LAUSR

Abstract The gas permeability of coalbeds is of critical significance to gas exploitation and recovery in coal seams. These properties are affected by bedding plane orientation. In this paper, the influence of different bedding angles in coal on mechanical properties, and gas permeability behavior in a complete stress–strain process is investigated. Experimental results reveal that with an increase in the bedding angle, the number of channels was found to increase along with the initial permeability. The increased bedding angle also caused the compression strengths of the coal sample to decrease initially and then increase. The corresponding compression strength was highest at a bedding angle of 0° followed by a bedding angle of 90°. Under these two conditions, the failure surface of coal was usually due to tensile splitting. The coal strength was lowest at a bedding angle of 60°, where the coal mass experienced shear failure during the bedding plane. The coal sample at a bedding angle of 30° exhibited compound split-shear failure.