A sensitivity analysis of a Landslide to assess the influence of shear strength parameters and groundwater conditions on slope stability of Kaande Landslide

Abstract

Slope instability is a persistent geohazard in the hilly regions of Nepal, with the Kaande landslide area in Kaski District being particularly vulnerable. This study evaluates the sensitivity of key geotechnical parameters controlling slope stability at the Kaande landslide using numerical modeling. Slope stability analyses were performed in Phase2 using the Mohr Coulomb failure criterion. Field investigations involved detailed slope profiling and soil sampling through open pit tube sampling, followed by laboratory testing to determine cohesion, internal friction angle, and unit weight. Gradation analysis classified the soil as SM–SC. A sensitivity analysis was conducted by varying cohesion, internal friction angle, and Groundwater Table (GWT) conditions individually while keeping other parameters constant. Analyses were carried out for three representative slope sections, and slope failure was identified at a Strength Reduction Factor (SRF) of 1. The relative influence of each parameter was quantified using coefficients of determination. Results show that slope stability is most sensitive to changes in the internal friction angle, with critical values of 28.93°, 29.04°, and 26.41° for Sections 1, 2, and 3, respectively. GWT variation was identified as the second most influential factor, while cohesion had a comparatively minor effect due to its low magnitude in SM–SC soils. The study concludes that frictional resistance and groundwater conditions are the primary controls on slope stability at Kaande. These findings provide a practical basis for designing effective slope stabilization and groundwater management measures in similar geological and geomorphological settings across Nepal.