Abstract: To investigate the influencing factors of the permeability of loaded coal mass containing gas, with the self-developed thermo-fluid-solid-stress coupling equipment for gas-bearing coal mass, the gas permeability characteristics of coal mass in the conditions of different effective pressure, pore pressure and temperature were analyzed in this paper. In addition, by considering the amount of adsorption deformation, the pore gas compression amount, and the variable quantity of temperature expansion, the qualitative and quantitative relationships between the permeability of loaded coal mass and the effective stress, pore pressure, temperature were established, respectively. The results show that when the temperature is under a certain value, the permeability presents negative exponentially proportional to the confining pressure. When the confining pressure and axial compression are fixed, the permeability and pore pressure of coal sample appear V-shape relationship while considering the Klinkenberg effect. According to experimental results, the critical value of pore pressure while Klinkenberg effect occuring were obtained when the confining pressure are 2.0 MPa and 3.0 MPa respectively. Meanwhile, the relationship between the temperature and permeability isn’t the monofonic function under different effective stress, but exists a turning point in the curve. Permeability increases with the increase of temperature and presents outward expansion in the low stress areas, while it decreases with the increase of temperature and presents inward expansion in the high stress areas. Finally, the permeability calculation formula under the combined impact of pressure and temperature was proposed.

Key words: loaded gas-bearing coal mass, permeability, confining pressure, pore pressure, effective stress, influencing factors