Effect of different bedding directions on coal deformation and permeability characteristics.

A self-developed device called the gas-bearing coal heat solid coupling servo seepage device was used to conduct the percolation test of two different coal samples (parallel bedding coal and perpendicular bedding coal) under different condition settings to study the differences of deformation and permeability between these two types of coal samples. In the first section of the percolation test, the effective stress and gas pressure remained the same, while the axial pressure and confining pressure were different. In the second section, the gas pressure and hydrostatic pressure remained the same, while the effective stress was different. The result shows that the degree of fracture along the direction of z of parallel bedding sample is bigger than that of vertical bedding sample. The total degree of vertical stratification fractured specimen "φ" is bigger than the parallel bedding sample. In coal, the total fracture of vertical bedding direction is bigger than that of parallel bedding direction. The degree of fracture of parallel bedding sample is bigger than that of vertical bedding sample. Under hydrostatic pressure, the degree of fracture of parallel bedding direction is bigger than that of vertical bedding direction. According to the theory of tablet fluid, quadric relationship between permeability and radial strain can be obtained. The initial crack coefficient of parallel bedding sample is 1 .5-2. 0 times bigger than that of vertical bedding sample in coal. When the flow channel is considered as transfixion crack, the product of the initial crack coefficient and the square of the initial fracture aperture of parallel bedding sample is 1.5-2. 0 times bigger than that of vertical bedding sample. [ABSTRACT FROM AUTHOR]