Finite Element and Vulnerability Analyses of a Building Failure due to Landslide in Kaithakunda, Kerala, India

Abstract

Rainfall-induced landslide is one of the major natural disasters in the Western Ghats of India. Kerala state in southern India received unprecedented heavy rainfall from July to August 2018. The rainfall received was higher than the average for the past 100 years. The present study discusses the investigation of vertical cut failure at Kaithakunda, located in Malappuram district, Kerala, India. It was due to the series of medium rainfall followed by a short period of extremely heavy rainfall. The heavy rainfall triggered the slope failure, which led to the damage of the building and the death of three residents of the building. The index and engineering properties of the soil were evaluated from the laboratory tests. The tests revealed that the soil was silty sand (SM) with low permeability. Tests on the mineral composition and microstructure fabric nature of the soil revealed that the soil was formed due to the weathering action of the parent charnockite rock. The finite element analysis of the slope was carried out using PLAXIS 3D. The analysis was carried out in two stages. The original slope before the vertical cut was modelled as the first stage. The vertical cut was modelled in the second stage to study the actual site condition before failure. The failure occurs due to the increase in pore water pressure in the soil, thereby reducing the matric suction and shear strength of the soil. The vulnerability of the building located near the cut slope is studied using the Support Vector Method to investigate the effect of material on the failure. The results showed the importance of the material properties in the increase of building resistance to 20%.