Analytical Method for Calculation of Surrounding Rock Pressure of Shallow-Buried and Unsymmetrically Loaded Tunnel Adjacent to Variable Slope
YAN Tao1, LI Kunjie1, MOU Zhiheng1, ZHANG Jiaxin1, YU Li1, LI Qi2, LI Guoqing1, PENG Tao3
1. School of Civil Engineering，Southwest Jiaotong University，Chengdu 610031，China; 2. College of Architecture and Urban-Rural Planning，Sichuan Agricultural University，Chengdu 611830，China; 3. Chengdu Surveying Geotechnical Research Institute Co. Ltd. of MCC, Chengdu 610023, China
Abstract：At present the surrounding rock pressure of shallow-buried and unsymmetrical loading tunnels is generally calculated by code for design of road tunnel. However，when the two portal parts of twin tunnels are not located at the same mileage，one of them will be constructed adjacent to the excavated subgrade slope，rather than under a natural mountain slope. In this case，the code is not applicable to the calculation of surrounding rock pressure of the tunnel. To solve this problem，an analytical solution for calculating the surrounding rock pressure of the shallow-buried and unsymmetrically loaded tunnel adjacent to variable slope is proposed using the limited equilibrium theory，taking a highway tunnel in Anhui province as a prototype. The results indicate that due to the variable slope，the vertical pressure in the surrounding rock of deep-buried side calculated by the modified algorithm is smaller than that calculated by the code with a relative error of 15.98%，while values of horizontal pressure in the deep-buried rock remain unchanged. However，in the surrounding rock of shallow-buried side，both vertical and horizontal rock pressures calculated by the modified algorithm are smaller than that by the code，with relative errors being 24.93% and 5.50% for vertical and horizontal pressures，respectively. Therefore，the variable slope has a greater influence on the shallow side. In addition，the surrounding rock with variable slope has a larger bias rate than that with a natural slope. Values of stress，equivalent stress and rock displacement of the former are approximately 1–5 times larger than those of the latter，indicating that the tunnel with variable slope is more unsafe.
严涛, 李坤杰, 牟智恒, 张佳鑫, 于丽, 李琦, 李国庆, 彭涛. 变坡条件下浅埋偏压隧道围岩压力解析法[J]. 西南交通大学学报, 2020, 55(3): 531-536.
YAN Tao, LI Kunjie, MOU Zhiheng, ZHANG Jiaxin, YU Li, LI Qi, LI Guoqing, PENG Tao. Analytical Method for Calculation of Surrounding Rock Pressure of Shallow-Buried and Unsymmetrically Loaded Tunnel Adjacent to Variable Slope. Journal of SouthWest JiaoTong University, 2020, 55(3): 531-536.
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