This paper introduces the innovative technique to release the bursting liability of coal seam via microwave irradiation. To verify the feasibility of this environment-friendly technique, a series of laboratory tests incorporating acoustic emission (AE) investigation were carried out. Test results indicated that both the uniaxial compressive strength (UCS) and bursting energy index of raw and water-soaked coal samples were significantly reduced. In particular, the bursting liability was reduced by one level when the values of UCS were compared, the evidence of which is the variation of wave velocities of tested coal samples. It can also be found from the events and hits in the complete stress-strain curve and the cumulative curve of acoustic emission that the elastic modulus of the raw and water-soaked coal samples subjected to microwave irradiation decreased by 58.42% and 29.63%, respectively. This facilitates the entry into the stage of stable crack propagation more quickly, the growth rate and size of the cracks were slower and more uniform, and there were no smaller coal fragments ejecting during the failure process of the coal samples. Meanwhile, the proportion of high-energy events released in coal samples experienced a decline after the treatment of the microwave. Moreover, microwave heating principally promoted the initiation and expansion of microcracks in coal samples under the influence of microwave power of 1 kW and a heating time of 120s, which may cause the overall damage of large fractures to break into multiple small and medium cracks. Based on the experimental results, the conceptual process of using microwave in weakening the bursting liability of coal seam was then proposed, which will be the meaningful reference for microwave-assisted oil recovery and coal bed methane production.

中文翻译：

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微波辐照易爆煤样品的改性

介绍了利用微波辐照解除煤层爆裂倾向的创新技术。为了验证这种环保技术的可行性，进行了一系列包含声发射 (AE) 调查的实验室测试。测试结果表明，原煤和水浸煤样品的单轴抗压强度（UCS）和爆破能指数均显着降低。特别是，当比较UCS值时，爆破倾向降低了一个水平，其证据是测试煤样的波速变化。从完全应力应变曲线和声发射累积曲线中的事件和命中还可以发现，微波辐照后原煤和水浸煤样品的弹性模量分别降低了58.42%和29.63% . 这有利于更快地进入稳定裂纹扩展阶段，裂纹的扩展速度和尺寸更慢且更均匀，并且在煤样破坏过程中没有较小的煤碎片喷出。同时，微波处理后煤样中释放的高能事件比例有所下降。此外，在1 kW微波功率和120 s加热时间的影响下，微波加热主要促进煤样微裂纹的萌生和扩展，可能造成大裂缝的整体破坏，破裂成多个中小裂缝。根据实验结果，提出了利用微波弱化煤层爆裂倾向的概念流程，对微波辅助采油和煤层气生产具有重要参考意义。