Abstract: Based on self-developed triaxial servo gas-seepage experimental device of gas heat solid coupling, gas-seepage experiments were conducted on coal rock under the combination of different axial compression, confining pressure and gas pressure, complete stress-strain under combination of different confining pressure and gas pressure and influence law of coal-rock permeability under different stress combination were researched. The result indicates that there are three stages of permeability of coal-rock with the change of volumetric stress; permeability decreased with the increase of confining pressure, and it shows conical relationship with confining pressure, the influence of confining pressure was bigger than axial compression to permeability under the condition of certain axial compression and gas pressure; Permeability decreased first then increased with the increase of gas pressure, and it shows cubic curve relationship with gas pressure, slippage effect occupies an leading position at stage of permeability decreasing under the condition of certain axial compression and confining pressure; Permeability increase with the increase of axial compression, it decreases with the increase of confining pressure and shows linear law under conditions of a certain gas pressure and the same volumetric stress.

Key words: Coal-rock, Stress combination, Permeability