强降雨条件下坝肩边坡抗滑稳定性分析

Stability Analysis of Abutment Slope Subjected to Heavy Rainfall

基于饱和-非饱和渗流理论和非饱和土强度理论,建立降雨条件下边坡稳定性分析有限元数值模拟模型,研究考虑强降雨条件下渗流场变化导致饱和区渗透力变化而影响边坡稳定性的强度折减分析法。将此方法应用于广东省乐昌峡左岸坝肩边坡,进行降雨过程边坡渗流变化情况及稳定性变化分析。分析结果表明:在强降雨条件下,地表水入渗将直接导致非饱和区范围缩小、压力水头升高及局部暂态饱和区出现;考虑饱和区渗透力变化的影响,降雨入渗时边坡稳定性将会下降,但由于边坡开挖使得坡角较为平坦,而且上层强风化层的渗透系数较低,故此时边坡仍然处于稳定状态。

Based on the theorem of saturated-unsaturated infiltration and the strength theory of unsaturated soils, the numerical model of slope stability subjected to rainfall is established. That is a strength reduction method, which can consider the influence of seepage load change in the saturated zone. It applies to the deformation calculation and stability evaluation of a left bank abutment slope in the Lechang Gorge in Guangdong Province. Research results show that the range of unsaturated zone would decrease; the pressure water head would increase and the transient saturated zone would appear because of strong rainfall. The factor of safety of engineering slope would decrease due to the seep load change in the saturated zone, but the excavation of slope makes the slope angle flat and the low permeability coefficient of the strong weathered upper layer, so the slope still remains stable.