浅埋偏压隧道边坡稳定性分析

Slope Stability Analysis of Shallow Buried Tunnel Under Bias Pressure

基于有限元软件建立三维弹塑性模型,依托某隧道边坡工程,探讨了“锚杆+抗滑桩”联合支护参数对边坡稳定安全系数以及最大剪应变的影响,进而得到最佳支护方案。通过现场监测结合数值模拟,对比了有无该支护方案下边坡及隧道的围岩变形特征,利用抗滑桩应力与锚杆轴力的分布特征,再次明确该方案的支护效应。结果表明:最佳支护方案为方案A (抗滑桩14 m、锚杆14 m),支护后的边坡安全系数显著提高,抗滑桩与锚杆相比对边坡的安全系数影响更大;相较于无加固工况,联合支护下边坡的水平位移与竖直位移显著降低,土体变形区范围明显缩小;抗滑桩体主要承受压应力,最大值出现在桩中部,总体呈现“中端大,上下两端小”的分布模式;锚杆轴力随着锚固深度增加呈现线性减少趋势;隧道变形实测数据与数值模拟结果基本吻合,联合支护方案对控制隧道变形有显著效果。

In this paper, a three-dimensional elastic-plastic model was established based on the finite element software. Relying on a tunnel slope project, the influence of “bolt + anti-slide pile” support parameters on the safety factor of slope stability and the maximum shear strain was discussed, and then the best support scheme was obtained. Through field monitoring and numerical simulation, the deformation characteristics of surrounding rock of slope and tunnel with or without this support scheme were compared. Using the distribution characteristics of anti-slide pile stress and bolt axial force, the support effect of this scheme is clarified again. The results show that the best support scheme was A(anti-slide pile 14 m, bolt 14 m), the safety factor of the slope after support is significantly improved, and the anti-slide pile has a greater impact on the safety factor of the slope than the anchor bolt. Compared with the condition without reinforcement, the horizontal displacement and vertical displacement of the slope under combined support are significantly reduced, and the range of soil deformation area is significantly reduced. The anti-slide pile mainly bears the compressive stress, and the maximum value appears in the middle of the pile, which generally presents the distribution mode of “large in the middle and small at the upper and lower ends”. The axial force of bolt decreases linearly with the increase of anchorage depth. The measured data of tunnel deformation are basically consistent with the numerical simulation results, and the combined support scheme has a significant effect on controlling tunnel deformation.