Abstract
In order to accurately grasp the characteristics and influencing factors of gas explosion in heading face, the mathematical model of gas explosion was determined. According to the actual size of a heading face of a coal mine, a 3D geometric model with a length of 100 m was established, and the effects of ignition energy and gas explosion equivalent on the gas explosion characteristics of the heading face were analyzed. The results show the following. (1) The mathematical models for numerical simulation of gas explosion can accurately simulate the gas explosion and its propagation process. The time-space step size has a great influence on the simulation results. The grid spacing for numerical simulation of mine gas explosion is determined to be 0.1 m and the time step length is determined to be 0.001 s. (2) The ignition energy has a limited effect on gas explosion characteristics. It only has a certain influence on the gas explosion process, but has little influence on the overpressure of shock wave. The larger the ignition energy is, the faster the explosion reaction speed is, and the maximum overpressure increases slightly. When the ignition energy increases to a certain value, the time of peak shock wave and the maximum overpressure both tend to be stable. The ignition energy has little effect on gas explosion characteristics when an explosion accident occurs underground with a large amount of gas accumulation. (3) The gas explosion equivalent has a great influence on the overpressure of gas explosion shock wave. The higher the explosion equivalent is, the greater the pressure is, and the peak value of the shock wave overpressure increases with the explosion equivalent as a power function. The research results have important guiding significance for the research and development of new technology for prevention and control of gas explosion.
Highlights
Coal mine gas explosion accident is one of the most serious disaster accidents [1], especially the major and large gas explosion accident, resulting in a large number of casualties and serious equipment damage
Mine gas explosion can be regarded as a gas explosion process in which methane–air mixed gas is ignited by external fire source, which can be divided into two stages: ignition and propagation. e destructiveness of explosion is mainly reflected in the propagation stage [5], that is, the combustion of combustible and the mechanical damage in the propagation of explosion shock wave caused by the propagation of explosion flame [6]. e destructiveness of explosion is mainly reflected in the propagation stage [5], that is, the combustion of combustible materials caused by the propagation of explosive flame and the mechanical damage caused by the propagation of explosive shock wave [6]. rough studying the propagation law of gas
Chongqing Coal Research Institute of China carried out a gas explosion test with methane–air premixed volume of 100–200 m3 in a square single-head straight lane with a section of 7.2 m2 and a length of 900 m [14]. e National Institute for Occupational Safety and Health (NIOSH) conducted an experiment on the damage characteristics of closed walls caused by methane gas explosion with a maximum methane–air premixed volume of 210 m3 in a straight mine lane with a section of about 12.5 m2 and a length of about 480 m [15]
Summary
Coal mine gas explosion accident is one of the most serious disaster accidents [1], especially the major and large gas explosion accident, resulting in a large number of casualties and serious equipment damage. For the current research results, no matter the experimental research or numerical simulation, most of them study the gas explosion characteristics and shock wave propagation law in laboratory small-size pipelines or local roadway, so they cannot objectively and quantitatively reflect the propagation law of gas explosion shock wave in real scale of mine. Considering the risk and cost of gas explosion test research at the existing mine scale, methane–air premix volume is small, and roadway configuration and sensor layout are relatively simple, which are not enough to fully reflect the propagation law of gas explosion shock wave at the real mine scale. (3) Under the influence of coal seam gas occurrence and system ventilation, the gas accumulation amount in roadway is different, and the influence of gas accumulation amount (gas explosion equivalent) on the gas explosion characteristics and shock wave propagation law in heading face has not been studied. It has important guiding significance for accurately predicting the propagation law of gas explosion shock wave and effectively controlling the destructive effect of gas explosion in mine
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