The method for determining the critical value of the outburst hazard indicator by the complex spectral-acoustic method for specific mining and geological and mining conditions of mine workings is presented. For identification of the outburst hazard criterion, two-stage model of the outburst preparation is considered. In accordance with this model, the first stage of the outburst preparation consists in the formation of the block coal structure in the face space due to the development of the cracks under the influence of the rock pressure and in-situ free gas pressure. The second stage is the beginning of squeezing-out into the working of the layer of coal formed by several blocks from the mouth of the cavity of the prepared outburst. It is shown that the current limit value of the outburst hazard indicator for the crack development stage is in most cases less than for the stage of squeezing-out into the working of the coal layer (in the mouth of the future outburst cavity). Therefore, the conclusion was made, that the criterion of the microseismic method for predicting the outburst hazard is necessary but not a sufficient condition for the beginning of the coal and gas sudden outburst. Procedure for the current forecast of hazard outburst by the proposed complex spectral-acoustic method is as follows: the current value of the outburst hazard indicator shall be continuously measured in the form of the ratio of the amplitudes of high-frequency and low-frequency parts of the «noise» spectrum of the operating equipment; continuous correction of the current critical value of the outburst hazard indicator shall be carried out by continuously measured values of methane concentration at the roadhead of the working and periodically measured strength values of the least durable patch of coal; continuous comparison of the current value of the outburst hazard indicator with its current critical value shall be carried out, based on which the conclusion will be made on the level of the current outburst hazard.
Read in №8 of 2019 year "Determination of the Outburst Hazard Criteria for the Complex Spectral-Acoustic Method of Forecast"
27 авг 2019