ДОСЛІДЖЕННЯ ВПЛИВУ ВОЛОГОСТІ ВУГІЛЬНОГО ПЛАСТА НА РОЗВ’ЯЗУВАННЯ ГАЗОДИНАМІЧНИХ ПРОЦЕСІВ У ВИБОЇ ГІРНИЧОЇ ВИРОБКИ

Abstract

Purpose. Determination of influence of changes in the coal properties and phase permeability dur-ing moistening on the outburst hazard of the coal seam and calculation of the safe level of coal moisture. Methods. A mathematical model of the course of gas-dynamic processes in the mine face in the out-burst-hazardous zone near the tectonic fault has been developed, taking into account the presence of wa-ter in the crack-pore space of the coal. The system of equations has been solved using the finite element method. Calculations were performed for four cases: without taking into account the influence of water, with the influence of water on the change in phase permeability, with the influence of water on the modu-lus of elasticity and Poisson's ratio. Results. The calculation of geo-mechanical and filtration parameters under the condition of mini-mum natural moisture saturation sw=1% showed that under the desired boundary and initial conditions, a gas-dynamic process begins: the zone of inelastic deformations rapidly grows from the mine face along the coal seam, the methane pressure in the coal seam near the roadway rapidly drops, coal ejection oc-curs and a cavity is formed in the coal seam. Then geo-mechanical processes and the process of methane filtration return to a quasi-stationary state. As a result of performing a series of numerical calculations with varying moisture values in the crack-pore space of the coal seam, it was established that for the de-sired boundary and initial conditions, gas-dynamic process in the mine face begins when sw<24%. If this limit is exceeded, the gas-dynamic process in the near-face zone of the coal seam does not start. A de-crease in the phase permeability for methane leads to the neutralization of the outburst-hazardous prop-erties of coal. If we take into account the decrease in the value of the modulus of elasticity and the in-crease in Poisson's ratio when the water content increases in the crack-pore space of coal, then the safe limit of moisture saturation decreases additionally. Scientific novelty. The influence of changes in coal properties and phase permeability during hu-midification on the outburst hazard of a coal seam has been determined. The safe level of coal moisture saturation for desired boundary and initial conditions has been calculated. Practical significance. A numerical model has been developed that allows determining the safe lim-it of moisture saturation under specific conditions, at which the course of geo-mechanical and filtration processes in the coal seam does not acquire a dynamic character.