降雨条件下考虑饱和渗透系数变异性的边坡可靠度分析

土体饱和渗透系数表现为天然的变异性，为此基于Green-Ampt模型建立了考虑饱和渗透系数变异性的降雨入渗物理模型，并藉此模型确定了坡体湿润锋深度和含水率分布。然后结合无限长非饱和土边坡稳定模型得到解析形式的反映边坡稳定性的极限状态函数。采用Monte Carlo法对饱和渗透系数进行随机抽样并最终建立降雨条件下考虑饱和渗透系数变异性的边坡概率分析框架。针对一假想边坡，探讨了饱和渗透系数的变异系数、降雨持时和降雨强度对边坡破坏概率以及破坏发生时间概率分布的影响，结果表明：在降雨初期，边坡的破坏概率随饱和渗透系数变异性的增强而逐渐增加，但随着降雨的持续，破坏概率开始随变异性的增强而显著降低；滑坡最可能发生时间的大小并不受饱和渗透系数变异性的影响，而是直接取决于降雨强度；滑坡最可能发生时间所对应的概率却随变异性的增强而逐渐减小。

Reliability analysis of slope stability considering variability of soil saturated hydraulic conductivity under rainfall infiltration

The saturated hydraulic conductivity is inherently variable. An extension infiltration model considering the variability of saturated hydraulic conductivity is established using the classic Green-Ampt model; and then the corresponding depth of the wetting front and the distribution of water content are determined. Meanwhile, a closed form of the limit state function is presented, based on the combination of the extension of the Green-Ampt model and the infinite slope stability model. Random number sequences of saturated hydraulic conductivity are generated following a lognormal distribution using the Monte Carlo simulation method. For a hypothetical slope that is subjected to steady-state rainfall infiltration, a series of parameter analyses is conducted. The results show that the cases with a smaller coefficient of variability have a smaller failure probability in the initial stage of rainfall infiltration. However, as rainfall progresses, the cases with a smaller coefficient of variability have a larger probability of failure instead. The most likely failure time of the slope is not affected by the coefficient of variability, but depends on the intensity of rainfall. The corresponding probability of the most likely failure time decreases with the increase of the variability.