Numerical Simulation Study On The Influence Of Mining Disturbance On Parameters Of Aquifer

Jurassic Coalfield at Northern Shaanxi is located in arid and semi-arid climate regions of our country and is our country main coal production base.Coal mining industry is in a period of rapid development in there,its annual production is more than 250 million tons.The overall lower precipitation and the higher precipitation infiltration rate of the surface determine that groundwater is the main water supply source in the region,but the coal mining has a certain influence on the regional groundwater environment.In the process of coal mining,the disturbance of the regional stratum,the large pumping water test and the long-term drainage of mine drainage will have different influences on the characteristics of aquifer.Accordingly,the groundwater circulation condition and the change of groundwater resource properties are correspondingly.Aquifer parameter is an important index to characterize this process.In this paper,the study area is selected as the research area of the south region of the Ningtiaota coal mine in northern Shaanxi province,and the variation characteristics of permeability and water storage rate of aquifer under the mining disturbance are studied.In this study,first we compared the main water chemistry characteristics of different aquifers by water chemistry sampling and analyzing.Then we did numerical modeling of the groundwater flow in the main aquifer of coal seam roof to study the influence of mining disturbance on main hydrological parameters of aquifer.This study has important scientific significance and practical value on the deep understand the variation of aquifer parameters caused by mining,scientific evaluation the water resources under the interference condition,reasonable prediction of mine inrush and so on.Studies have shown that:1.The dominant hydrochemical facies are HCO3-Ca in the Quaternary alluvial aquifer,HCO3-Ca·Na in the fissured aquifer of the Jurassic formation,and HCO3-Ca·Na in the major hydrochemical types of surface water in the region.Jurassic sandstone formation has good permeability,the hydraulic relationship between the Quaternary aquifer and Jurassic aquifer is weak.The dissolution of carbonate is one of the main water-rock interactions during the formation of Jurassic groundwater.The dissolution of sulfur-containing minerals and carbonate are the important water-rock interactions in the formation of surface water.2.On the basis of analyzing the dynamic characteristics of groundwater in Ningtiaota mining area,used the Underground flow simulation software,built the geological entity model and hydrogeological conceptual model of the south region of Ningtiaota coal mine.The hydrogeological characteristics of Ningtiaota coal mine area are clearly shown in the model?The groundwater of the Quaternary aquifer in the Ningtiaota coal mine area mainly receives the supply of atmospheric precipitation,then moves from the watershed area with high terrain to the lowlying terrain and forms surface water.The Jurassic sandstone aquifer receives side supply,population flows from west to east,and discharge to the northeast and southeast respectively.3.The results of underground water flow field simulation and hydrogeological parameter calibration in 2014 and 2017 in the research area were compared and analyzed,then the variation law of the parameters of overlying aquifer under mining disturbance is illustrated.In the 2017 numerical model,The permeability coefficient of the zone where the permeability coefficient changes the most in the mining face changes from 2.5m/d to 12.0m/d,the permeability coefficient of the area around the mining face changed most significantly from 0.075m/d to 0.78m/d.