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<p>The rupture of coal and rock releases acoustic emission (AE) signals, which are widely used to predict the occurrence of coal-rock dynamic hazards. As the mining rate affects the AE characteristics and owing to a lack of comprehensive analysis of AE characteristics at different rates, uniaxial compression experiments at different loading rates were designed to analyze the AE signals in the time and frequency domains and conduct fractal analysis of the entire process of coal-rock compression. The results show that: before coal-rock damage, in the time domain, the AE energy corresponds well with the rate of stress decrease, and its responses preceded the stress drop by 5–20 and 15–30&#xa0;s in rock and coal samples, respectively. There is an inflection point of the cumulative AE counts of the rock before damage, and the cumulative AE counts of the coal increase in a smoother manner; in the frequency domain, the micro- and large cracks correspond to the high- and low-frequency signals, respectively. Before the damage of coal and rock, the peak frequency band is heavily concentrated near high frequency, and the larger the loading rate, the more concentrated is the frequency distribution; in the fractal domain, the distribution ranges of fractal parameters ∆<i>α</i> and ∆<i>f</i>(<i>α</i>) increase, and the significant increase in ∆<i>α</i> and ∆<i>f</i>(<i>α</i>) values lower than 0.75 and 0, respectively, indicates a precursor to the rupture of coal and rock. The distribution ranges of ∆<i>α</i> of coal show a tendency to increase with increasing loading rate, and the those of rock do not change considerably. Overall, the precursor characteristics of coal and rock rupture can be comprehensively expressed by the distribution ranges of the average count, average energy, average peak frequency, and ∆<i>α</i>.</p>

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Time–frequency-fractal Characteristics of Acoustic Emission Signals During Coal-rock Rupture at Different Loading Rates

  • 期刊论文

  • 发表日期：

    2025年8月27日

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  • Baolin Li,
  • Xinyu Sun,
  • Enyuan Wang,
  • Nan Li,
  • Xiaofei Liu,
  • Xiong Cao,
  • Wenyi Liu

摘要

The rupture of coal and rock releases acoustic emission (AE) signals, which are widely used to predict the occurrence of coal-rock dynamic hazards. As the mining rate affects the AE characteristics and owing to a lack of comprehensive analysis of AE characteristics at different rates, uniaxial compression experiments at different loading rates were designed to analyze the AE signals in the time and frequency domains and conduct fractal analysis of the entire process of coal-rock compression. The results show that: before coal-rock damage, in the time domain, the AE energy corresponds well with the rate of stress decrease, and its responses preceded the stress drop by 5–20 and 15–30 s in rock and coal samples, respectively. There is an inflection point of the cumulative AE counts of the rock before damage, and the cumulative AE counts of the coal increase in a smoother manner; in the frequency domain, the micro- and large cracks correspond to the high- and low-frequency signals, respectively. Before the damage of coal and rock, the peak frequency band is heavily concentrated near high frequency, and the larger the loading rate, the more concentrated is the frequency distribution; in the fractal domain, the distribution ranges of fractal parameters ∆α and ∆f(α) increase, and the significant increase in ∆α and ∆f(α) values lower than 0.75 and 0, respectively, indicates a precursor to the rupture of coal and rock. The distribution ranges of ∆α of coal show a tendency to increase with increasing loading rate, and the those of rock do not change considerably. Overall, the precursor characteristics of coal and rock rupture can be comprehensively expressed by the distribution ranges of the average count, average energy, average peak frequency, and ∆α.