Focusing on outburst coal and nonoutburst coal

the permeability experiments on the outburst coal and nonoutburst coal briquettes during the complete stress-strain process were designed using “Coal Containing Gas THM Coupling System”; to study their permeable properties in the complete stress-strain process. The results show that: during the complete stress-strain process

the deformation of outburst/nonoutburst coal showed similar trends with gas volume flow velocity

which means

in the complete stress-strain processes of both kinds of coals

gas volume flow velocity is tightly related with the damage deformation process of coal. The gas volume flow velocity decreased with the compressing of coal volume

decreased to the lowest value when the coal volume was compressed to the minimum; and then when coal volume began to expand

gas flow velocity turns to increase. The gas volume flow velocity decreased with the increasing of confining pressure; and the higher the confining pressure was

the smaller the changing rate of gas volume flow velocity to strain was. The properties of coal show an evident effect on gas permeation; so the permeability could be treated as a significant criterion for the judgement of coal-gas outburst criticality.