Analysis of Slope Failure Using Finite Element Method: A Case Study of the Dehradun Region, India

ABSTRACT Slope destabilization in urbanizing areas, particularly along road-cut hill slopes, poses significant risks to infrastructure and human safety. This study focuses on assessing the stability of slopes in the Siwalik range, a region prone to landslides due to its geological characteristics. Utilizing numerical modeling techniques, specifically the Finite Element Method (FEM) and the Shear Strength Reduction (SSR) technique, we evaluated the stability of various locations along a dilapidated road in Dehradun District, India. The analysis incorporates local geological conditions, including joint abundance and rock mass properties, to determine factors such as total displacement, shear strain, and strength reduction factors (SRF) of the slopes. Our findings reveal a distinct, albeit subtle relationship between SRF and the slope mass rating (SMR). Locations with SRF < 2.35 and ‘Partially stable’ classification were identified as having higher risks of failure compared to those location with SRF > 2.35 and ‘Stable’ classification. Nearly half of the studied slopes are partially stable. Among them, those with relatively low SRF of ≤ 1.52 (four in number or ~25% of all studied slopes) may be poised for failure in the long run. One of the slopes that failed subsequent to the completion of our site study was classified as ‘Partially Stable’ with ‘Fair’ rock (rock mass rating [RMR] classification) and had a SRF of 1.13 (i.e., < 2.35), thus validating our predictions. Moreover, locations classified as ‘Stable’ have substantially higher joint normal stiffness compared to those classified as ‘Partially Stable’. The study underscores the importance of continuous monitoring and proper slope management to mitigate the risk of landslides in this region.