Mechanism of coal and gas outburst disaster in low permeability coal seam mining face

In order to effectively reveal the mechanism of coal and gas outburst in the working face of low permeability coal seam, and improve the pertinence and effectiveness of monitoring and prevention,the central mechanical model of outburst disaster was established based on factors such as gas occurrence state and mining disturbance. Similar simulation experiments and field experiments have verified the theoretical hypothesis, the disaster-causing mechanism of central body was revealed, and the correlations between microseismic and outburst hazards was verified. The results of similar simulation experiments show that the centrosome gradually inoculates and develops when the coal wall is about 60-20 m away from the central body, and the risk of central body outburst increases sharply at 20-10 m. This range is the macroscopic critical mass of central body outburst, which is the key prevention period and position. This conclusion has been verified in the test of No.15112 working face of Sijiazhuang Mine based on the K1 value of drilling cuttings gas desorption index, and the hypothesis of disaster-causing mechanism of outburst disaster center body has also been verified.The results show that the adsorbed gas is largely desorbed into free gas due to local fragmentation and the increase of permeability in heterogeneous holes such as joints and cracks, and mixed with pulverized coal to form a gas-solid two-phase fluid with high energy, forming a outburst disaster center. The center body exists objectively in the low permeability coal seam, and occurs in multiple locations. The mining effect provides external driving force, which leads to changesin the stress environment and gas state of the coal seam, and is easy to induce the center body outburst. From the perspective of of central body hazard, there is a good fitting relationship between microseismic and outburst danger, indicating that microseismic is an effective means of outburst danger monitoring, which provides a direction for further improving the pertinence and effectiveness of outburst monitoring and prevention.