大坪山深埋公路隧道地应力场分布规律探讨

Discussion on Distribution of In-situ Stress in Highway Tunnel with Great Depth in Daping Mountain

针对大坪山隧道埋深大、断层带穿越、围岩局部较破碎、整体稳定性差等特点,采用三维有限元法反演隧址区初始地应力场并建立三维地质模型,模拟在自重、水平方向挤压和剪切等4种工况下的构造应力场;用最小二乘法求解回归系数及实测点的计算值,与实测值应力分量对比,给出隧道洞轴线主应力等值线图,探讨隧址区初始地应力场的分布规律及影响因素,结果表明:地应力测试方法、回归公式的相关性和模型的精度、地形和地质构造、边界条件的施加方式及测点岩体质量等均会影响地应力场的反演结果。

According to the characters of the tunnel with great depth in Daping Mountain, where fault zone exists, the surrounding rock is partly broken and overall stability is poor, the initial geostress field of tunnel area is analyzed by 3D multivariate FE regression. A 3D computational model is established to compute geostress in four cases, including gravity, tectonic stress field for horizontal extrusion and shear etc. And the regression coefficients are solved using the least square method, and then, the calculation value is compared with the measured stress components. Principal stress isoline of tunnel axis is plotted and the regularities of geostress distribution and their influencing factors are investigated. The results show that ： the inversion results of the stress field are affected by many factors, such as methods of stress testing, the correlation of regression formula and the precision of the model, the terrain and the geological structure, the way on boundary conditions, rock quality and so on.