准东大井矿区巨厚煤层开采覆岩含水层渗透特性研究

Study on the permeability of overlying aquifer associated with the mining of the super-thick coal seam in Dajing mining area of eastern Junggar coalfield

基于准东大井矿区赋岩柱状及岩性,构建了赋岩物理模型与数值模型。基于该模型,开展了赋岩位移与含水层渗透特性的模拟研究。结果表明:开采首分层覆岩含水层各测点位移随开挖长度的增加而增加;测点1~#物理模拟开挖至70～250m及数值模拟开挖至100～300m时,位移呈快速增加,其后位移变化稳定;测点2~#物理模拟开挖至70～420m及数值模拟开挖至250～500m时,位移呈快速增加,其后位移稳定;测点3~#物理模拟开挖至430～600m及数值模拟开挖至450～600m时,位移快速增加。物理相似模拟及数值模拟各测点变化趋势基本一致;覆岩含水层各测点有效应力与孔隙介质渗透率呈负相关;覆岩含水层各测点有效应力与裂隙介质渗透率呈正相关。开挖1～5分层渗透率大小为:测点1~#>测点3~#>测点2~#;开挖6～8分层渗透率大小为:测点3~#>测点1~#>测点2~#;覆岩含水层渗透特性与覆岩孔隙-裂隙双重介质动态变化特征有关,与采动覆岩应力变化具有耦合效应。

Based on the deposition of overlying rocks and their properties,the authors establish the physical model and the consequent numerical model.With these two models,the simulation of overlying rocks movement and the permeable characteristics of aquifers are investigated.The results show that the displacement of referring points from the physical similar experiment has the same change as that from numerical simulation for the mining of the first sub-layer of the super-thick coal seam in eastern Junggar coalfield.During mining of the first sub- layer,the displacement of reference point 1 # increases quickly from the mining period of 70- 250 m for physical experiment and 100-300 m for numerical simulation respectively,then stays stable.The displacement of reference point 2 # increases quickly from the mining period of 70 -420 m for physical experiment and 250-500 m for numerical simulation.And the displacement of reference point 3 # increases quickly from the mining period of 430-600 m for physical experiment and 450-600 m for numerical simulation.For the porous medium,a negative correlation exists between the permeability and the effective stress for each reference point of overlying aquifer.For the fracture,a positive correlation exists between the fracture permeability and the effective stress for each reference point of overlying aquifer.Further simulation shows that the values of permeability with reference points present an order as 1 #> 3 #>2 # during the stage of mining No.1 sub-layer to No.5 sub-layer one by one.Meanwhile,the values of permeability of reference points also demonstrate an order as 3 #>1 #>2 #.From this study,it s obvious that a coupling effect exist among the effective stress,the porous permeability and the fracture permeability of aquifers.