Dangerousness Evaluation Of Water Inrush In Fault While Mining Lower Coal Under Pressure In Baodian Coal Mine

The lower coal seam supplementary survey, hydrologic observation and geological structure datum were analysed based on the Baodian Coal Mine which is mining the lower coal seam with floor pressure.In addition, the risk of water inrush was evaluated by using the results of water injection tests in Yanzhou mining area.Through the analysis of water pressure and water-abundance of the confined aquifers, the thickness and the lithological combinations of aquicludes under the lower coal floor, and combining the water inrush coefficient method to get the judgement. The Thirteen Limestone has some threat in mining lower coal under pressure. the effect of Fourteen Limestone are relatively limited. Ordovician Limestone has slight threat in normal structure floor, but must pay attention to the supplement effect to other aquifers. The fault fracture zone is weakly place to all confined aquifers, the dangerousness of water inrush exist in there.The water inrush coefficient method is empirical, the applicability of it awaits proof. In order to get the further jugement, combining the achievement of the impermeability research in Yanzhou mining area. Revealing the water resistance ability of different structure floors, by comparing and analyzing 18 water injection tests in normal and disturbed floor. Come up with the quantified index of impermeability and the evaluation model, and adopted these method to evaluate the lower coal mining under pressure. Confirmed the major threat to normal floor is derived from the Thirteen Limestone, the effect of the Fourteen Limestone is weakly, and the Ordovician Limestone would threat mining through fault fracture zone.Lastly, regard the evaluation result as the direction, take various factors into account, gave suggest of water prevention and cure to lower coal ming under pressure. Suggest discharging the thin limestone in Benxi Formation. For Ordovician Limestone, first, obstruct the hydraulic relation with the aquifers upon it, second, reserve the waterproof pillar to deal with the water inrush in faults. In addition, combined the impermeability evaluation index with the require of fault water proof pillar reservation in Mine Hydrogeologic Regulation, to give some optimization suggestion to the scheme of fault waterproof pillar in Baodian Coal Mine.