Analysis on coal and gas outburst mechanism of beding shear zone

In order to determine the mechanism of coal and gas outbursts in the shear zone of coal seam, the formation mechanism of the shear zone was analyzed by Mohr-Coulomb theory based on the analysis of the stress state in the shear zone seam, and the variation characteristics of coal seam, gas content and gas pressure characteristics and the effect of ground stress on outbursts were also analyzed. The results showed that it was easy to cause thin coal zones when the coal seam dip was close to the critical angle of shearing slip. While, when the dip was far from the critical angle, the thickness of coal seam increased and the dramatic change region of coal seam is the stress concentration zone with high stress gradient; the compressive stress, the surface physicochemical structure and the drastic changes in thickness of coal seam made the characteristics of high gas content and pressure in macro perspectives, in micro perspectives the pore morphology of mylonitized coal with flask shape provides necessary medium conditions for the occurrence of coal and gas outburst. It was mainly with outbursts in compactly folded region, while in loosely folded zone it was mainly with extrusion and poured out. The main reasons of coal and gas outburst in the shear zone of coal seam are high ground stress, high gas pressure and developed tectonic coal.