Effects of the size of particles on rainfall-induced slope instability in granular soils

Rainfall-triggered landslides is a common natural hazard with significant consequences all over the world. Most available methods for predicting rainfall-triggered landslides are based on regional statistical data of past slope failures and rainfall records rather than a physically based model that takes the mechanism of the problem into account. Stability of slopes in unsaturated soils is mainly affected by suction distribution, which influences seepage and shear strength. Soil-water characteristic curve (SWCC) plays a critical role in suction distribution of the soil. This parametric study investigates the effects of changes in the size of particles, and related changes in SWCC, on the stability of an unsaturated slope under rainfall. A numerical model has been created for a real flume experiment, and a sensitivity study has been carried out. Results show that changes in the size of particles, and related changes in SWCC, cause significant changes in the stability of the slope, the time to failure, and triggering-rainfall intensity-duration threshold. This study could be useful for early warning for rainfall-triggered landslides