Analysis on statics of coal and gas extrusion based oncoupling function of stress inclusion

In order to analyze the coal and gas extrusion mechanism occurred in the mining and excavation process of the coal mine, based on a hypothesis of "a closed stress", an assumption was made that the local stress concentration or an energy concentrated "stress inclusion" existed in the coal mining and excavation. In a comprehensive consideration on a combined effect of the closed stress, mining stress and gas pressure, a stressed model of the coal with the stress inclusion was established. Based on the basic theory of the elastic mechanics, the stress distribution law of the gassy coal with the stress inclusion was derived.The result showed that when the mining and excavation face had a certain distance to the stress inclusion, the gassy coal would be failure along the direction of the maximum principal stress. When the mining and excavation face getting closer to the stress inclusion affected by the combined effect of the overburden strata, stress inclusion and gas, the coal would have dynamic phenomena occurred along the direction of the maximum principal stress and the wedges and lip holes were formed. The influence coefficients of the mining and excavation would determine the size of the holes after the dynamic phenomena. The analysis results could provide a new idea to recognize the dynamic phenomenon of the coal and gas and could provide the theoretical support of the prevention and control measures.