立体交叉隧道围岩变形特性及合理净距的稳定性研究

通过超前地质预报和三轴压缩试验对立体铁路隧道交叉段围岩进行分析,同时基于强度折减法对交叉段围岩安全稳定性进行数值模拟分析。主要得出以下结论:三轴压缩试验表明随围压增大,围岩的非线性应变软化效应不断消散;围压在应变软化及强度残余出现之前显示出较高的敏感性,应在此阶段前对围岩进行支护防止出现坍塌;数值模拟结果表明边墙的变形量最大,其次为交叉区段,上跨隧道拱顶和下穿隧道仰拱处最小;且上跨隧道的仰拱、交叉中心区段以及下穿隧道的拱顶随着净间距的增长其变形量变化最为明显;立体隧道交叉段之间存在明显的塑性区叠加现象,且随着隧道净间距的减小,交叉段围岩塑性区不断增大,同时围岩变形量也随之增大。

The surrounding rock of the cross section of the three-dimensional railway tunnel is analyzed by advanced geological prediction and triaxial compression test,and the safety and stability of the surrounding rock of the cross section is numerically simulated and analyzed based on the strength reduction method.The main conclusions are as follows:the triaxial compression test shows that the nonlinear strain softening effect of surrounding rock dissipates with the increase of confining pressure,and the confining pressure shows high sensitivity before strain softening and strength residue.The surrounding rock should be supported before this stage to prevent collapse.The numerical simulation results show that the deformation of the sidewall is the largest,followed by the cross section,and the arch of the upper span tunnel and the inverted arch of the tunnel are the smallest.And the deformation of the inverted arch,the cross center section of the upper span tunnel and the vault of the lower tunnel changes most obviously with the increase of the net distance,and there is an obvious superposition of the plastic zone between the intersection sections of the tunnel,and with the decrease of the net spacing of the tunnel,the plastic zone of the surrounding rock of the cross section is increasing,and the deformation of the surrounding rock is also increasing.