Granite residual soil is widely distributed in southern China

and it has many poor physical and mechanical properties. Slopes of this type of soil are prone to deformation and failure under the action of rainfall. Therefore

it is of great significance to study the rainfall infiltration mechanism in granite residual soil slopes. On the basis of Green-Ampt model

the initial moisture content

underground water level and unsaturated characteristics of the soil are comprehensively considered. An infiltration model suitable for different rainfall conditions is established

and verified by comparison between numerical simulations and other models. Then

the proposed model is used to analyze granite residual soil slopes under three typical rainfall conditions. The results show that the initial water content has little effect on the migration rate of the wetting front when it is far from groundwater level

whereas the migration rate increases gradually when the wetting front is near groundwater level

presenting an exponential trend. In the same rainfall time

under the condition that the rainfall intensity is slightly greater than the saturated permeability coefficient of soil

the wetting front migration depth is the largest and the slope stability factor decreases the most.