Experimental study on permeability characteristics and adsorption swelling of coal considering temperature effect

Using the triaxial servo-controlled seepage equipment for the thermo-fluid-solid coupling of coal containing methane to simulate the changes of permeability characteristics caused by the increase of depth of mining,an experi- mental study on the permeability during the process of loading tests under different temperatures was carried out,and a adsorption swelling model considering the effect of temperature was developed to study the influence of temperature and pore pressure on the swelling of coal. The results are shown as follows:① With the increase of pore pressure,the axial strain decreases at lower temperature (30,40 ℃ ) and increases at higher temperature (50,60 ℃ ). In addition, the radial strain and volumetric strain decrease with the increase of pore pressure;② With the increase of pore pres- sure,the permeability of coal decreases first and then increases slightly. The trend of the permeability of helium at dif- ferent temperatures is similar to that of methane and the permeability is higher than that of methane;③ The variable quantity of permeability caused by slippage effect ( Δkb ) increases with the increase of temperature. The variation of permeability caused by adsorption swelling ( Δks ) decreases with the increase of pore pressure and then tends to be gentle. With the increase of temperature,Δks increases gradually;and ④ Under the same pore pressure,Δks consider- ing the effect of temperature is higher than that without considering the temperature. During the loading process,the to- tal amount of reduction of Δks considering the effect of temperature is greater than that neglecting it.