There are extensive studies on electromagnetic radiation (EMR) effects during coal and rock deformation and fracturing processes, but few systematic studies on the EMR features of gas-bearing coal under impact failure circumstances. In order to investigate whether the EMR is affected by the gas (CO₂,CH₄,N₂) sorption, coal type and impact energy, we performed a series of impact loading tests on both briquette coal specimens (BCSs) and raw coal specimens (RCSs) at various pore pressures (0–1.5 MPa). We developed a drop hammer test apparatus to allow impact loading tests on gas-bearing coal, and recorded the EMR signal of the damage of coal simultaneously. The result showed that (i) the amplitude range of the EMR signal generated by the impact damage of the gas-bearing coal is approximately 10–600 mV, with an effective duration time of 3–1500 ms and accumulated energy of 0.1–1000 μJ; (ii) when pore pressure is increased, the maximum amplitude, duration and pulse counts of the EMR decrease accordingly; (iii) the coal powder size and impact energy affect damage features and EMR characteristics, where a higher impact impulse causes more severe damage to coal specimens and (iv) the influence of the presence of adsorptive gas on the EMR signal caused by the destruction of coal bodies has both enhancement and reduction effects. During the early warning assessment of coal and gas outbursts using EMR parameters, not all the waveform parameters are sensitive to coal mine methane, but the significant effect of methane on signal volatility should be considered.

中文翻译：

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含气煤动态压裂过程中瞬变电磁辐射特征的实验研究

对煤，岩石变形和压裂过程中电磁辐射（EMR）的影响进行了广泛的研究，但在冲击破坏情况下，对含气煤的EMR特征的系统研究很少。为了调查EMR是否受气体（CO ₂，CH ₄，N ₂）吸附，煤类型和冲击能，我们在各种孔隙压力（0-1.5 MPa）下对块煤样本（BCSs）和原煤样本（RCSs）进行了一系列冲击负荷测试。我们开发了一种落锤测试设备，可以对含气煤进行冲击载荷测试，并同时记录煤损坏的EMR信号。结果表明：（i）含气煤的冲击破坏所产生的EMR信号的幅度范围约为10–600 mV，有效持续时间为3–1500 ms，累积能量为0.1–1000μJ ; （ii）当孔隙压力增加时，EMR的最大幅度，持续时间和脉冲数会相应减少；（iii）煤粉的大小和冲击能量会影响其破坏特征和EMR特性，较高的冲击脉冲对煤样造成更严重的破坏，并且（iv）吸附气体的存在对煤体破坏引起的EMR信号的影响既有增强作用，也有还原作用。在使用EMR参数对煤与瓦斯突出进行预警评估期间，并非所有波形参数都对煤矿甲烷产生敏感，但应考虑甲烷对信号波动性的重大影响。