Subsidence Analysis for Old Abandoned Board and Pillar Coal Mines Using ANSYS and Monte Carlo Simulation

Abstract

Mine Subsidence is a phenomenon of lateral or vertical ground movement caused by a failure initiated at the mine level of man-made underground mines and an abandoned mine is a site where mining activities occurred but acceptable mine closure and reclamation did not take place or was incomplete. Subsidence is one of the major problems which is faced over an old abandoned mine. Presently there are limited means or methods which can predict subsidence over an old abandoned coal mine at a shallow depth efficiently and the precautionary methods that should be taken in these situations. This research paper will cover the possible causes which can lead to subsidence above an old abandoned board and pillar coal mines at a shallow depth. The research includes the calculation of the factor of safety for pillars and analysis of FoS using ANSYS and Monte Carlo Simulations for ascertaining subsidence. An old abandoned coal mine of South Eastern Coalfields Ltd. (SECL, a subsidiary of Coal India Limited), was considered for the study of coal pillar fatigue and eventual crushing of pillars over a long duration of time, simulation analysis of stress and strength of coal pillars over a long period, change in behavior of factor of safety as the dimension of the pillars changes.