LANDSLIDE BACK ANALYSIS USING ROCK MASS CLASSIFICATION AND LIMIT EQUILIBRIUM METHOD IN SECTOR X, “H” AND “S” AREA, PT ASMIN BARA BRONANG, KAPUAS TENGAH DISTRICT, KAPUAS REGENCY, CENTRAL KALIMANTAN

• Main Author: Raihan, Muhamad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/77531
• Institution: Institut Teknologi Bandung

PT Asmin Bara Bronang which operates in the Barunang Village, Kapuas District, Kapua District, Kalimantan District is one of the coal companies that implement an open mining system that has many slopes in the mining process. The aim of this study is to make recommendations for the geometry of the open slope of the mine of PT Asmin Bara Bronang on the Sector X pit “S” and “H” areas optimally and to meet the safety factor standards in accordance with the Keputusan Menteri ESDM Nomor 1827/K/30/MEM/2018 based on the landslide event that occurs using Rock Mass Rating and the limit balance method. In general, lithology in the research area is grouped into five units of geotechnical rocks, namely, the upper claystone unit, the upper sandstone unit and the bottom claystone unit, the bottom sandstone unit, and the coal unit. From the results of the mass classification of the rocks it is obtained that the top claystone unit, top sandstone unit, and coal unit classified into class IV (Poor Rock), the lower claystone units and the low sandstone unit classified into class II. (Good Rock). Based on the results of field observation and slope cross section model obtained the cause of the occurrence of slope in the area “S” is caused by sand loose material with steep slope, while in the region “H” due to the coal strength degradation. Based on back analysis using the limit equilibrium method showed that the sand grained soil material in the “S” area had a cohesion of 0 KPa and friction angle of 25?, the weak layer in the "H" area had cohesion 6,9 KPa, and the friction angle of 15,27?. From the results of the slope geometry test, the area “S” is recommended to be cut on slopes starting from elevation 70 with a bench height of 10 meters, bench width of 20 meters, number of benches 2, and bench slope of 40?, the “H” area is suggested to be hoarded using counterweight material that starts at elevation -5, with the bench height of 5 meters, bench width of 15 meters, number of bench 3, and bench slope of 45?