Coordinated prevention mechanism of pressure-relief and coal and rock properties modification for coal and gas outburst in deep mining of coal mines

The deep mining of coal mines leads to some significant changes in the physical properties of coal and rock, stress environment and gas occurrence law. New disaster features such as stress-driven gas outburst and coal and gas outburst under low gas pressure condition have appeared. In order to guide the prevention and treatment of coal and gas outburst in deep coal mines,the theoretical permeability model of tectonic coal body prone to outburst is estab-lished. The coordinated prevention mechanism of pressure-relief and coal and rock properties modification for coal and gas outburst is revealed based on the key structural body theory of coal and gas outburst. The research result shows that the core of prevention and control coal and gas outburst is efficient gas extraction,and the key is to reduce ground stress. This pressure relief has multi-effects of reducing elastic strain energy,improving the coal permeability,promo-ting gas extraction and reducing the gas internal energy. The prevention and control measures of coal and gas outburst in deep coal mines should be implemented according to two concrete conditions including relieving pressure and reforming coal & rock medium property. In some special areas of coal mines,after adopting the pressure relief measures and implementing gas extraction,other auxiliary measures should be taken to improve the outburst resistance and restrain the gas desorption to ensure mining safety in deep coal mines.