Effect Of Rainfall Infiltration On Stability Of A Tropical Slope From Western Pacific

Tropical cyclones are common to islands in western Pacific including Guam, and they bring large amounts of rainfall within a short duration, thereby triggering landslides. It is well understood that accurate modeling of the response of the hillslope to shallow landslides resulting from heavy rainfall in mountainous basins requires consideration of unsaturated soil mechanics principles. In this study, soil was collected from shallow depths along slopes of a reservoir in southern Guam, and soil water retention curves (SWRC) were obtained in the laboratory. Furthermore, results are presented from transient seepage analyses coupled with limit equilibrium method-based slope stability analyses on a typical slope. Comparison of results with and without a rainfall event captures the sudden drop in matric suction and factor of safety of the slope due to infiltration, which confirms that storm events are the leading cause of landslides in hillslopes located in tropical environmental settings.