| Taking Xiaoxigou tunnel on Zhangjiajie-Sangzhi second-class highway as background, according to the weak broken wall rock, a comprehensive research method composed of in-situ test,numerical simulation and back analysis methods, was adopted to study the stability of surrounding rock and characteristics of support structure in weak broken wall tunnel concretly, some conclusions with guiding significance and practical value were obtained as following:(1) Combining actual construction condition, the inner force of tunnel initial support and lining structure, and surrounding rock pressure were tested in-situ, also its results were analyzed, based on that, the stability of surrounding rock and the characteristics of tunnel support structure in weak broken wall rock were evaluated and discussed preliminarily.(2) By means of plane FEM, the force states of lining structure and the effects of it against to stability of surrounding rock at different surrounding rock classification and burial depth were analyzed concretely, the dynamic force characteristics of support structure and stability of surrounding rock at different contruction stages in weak broken wall rock were revealed.(3) 3D simulating models were established furtherly, some working conditions at different burial depth and surrounding rock classification were calculated. The effects of bench length against to stability of surrounding rock, when the construction method is bench method, were compared, and the reasonable bench length of weak broken rock was proposed.(4) Based on the field test results, the surrounding rock pressure actes on lining structure of Xiaoxigou tunnel was back analyzed, so the size,distribution features and change laws of surrounding rock pressure of shallow buried tunnel in weak broken wall rock were ensured preliminarily. |
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