| Improper mining of coal mines will cause damage to the water resources and water environment of the mining area,especially in areas with relatively fragile ecological environment,which will further aggravate ecological deterioration.At present,the prediction of mine water inflow mainly focuses on single working face or mining area,and it is not enough to pay attention to the influence of long-term mining of coal groups in the gully on groundwater environment.The Toudaoheze gully was selected as the study area,and the hydrogeological conditions of the gully were analyzed.A three-dimensional numerical model of groundwater unsteady flow in the complete area of gully was constructed.The simulation process of gradually increasing goaf area is realized by changing the space step of goaf.The numerical model is verified and identified based on the monitoring data of groundwater and surface water in the gully and the water inflow of coal mine groups.Taking 9#coal mine as an example,the mine water inflow of fully mechanized mining and filling mining is predicted,and the environmental impact of mine water inflow is studied and analyzed.The main research results are as follows.(1)According to the fracture-mining ratio,the height of water flowing fractured zone in fully mechanized coal mining in 9#coal mine is 192m.The fully mechanized coal mining in coal mine will lead to all Quaternary phreatic aquifers in the mining area,which will cause the Quaternary loose rock pore water to be directly imported into the mining roadway and working face.The development height of water flowing fractured zone in strip filling mining method is 5～38m,and the filling mining in coal mine will not lead to Quaternary phreatic aquifer.(2)Using the numerical model of coal mining group,the mine water inflow and groundwater level of two types of mining methods(three mining schemes)in the coal mining area are predicted.In fully mechanized mining(Scheme 1),the increase of mine water inflow is 0.70×10~4m~3/d,and the decrease of groundwater level in mining area and region is 0.21～17.92m.In the two cases of strip-filling mining(Scheme 2-1,Scheme 2-2),the increase of mine water inflow is 0.14×10~4m~3/d and 0.11×10~4m~3/d respectively,and the decline of groundwater level in mining area and region is 0.04～0.85m and 0.01～0.44m respectively.(3)According to the mine water inflow of collective mining,the influence of simulated coal mining on regional groundwater resources and ecological environment is,the overflow reduction caused by water inflow in coal mining group is 2.46×10~4m~3/d,the decline of groundwater level causes the groundwater level depth of 33.27km~2to below 8m,and the groundwater level depth of 63.30km~2to drop from 3 to 5m to below 5m,which inhibits the growth of mesophytes in the region and causes the succession of mesophyte vegetation to xerophyte vegetation.(4)Based on the numerical model of collective mining,the influence of mine water inflow in different mining methods on water environment and ecological environment in 9#coal mine is predicted as follows.In fully mechanized mining mode(Scheme 1),the mine water inflow has a great influence on the regional groundwater overflow,surface water runoff,aquifer resources and reservoir water volume of the Salawusu Formation.The large decrease of groundwater level in the mining area and nearby caused by coal mining will further reduce the area of critical buried depth supporting vegetation growth,and aggravate the atrophy and even death of ecological vegetation.In the two cases of strip filling mining(Scheme 2-1 and scheme 2-2),mine water inflow has little effect on regional water environment and ecological vegetation.The filling mining method can be adopted when coal mining in the area with small thickness of strata above coal seam.The results can provide reference for the formulation of mining schemes in the study area or similar coalfields and the scientific treatment of the relationship between coal resource exploitation and ecological environment protection. |
PDF Full Text Request