of the pressure arch is about 1.35 times the tunnel′s excavated span.
.Surrounding Rock Stress in the Failure Process of a Tunnel Buried in an Inclined Soft/Hard Interbed Stratum[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(4): 68-76
2017, Vol. 54 