STABILITY ANALYSIS OF OPEN STOPES IN SILL PILLAR #2840 DUE TO SILL PILLAR #2840 EXTRACTION USING NUMERICAL AND EMPIRICAL APPROACHES AT THE BIG GOSSAN MINE

• Main Author: Imam Maulana, Astian
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/77059
• Institution: Institut Teknologi Bandung

Mining activities that are far from the surface cause the stress redistribution. This stress redistribution can be reduced by means of a sill pillar. Sill pillar #2840 is still economically valuable, so it is planned to be mined. The stress distributed due to sill pillar #2840 extraction in each mining sequence needs to be analyzed to observe the stability condition of the open stope in sill pillar #2840. The benefit of this research is that it can find out how many sill pillar #2840 can be mined. The stability can be calculated by considering the induced stress around the open stope. This research was conducted by looking at the stability conditions of each domain around the open stope and customized to the mining sequence from mining sequence or frame 129 (before sill pillars #2840 are mined) to frame 168 (after sill pillars are mined). The calculation of the Safety Factor (FS) will be carried out using a numerical approach with RS2 software using the Generalized Hoek-Brown failure criterion for hard rock and the Mohr-Coulomb failure criterion for paste fill, an empirical approach using a Modified Stability Number (N') (Potvin, 1988) and Extended Mathews Stability Number (N) (Mawdesley, 2001) to calculate the stability of hard rock around the open stopes. To consider the vibration factor in mining activities, the FS > 1.3 criteria are applied. The results of numerical approaches that show unstable condition or below FS criteria will be verified by Sakurai chart. From the 69 stopes in sill pillar #2840, the stopes can be mined of 71% or 49 stopes, where the most unstability results are found in paste fill material.