Acoustic-Gas Coupling Response Law in the Whole Process of Coal and Gas Outburst

Abstract

The intensification of the global energy crisis has led to an increasing demand for coal. China is a major coal-producing country in the world and also the country with the most severe coal and gas outburst disasters. Thus, the coal and gas outburst experiment was conducted, and the following results were obtained: the whole outburst process was divided into three stages, namely the outburst preparation stage, the outburst gestation stage, and the outburst development stage. The gas pressure and acoustic emission signals show significant changes in all three stages, while the variation patterns are different. The gas pressure changes were strongest and the acoustic emission signals were highest during the development stage. Therefore, the outburst development stage was further subdivided into four phases, and the correlation between acoustic emission and gas pressure in each phase was analyzed in detail. Furthermore, the acoustic emission signals in three stages were compared and analyzed. The peak values of acoustic emission count and energy reached 285 times·s−1 and 245 V in the preparation stage and reached 265 times·s−1 and 231 V in the gestation stage, respectively, only 1.66%~1.78% and 2.19%~2.32% of the development stage, namely 15,980 times·s−1 and 10,566 V. Moreover, it was found that the cumulative count and cumulative energy showed a parabolic relationship with the development time of the outburst. Based on the above experimental results, during the production process in coal mines, the dangerous state of outbursts can be monitored through gas pressure changes in the outburst preparation stage and gestation stage. Once in the development stage, more sensitive signals of acoustic emission and their fitting results are used for outburst hazard monitoring and early warning. Monitoring and warning of outbursts of combined gas pressure and acoustic emission signals can effectively improve the safety level of coal mine production.