Numerical study on the factors influencing the stability of the unsaturated soil slopes under rainfall infiltration

Based on the saturated-unsaturated seepage theory and shearing strength theory, the coupling analysis of the seepage field and the stress field was carried out by the numerical simulation using the two-phase flow configuration in FLAC. The safety factor of the slope was calculated by the shear strength reduction method. The influence of the duration and intensity of the rainfall and soil´s saturated permeability coefficient to the slope stability was investigated. The results show that as the duration of the rainfall increases, the safety factor of the slope decreases; while the intensity of the rainfall keeps smaller than the saturated permeability coefficient, there is a positive correlation between the saturated permeability coefficient and the safety factor.