Analytical solution of rainfall infiltration for vegetated slope in unsaturated soils considering hydro-mechanical effects

Developing analytical solutions for water flow in partially saturated soil slopes is a significant issue in practical engineering. In this study, an analytical solution to rainfall seepage into vegetated unsaturated soil slopes considering hydro-mechanical coupling is proposed using Green's function. The proposed analytical solution is compared with the solution of finite element method. Combined with the limit equilibrium method, the proposed analytical solution is used to assess the slope stability. Parametric studies are performed to investigate the effects of slope angle, rain intensity, suction-based elastic modulus, and transpiration rate on pressure head and factor of safety for slopes. The results show that the pressure head and factor of safety (Fs) decrease with the increase of slope angle or rain intensity. As the transpiration rate increases, the pressure head and Fs increases. The smaller the absolute value of the suction-based elastic modulus, the more obvious the effect of hydro-mechanical coupling on Fs. Additionally, the vegetated slope stability varies more greatly than that of bare slopes due to the hydro-mechanical coupling effect. The proposed analytical solution is simple in form and has few input parameters, which can be used as a simple and effective method for analyzing rainfall infiltration in vegetated slopes.