The landfall probability of highwall slope’s geometry in PT. Mahakam Prima Akbar Sejati, East Borneo Province

Abstract

PT. Mahakam Prima Akbar Sejati is a coal mining company that uses the open pit mining method which in its implementation will make slopes with certain geometries. This research was conducted in PIT ‘N’ section A-A ‘Highwall MPASGT-01 and section B-B’ Highwall MPAS GT-02, aimed to determine the value of safety factors that are safe and in accordance with the minimum safety factor values set by the company, namely ≥ 1.3. The safety factor value is determined by the Bishop method for overall slope, from the geometry of section A-A ‘Highwall 01, an individual slope angle (α) of 65 °, bench width of 5 meters, height (h) of 10 meters, with a total of nine individual slopes formed slope, will produce an overall slope (Overall Slope) with 48 ° slope angle dimensions, 90 meters high, and has a safety factor value of 1.46 with a cumulative collapse of 13.48%. For the B-B ‘Highwall MPAS GT-02 section, an individual slope angle (α) of 65 °, bench width of 5 meters, height (h) of 10 meters, with the number of individual slopes formed by eight slopes will produce an overall slope (Overall Slope) with a slope angle dimension of 48 °, a height of 80 meters, and has a safety factor value of 1.52 with a cumulative collapse of 8.90%.