南江县古坟坪滑坡降雨入渗观测与稳定性分析

为研究降雨条件下浅层土质滑坡的入渗规律及其对稳定性的影响,以南江县古坟坪滑坡为例,对该滑坡区及其邻近区域开展了不同深度体积含水率和基质吸力监测。结合实时降雨量资料,分析降雨条件下坡体内部的含水率和吸力的动态变化过程,并基于无限边坡模型开展坡体稳定性计算。结果表明:2^#监测点位于滑坡邻近区域,初始体积含水率随深度的增加而减小,但滑坡区后缘存在基岩汇水点,导致1^#监测点初始体积含水率随深度的增加而增加;1^#监测点基岩面处存在入渗的优势通道,降雨时基岩面处体积含水率最先响应;降雨过程中稳定性系数随着深度的增加不断减小,最危险的滑动面处于基岩面,但是现阶段滑坡处于稳定状态,稳定性系数>1。通过对滑坡体入渗规律和稳定性的分析,可为该类典型滑坡的预报预测、危险性评估及灾害治理提供科学的理论依据。

Rainfall Infiltration and Stability of Gufenping Landslide in Nanjiang County

In an attempt to study the infiltration law and its effect on the stability of shallow landslide induced by rainfall, the volumetric water content and matric suction at different depths of Gufenping landslide in Nanjiang County and its adjacent areas were measured. The dynamic changes of water content and matric suction in slope under rainfall condition were examined in association with real-time rainfall data. Moreover, the slope stability was calculated by using an infinite slope model. Results revealed that the initial volumetric water content at monitoring point 2^#, which is located in the adjacent of landslide, decreased as depth increased; the initial volumetric water content at monitoring point 1^#, however, augmented as the point went deeper due to a groove on the bedrock surface of the scarp of landslide. In rainfall condition, the volumetric water content at the bedrock surface responded the most rapidly in the presence of a favorable seepage channel. In the meantime, the factor of safety reduced with the increase of depth, with the most dangerous sliding surface along the bedrock surface. Nevertheless, the factor of safety is larger than 1, indicating that the landslide is still stable at present. The research results are expected to provide a scientific basis for the forecasting, risk assessment and disaster management of shallow landslides.