Determination of Geotechnical Properties of Soil and Disaster Vulnerability Analysis

This research aims to understand the factors and processes contributing to landslides by determining the geotechnical properties of soils and conducting numerical analyses of slope failures along the state highway in the eastern part of Mizoram, where Melbuk village is situated uphill of the study sites. This study employed geotechnical approaches and numerical analyses to determine the factor of safety. Due to toe-cutting for the construction and widening of the road, landslides triggered by rainfall occurred. Two landslides, at location 1 and location 2, were investigated where slope failure occurred down slope of Melbuk village. The stability of the slopes and probable landslide mechanisms were determined using various techniques, including limit equilibrium techniques, which evaluate the driving and resisting force equilibrium along possible failure surfaces. The Limit Equilibrium Method is extensively used in geotechnical engineering to assess slope stability and suggest remedial measures. From the Atterberg limit of the soil, it is observed that location 1 soil has silty-clay soil and location 2 has silt soil. The laboratory analysis of soil obtained by direct shear test concluded that the cohesion and angle of friction for location 1 is greater than location 2, indicating that location 1 has higher stability. The stability of the slopes was analyzed, and the factor of safety obtained by different methods is 0.827 and 0.719, respectively. Both the study sites has factor of safety less than 1, indicating an unstable slopes which are highly vulnerable to sliding. A debris slide is observed at both study sites. Hence, remedial measures are suggested based on the research findings.