Analysis of Rainfall-Induced Slope Failure Using Monte Carlo Simulations: A Case Study

Climatic changes influence the depth of slip surface drastically. Slope failures particularly, failures caused by rainfall, slip surface lie above the water table (i.e., in unsaturated zone). In this zone, suction develops, which increases the slope stability in dry conditions. During rainfall, water infiltrates into the soil pores due to which suction stress decreases significantly, and thereby, stability of slope decreases. Relation between soil suction and soil water content can be represented using soil water characteristic curve (SWCC). The measured SWCC, hydraulic conductivity (\(k_{\text{s}}\)) of the soil are inherently variable. Conventional approaches may render unrealistic safety of the slope sometimes, as they do not account for variability. Therefore, it is highly appropriate to develop a reliability-based design (RBD) for stability analysis of rainfall-induced slopes. In this study, an efficient reliability analysis using Monte Carlo Simulations (MCS) is presented for rainfall-induced slope failures. A case study on shallow slope failures near Seattle, Washington, which are of sandy colluvium deposits on steep coastal hill slopes, is presented.