强降雨作用下昔格达边坡渗流特性及稳定性分析

昔格达地层分布于中国西南，其工程性质极差。为分析上覆第四纪残坡积物的昔格达组粉砂土边坡在强降雨作用下的渗流特性及稳定性，结合石棉县莫家岗滑坡，用数值模拟方法研究坡体渗流规律；用Morgenstern-Price方法计算各时刻坡体稳定性系数，并分析其变化规律。结果表明：雨水在坡体中逐层入渗，雨停后渗流过程将继续发展，由于存在土层分界面，坡体渗流特性不同于均质坡体；降雨过程中，孔隙水压力发生增长的范围在界面附近加速拓展，雨停后，土层分界面附近第四纪残坡积物仍处于近饱和状态；降雨入渗导致坡体边坡稳定性系数下降，且稳定性系数变化对降雨的响应存在滞后性。

Analysis of seepage characteristics and stability of Xigeda Formation slope under heavy rainfall

Xigeda Formation is distributed in southwest of China, and its engineering properties are very poor. In order to analyze seepage characteristics and stability of silty sand slope of Xigeda Formation overlying Quaternary residual slope sediments under heavy rainfall conditions, seepage law of slope is studied by numerical simulation based on Mojiagang landslide in Shimian County; Morgenstern-Price method is used to calculate safety factor of landslide and to analyze their variation laws. The results show that: rainwater infiltrates into slope layer by layer, and seepage process will continue after rainfall. As the existence of soil layer interface, seepage characteristics are different from homogeneous slope; during the rainfall process, the range of pore water pressure growth accelerates near the interface, and the Quaternary residual slope sediments near the interface is still in a near-saturated state after the rainfall; rainfall infiltration leads to reduction of safety factor of the slope, and stability has a lag in response to rainfall.