Skripsi
KAJIAN AWAL GEOTEKNIK UNTUK REKOMENDASI RANCANGAN GEOMETRI LERENG PIT DI PT GENTALA BUMI NUSANTARA JOB SITE PT BAKTI NUGRAHA YUDA, PROVINSI SUMATERA SELATAN
PT Bakti Nugraha Yuda is an energy and coal mining company whose production operations operate in Ogan Komering Ulu Regency, South Sumatra Province. The mining activity plan will be carried out using the strip mine method. The angle of the slope is planned to have a depth of 65 meters. The slope in the mining activity has the potential to be deformed which can cause landslides if the slope geometry used is not optimal, so it is necessary to design an optimal slope geometry in terms of stability and also conservation of natural resources. The location of the research was carried out in the planned Kibang and Mendawai pits with an incision from north to south in the DH 04 drill hole which is planned to have a depth of 65 meters and an incision from west to east in the DH 03 drill hole which is planned to have a depth of 35 meters. Mining slope analysis has the potential for arc avalanches using the Bishop, Janbu Boundary Equilibrium method, and probability analysis is carried out by paying attention to seismic factors. The slope modeling uses the approach of physical and mechanical properties of rocks from laboratory data tests. The analysis was carried out with variations in slope slope and analyzed in static and dynamic conditions with groundwater level (MAT) 8H according to Hoek and Bray, 1981, the seismic factor is 0.15g assuming vibration due to the load of mechanical equipment and mining activities, a single slope is considered stable if the Safety Factor (FK) ≤ 1.1 and the Landslide Probability (PL) is 25%-50% while the overall slope is stable if the FK ≤ 1.2 and PL 15%-20% (in accordance with the Ministry of Energy and Mineral Resources No. 1827 K/30/ MEM/2018). The results of the analysis using the boundary equilibrium method with the Rocscience Slide v.6.0 program obtained a single slope recommendation with a height of 10 meters and a slope angle of 60° for sandstone materials while a height of 5 meters and a slope angle of 15° for topsoil materials, claystone, and coal. On the overall slope of the DH 04 borehole with a height of 65 meters with an overall slope angle of 12° and a bench width of 30 meters in a rather dry condition (8H) while on the overall slope with a borehole DH 03 a height of 35 meters has a slope angle of 12° and a bench width of 15 meters in a rather dry condition (8H). Seismic factor analysis results that slopes in dynamic conditions have a lower safety factor compared to static conditions while the probability of landslides in dynamic conditions is higher compared to static conditions.