PREDICTION OF MULTI-SEAM MINING-INDUCED SURFACE SUBSIDENCE IN UNDERGROUND COAL MINE IN INDONESIA

This paper attempts to predict the surface subsidence induced by multi-seam longwall mining in PT Gerbang Daya Mandiri (GDM) underground coal mine Indonesia. Several numerical models of under various depths were built finite difference code software “FLAC3D” which was used as a tool for simulations. Effect sequence and influence lower seam firstly investigated. The angle draw (AoD) maximum (Smax) describe characteristics subsidence. Based on simulated results, it is indicated that undermining provides better compared overmining. Mining an order will not cause any difficult conditions seam, whereas some ground control problems upper are expected when mined overmining order. Under all undermining, extracting panels significantly influences magnitude AoD Smax increase after mined. indicates very large applied at GDM mine. An application countermeasures such adopting pillar width small panel suggested this minimize caused mining. Minimizing therefore numerically investigated paper. found decrease larger narrower adopted. use result smaller Smax.