Predicting factors of safety for soil slope stability based on various slope characteristics and rainfall conditions

The occurrence of rainfall has resulted in multiple instances of slope failure in the Klang Valley region of Malaysia. Bukit Antarabangsa, located in the Ampang District of Selangor, Malaysia, has been prone to frequent slope collapses for a long time. However, the specific elements, apart from rainfall, that contribute to landslides in the area have not yet been discovered. The objective of this study is to examine the effC•cts of varymg degrees of rainfall intensity and duration on distinct land formations to enhance the understanding of the complex mechanism of landslides at Bukit Antarabangsa. This study has chosen three locations each in Bukit Antarabangsa and Universiti Pertahanan Nasional Malasyia (UPNM) campus area for the purpose of collecting samples and conducting tests. The laboratory conducted an examination of both disturbed and undisturbed soil samples to assess the soil's fundamental and hydraulic properties. This analysis included evaluating the soil's sieve analysis, Atterberg limits, shear strength, falling head permeability, and pressure plate extractor. The results are employed for numerical simulation in the SEEP(W and SLOPE!W modules of the Geostudio software. Parametric studies are performed on different slope configurations, including slope angle, height, and piezometric line, during rainfall periods extending two and eight hours. The real-time intensity of rainfall is tracked by monitoring the rainfall intensity at the closest rainfall station for the purpose of simulation. A factor of safety (FOS) was determined for each individual scenario. The numerical simulation results indicate that slope failure occurs when the shear strength of the soil decreases with an increase in soil moisture content due to a decrease in soil suction. The soil samples exhibit variations in matric suction, hydraulic conductivity, effective internal friction angle, and effective cohesion. The hydraulic and mechanical properties of each soil sample influence its slope safety factor, even when subjected to similar slope conditions in simulations.