Analysis of energy conditions for coal and gas outburst and factors influencing outburst intensity

The aim of this paper is to further investigate the influencing factors on outburst intensity of coal and gas due to the limited studies of its mechanisms. An expression of elastic potential energy released by coal is derived by establishing a three-dimensional outburst model and calculating the volume of irregular outburst pore. Based on analyzing gas internal energy and the energy after outburst, we propose an energy conditional model for the occurrence of coal and gas outburst and a forecast model of outburst intensity. These two models are applied to calculate the energy changes prior and after outburst, according to the statistical analysis of ten times of coal and gas outbursts. It is noted that the energies are almost the same between prior outburst and after outburst, and even the predicted values of outburst intensity are basically equal to the statistic ones. Therefore, the proposed models are verified to be valid, which provide a quantitative approach for analyzing the coal and gas outburst in terms of energy. Furthermore, the proposed procedures are successfully used to analyze the factors influencing outburst intensity of Zhongliangshan colliery and Huachu colliery. The results show that the outburst intensity is mainly dominated by the geostress of coal seam and gas content, and trivially affected by sturdiness coefficient and footage; the sensitivity of outburst intensity to gas content is higher than that of geostress.