Analytical Stability Analysis of Rainfall-Infiltrated Slopes Based on the Green–Ampt Model

Abstract

Rainfall infiltration can alter the pore-water pressure and decrease matric suction, which can lead to slope instability and landslides. Most of the previous numerical studies conducted on rain infiltration have assumed a two-dimensional (2D) failure mechanism, which neglects the three-dimensional (3D) characteristics of slopes. An analytical assessment framework was developed using the upper-bound theorem of limit analysis to determine the factor of safety and failure pattern in the case of a 3D vertical cut slope under diverse rainfall situations combined with the unsaturated soil mechanics. The Green–Ampt model was adopted to depict the infiltration process and the progression of the wetting front into the soil. The slope factor of safety was determined using the energy balance equation by adopting the strength reduction approach. The validity of the framework was verified using the numerical simulation method. The effects of duration, intensity, and patterns of rainfall and the 3D traits of slope on the slope failure pattern and stability were determined. A set of design charts was included for the preliminary design. The present study quantitatively determines the stability of slopes susceptible to rainfall infiltration.