Experimental study on anisotropic permeability rule of coal bearing methane

In order to study the characteristics of anisotropic seepage of coal bearing methane,the raw coal samples were taken. Based on the tri-axial seepage experimental system the study of anisotropic seepage rule of coal bearing methane was carried out. The calculation method of the principal value and its azimuth of anisotropic permeability of coal bearing methane were determined. Permeability anisotropic ratio of coal bearing methane was defined. Permeabili- ty anisotropic dynamic variation rule and the phenomenon of the change of the dominant flow direction of coal bearing methane were analyzed emphatically. The results show that the flow of methane of coal has the very obvious character- istics of anisotropy,the calculation method of anisotropy permeability of coal bearing methane proposed in this paper is simple and effective. The coal bearing methane has strong stress-sensitivity,and the variation rule between permeability of methane of coal and effective stress is according with negative exponential function. The change of the permeability anisotropy of methane of coal with effective stress shows an obvious dynamic change law of development,the dominant flow direction of methane of coal exists the phenomenon of change.