STABILITY ANALYSIS OF HIGHWALL AND SIDEWALL SLOPE WITH FINITE ELEMENT METHODE AT PT XYZ COAL MINING IN EAST KALIMANTAN

• Main Author: Risky Pratama, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67207
• Institution: Institut Teknologi Bandung

PT XYZ is a coal mining company with an open-pit mining method to extract the coal. In the sustainability of open pit mines, one of the important aspects that needs to be considered is geotechnical, especially the stability of the slopes. The level of slope stability is expressed by the values of Safety Factor (FK) and Probability of Cladding (PK). On the highwall slopes and sidewalls of the PT XYZ coal mine will be analyzed to assess the stability of the slopes. The method used to analysis the stability of the slope is a numerical method, namely finite element method using shear strength reduction. The input parameters in the analysis are cohesion, friction angle, unit weight, young modulus, poisson ratio, and Tensile strength. Meanwhile, in determining the pk value, the data processed descriptive statistics to obtain the average value and standard deviation. The value will be an input in determining the PK value with the point estimate method. The existing slope model was analyzed using the Rocscience Phase2 8.0 software with reference to the existing pit conditions in September 2021. Highwall slopes are indicated to be unsafe because the FK and PK values do not meet the standards of the KepMen ESDM 1827K/30/MEM/2018 where for static FK values > 1.3; Dynamic FK > 1.1; and PK < 5% while the sidewall slope is safe because the FK and PK values meet the criteria. Recommendations for improvement are carried out on highwall slopes by hitting the overall slope, namely by widening the dimensions of the bench from 5 meters to 8 meters plus the inter-ramp at two levels with dimensions of 15 meters or widening the dimensions of the bench to 10 meters. The next recommendation is in the form of creating waterways to overcome surface water so that the Hu value is estimated at 0.6. Based on the recommendation to widen the bench to 8 meters and the addition of a 15-meter ramp, the FK statis value was obtained 1.3, FK dynamics 1.13 and PK 2.58% for A-A'. While B-B', FK statis 1,301, FK dynamics 1,169 and PK 3.19% at Hu 0.6. Meanwhile, for the recommendation for widening the bench up to 10 meters, the FK statis value was 1.39, FK dynamics 1.22 and PK 2.18% for A-A'. While B-B', FK statis 1.32, FK dynamics 1.15 and PK 4.2% 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.