DAMAGE OF POROUS MEDIA CONTAINING PRESSURIZED GAS BY UNLOADING AND THE MAXIMUM DAMAGE PRINCIPLE FOR CRITICAL OUTBURST

Damage of porous media containing pressurized gas by unloading is formulated using a simple failure model and neglecting percolation. The damage can be shown to be caused by a discontinuous rarefaction wave—— a “damage wave”. Also, there exists a maximum damage wave,which satisfies C J condition as in the case of steady deflegration.A maximum damage principle for critical outburst is proposed.