ROCK SLOPE STABILITY ANALYSIS IN LHOKNGA HIGHWAY AT 17.8 KM, ACEH BESAR DISTRICT

Rock slope stability was assessed using the slope kinematic analysis method and rock mass classification on the roadside slope of Banda Aceh - Calang at 17.8 Km in Lhoknga Subdistrict, Aceh Besar District. This study aims to determine the types of landslides that will occur in the future by determining the Rock Mass Rating (RMR) and analyzing stability based on the Slope Mass Rating (SMR). The data acquisition of rock mass structures performed the scan line method along the slope. The data taken are dip and strike of the discontinuity plane, and the conditions of discontinuity in the form of persistence, aperture, roughness, infilling, weathering and groundwater conditions. Slope kinematic analysis was conducted based on stereographic projection and analyses of both rock slope quality and stability were based on RMR and SMR parameters. The result of the slope kinematic analysis shows that landslides occur in slope 1 will be in wedge and planar forms. On slope 2, possible failure is in the form of toppling due to the joint set positioned opposite to the slope direction. The RMR value in slope 1 is 63, categorized as Good rock and the RMR in slope 2 is 57, which is in the medium rock category. The lowest SMR value in slope 1 was 29 as a Bad class for planar failure, and 53 as a Normal category in slope 2 is toppling failure. Slope 1 has a 60 % probability of a planar failure event.