DOI: 10.21440/0536-1028-2019-6-51-59

Smirnov V. G., Dyrdin V. V., Kim T. L. The factor of outburst hazard of coal seams zones, conditioned by coal particles size. Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal = News of the Higher Institutions. Mining Journal. 2019; 6: 51–59. DOI: 10.21440/0536-1028-2019-6-51-59

Introduction. Parameters and features of coal seams which experienced coal and gas outbursts are actively studied to specify the mechanism and develop the methods of forecasting and preventing coal and gas outbursts. Outbursts emit from weak, crumpled coal members.
Research aims to investigate the influence of coal seam grains size on the development of coal and gas outbursts with the account of possible modification of coal strength and filtration properties.
Methodology. Theoretical analysis of coal particles size and the size of incipient cracks influence on the formation of coal and gas outbursts.
Theoretical part. The research has shown that with the reduction of coal particles average size, the flow of gas which develops from the internal volume of coal into the free form increases, the coefficient of permeability decreases; it leads to the growth of gas pressure gradient in the marginal zone. The size of particles depends upon the conditions of coal development and occurrence. In certain geological periods coal breaks up when a part of a massif is broken by the forces of rock pressure. The size of coal particles influences the range of equilibrium conditions, under the violation of which coal and gas outburst develops.
Results. Based upon the conditions of balance of a minute volume of coal with oriented cracks, the criterion of coal and gas outbursts development has been formulated; it shows that with the reduction of cracks size as a power function, the probability of coal and gas outbursts increases, when other conditions remain constant.
Summary. The factor of coal and gas outbursts generation has been formulated, expressed in terms of coal particles size to the power of 2.5 whereby the probability of outburst generation linearly increases under the grow of coal seam gas content, methane diffusion ratio out of the internal chamber to the surface of coal particles and under coal strength reduction.

Key words: gas-dynamic events; marginal zone; coal; methane; coal and gas outburst; cracks; breakdown; size of grain; filtration.

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Received 15 May 2019