Analysis of stress path and failure mode of surrounding rock during Mine-by test tunnel excavation
LI Jianhe1，2，SHENG Qian1，ZHU Zeqi1，LENG Xianlun1，NIU Limin3，LIU Shiwei1，2
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. University of Chinese Academy of Sciences，Beijing 100049，China；3. Changjiang Institute of Survey，Planning，Design and Research，Wuhan，Hubei 430010，China)
Abstract：During the underground excavation，the stresses in surrounding rock follow the complex paths. It is a key issue to describe the stress path and its effect on the surrounding rock correctly in underground engineering. The complex stress paths and failure modes of surrounding rock during Mine-by test tunnel excavation are discussed based on three parameters including the crack initial criterion(CIC)，the stress ratio and the lode parameter. It is shown that the disturbance of stress field is mainly concentrated near the excavation face within the scope of the tunnel diameter and the damage of surrounding rock is controlled by the highly concentrated deviatoric stress and stress axis rotation. As the excavation face advances，the deviatoric stress concentration increases and the stress ratio reduces at the top and the bottom of the surrounding rock，where a v-shaped spalling has been formed gradually. The surrounding rock of the tunnel wall unloads gradually，and the damage is changed to be controlled by the tensile stress. The stress path of in-situ rock is more complex than that in laboratory because of the effect of stress rotation. During the excavation of Mine-by test tunnel，the rotation of the major principal stress direction is hardly changed at the top and the bottom of surrounding rock，and the intermediate principal stress and minor principal stress rotate 35.2 degrees before returning to the initial direction. Since the intermediate principal stress has exceeded the rock mass crack initiation strength(CIC＞1)，the stress rotation aggravates the damage degree of surrounding rock.
李建贺1，2，盛 谦1，朱泽奇1，冷先伦1，牛利敏3，刘世伟1，2. Mine-by试验洞开挖过程中围岩应力路径与破坏模式分析[J]. 岩石力学与工程学报, 2017, 36(4): 821-830.
LI Jianhe1，2，SHENG Qian1，ZHU Zeqi1，LENG Xianlun1，NIU Limin3，LIU Shiwei1，2. Analysis of stress path and failure mode of surrounding rock during Mine-by test tunnel excavation. , 2017, 36(4): 821-830.
2017, Vol. 36 
