Intense rainfall and extreme modifications to the slope are the immediate triggering factors of landslides and slope instability in the Western Ghats of Kerala, India. An increase in the frequency and intensity of rainfall and its adverse impact on the stability of slopes have demanded slope stability analysis and the adoption of suitable mitigation measures to retard slope failure. This study examines the role of matric suction and pore water pressure variations caused by rainwater infiltration in slope stability. Suction is one of the factors that hold the soil particles together and provide necessary shear strength, hence improving slope stability. During monsoons, water infiltrates the soil which leads to a reduction in soil suction and therein the shear strength and increasing susceptibility to landslides. The study focuses on the rainfall-induced slope failure at Kormala, Muvattupuzha in Kerala, India, where a devastating landslide took place. A laboratory study was conducted on soil samples obtained from the location to obtain the soil properties and soil suction parameters. The resilience of the slope in proximity to Muvattupuzha was assessed numerically for slope stability using a combination of finite element and limit equilibrium analysis software. The variation in pore water pressure across various sections of the slope by varying rainfall intensities was analysed and the change in the factor of safety (FOS) with respect to time at different intensities was compared. The results indicate that infiltration-induced changes in matric suction significantly influence slope stability. At lower rainfall intensities (I = 0.2 Ksat), suction reduction was minimal and the slope remained stable while for moderate intensities (I = 0.4 Ksat and I = 0.6 Ksat), noticeable reductions in suction occurred, particularly near the surface and at the slope toe, leading to a marginal decline in FOS. However, at higher rainfall intensities (I >= 0.2 Ksat), infiltration exceeded the hydraulic conductivity of the soil, causing a rapid decrease in suction and led to near-saturation conditions, especially at the crest and toe sections. Hence, proper and periodic monitoring of the rainfall intensities and soil suction is required for enhanced resilience to slope instability and landslides in this and surrounding regions.

来源平台：INDIAN GEOTECHNICAL JOURNAL