降雨入渗对花岗岩残积土高路堤边坡稳定性的影响

为研究降雨入渗对花岗岩残积土高路堤边坡内部水位线分布、负孔隙水压力消散、稳定性的影响, 采用Geo-studio软件中的seep模块模拟短时间特大暴雨、长时间小强度降雨两种工况下边坡的入渗规律, 并结合花岗岩残积土遇水软化的特性以及饱和-非饱和理论对现有的饱和-非饱和抗剪强度理论、土体重度进行修正, 最后将渗流计算的孔隙水压力导入到FLAC^3D中对路堤稳定性进行数值模拟, 结果表明:花岗岩残积土高路堤边坡内部水位线随降雨历时增加由坡脚逐渐上升;相同降雨量下, 长时间小强度降雨对边坡内部水位线上升的影响明显大于短时间特大暴雨工况;综合考虑负孔隙水压力的消散、软化效应、土体重度变化等因素的影响, 短时间特大暴雨对边坡稳定性影响较小, 长时间小强度降雨对花岗岩残积土高路堤边坡稳定性影响较大。

Impact of Rainfall Infiltration on Slope Stability of High Embankment with Granite Residual Soil

In order to analyze the effect of rainfall infiltration on water line inside  embankment slope, negative pore water pressure dissipation and slope stability, the infiltration pattern was investigated by simulating two conditions (short-time particularly extraordinary rainstorm and long sustained rainfall) with the seep module of Geo-Studio software. The existing saturated-unsaturated shear strength theory and unit weight of soil were modified based on the characteristics of granite residual soil being softened with water, as well as saturated-unsaturated theory. Finally, the pore water pressure obtained from seepage calculation was induced into FLAC^3D for the numerical simulation of embankment stability. It is found that with time going by, the water line inside the embankment of granite residual soil increases gradually from the slope foot, and with the same precipitation, the sustained small rainfall brings greater influence on the rising of water line inside the slope. With negative pore water pressure dissipation, softening effect and unit weight of soil taken into comprehensive consideration, it is concluded that sustained small rainfall, compared with short-time particularly extraordinary rainstorm, will bring greater impact on the slope stability for the embankment of granite residual soil.