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COAL PERMEABILITY CHANGE CAUSED BY MINING-INDUCED STRESS

Lulu Zhang 1,  
Bo Li 2  ,  
Jianping Wei 3,  
Zhihui Wen 3,  
 
1
State and Local Joint Engineering Laboratory for Gas Drainage & Ground Control of Deep Mines in Henan Polytechnic University
2
Collaborative Innovation Center of Coal Work Safety, Henan Province, Henan Polytechnic University, Jiaozuo, China
3
State and Local Joint Engineering Laboratory for Gas Drainage & Ground Control of Deep Mines, Henan Polytechnic University, Jiaozuo, China
4
State and Local Joint Engineering Laboratory for Gas Drainage & Ground Control of Deep Mines, Henan Polytechnic University, Jiaozuo, China
Mining Science 2019;26:203–222
KEYWORDS
TOPICS
ABSTRACT
To study coal permeability evolution under the influence of mining actions, we conducted a sensitivity index test on permeability to determine the influence of axial and confining stresses on coal permeability. Loading and unloading tests were performed afterward, and the differences between loading and unloading paths in terms of strain and permeability were studied. A permeability evolution model was built in consideration of absorption swelling and effective stress during modeling. An effective stress calculation model was also built using axial and confining stresses. The calculation results of the two models were compared with experimental data. Results showed that permeability were more sensitive to confining stress than axial stress, and effective stress placed a large weight on confining stress. Large axial and radial deformations at peak strength were observed during unloading. In the unloading phase, the permeability of coal began to increase, and the increment was enhanced by large initial axial stress when confining stress was loaded. permeability sensitivity to axial and confining stresses were used to explain these permeability changes. The calculation results of the models fitted the experimental data well. Therefore, the proposed models can be used to calculate effective stress on the basis of axial and confining stresses and describe permeability change in coal under the influence of mining actions.
CORRESPONDING AUTHOR
Bo Li   
Collaborative Innovation Center of Coal Work Safety, Henan Province, Henan Polytechnic University, Jiaozuo, China
 
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