Modified Green–Ampt Model Considering Vegetation Root Effect and Redistribution Characteristics for Slope Stability Analysis

The Green–Ampt (GA) model is widely applied in practice because of its simplicity and relatively few parameters. However, the GA model and its modifications are mostly only suitable for uniform rainfall, and rarely account for the effect of water uptake by vegetation roots. In this study, a modified GA model that accounts for both roots and moisture redistribution is proposed to assess slope stability. Compared with the numerical solution, the modified GA model slightly overestimates the wetting front depth and underestimates the moisture content of surface soil. The hydrological and mechanical effects of vegetation roots on slope stability are also incorporated in the proposed model. Parametric analyses are performed to investigate the effects of parameters including rainfall intensity on the safety factor ( F s ). The results show that the wetting front depth decreases/increases with the increase of slope angle/rainfall intensity, and F s of the slope decreases with the increase of slope angle and rainfall intensity. The safety factor of the slope is negatively correlated with rainfall duration and initial moisture content. Exponential and triangular roots have more significant effect on reinforcing shallow soils than uniform roots. The safety factor of the shrub-covered slope is 1.45 times that of the bare slope. The proposed method has the advantages of simplicity and few parameters.