A hillslope flow model is developed considering 3D saturated and unsaturated flow of water during rainfall events. A finite difference-based numerical model of hillslope flow processes is developed. Four different experiments are done to see the effects of a single- and double-layered soil in pore-water pressure dynamics and slope failure. Results from the numerical model are verified with experimental results. The numerical and experimental values of the pore-water pressure and moisture contents are in good agreement. The results show that the hillslope heterogeneity caused by multiple layers of soil has greater influence on hillslope pore-pressure dynamics and slope failure patterns. The depth of slope failure shows high dependency on layering characteristics of the soil slope and pattern of rainfall. The proposed model provides a perspective on failure mechanism of a single- or double-layered slope under rainfall infiltration.