Three-Dimensional Slope Stability Analysis and Volumetric Estimation of Slope Failure

PT X is a nickel ore mining company based in Pomalaa, Southeast Sulawesi. The hauling road of PT X is through mountainous terrain. Slope failure becomes an issue and might be risking the safety of operations and production. Thus, geotechnical analysis is required to analyze the slope behavior. Most geotechnical analyses are conducted in 2D and assume that the slope has infinite dimensions. In actual conditions, all slopes have finite dimensions. Thus, three-dimensional effects should be considered. This research determines the instability mode, evaluates the factor of safety (FoS), and also estimates the volume of failure. The 3D kinematic analysis (KA) is used to get the slope mode of instability, and the 3D limit equilibrium method (LEM) is used to determine the FoS of the slope and estimate the volume of failure. The 3D kinematic analysis determines that the mode of failure for the slope is wedge sliding, with the direction of sliding heading towards N64°E. The LEM analysis is also integrated with the sliding direction and discontinuities based on KA result. The 3D LEM analysis also generates a volume estimation for each calculation method based on the global minimum slip surface. Although the slope stability is relatively stable and reaches the acceptance criteria of the FoS, the potential for wedge sliding should be a concern to have detailed research to determine the best stabilization method.

Keywords : geotechnical investigation, 3D model, 3D structure extractions, drone mapping, semi-automated