Experimental Study on Permeability Response Characteristic of Low Permeability Coal Samples Under Axial Load and Confining Pressure

To research the permeability variation laws of low permeable coal samples under changing axle load and confining pressure, we carry out an experimental research on coal permeability under different confining pressure and axle load using a self-developed resultant stress-strain triaxial seepage test system based on servo temperature control. The test results demonstrate that: the permeability decreases with the change of axle load and confining pressure, but the effect of confining pressure on permeability is higher than that of axial pressure; the relation of confining pressure σ₂to permeability K can be expressed as K＝ａｅ^-0.45σ₂, the fitting coefficient a decreases with the increase of axial pressure; when axle load and confining pressure are within the range of 1 MPa to 10 MPa, their relation to permeability can be written as K＝15.426 23ｅ^-0.45σ₂－0.261 94σ₁ｅ^-0.45σ₂.