Numerical Simulation Of The Influence Of Mining On The Groundwater In A Coal Mine In The West Of Yu(lin)-Shen(mu)mine Area

Coal is a very important energy resource to support the development of national economy.The Jurassic coal field in the northern Shaanxi province is an important part of chinese energy and chemical industry base,in which coal resources are rich,with good quality,superior mining conditions and great development potential.There are Zhiluo Formation aquifer and Quaternary aquifer overlying the coal seams,which water yield property are better.Therefore,the prediction of water yield of mine has an important theoretical value and practical significance for ensuring the safe production of coal mines,preventing water brusting in mines accidents,and strengthening comprehensive utilization of mine water resources.Taking a coal mine in the western Yu(lin)-Shen(mu)mining area as the research object,and by means of the lumped parameter model and distributed parameter model,this paper predicted the development height of diversion fissure zone,established a numerical model of groundwater flow and forecasted the water yield of mine of aquifers overlying 2^-2coal.The research results were obtained as followed:Firstly,the ratio relationship between the development height of diversion fissure zone and mining height is determined.The development height of diversion fissure zone is 159m,26.50 times of the mining height of 6m,simulated by UDEC software during the mining process of 2^-2coal.According to the ratio between the mining height and the height of diversion fissure zone of 2^-2coal can mostly reach jurassic Zhiluo formation,and partly in Anding formation.Secondly,the formulas of hydraulic conductivity of Anding Formation and Zhiluo Formation are derived.Based on the pumping test data in the area and the thickness of each rock in the pumping borehole,the hydraulic conductivity formulas of Anding Formation and Zhiluo Formation are derived.Hydraulic conductivity of boreholes without subjected to pumping test data can be estimated,thereby to improv the accuracy of groundwater resource evaluation.Thirdly,a numerical model of groundwater flow in the study area were constructed.Based on the geological and hydrogeological conditions in the study area,a numerical groundwater flow model were constructed.The model was identified and verified by groundwater monito-ring data,groundwater balanceand groundwater flow field,and relevant hydrogeological parameters were obtained.Fourth,The water yield of mine in the early mining area was forecasted.Based on the numerical model of groundwater flow,annual average water yield of mine of coal mine in the study area is 777.05m³/h.and the normal water yield of mines obtained by the analogy method is 912m³/h in the study area.From the perspective of safe production,it is recommended that the normal water yield of mines should be 777.05?912m³/h,and the maximum water yield of mines should be 932.46-1098m³/h in the area.Fifth,the influence of 2^-2coal seam mining on the phreatic water of the Quater-nary Salawusu Formation and the confined aquifer of the Zhiluo Formation is analyz-ed.By comparing the changes of the flow field before and after mining,it is concluded that the 2^-2coal seam mining don't have influence on the Salawusu Formation aquifer;while the Zhiluo Formation aquifer will have a larger cone of depression.The research results above can provide a basis for the sustainable development of the energy and chemical industry base in the northern Shaanxi province,the sustainable use of water resources,and the ecological protection and high-quality development of the Huanghe River Basin.