Slope Stability Analysis as Applied to Rainfall- triggered Landslide in Itogon, Benguet Province, Philippines

Abstract

Rainfall-triggered landslides are common in places where typhoons are frequently occurring such as the Philippines which experiences at least 20 typhoons per year. Heavy rainfalls saturate soil and affects the stability of the slopes causing landslides. A catastrophic rainfall-triggered landslide happened in Brgy. Ucab, Itogon, Benguet in Luzon Island which occurred during the Tropical Cyclone Mangkhut or locally known as Typhoon Ompong on September 15, 2018 having 94 casualties. The study focused on slope stability analysis of rainfall-triggered landslides to help improve the current understanding of the rainfall-triggered landslide in the area. The findings of the study can be used in modeling rainfall-triggered landslide hazard maps. The slope model of the landslide in Itogon was modelled using GEO5 2020. Both the analytical method of the Simplified Bishop Method and the numerical solution provided in the software GEO5 2020 were used in analyzing the slope stability of the landslide. The slope stability analysis showed that the slope was unstable upon considering factors such as its geological and hydrological characteristics agreeing with the disastrous event that transpired.