Distribution characteristics of pulverized coal and stress–gas pressure–temperature response laws in coal and gas outburst under deep mining conditions

Abstract

Deep mining will increase the likelihood of coal and gas outburst accidents and do harm to the safety of coal mining. In this study, a coal and gas outburst experiment under deep high-stress conditions was carried out and stress-gas pressure-temperature response laws in coal and rock surrounding the burst hole were evaluated. The experimental results showed that the stress response around the burst hole was intense and stress variation decreased as distance from the position to burst port increased. The gas pressure in the coal decreased sharply and oscillated several times during the burst process. The maximum rebound range was 0.05 MPa during this process. The decreasing rate of gas pressure reduced with the increase of the position-burst port distance. The temperature response near the burst port was stronger than peripheral area. The gas internal energy was still the main energy source of coal and gas outbursts, accounting for 75% of the total energy, and played a key role in the burst process. The contribution of elastic potential energy was 22% under deep high-stress conditions in this study. Based on the analysis of burst energy, the gas and stress were key factors of an outburst. K E Y W O R D Scoal and gas outburst, deep high-stress conditions, elastic potential energy, gas internal energy, multiphysics field | INTRODUCTIONCoal and gas outbursts which are dynamic phenomena of mine gas are caused by throwing numerous coals and rocks carrying a great deal of air into the mining space suddenly. [1][2][3][4][5] In the transportation industry, the ejected coal gas can spread for even thousands of meters against the wind or fill in the entire roadway on other conditions. 6-10 A mixture of coal and gas and the fire source in the roadway may cause gas explosions, coal dust explosions, gas and coal dust explosions, and so forth, which seriously harm the safety of mine workers and cause large financial losses. [11][12][13][14][15][16] A series of hypotheses on the mechanism of coal and gas outbursts have been established in major coal-producing countries, including China, Canada, Australia, and Poland, by means of theoretical analysis, laboratory test, numerical simulation, field test, and so forth, 17-21 mainly gas, geostress, synthesis, chemical nature, and synthetic action

Ensuring a safe geomechanical state of the rock mass surrounding the mine workings in the Karaganda coal basin, Kazakhstan

“…This helps to maintain the stability of underground mine workings in difficult mining-geological conditions of significant mining depths or weak host rocks [6], [7]. The increasing depth of mining inseam minerals and the associated increase in rock pressure requires the development of fundamentally new approaches to ensuring a stable state of underground mine workings [8].…”

Experimental Assessment of Combined Contribution of Coal Mass Diffusion and Seepage to Methane Migration under In Situ Stress Conditions

“…4,5 However, with the long-term mining for many years, the shallow resource reserves are on the verge of exhaustion, thus ushering in the chapter of deep mining year by year. 6 However, gas disasters are more serious at deeper coal seams. 7−9 In response, pre-extraction of coal seam methane is the most effective engineering method to ensure safe and efficient mining, in which case the extracted methane can also be employed as clean energy.…”

“…Coal, a primary natural resource, still takes the lead in China’s energy structure at present. − In order to ensure the efficient and steady development of society and economy, the total mining amount of coal resources has always remained at a high level. , However, with the long-term mining for many years, the shallow resource reserves are on the verge of exhaustion, thus ushering in the chapter of deep mining year by year . However, gas disasters are more serious at deeper coal seams. − In response, pre-extraction of coal seam methane is the most effective engineering method to ensure safe and efficient mining, in which case the extracted methane can also be employed as clean energy .…”

Experimental research of the geo-stress evolution law and effect in the intact coal and gas outburst process

“…Lu et al and Xu et al analyzed the desorption of adsorbed gas in the process of outburst, from the microscopic view (Lu et al, 2011). It is considered that the cause of coal and gas outburst is the failure and instability of the coal body that is caused by the gas pressure gradient, and the free gas is involved in the process of coal and gas outburst in the form of work done by expansion (Xie et al, 2017;Zhao et al, 2022b). The first condition for adsorbed gas to participate in the outburst work is to quickly transform into free gas during the burst.…”