Experimental study on the permeability of coal samples with different heights under cyclic loading and unloading
WANG Chenlin1，ZHANG Xiaodong1，2，LI Guizhong3，DU Zhigang1，ZHANG Shuo1
(1. School of Energy Science and Engineering，Henan Polytechnic University，Jiaozuo，Henan 454000，China；2. Collaborative Innovation Center of Coalbed Methane(Shale Gas) in Central Plains Economics Zone，Jiaozuo，Henan 454000，China；
3. Langfang Branch，PetroChina Exploration and Development Research Institute，Langfang，Hebei 065007，China)
Abstract：In order to obtain the permeability variations of coal samples with different heights under cyclic loading，triaxial loading seepage experiment device was used to carry out the cyclic axial loading and unloading compression tests on coal samples with the same diameter and different heights. The results show that the permeability decreases with the increasing of the axial compression in the loading stage. The permeability increases with the decreasing of the axial compression in the unloading stage. The relationship between the permeability and the axial compression is a negative exponential function and the stress sensitivity of permeability decreases with the increasing of cycle numbers. The permeability has a significant difference during the loading and unloading stage and the permeability difference decreases with the increasing of cycle numbers. The permeability reduction mainly occurs in the initial stage of loading and unloading. There are significant differences in stress sensitivity for coal samples with different heights. The stress sensitivity decreases with the increasing of the height to diameter ratios of coal samples. During the loading and unloading stage，the reduction of dimensionless permeability increases with the increasing of the height to diameter ratio. After cyclic loading and unloading，the reduction rate of permeability increases with the increasing of height to diameter ratio. The recovery rate of permeability decreases with the increasing of height to diameter ratio.
王辰霖1，张小东1，2，李贵中3，杜志刚1，张 硕1. 循环加卸载作用下不同高度煤样渗透性试验研究[J]. 岩石力学与工程学报, 2018, 37(10): 2299-2308.
WANG Chenlin1，ZHANG Xiaodong1，2，LI Guizhong3，DU Zhigang1，ZHANG Shuo1. Experimental study on the permeability of coal samples with different heights under cyclic loading and unloading. , 2018, 37(10): 2299-2308.
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2018, Vol. 37 
