不同降雨条件下含软弱夹层土坡渗流特性数值分析

为了研究含软弱夹层土坡在不同强降雨条件下的渗流特性, 以临长高速公路(京珠高速湖南临长段)左侧某含软弱夹层失稳边坡为研究对象, 采用有限元Geo-studio软件建立含软弱夹层土坡数值计算模型, 基于饱和-非饱和渗流理论, 拟定大雨、暴雨及大暴雨3种强降雨条件, 开展了不同降雨条件下含软弱夹层土坡的渗流特性研究。研究结果表明, 当累积降雨量一定时, 3种降雨条件引起含软弱夹层边坡孔隙水压力变化程度大小顺序为：大雨>暴雨>大暴雨; 由于软弱夹层的存在, 边坡因雨水入渗而发生滑坡的进程有所提前; 3种降雨条件下, 坡面湿润峰在粉质黏土层内大体呈现为均匀入渗, 在软弱夹层内呈现“V”字型分布。降雨量一定的情况下, 降雨等级为大雨时的湿润峰发展速率最快, 暴雨次之, 大暴雨最慢。

Numerical Analysis for Seepage Characteristics of Soil Slope with Weak Intercalations under Different Rainfall Conditions

A slope with weak intercalation on the left side in Lin-Chang Expressway (Lin-Chang Section in Hunan Province of Beijing-Zhuhai Expressway) was selected to study the seepage characteristics of soil slopes with weak intercalated layers under different heavy rainfall conditions. The Geo-studio software is used to establish a numerical calculation model for such weak intercalated soil slopes. Based on the saturated-unsaturated seepage theory, three rainfall conditions including heavy rain, rainstorm and heavy rainstorm were selected in the study. Results showed that at a certain precipitation accumulation, the pore water pressure of the slope with weak intercalation under three rainfall conditions changed in the following orders: heavy rain> rainstorm > heavy rainstorm. Due to the existence of weak intercalations, the landslide caused by rainfall infiltration into slope would be progressed ahead of the predicted time. Under three kinds of rainfall conditions, the wet peak of the slope surface appeared to be uniform infiltration in the silty clay layer, and presented to be “V” shape distribution in the soft interlayer. With the constant precipitation, heavy rain would lead to the fastest development of wet peak, followed by rainstorm, while heavy rainstorm would result in the slowest development of the wet peak.