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Effects of the effective stress on deformation and permeability of coal |
ZHU Jie1,2,WANG Xue1,YU Pengcheng1,CHEN Mengda1,CHEN He1,HE Fa1 |
(1. School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;
2. State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China) |
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Abstract In order to investigate the effect of the effective stress on deformation and permeability of coal,the strain and permeability of coal cores from No. 9 coal seam of Zhaogezhuang Coal Mine in Kailuan Mine area were measured with the triaxial servo-controlled seepage device. The experiments were carried out under two types of conditions. One type of condition was to reduce the inlet gas pressure while the confining stress was kept constant. Another type of condition was to reduce the gas pressure and confining stress synchronously. The coal shrinkage was found to increase with the effective stress. There was a linear correlation between the volumetric strain of coal and the effective stress within the range of 5.2 MPa and 6.5 MPa. When the effective stresses were outside the range,the stress-strain lines were not straight anymore,and coal dilatation was observed from some samples. The gas flow velocity decreased with the decreasing of gas pressure of inlet port. However the coal permeability increased regardless the decreasing or increasing of effective pressure. Therefore the effect of gas slippage should be considered when the coal permeability change with effective stress is investigated.
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[1] |
PAN Z,CONNELL L D. Modelling permeability for coal reservoir: A review of analytical models and testing data[J]. International Journal of Coal Geology,2012,92(1):1-44.
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