Sensitivity analysis of factors affecting coal and gas outburst based on a energy equilibrium model

Considering the distribution of stress field in coal rock and the features of outburst hole, a three-dimensional structural model describing the coal and gas outburst was established based on the analysis of the stages and the energy dissipation of coal and gas outburst. The elastic potential of rock was introduced into the model and the mobile power and crushing energy were calculated according to the stacking states of coal and surface energy of fracturing. A model of energy conditions and a model of intensity assessment for outburst were established and verified with real cases. Based on the energy condition of outburst, Morris screening method was used to analyze the sensitivity of the influencing factors of outburst. Gas energy is found to be the main energy source of coal and gas outburst and plays the leading role in the process of outburst. The results from the models of outburst energy condition and outburst intensity assessment deviate little from the ones of the actual outburst cases. In the cases of the coal mines at Zhongliangshan and Huachu, the coal gas content is the primary factor affecting the intensity of outburst, the gas emission and the outburst energy and had the highest sensitivity. The gas diffusion coefficient, gas pressure and porosity are found to be secondary and the sensitivity of other parameters of the rock is close to zero.