Weathered Rock Slope Stability Assessment and Risk Mitigation Measures—A Case Study from UKM Campus, Bangi, Selangor, Malaysia

Abstract

A cut slope, located in front of the Faculty of Social Sciences and Humanity (FSSK) building, Universiti Kebangsaan Malaysia (UKM), Bangi, Selangor failed after a heavy rainfall in November 2012. The main objectives of this study are to assess and characterize the landslide hazards to identify the geological parameters contributing towards the hazards and to recommend suitable risk mitigation measures. The study has been carried out by discontinuity survey, soil and rock testings and kinematic stability analysis. The studied slope is made up of predominantly of highly to completely weathered phyllite, graphitic phyllite and quartzite. The phyllite is generally weak rock and has very low durability, while graphitic phyllite and quartzite are generally medium strong rocks with low durability. The slope is dissected by at least 5 sets of discontinuities (mainly joints and foliations), which exerted profound control on the geometry of the slope failure. Kinematic stability analyses indicated that the slope is unstable and have undergone planar, wedge and/or combined modes of failure. To mitigate the risk for retrogressive failure, the slope has been stabilized with active netting (wire mesh with soil nails). The slope is also equipped with sufficient drainage system to control surface runoff and vegetation cover shown a typical example of the importance of geological studies in identifying the root causes for a failure of weathered cut slope and recommended methods for stabilization and remediation of a failed weathered cut slope in a wet tropical country such as Malaysia.