浅埋隧道破裂面的极限平衡分析法

为了获得浅埋隧道破裂面稳定性定量评判指标,采用极限平衡原理与变分方法分析浅埋隧道破裂面的分布状态,以此为基础,建立以安全系数为评判指标的浅埋隧道稳定性分析方法。结合数值模拟分析得出,围岩破裂面接近直线,起始点位于隧道拱腰至拱顶区域,随着隧道埋深的减小,产生冒顶的区域越向拱顶集中,且数值模拟获得的破裂区域与理论结果较接近;埋深对隧道安全系数影响较小,围岩内聚力和内摩擦角对隧道安全系数影响显著,随着内聚力和内摩擦角增加,隧道安全系数增加;F为静止土压力时,理论分析和数值模拟所获安全系数发展趋势一致,且所获得安全系数小于数值模拟结果,较为保守。

Analysis on Shallow Tunnel Sliding Surface with Limiting Equilibrium Method

In order to elicit shallow tunnel's sliding surface and quantitative stability judging index,sliding surface of shallow tunnel is studied on the basis of limit equilibrium method and variation principle.Safety factor serves as stability judging index,and the method of shallow tunnel stability analysis was set up.Theoretical method and numerical simulation were analyzed comparatively and following conclusions were got.Firstly,results of the two methods show that sliding surface starting point locates between hance and crown.When shallow tunnel buried depth is decreasing,their potential sliding zone moves to the crown,and numerical damage zone is close to the zone surrounded by theoretical sliding surface.Secondly,buried depth has little influence on tunnel safety factor,but surrounding rock cohesion and internal friction angle have great influence on tunnel safety factor.When cohesion and internal friction angle is increasing,tunnel safety factor enhances.Lastly,when F is equal to static earth pressure,safety factor got by numerical and theoretical change in the same way,and theoretical safety factor is more conservative than the numerical result.