A novel physical model of coal and gas outbursts mechanism: Insights into the process and initiation criterion of outbursts

Coal and gas outburst (outburst) is one of the most serious disasters in the underground mining industry. Understanding the mechanism of outbursts is essential to predict and prevent the outbursts. In this work, a key structural body model of outbursts was firstly proposed by considering the geological structure and environmental conditions of outbursts. Based on the key structural body model, the process of outbursts was illustrated and compared with previous insights in detail. The mechanical and energy initiation criterions of outbursts were further established through the theoretical analysis. The simulation experiment of outbursts and case of outbursts were applied to study the new model and verify the initiation criterions of outbursts. The results show that the initiation pressure of outbursts in our tests was 0.4 MPa, which is not related to gas type. Compared with CO2 and N2, the occurrence of outburst at 0.4 MPa for He indicates the initiation of outbursts is mainly determined by the free gas. At the same gas pressure, the mass of the ejected coal and the relative intensity of outbursts for CO2 were the largest, while the lowest for He. This phenomenon is because the CO2 has the strongest adsorption ability, which could provide enough energy for transporting the coal powders after the initiation of outbursts. Both the experimental results and case analysis proved the rationality of the mechanical and energy initiation criterions of outbursts. Therefore, the key structural body model could reveal the initiation mechanism of outbursts and provide the guidance for prediction and prevention of outbursts.