Gas emission characteristics of tectonic coal in the initial stage: Application for coal and gas outburst prediction

Coal and gas outburst is one of the most disasters threating the safety and production of coal mines. Accurate description of the gas emission characteristics in the initial stage for tectonic coal is the key to improving the prediction accuracy of coal and gas outburst. In this work, the gas emission test of original and tectonic coal particles under the constant temperature was carried out. The optimal mathematical model suitable for the gas emission in the initial stage was then analyzed. Moreover, the time influencing factors of the optimal mathematical model were discussed. The research results show that cumulative gas desorption amount during 0-7 minute for tectonic coal is 1.28-1.41 times as much as that for original coal. The applicability of current mathematical model for describing the gas emission characteristics of tectonic coal in the initial stage has limitations. Five typical mathematical expressions are selected and compared to fit gas emission curve in the initial stage. Considering the sensitivity of parameters in outburst prediction, the optimal mathematical model was obtained. In addition, the time factor has a great influence on the application effect of mathematical model in coal and gas outburst prediction. For current mathematical model, the errors of tectonic coal are all negative. The greater the gas pressure and the later the measurement time, the greater the error. The errors in 1~6 min are -0.46%~-1.78%, and the errors in 2~7 min are -1.00%~-3.86%, which is not conducive to the safety of outburst prediction. Therefore, the optimal mathematical model has the possibility to overcome the limitations of current mathematical model. The research results provide a theoretical basis for the correction of coal and gas outburst prediction indicators.