Abstract An outburst of coal and gas is defined as a rapid release of a large quantity of gas in conjunction with an expulsion of coal into the mine workings in coal mines. It is a major dynamic hazard during coal mining and has to be controlled for mining safety. Despite significant advances made in outburst studies, the outburst incidence continues to occur. A variety of indices have been developed in assessing outburst risk such as gas content, gas desorption rate and coal strength. However these indices are empirical or based mainly on localized experience. Aiming to develop a more scientifically solid index in outburst risk assessment, energy approach was adopted in this study to explain the outburst process, i.e. the outburst is treated as a rapid energy release process in coal. Experimental investigations on outbursts with respective gas pressure of 0.4 MPa, 0.6 MPa, 0.8 MPa, 0.9 MPa and 1.0 MPa were conducted. The mass and size distributions of ejected coal were analyzed. Based on testing results, the outburst effective energy in coal (including expansion energy of free gas in pore and the energy of desorption gas in coal structure), and the outburst energy of fragmenting and moving coal particles were both calculated. Finally, the outburst threshold value of energy strength was determined. Results show that: (1) the outburst effective energy and the energy for coal fragmentation and movement both positively correlate with gas pressure; (2) the minimum energy strength of about 1.1 MJ/m3 in gas-bearing coal is required for an outburst to occur; (3) compared with free pore gas energy, the desorption gas energy from coal plays a decisive role in outburst initiation and propagation, which is in good agreement with the popular view that coal and gas outburst is gas-driven. Outcomes of this study indicate that the risk of outbursts could be effectively minimized through reduction in coal seam gas energy.

中文翻译：

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煤矿安全用能强度突出阈值的试验确定

摘要 煤与瓦斯突出被定义为大量瓦斯的快速释放，伴随着煤被排入煤矿的矿井工作。它是煤矿开采过程中的主要动态危害，为了开采安全必须加以控制。尽管在爆发研究方面取得了重大进展，但爆发发生率仍在继续发生。已经开发了多种指标来评估突出风险，例如瓦斯含量、瓦斯解吸率和煤强度。然而，这些指数是经验性的或主要基于本地化经验。为了在突出风险评估中制定更科学的可靠指标，本研究采用能量方法来解释突出过程，即将突出视为煤中的快速能量释放过程。分别对气体压力分别为 0.4 MPa、0.6 MPa、0.8 MPa、0.9 MPa 和 1.0 MPa 的突出进行了实验研究。分析了喷出煤的质量和粒度分布。根据测试结果，计算了煤中的有效突出能量（包括孔隙中游离气体的膨胀能和煤结构中解吸气体的能量），以及破碎和移动煤粒的突出能量。最后确定了能量强度的爆发阈值。结果表明：（1）突出有效能量和煤破碎运动能量均与瓦斯压力呈正相关；(2) 发生突出需要含气煤的最低能量强度约为 1.1 MJ/m3；(3) 与自由孔隙气能相比，煤的解吸瓦斯能对突出的发生和传播起决定性作用，这与目前普遍认为的煤与瓦斯突出是气体驱动的观点是一致的。这项研究的结果表明，通过降低煤层瓦斯能量可以有效地降低突出风险。