中文摘要：

四川南江红层地区在降雨期间往往发生大规模的群发性低缓浅层土质滑坡,滑坡上覆土层普遍在1～5m之间,以3m居多。针对该地区的浅层土质滑坡,根据相关资料及现场调查,概化得到了该类斜坡的地质剖面及岩土层性质,利用Geo-studio分析了土厚1～5m斜坡基覆界面处孔隙水压力的变化及土层中湿润线的动态变化,计算了斜坡的瞬态稳定性;试验取得不同含水率下的土体c、φ值,研究软化作用对斜坡稳定性的影响。结果表明：土层越厚,基覆界面处累积的孔隙水压力越大,斜坡稳定性系数越小,斜坡稳定性变化与基覆界面处孔隙水压力的发展变化关系密切;土层越薄,雨水入渗途径越短,基覆界面接受雨水软化的时间越长,土体抗剪强度衰减越多;c、φ值越低,斜坡稳定性系数越低。抗剪强度c、φ是影响该类斜坡稳定性的重要因素之一。

英文摘要：

Lots of shallow landslides in residual soil slopes are triggered by rainfall in the red-bed area of Nanjiang. Most of them occurred in slopes with thicknesses from 1 to 5 m of residual soil,and the majority were 3 m,the grade range from 5° to 20°. Geological conditions of residual soil slopes and climate condition in the redbed area of Nanjiang are presented. The cross-sections and engineering properties of the residual soil slopes are presented. A finite element software,Geo-Studio,is used to study the change in pore-water pressure and the phreatic line with thicknesses of residual soil from 1 to 5 m. Their transient stabilities are calculated and analyzed. Change in c and φ influences the slope stability due to the softening. Results from the parametric analyses show that the thicker the residual soil is and the greater the cumulative pore-water pressure on the bedrock cover interface is,the lower the cumulative pore-water pressure and stability factor are,the more closely the stability of slope is related to the pore-water pressure on the bedrock cover interface. The thinner the residual soil is and the longer the time of softening is,the weaker the strength of rock mass is. The slope stability decreases with a decrease in shear strength c and φ and a fall in stability factor. The shear strength c and φ is one of the important factors affecting the slope stability.