Experimental study on permeability of soft rock of Beizao Coal Mine

Considering the relation between permeability-strain curve and rock failure process of roof of Beizao Coal Mine, the relationship among permeability, strain and stress of rock is analyzed based on the permeability-strain curve and permeability-stress curve under complete stress-strain path. The results show that the rock can be divided to three groups, that is, sandstone, mudstone and sandstone with coarse gravel. The lowest permeability of rock corresponds to its expansion point. The stress-strain path can be divided into three stages, which are compaction-elastic range, yield range of pre-peak and post-peak range. It is proposed that the change of rock permeability is caused by the interaction of the smaller micro-scale level burst, which results in the formation of permeable channels.