Substantiation of the geophysical criterion of origin of coal and gas sudden outburst for the option of fulfilling spectral-acoustic method of the current forecast is presented in the article. It is based on the dependence of the median of the amplitude-frequency characteristic of the operating mining equipment noise on the main outburst hazard factors. For the main factors the rock pressure, in-situ gas pressure and coal strength are adopted. The outburst hazard indicator is defined as the ratio of the amplitude-frequency characteristic medians in the current and critical state. Critical state is reached at the beginning of the fulfillment of one of the stages of the outburst running. Two stages of preparation for running are considered. The first stage is the beginning of the development of cracks and the formation of coal block structure in the face space. As the second stage, the process of coal layer extrusion into the working from the mouth of a future outburst cavity is used. The coal layer is represented by pieces formed at the first stage. The limit value of the outburst hazard indicator corresponds to the state when the average current stress in the face reaches the limit value, at which any of the two stages of outburst preparation begins. Outburst hazard criteria are substantiated for both stages of outburst preparation. For them, the impact on the limit values of the outburst hazard index of coal strength and gas in-situ pressure is considered. It is shown that with the gas pressure increase, and the decrease in coal strength, the limiting current value of the outburst hazard indicator decreases linearly. For continuous current monitoring of gas pressure, the methane concentration control is used by gas control equipment in the atmosphere of the working near the face. Coal strength control is performed by the strength gauge designed by IGD named after A.A. Skochinsky (implementation of a punch pin into the coal under spring action). It was established that with the increase of methane concentration, the limit current value of the outburst hazard factor for both stages decreases nonlinearly.
Read in №12 of 2019 year "Median of the Amplitude-Frequency Characteristic of Noise of Operating Mining Equipment as an Indicator of Outburst Hazard"
11 дек 2019