Effect of Dry-wet Circulation on Permeability of Coal Containing Gas

In order to study the effect of dry-wet circulation on permeability of coal containing gas,by using the selfdeveloped coal containing gas thermal-hydrological-mechanical (THM) coupling experimental equipment,an experimental study about the permeability of raw coal was made under different dry-wet cycles and different average effective stresses.The research results showed that:under the condition of a constant temperature and dry-wet cycles,with the increase of average effective stress,the permeability of coal samples showed a logarithmic function decreas.The sensitivity coefficient of average effective stress to permeability increased with the increase of coal sample dry-wet cycles,decreased with the increase of average effective stress.Under the condition of a constant temperature and an average effective stress,the permeability of coal samples increased with the increase of coal sample dry-wet cycles,and the relationship between coal sample permeability and dry-wet cycle can be expressed by linear function.The more dry-wet cycles,the stronger the water absorption of the coal sample,the greater the saturation moisture content.