Strata control problems in and around fault planes of Central India coal basins

Strata control problems in underground coal mining account for highest fatal and serious injuries to workers. These problems are due to operational, geological and geo-technic parameters. Efforts are being made in various Indian coal mines to replace conventional timber supports by boltings, stitchings, hydraulic/friction props, chocks and shield supports for safety. Operation in and around faulted zones in Kamptee and Kanhan coalfield of Central India posed most serious challenge to safety of miners. Evaluation of orientation, throw and frequency of faults along with cleats and joints were studied with a view to evolving safe and economic system of supports and method of mining. Faults are the main geo-structural features disturbing bord and pillar and longwall workings. The fault throw up to the working height could be tackled without major change in layout and hence were called small throw faults. Over 20faults of throw within a metre to 60 m were observed in depth for gouge thickness and associated strata control problems. Faults with 10 m throw and above in creased face cleat and mjor joint frequency from 11m-1 to 16 m-1 and above and 4 m-1 to 10 m-1reswpectively within 5 to 50 m of its position. Orientation of face cleat and major joint west was also influenced by such faults which were classified as major faults. Entries along the major and the minor faults suffered from severe strata control problems. For better roof condition, drivages shouid be laid 20-45° across the faults; reinforcement of supports by way of stitchings and use of M.S. cross-bars along with conventional supports should be installed immediately in the faulted zones to avoid deterioration of exposed strata