STABILITY ANALYSIS OF HIGHEALL AND SIDEWALL SLOPE PT XYZ’S OPEN COAL MINING IN EAST KALIMANTAN

• Main Author: Ageng Pangestu, Yoga
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67228
• Institution: Institut Teknologi Bandung

In open pit mines, the geotechnical aspect is one of the aspects that must beconsidered, especially the stability of the slopes. Stability of the slope is expressed by values of Safety Factor and Probability of Failure. On the highwall and sidewall coal pit PT XYZ will be analyzed to assess the stability of the slope. The method used to analyze the stability of the slopes is limit equilibrium method especially Bishop simplified. The parameters included in analysis are cohesion, friction angle, and natural density. As for the determination of the probability of failure value, the data is processed with descriptive statistics to obtain the average value, standard deviation, then a goodness of fit test is carried out with the Kolmogorov-Smirnov (KS) and Akaike Information Criterion (AIC method) to find out type of data distribution. The slope model was analyzed using Rocsience Slide v6.0 software with reference model is existing pit conditions of September 2021. Highwall slopes are indicated to be unstable because the values of SF and PoF do not meet the standards of the Minister of Energy and Mineral Resources Decree 1827K/30/MEM/2018 where for static SF values > 1.3; Dynamic SF > 1.1; and PoF < 5%, while the sidewall slope is safe because the SF and PoF values meet the criteria. Recommendations for stabilize are carried out on highwall slopes by decrease the overall slope by widening the dimensions of the level from 5 meters to 8 meters and add the interramp on two levels with dimensions of 13 meters. The next recommendation is creating water channel to decrease surface water and creating horizontal drainage to decrease ground water inside the slope. Based on these recommendations, the static SF value was 1,349, dynamics SF 1,209 and PoF 0% for P-27. While P-28, static SF 1.301, dynamics SF 1.169 and PoF 0% at Hu 0.6. So that it can be stated that the highwall slope is safe and meets the criteria according to the Decree of the Minister of Energy and Mineral Resources 1827K/30/MEM/2018.