考虑降雨及开挖影响下的厚覆盖层边坡渗流特征及稳定性

摘要

Based on the slope failure mechanism of overburden slope,combined with the cut overburden slope on the ground of Guihai expressway in GuangxiZhuangAutonomousRegion,three rainfall schemes were designed.Using finite element analysis software,the thick overburden slope seepage characteristics and stability were studied considering the effects of precipitation and excavation.The results show that for the form of “overburden soil+bedrock” slope,the saturation line in the toe of slope changes as a“J”shape in the condition of intensive rainfall.When the soil in the toe of slope is saturated,the saturation line moves upalong the soil-rock interface.Under the same condition,the excavation of slopemakesrainfall infiltration faster,the “J” shape of saturation line is more obvious,and the saturation line is higher after excavation.Dominant factors of slope stability in the initial condition are the initial intensity of the rainfall and the condition of slope excavation,dominant factors of change rate of slope stability are the rainfall intensity and rainfall duration.%基于厚覆盖层边坡失稳机理，结合广西桂林—北海高速公路某覆盖层路堑边坡实地情况，设计雨型相同但降雨量不同的3种方案。采用有限元计算软件对考虑降雨及开挖影响下的厚覆盖层边坡渗流特征及稳定性进行研究。研究结果表明：对于形式为“覆盖层土体+基岩”的边坡，其在强降雨作用下坡脚内部浸润线呈“J”形变化；坡脚土体饱和后浸润线沿土−岩交界面向上移动；在同等条件下，边坡开挖导致降雨入渗速度加快，浸润线呈的“J”形变化的特征更明显，且上升高度较开挖前有所提高；决定边坡初始状态下稳定性的主要因素有降雨初始强度与边坡开挖状态，而决定边坡稳定性变化幅度的主要因素为降雨强度与降雨持续时间。