Rock slope stability assessment by using RMRB and SMR methods for future development around Gunung Lang, Ipoh, Perak

Abstract

The unfavourably oriented discontinuities with respect to the slope cutting orientation may results in rock slope failure or instabilities. The main factor that influences the rock slope stability is the geological factors. The role of geology on slope problems and assessment is variable, according to the subsoil constituent and structures itself. Generally, rock masses are contains a plane of weaknesses such as fault, joint, bedding plane, foliation, dyke, folds, etc. Therefore, those structures will drive a rock mass on a slope to break down. Geological processes also play the role in the rock slope stability. These are due to weathering (expose with air and water), surface erosion, seepage occurs along open joints and the chemical reaction in the intact rock with water that produce high porosity (e.g. limestone). To determine the instabilities of rock falls, basic rock mass rating (RMRb) and slope mass rating (SMR) assessment were conducted on rocks slope in Gunung Lang. The study area is divided into three slope zone; GL-1, GL-2 and GL-3. The results indicates that the rock slopes have two possible modes of failure consisting of planar failure and wedge failures. Rock slope GL-1 is relatively in stable condition. Rock slope GL-2 has potential mode of wedge failure. The slope is considered as partially stable and its probability of failure is 40%. Rock slope GL-3 have potential modes of wedge and planar failures. Therefore, the slope is considered as unstable and its probability of failure is 60%.