Analytical solution for infiltration into single-layer cover under heavy rainfall events and its application for slope stability analysis

In recent years, the extreme rainfall events have occurred frequently in China, and so investigating the infiltration law and slope stability of single-layer soil covers under heavy rainfall events is of great significance. An analytical solution for rainwater infiltration into single-layer soil covers is derived based on the two-dimensional governing equation for unsaturated flows. This analytical solution is obtained by employing the constant flow rate and constant pore water pressure head as the top boundary conditions of the cover before and after the surface soil reaches saturation during a heavy rainfall event. The analytical solution is validated by comparing with the results of the finite element software Geostudio-Seep/W. Based on the analytical solution and the theory of shear strength of unsaturated soils, the variation of the factor of safety of a single-layer soil cover under a heavy rainfall event is analyzed. The results indicate that the greater depth the potential sliding surface, the slower the response of the factor of safety to rainfall. During the whole rainfall period, the factor of safety with the bottom surface of the cover as the sliding surface remains the smallest, indicating that the cover is most prone to sliding along this sliding surface. The analytical solution obtained in this study provides a simple and practical tool for evaluating the anti-seepage performance and stability analysis of single-layer soil covers.