Abstract: The method of rainfall infiltration analysis directly affects the prediction and prevention of rainfall-induced landslides. Green-Ampt (GA) model, which has clear physical meaning and few parameters, has been paid more and more attention in the analysis of rainfall-induced landslides. However, this method ignores the existence of the unsaturated layer of the wetting layer and the seepage of the saturated layer, which affects the calculation accuracy. In view of the above deficiencies, the LSGA model is established based on the stratified hypothesis and the saturated layer seepage, and the expression of slope stability coefficient is established. All results show that LSGA model can be simplified to GA model for infinite slope without considering the stratified hypothesis of wetting layer, which indicates that GA model is a special case of LSGA model. The slope infiltration depth and instability time of GA are obviously behind the LSGA model. The saturated layer seepage has slight effect on the characteristics of the wetting layer, but has a great influence on the stability of slope. On the contrary, the effect of slope length on wetting layer characteristics is important, but the effect on slope stability is slight. All results obtained by using LSGA model and the stability evaluation method are basically consistent with the phenomena revealed by the model test, which proves that the method has better accuracy and reliability than others.

Key words: rainfall infiltration, Green-Ampt model, stratified hypothesis, seepage, slope stability