Apprehension of Subsidence over Old Workings: A Case Study

An old and abandoned coal mine working especially at shallow depth leaves the scope to disrupt the surface topography and in turn structures as the concern for pot-hole occurrence always prevails in post-mining areas. thus, acomprehensive understanding of stability of ground is a strategic factor prior to erection of infrastructure over underground old coal mine and hence requires indispensable investigation for safety viewpoint. A methodology has been adopted at Surakachar 3&4 Inclines of south Eastern Coalfields Limited (SECL) to effectively gauge pot-hole occurrence. In addition to gathering geo-mining parameters the study envelops detailed site history, a guideline to show the path for precise evaluation of goal. Possibility of pot-hole has been predicted taking into consideration the bearing parameters viz. depth, uniaxial compressive strength of rock, geological discontinuity and water seepage. The potential zones with reference to rating have been identified and accordingly demarcated the grade of risk. Issue related to erection of heavy infrastructures over the disturbed strata caused be depillaring caved panels has been discussed