Rainfall infiltration of multi-layer soil slope with an modified green-Ampt model

The Green-Ampt (GA) model is of profound significance for evaluating shallow slope stability caused by rainfall. However, the actual situation of non-uniform initial moisture content at different soil depths and the application of multi-layer soil has rarely been explored. Therefore, the purpose of this study is to provide a modified Green-Ampt model (MGA) that comprehensively considers the non-uniform initial water content at different soil depths and multi-layer soil on slopes. The model is validated using numerical simulations and classic GA model calculations. Additionally, the model is applied to analyze the infiltration process of a multi-layer soil slope under three rainfall conditions and slope gradients in eastern Hubei, China. The results indicate that the wetting front depth increases with increasing rainfall intensity and slope gradient. Furthermore, the infiltration rate of the wetting front suddenly increases at the soil-layer interface. The stability of multi-layer soil slopes decreases as the infiltration rate increases. During disaster prevention and control of multi-layer soil slopes in eastern Hubei China, particular attention should be paid to the short infiltration time of heavy rain and long infiltration time of medium rain.