降雨条件下浅层滑坡是一种常见、多发的地质灾害现象，为了解边坡稳定性随降雨入渗过程的变化情况，以Green-Ampt入渗模型为基础，并考虑了动水压力的作用，建立了降雨入渗条件下浅层滑坡的概念模型，分别推导了降雨前有、无地下水位条件下的边坡安全系数与降雨时间的关系表达式。从分析结果中可以看出，对于这两种情况下边坡稳定性发生突变的主要原因归结于：前者为在湿润锋与地下水位面接触的短时间内，滑带处的孔隙水压力迅速增高；后者为滑带在浸水饱和情况下，岩土体的强度迅速降低。在此基础上，根据降雨过程中边坡是否达到饱和，提出边坡饱和临界时间的概念，考虑了初始降雨强度小于土壤入渗能力的情况。这个时间可以作为一个参数指标用于浅层滑坡的预警。

Rainfall-induced shallow landslide is a type of commonly occurring geohazards. To explore the evolution of the slope stability during a rainfall event, a conceptual model of rainfall-induced shallow landslide with considering the effect of transient pore water pressure is developed based on the Green-Ampt infiltration model, and the relationship between the factor of safety and precipitation duration for the slope with or without ground water is developed. The results show that for the slope with underground water, the pore water pressure in the slip zone drastically increases once after the wetting front touches the groundwater table; for the slope without ground water, the slip zone become inundated in the water and the soil strength decrease quickly. Based on these results, and according to whether the shallow landslide is completely saturated or not during rainfall, a concept of critical saturating time is proposed, with considering the case that the initial rainfall intensity is less than the soil’s infiltration ability. This critical time can be used as a parameter for early warning the shallow landslide.