Perancangan Geoteknik Lereng Tambang di PT Bukit Tampomas Lestri

Abstract

Abstract. PT Bukit Tampomas Lestari is one of the companies currently applying for a mining business license for sirtu (sand and gravel) commodities, located in Legok Kaler Village, Paseh Subdistrict, Sumedang Regency, West Java Province. The planned mining system is open-pit mining using the quarry method. A geotechnical study is necessary to determine a safe and optimal slope geometry. Material property parameters were obtained from laboratory testing of intact rock, covering both physical and mechanical rock properties. Slope stability analysis was carried out using the Limit Equilibrium Method (LEM) with the Morgenstern-Price method and the Mohr-Coulomb failure criterion, using Slide 6.2 software to design slope model simulations based on slope geometry (height and angle). From the factor of safety (FoS) values obtained through this modeling, further analysis was conducted to determine the recommended single slope and overall slope design. Based on the research results, it was found that the rock units at the study location consist of andesite, basaltic andesite, and andesite lava. The recommended simulation results for the single slope model, across the three different lithologies, indicate a slope height of 9 meters and a slope angle of 85°, in accordance with the specifications of the Komatsu PC 200 excavator, which has a maximum digging reach of 9,380 mm. The factor of safety (FoS) values for the single slope for each lithology are as follows: andesite 1,698, basaltic andesite 8,109, and andesite lava 7,480, under saturated groundwater conditions. The recommended design results for the overall slope model, based on pit geometry (height and angle), are as follows: Section A–A' with FoS 1,139, an overall slope height of 45,050 meters and a slope angle of 67°; Section B–B' (Left to Right) with FoS 1,767, an overall slope height of 32,802 meters and an angle of 63°; Section B–B' (Right to Left) with FoS 1,187, a height of 38,833 meters and a slope angle of 60°, Section C–C' with FoS 2,675, an overall slope height of 25,675 meters and an angle of 66°.

Keywords: Slope Stability, Limit Equilibrium Metho,Morgenstern-Price, Mohr-Coulomb, Factor of Safety, Single Slope, Overall Slope.