SLOPE STABILITY ANALYSIS IN COAL MINE USING LIMIT EQUILIBRIUM METHOD AND FINITE ELEMENT METHOD IN BLOCK 8 BINUNGAN MINE OPERATION 2 PT BERAU COAL, BERAU DISTRICT, EAST KALIMANTAN

• Main Author: Farel Putrafidi, Muhamad
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/69843
• Institution: Institut Teknologi Bandung

PT Berau Coal is coal mining company located in Berau Regency, East Kalimantan Province that uses the open-pit mining method. PT Berau Coal mines coal in the Latih Formation (Tml) which is Middle Miocene in age and has many economical coal reserves. The purpose of this research was to analyze the slope stability of the open pit mine at PT Berau Coal, precisely at Binungan Mine Operation 2 block 8 in Pit C2 Area which is located at coordinates 1º53’16.96” N, 117º16’00.06” E until 1º55’37.53” N, 117º18’56.81” E and provides safe and optimal overall slope angle and design for mining operations. This research was conducted using two methods, which is the limit equilibrium method and the finite element method which aims to determine the value of the Factor of Safety (FS) of mine slope at Pit C2 with reference to the decree of the minister of energy and mineral resources no 1827/K/30/MEM/2018 and the geotechnical standard of PT Berau Coal. In the research area there are four lithologies, namely sandstone, mudstone, coal, and carbonaceous mudstone. Rock physical and mechanical properties were obtained from laboratory tests and lithologies was obtained from geotechnical drill logs located around the area. Pit C2 is divided into six different cross-sectional lines (F1-F6). Based on the slope stability analysis that has been carried out, assuming pore pressure is 1 psi and seismic loading factor is 0.03 g, using the limit equilibrium method, the value of the factor of safety and the probability of failure in the F1-F6 sections respectively are 1.48; 1.48; 1.54; 1.25; 1.44; 1.20 and 0.9%; 0.2%; 0.1%; 5%; 0.5%; 8.6%; while using the finite element method, the value of the factor of safety and the probability of failure at the F1-F6 cross-sections respectively are 1.35; 1.38; 1.42; 1.21; 1.34; 1.09 and 5.34%; 2.95%; 2.06%; 9.42%; 4.25%; 28.01%. Based on the analysis, the value of the factor of safety on the F4 and F6 sections are in unstable condition, Therefore, the overall slope angle must be sloped by 3º at the F4 and F6 sections.