Experimental study on permeability of coal sample subjected to triaxial stresses

摘要

The permeability of coal subjected to triaxial compression was investigated to relate it to the change of stresses state, analogous to mining-induced redistribution of stress in the surrounding rock. Results show that the permeability of coal sample under triaxial compression tends to decrease with the increase in stress in each loading direction, which indicates that permeability of the coal is actually controlled by the evolution of cracks in the coals. It also means that the orientation of cleats and maximum principle stress could significantly controls the permeability of intact coal. In other words, loading stress vertical to face cleats can be much easier to narrow the aperture of face cleats of the intact coal sample. Besides, the broken coal sample under higher stress level shows higher permeability than that of the intact coal under lower stress environment. That is partly because that the higher stress level is applied, the more likely the broken coal is to crush, which can contribute to the formation of the connected crack and in turns increase the permeability of coal.