Analisis kestabilan lereng untuk area redisturb pit pqrt site lati PT Berau Coal
S Salah-satu cara pembukaan lahan timbunan bekas penambangan (redisturb) di Site Lati dilakukan dengan cara loading menggunakan shovel PC4000. Namun kajian pada PT Berau Coal terbatas pada material redisturb dengan kategori soft-firm hingga very-stiff dan belum memasukkan kategori material hard. Sehingga diperlukan kajian material hard terhadap kestabilan lereng khususnya pada area penggalian. Penelitian ini menggunakan metode pengamatan langsung untuk kondisi material redisturb di lapangan, kemudian melakukan evaluasi kuantitatif data sekunder SPT sehingga diperoleh properties material redisturb. Gambaran area redisturb diperoleh melalui bor survey 19 titik pada area redisturb timur dengan dibuat section B. Kemudian dilakukan simulasi menggunakan metode elemen hingga dengan software Phase2. Kestabilan lereng material redisturb memiliki nilai critical SRF 1,22 dan nilai PF sebesar 3,12% untuk jarak displacement material hard sebesar 0,91 meter. Sehingga secara keseluruhan lereng redisturb tergolong aman. Kestabilan lereng terhadap aktivitas loading PC4000 diperoleh hasil critical SRF 1,22 dan PF sebesar 3,12%. Nilai displacement material pada area hard redisturb sebesar 0,91 meter, material soft-firm 1,19 meter, material stiff 1,12 meter dan very stiff 1,05 meter.
O One of the ways to clear ex-mining landfills (redisturb) at Site Lati is by loading it using a PC4000 shovel. However, the study at PT Berau Coal was limited to redisturb materials in the soft-firm to very-stiff categories and did not include the hard material category. So it is necessary to study the hard material for slope stability, especially in the excavation area. This study used the method of direct observation of the redisturb material conditions in the field, then carried out a quantitative evaluation of SPT secondary data to obtain the redisturb material properties. An overview of the redisturb area was obtained through a 19-point drill survey in the east redisturb area by creating section B. Then a simulation was carried out using the finite element method with Phase2 software. The slope stability of the redisturb material has a critical SRF value of 1.22 and a PF value of 3.12% for a hard material displacement distance of 0.91 meters. So that overall the redisturb slope is classified as safe. Slope stability to loading activity obtained a critical SRF of 1.22 and a PF of 3.12%. The material displacement values in the hard redisturb area are 0.91 meters, soft-firm materials are 1.19 meters, stiff materials are 1.12 meters and very stiff are 1.05 meters.