Research On The Influence Of Coal Mining On Groundwater

In the process of large-scale coal mining,due to the close connection between the coal seam and the groundwater aquifer,it may affect the groundwater and cause different degrees of water damage.Ningdong Energy and Chemical Base is an important coal mining area in my country.It is rich in minerals and has excellent mining conditions.The coal seams in the area are closely connected with the Zhiluo Formation aquifer and the Quaternary aquifer.Therefore,the study of the impact of coal mining on groundwater is very important for the safety of the mining area.Production and water resources protection have important theoretical value and reference significance.In this paper,an important coal mine in the north of Ningdong Energy and Chemical Industry Base is taken as the research area.On the basis of data collection and field investigation,the theoretical calculation,AHP,comprehensive index evaluation and numerical simulation methods are comprehensively used to carry out a research project based on ArcGIS and Visual MODFLOW.The height of the water-conducting fissure zone of the first 2#coal seam in the coal mine,the comprehensive evaluation of the impact of coal mining on groundwater,and the prediction of groundwater level changes.The research results have certain reference significance for groundwater protection in the region.The results of the study are as follows:(1)The minimum height of the water-conducting fracture zone in the study area is 16.53 m,the maximum is 93.89 m,and the average is 33.49 m.The thickness of the overlying rock is 1.50～85.29 m,with an average of 31.16 m.The thickness of the aquifer is 17.59～82.50m,the permeability coefficient is 0.0015～0.13 m/d,the unit water inflow is 0.02～0.32l/s m,and the water richness of the aquifer is weak;(2)Carry out the evaluation of the impact of coal mining on groundwater,and select the height of the water-conducting fracture zone,the thickness of the overlying rock layer,the thickness of the aquifer,the permeability coefficient and the unit water inflow as the evaluation indicators.0.207,0.131,0.104,0.065,and further carry out the evaluation of the impact of coal mining on groundwater.The evaluation results show that the overall influence of coal seam mining on aquifers is gradually weakening from north to south,and the seriously affected areas are mainly located in the northern part of the mine field,accounting for 15.13%of the mining area,and the remaining areas are relatively less affected by coal seam mining;(3)Construct a hydrogeological conceptual model and a mathematical model of groundwater flow in the study area,and predict the groundwater level changes on the 744th,1190th and 2098th days after coal mining based on Visual MODFLOW.The results show that the water level of the Quaternary submerged aquifer does not change and the flow direction of the flow field does not change after mining;the water level of the confined aquifer in the Zhiluo Formation drops significantly after the coal seam mining.On the 1190th day,the water level was wider than the descending funnel and was connected to the water level.By the 2098th day,the confined water level dropped by about 4.9m,and the groundwater level tended to be stable,and the groundwater in the unexploited areas was less affected.