The Numerical Simulation Research Of Impacts Of Coal Mining On Loose Aquifer Under The Condition Of Porous Aquifer Base Plate Parameter Changes

Chang Village coal mine is located in changzhi basin of Shanxi Province. The local loess layer was thicker, especially the study of Chang Village coal mine S6 mining area.There the thick of loose aquifer was 46 ~ 125 m, and the average thickness was 88.2 m.This article mainly researched that in the thicker loess areas, when the height of the lead water fracture zones close to but not at the bottom of porous aquifer base plate under coal seam mining of S6 mining area of Chang Village coal mine, ruled out due to the factors of the conductivity fractured zone caused the overlying the quaternary system aquifer unwatering, it established a practical three-dimensional groundwater flow numerical simulation model. Then paper designed different simulation scheme, making the permeability and thickness of porous aquifer base plate changed with certain regular by changing the size of permeability coefficient at different positions of the mined-out area of coal seam after mining in the model, to analyse the different model design scheme for the influence law of unwater degree of overlying the quaternary system aquifer.The researches of scholars both at home and abroad were mainly aiming at the height of water fractured conducted loose aquifer floor, roof water inrush after coal seam mining.They didnot consider the situation of the height of water flowing fracture without conduction pore aquifer soleplate, the overlying aquifer inflowed seepage drainage of quaternary system aquifer groundwater; or only qualitative analysis if coal seam mining have influence or destruction for quaternary unconsolidated aquifer; or some scholars also analyzed quantitatively the influence to quaternary unconsolidated aquifer after coal seam mining by using numerical simulation, but they made the quaternary aquifer and other aquifer as a layer to study. It was fissure seepage. It was different from caving and fractured layer turbulence mechanism. Aiming at the shortcomings of the previous studies, this paper mainly studied the height of the lead water fracture zones close to but not at the bottom of porous aquifer base plate, the quaternary aquifer recharged the underlying aquifer through transfluence, lead to groundwater drainage, at the same time, the lithology of strata came up changes after coal mining. Model changed the lithology in the affected aquifer. Paper further analyzed the influence of the quaternary system aquifer unwatering under the change of porous aquifer base plate permeability、thickness.In this paper, the main research contents has the following points:1.In this paper, based on borehole data of Chang Village coal mine, Yu Wu coal mine and WangZhuang coal mine in the research area generated 3D model, combining with the geological and hydrogeological data 3D unsteady flow numerical simulation model was established, and model fitting correction. After coal seam mining of S6, the height of water fractured zone distanced the bottom of porous aquifer base plate 25 m, and Permian sandstone fracture aquifer groundwater drainage to the floor strata.2. On the basis of the above model, it obtained fractured zoned formation parameters, analysising rock permeability characteristics experiment at different positions of the mined-out area, fracture characteristics research in mined-out area and rock crushing degree test, etc. It designed different simulation schemes making the condition of coefficient of permeability of porous aquifer base plate was 10-4 cm/s, and the thickness of porous aquifer base plate changed from 0, 20 m, 40 m, 60 m to 80 m. With the increase of thickness, the quaternary system aquifer water level drawdown decreases, and water level drawdown gradually slow with the passage of time.3.It designed different simulation schemes making the condition of the thickness of porous aquifer base plate was 20 m, and the permeability coefficient of porous aquifer base plate changed from 10-2 cm/s, 10-3cm/s, 10-4cm/s, 10-5 cm/s, 10-6 cm/s to 10-7cm/s. With the decrease of the permeability coefficient, the quaternary system aquifer water level drawdown decreases, and water level drawdown gradually slow with the passage of time.