Effects of fast-desorbed gas on the propagation characteristics of outburst shock waves and gas flows in underground roadways

Abstract

Abstract Coal and gas outbursts are the most serious disaster in the underground mining. During an intense outburst, ejection of millions tons of coal and cubic meters of gas with high kinetic energy can cause death or injuries and even destroy underground facilities, the intensity of outburst shock waves and gas flows is highly related to the gas expansion energy, and the gas expansion energy requires the participation of a large amount of desorption gas. There is a significant difference in the gas desorption law between the pulverized coal and the unaffected coal. To investigate the effects of fast-desorbed gas on the propagation characteristics of outburst shock waves and gas flows, the particle size distribution characteristics of pulverized coal were obtained by site investigation. Then, gas desorption experiments were conducted for coal particles of various sizes at different gas pressures and temperatures. The results indicate that a segmentation function is reasonable for representing the gas desorption law during coal and gas outbursts. Based on the gas desorption law, numerical simulation for the propagation characteristics of outburst gas flows were conducted. The results show that fast-released gas compresses the air within the roadway, thereby generating outburst shock waves that propagate at high speed. The intensity of the outburst shock waves decrease with time. Simultaneously, the gas convective transport velocity is lower than that of the outburst shock waves, large areas of high-concentration gas in roadways are induced by the outburst gas flows.