Slope stability analysis of granitic residual soil in UPNM campus using strength reduction method

Geological hazard such as slope failure poses a great threat to human life and properties all around the world. Slope stability analysis is conducted to identify the critical slip surface and the factor of safety of the slope. It may be induced by many factors such as the infiltration of rainwater and surcharge loading including the groundwater movement where all the possible causes may reduce the strength of residual soil that is tremendously influenced by weathering condition. Commonly, the stability analysis is conducted by using the Limit Equilibrium Method (LEM) utilising analysis by using various method of slices. Alongside the innovation of technology and the development of knowledge, the Finite Element Method (FEM) has come to its function as a quick and robust tool for slope analysis. The main objective of this paper is to determine the stability of a slope in Universiti Pertahanan Nasional Malaysia (UPNM) campus based on finite element utilizing strength reduction method (SRM) using Plaxis software. The new slope construction on granitic residual soil in UPNM campus requires a study concerning the stability of slope as high groundwater table in this area had been discovered with spring water that seeps through soil and fractured rock at several locations particular at slope section greater than 45 0 . From the result, it is observed that the safety factor for slope angle reduced from 2.254 to 1.188 when the inclination angle increased form 15 O to 45 0 respectively by limiting the height up to 10 m at the uphill section. The results of this study had shown that FEM software such as Plaxis can be practically used to accessed stability of existing slope by utilising strength reduction method approach. In comparison, the slope with greater angle of 45 0 exhibits the least value of safety factor and smaller slip surface compared to that of more gradual slope in this study. This could help us identify the potential failure zone and implement possible remedial measures.