COAL PRE-OUTBURST PRESS-OUT CRITERIA FROM THE OUTBURST CAVITY MOUTH FOR SPECTRALACOUSTIC FORECAST METHOD
Journal Title: Вестник научного центра по безопасности работ в угольной промышленности - Year 2019, Vol 0, Issue 3
Abstract
Coal and gas sudden outburst development process is considered when, under the rock and gas pressure forces influence, a layer of a coal seam consisting of several coal lumps is abruptly pressed out into a working to the future cavity mouth. The geomechanical criterion for pressing out a layer of coal is determined in the form of the ratio of active (pressing out) and passive (preventing this pressing out) forces. The sum of lateral pressure force, the force caused by the pressure of free gas in the cracks, and the weight of the pressed out coal layer are considered as the active forces. The cohesive forces and internal friction of coal in the massif are taken as passive forces. For the geomechanical criterion, the geophysical criterion is substantiated by expressing the main physical parameters in terms of geophysical: the operating stresses stipulated by the rock pressure are determined by the spectral-acoustic method through the ratio of the high-frequency and low-frequency components of the acoustic signal generated at the face area by mining equipment acting on the face; the seam gas pressure is estimated by the gas analytical method from the concentration of methane in the working atmosphere; the strength of the most crumpled coal band is periodically measured on the face chest by the strength gauge of A.A. Skochinsky Mining Institute design through the depth of a steel cone hit with a spring mechanism penetration. The limiting (critical) value of the geophysical outburst hazard criterion is determined when the active and passive forces are equal. The influence of the acoustic, strength, filtration and accumulation properties of the face area on the critical value of the obtained geophysical criterion for the pre-outburst pressing out of the “coal plug” to the mouth of the future outburst cavity is analyzed. It is shown that with an increase in rock pressure and methane concentration at the face chest, and with a decrease in coal strength, the critical value of the hazard factor decreases.
Authors and Affiliations
A. V. Shadrin, Yu. A. Diiuk
Keywords
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