Abstract: Rainfall is one of the main factors that induce slope instability and damage, and the resulting economic losses are extremely huge. The effective stress and pore water pressure of unsaturated soil slope was compared and analyzed by the finite element numerical analysis software Geo-studio, with and without considering the coupling effect of seepage and stress. The effects of different rainfall intensities, durations and types on slope stability were studied. The results show that the coupling effect of seepage and stress accelerates the rise of surface pore water pressure and the dissipation of soil matrix suction and reduces the strength of soil. The safety coefficient obtained by the coupled analysis is smaller than that obtained by the uncoupled analysis. The greater the rainfall intensity is, the faster the rainwater infiltration speed is, and the faster the slope stability safety coefficient decreases. Moreover, the longer the rainfall duration is, the deeper the influence of rainfall infiltration is, and the lower the slope stability safety coefficient is. Under the action of frontal rainfall, the safety coefficient of slope stability decreases most rapidly, followed by the uniform rainfall, and finally rear frontal rainfall.

Key words: geotechnical engineering; rainfall; seepage-stress coupling; unsaturated soil; stability

摘要： 降雨是诱发边坡失稳破坏的主要因素之一，由此造成的经济损失极其巨大。通过Geo-studio有限元数值分析软件，在考虑/不考虑渗流-应力耦合作用情况下，对非饱和土边坡有效应力和孔隙水压力进行对比分析，研究了不同降雨强度、持时和类型对边坡稳定性的影响。结果表明：渗流-应力耦合作用使得表层孔隙水压力上升速度及土体基质吸力消散速度加快，土体强度降低，耦合分析得到的安全系数比非耦合分析小；降雨强度越大，雨水下渗速度越快，边坡稳定性安全系数下降速度越快；降雨持时越长，降雨入渗影响深度增加，边坡稳定性安全系数越低；前锋型降雨作用下边坡稳定性安全系数下降最快，其次是均匀型降雨，最后是后锋型降雨。

关键词: 岩土工程；降雨；渗流-应力耦合；非饱和土；稳定性