| Coal resources are closely related to groundwater resources,which will lead to a series of environmental problems such as drainage of aquifers,cut-off of rivers and ditches,and mine water disasters,which seriously threaten underground production operations.China's Inner Mongolia is rich in coal resources and stable in occurrence,which makes it easy to carry out large-scale,high-efficiency and high-intensity mining.However,due to the scarcity of vegetation and serious desertification in Inner Mongolia,high-intensity mining is encountered in the arid climate,and the shortage of water resources is becoming increasingly severe.Therefore,more attention should be paid to the protection of groundwater resources and water control projects in coal mines in this area.Guided by the theories of groundwater dynamics,hydrogeology,coalfield hydrogeology,etc.,this study selects a mine field in Shendong mining area of Inner Mongolia as the research object.Based on the collection of relevant hydrometeorological and borehole survey data,GMS numerical simulation software is used to establish a groundwater flow model that conforms to the hydrogeological conditions of the study area,simulate and predict the groundwater level,water volume and flow field under the influence of mining,and explore the change law of mine water inflow under high-intensity mining,so as to ensure the safe and efficient production of the mining area and promote the sustainable development of energy exploitation The main achievements are:(1)Using Kriging interpolation method in Surfer software to draw the groundwater isowaterline in the study area,it is concluded that the initial flow direction of groundwater is from northwest to southeast.Through the analysis of the water source and intensity of mine water filling,it is concluded that the atmospheric rainfall in the mining area is an indirect supply relationship to the mine,while Zhidan Group with strong water-rich property and good rock permeability and Zhiluo Formation,the overlying aquifer of coal seam,are the main water filling sources of the mine.(2)Based on the analysis of stratum structure and lithology in the study area,the aquifer is divided into Quaternary pore phreatic aquifer,Tertiary laterite aquitard,Cretaceous Zhidan Group aquitard,Jurassic Anding Group aquitard,Jurassic Zhiluo Group aquitard and Jurassic Yan'an Group aquitard from top to bottom,with three aquifers and three aquitards in total.Based on the 3D geological structure model generated from borehole data,the generalized boundary conditions,water flow characteristics and source-sink terms of the study area are input,and the groundwater flow movement in the study area is discretized in time and space.By using the finite difference method of Modflow,the hydrogeological conceptual model is established,and the stratigraphic combination and the spatial occurrence state of groundwater in the mining area are accurately grasped.After the model is identified and verified by the measured water level in observation well,a groundwater flow model which can represent the hydrogeological conditions in the study area is established.The corrected water flow model is used to predict the changes of groundwater level,water volume and flow field under the high-intensity mining activities in the next 10 years.The results show that mining has the greatest influence on the aquifer of Zhiluo Formation,and the groundwater level in the mines in each mining area drops obviously,forming multiple water level dropping funnels,the groundwater level drops as a whole,and the runoff conditions change,from the original northwest to southeast flow to the surrounding supply to the funnel center.Although the distance between Zhiluo Formation and Zhidan Group Aquifer is far away,the large amount of mine drainage also has a certain influence on the water flow field of Zhidan Group Aquifer.Under the action of water head pressure,the groundwater in this layer seeps vertically and overflows to supply Zhiluo Formation Aquifer,but the overall water flow field has no obvious change compared with the initial flow field.According to the theory of water balance,starting from the analysis of regional balance and interlayer balance,it is concluded that the groundwater in the study area under mining activities is in a positive equilibrium state.(3)In order to reveal the dynamic change law of mine water inflow in different mining positions,different mining areas and different mining progress,based on the numerical simulation method,combined with the mining plan from 2020 to 2025,the dynamic water inflow of coal mining working face is predicted.The simulation results show that the water inflow of mining area changes obviously,and the water inflow increases with the increase of mining intensity from 2020 to 2021.From 820.42m~3/h to 1086.26m~3/h,after the mining progress is stable,the water inflow shows a small downward trend,and it is stable at about 934.45m~3/h after2025.At the same time,the"Big Well Method"is used to calculate the water inflow of each mining panel,and the calculated values of the two methods are compared.The numerical simulation values fall within the calculation range of the big well method,which mutually verifies the accuracy of the two methods to a certain extent.This paper has 43 figure,9 table and 52 reference. |
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