Analisis Kestabilan Lereng SBD 546 dengan Menggunakan Metode Proyeksi Stereografis dan Klasifikasi Massa Batuan pada Tambang Terbuka PT. Newmont Nusa Tenggara, Batu Hijau. Kecamatan Sekongkang, Kabupaten Sumbawa Barat, Propinsi Nusa Tenggara Barat

Abstract

Batu Hijau is an open pit mine area of copper – gold, which is managed by PT Newmont Nusa Tenggara. The ore deposits in Batu Hijau are cylinder and be mined in successive and concentric phase, so that the slope stability become a problem which is often passed in engineering construction of slope mining. The philosophy of mining design in Batu Hijau is more emphasized at a slope management in order to manage and minimize the risk that maybe caused by slope instability. Data and information about mechanic features of rock, characteristics of rock mass discontinuity, and conditions of groundwater surface are important in slope stability analysis around borehole SBD 546 in open pit mine of Batu Hijau. Analysis of stereographic projection be conducted using software named DIPS, to determinate the general direction of discontinuity, slide type, and the possibility of sliding. Based on stereographic projection analysis, conclude that slope around borehole SBD 546 is secure of sliding risk. Investigation of slope strengthening which is recommended, conducted based on rock mass classification using Rock Mass Rating (RMR) and Slope Mass Rating (SMR) classification. The result of analysis indicate that slope around borehole SBD 546 is recommended to be given some options of slope strengthening, such as: 1) trench at slope edge (Toe Ditch) or netting, 2) spot or systematic bolting, and 3) concrete spurting at some parts of slope (spot shotcrete).