Slope Stability Analysis Considering Degradation of Soil Properties Induced by Intermittent Rainfall

This paper aims to emphasize the importance of considering the degradation of soil properties induced by intermittent rainfall infiltration in the slope stability analysis of unsaturated soils. A simplified linear degradation model and an exponential degradation model, which are characterized by degradation rate and maximum degradation degree, are used to determine the degradation coefficient at specific time steps within the intermittent rainfall. The proposed simplified linear degradation model is implemented through the commercial software package, Geo-studio 2018, specifically the Seep/w and Slope/w modules. The incorporation of soil degradation into the slope stability analysis is justified via comparisons against an example on the Geo-studio website. It is found that the number of sub-rainfalls exerts a significant influence on the minimum Factor of Safety (FoS) of the unsaturated soil slope stability, whereas the effect of rainfall intervals on the minimum FoS at the end of each sub-rainfall is trivial. The degradation of soil properties induced by intermittent rainfall infiltration can be properly simulated by the proposed simplified linear and nonlinear degradation models. It must be noted that decision making on early warnings can be different even for moderate rainfall with and without consideration of the degradation of soil properties.