Evolution of Seepage in Microfracture Structure of Coal Subject to 3D Stress Environment

In order to experimentally study the evolution features of gas seepage in the micropore structure of coal under the three-dimensional (3D) stress environment as in the mining heading roadway of coal mines, a true triaxial gas-solid coupling coal seepage test device was independently developed. Its 3D stress environment is supplied independently using 2D rigid and 1D soft load ways and controlled by the hydraulic servo system. Such a design can overcome the stuck problem often occurring in the loading processes. Experimental results show that the device can be used to well monitor the changes in structure and permeability of coal body subject to 3D stresses in three directions with good stability and reliability. The true triaxial gas-solid coupling coal body seepage test combined with the CT scanning coal body three-dimensional fracture model construction technology can systematically explore the deformation and seepage of the microscopic pore fracture structure of the coal body.