Abstract: According to the characteristic of in-situ stress redistribution of the coal surrounding rock caused by excavation, different stress on coal sample from Tunliu coal mine are jointed to investigate the coupled relation among permeability, stress and temperature under true tri-axial stress condition by using the test system of relative gas-liquid permeability of CGMS coal bed gas. The tests showed that the permeability of coal sample tends to decrease with the increase of stress and temperature, and Stress in different direction has different effect on permeability, which varies greatly. Temperature has less effect on the permeability significantly compared with the stress. Therefore, the relationship of permeability, stress and temperature is obtained and the effect of temperature and stress on permeability is theoretically analyzed.

Key words: Coal bed gas, Permeability, Stress path