Hypothesis about physical-chemical nature of gas-dynamic phenomena in coal mines

Abstract

Practical experience in the development of a gas-saturated coal-rock massif, as well as the results of scientific research, point to the imperfection of the existing ideas regarding the processes in the extremely stressed coal-rock massif, mechanisms of the occurrence and behavior of gas-dynamic phenomena (GDP). The conducted analysis for the problem state regarding the nature and mechanism of sudden outbursts of coal, rocks and gas, in general, confirm that the outburst hazard was due to the complex interaction of three main natural factors (stress state, gas factor and physical-mechanical properties of rocks) with technological ones, and the formation of outburst hazardous conditions occurs in geological environments that are characterized by certain properties and conditions. The purpose of the paper is to obtain new theoretical understanding of the GDP nature with taking into account geological conditions and the impact of external factors by developing a hypothesis regarding the physicochemical nature of the GDP. It is proved that relief of stresses arisen in the molecular structure under the impact of geological factors leads to the activation of relaxation processes in the substance. The relaxation of the accumulated energy system results in structural transformations with the release of low-molecular-weight compounds. According to this pattern, accumulation of gases genetically connected with fossil organic matter and the emergence of gas-dynamic phenomena.is formed in the coal-rock massif. The key point of the hypothesis is that partial stress relief of the coal-rock massif creates in the fractured zones of the coal bed conditions for relaxation of elastic energy accumulated in the molecular structure of coal, hence, promoting the activation of structural transformations by the free-radical mechanism, which results in the release of low-molecular-weight compounds (methane, in particular). Under appropriate conditions, in the zone of relaxation of elastic deformations, the process can assume an avalanche character, namely, initiate sudden outbursts of coal and gas. According to the physicochemical model of methane release in coal under the impact of geomechanical, geological, and technogenic factors, which is proposed within the framework of this work, partial discharge creates in the coal bed conditions for relaxation of the elastic energy accumulated in the molecular structure of coal. That is, it promotes the activation of structural transformations by the free-radical mechanism, the result of which is the release of low-molecular-weight compounds (methane). Under the condition of sufficiently high fracturing of the elastic deformation zone, the process acquires an avalanche character, that is, sudden outbursts of coal and gas are developed. Keywords: coal, coal mines, gas-dynamic phenomena, outbursts of coal and gas, stress-strain state.