低温处理煤岩的声发射及力学渗流特性研究
Study on acoustic emission and mechanical seepage characteristics of low temperature treated coal rock
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摘要: 为研究煤岩在低温处理过程中的损伤演化规律以及低温处理对煤岩力学和渗流性能的影响，通过实验测试分析了煤样在低温处理过程中的声发射特征以及低温处理后煤样的力学性能和渗流特性。结果表明：当常温煤样骤然进入低温环境中，0～1 000 s内声发射信号最密集且强度较大，中后期信号逐渐减少减弱，因此损伤主要发生在前1 000 s内，随着处理温度的降低，煤样声发射信号数量和强度都显著增加，信号幅值的分布比例大致相同，表明煤岩与外部环境温差越大，其损伤程度就越高；经过低温处理的煤样在三轴加载过程中其抗压强度、弹性模量和泊松比相较于常温煤样都有所减小，减小幅度与处理低温呈正比；经过0、-20、-40 ℃处理后的煤样，初始渗透率相较于常温煤样分别增长了8.15%、23.46%和74.87%。Abstract: In order to study the damage evolution law of coal and the influence of low temperature treatment on the mechanical and seepage properties of coal, the acoustic emission characteristics of coal samples during low temperature treatment and the mechanical and seepage properties of coal samples after low temperature treatment were analyzed through experimental tests. The results show that: when the normal temperature coal sample suddenly enters the low temperature environment, the AE signals are most dense and strong within 0-1 000 s, and gradually decrease and weaken in the middle and late period. Therefore, the damage mainly occurs in the first 1 000 s. With the decrease of the processing temperature, the number and intensity of AE signals of the coal sample increase significantly, and the distribution ratio of signal amplitude is roughly the same. It shows that the larger the temperature difference between coal and external environment, the higher the damage degree. The compressive strength, elastic modulus and Poisson’s ratio of coal samples treated at low temperature in the triaxial loading process are all reduced compared with those of normal temperature coal samples, and the decreasing amplitude is proportional to the low temperature treatment. The initial permeability of coal samples treated at 0 ℃, -20 ℃ and -40 ℃ increased by 8.15%, 23.46% and 74.87%, respectively, compared with normal temperature coal samples.
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Keywords:
- low temperature treatment /
- coal body damage /
- acoustic emission /
- triaxial loading /
- permeability
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