Slope Stability Analysis Considering Heavy Rainfall: A Case Study

Abstract

Rainfall infiltration is one of the important factors affecting the stability of a slope. Rainfall infiltration will change the groundwater level, which will cause a reduction in the mechanical characteristics of the soil. During the infiltration process, the progress of the wetting front in soil depth results in an increase in water content. An increase in hydraulic gradient associated with an increase in infiltration velocity could significantly reduce the safety factors of a slope. Indeed, between December 25th, 2013 and March 7th, 2014, the piezometric level of the studied slope located in northern Morocco increased by more than 1.7m, and after the rains of January 17th and the 18th, 2014, it exceeded 31 mm in 15 hours, and the horizontal soil displacement was accelerated significantly. This paper presents a methodology for slope stability analysis considering rainfall infiltration. Initially, the Green-Ampt infiltration model was used in this study to estimate the wetting front depth. Subsequently, the three-dimensional safety factors were calculated for each rainfall intensity using the Hovland method. Results show the relationship among the safety factors, the rainfall duration, and the depth of the wetting under rainfall and they also reveal that the rate of stability variation during infiltration is not significant.