3d analysis of effect of rainfall patterns on pore water pressures in unsaturated slopes

Rainfall-induced landslides are common natural disasters in many cities such as Hong Kong. During rainstorms, infiltration of rainwater reduces suction within an unsaturated soil slope. This leads to a reduction in shear strength of soils and hence landslides. Two-dimensional transient seepage analyses of pore water pressures in unsaturated soil slopes have been carried out. However, the influence of rainfall patterns on pore water pressure induced by infiltration has seldom been reported. In this paper, three-dimensional computer simulations were carried out to investigate the groundwater responses of an unsaturated cut slope subjected to three different rainfall patterns. Depending on the initial pore water pressures in the ground, rainfall patterns can have different degrees of influence on the groundwater responses. When the initial pore water pressures in the ground are low (i.e. high suction values), the advanced type A seems to be the most critical one for slope instability.