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<p>During deep excavation of coal resources, high geostress and complex hydrogeological conditions exacerbate the probability of hydrodynamic disasters. To investigate the failure mechanism of water-bearing coal and its associated geophysical response, uniaxial compression tests were conducted on coal samples with varying water saturation levels. The influence of moisture content on mechanical behavior and energy dissipation was analyzed, and the synergistic response of pressure-stimulated current (PSC) and acoustic emission (AE) was examined. Using correlation integral, the clustering fractal structures of microcracks in both time and space domains were quantitatively studied during the progressive failure process. Finally, the water–coal interaction mechanism and the effects of moisture were discussed from a microscopic perspective. The results indicated that as the applied stress increases, the occurrence of high-amplitude AE events rises, along with an increasing trend in PSC signals. The AE ringing count, cumulative energy, and PSC strength reach their peaks when water-bearing coal is loaded near catastrophic failure, at which point the stored elastic energy is rapidly released due to extensive microcrack propagation. An increase in water content leads to a gradual decline in compressive strength and the rate of energy dissipation. However, both the peak value and the increasing rate of PSC become larger, showing an opposite trend to AE signals. Load-dependent AE and PSC signals in water-bearing coal exhibit clustering fractal structures and power-law self-similarity, and the three fractal dimensions consistently display an overall downward trend as catastrophic failure approach. Moisture in loaded coal can mitigate stress concentration by dissolving clay minerals and shifting the failure mode of coal samples from oblique failure to axial splitting failure. This leads to a greater prevalence of intergranular fractures during crack propagation, as observed by scanning electron microscopy. The water–coal interaction mechanism is supported by the relative amplitude/average frequency results, which show that tensile cracks dominate the failure process, while the proportion of shear cracks decreases with increasing water content. These findings hold significant engineering value and offer crucial insights for the prevention and management of hydrological hazards in coal mining operations and provide theoretical support for enhancing the geological safety of coal mining engineering.</p>

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Acoustic and Current from Fracturing of Loaded Coal at Various Water Saturations

  • 期刊论文

  • 发表日期：

    2025年7月3日

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  • Xiaoran Wang,
  • Jinhua Wang,
  • Xiaofei Liu,
  • Yubing Liu,
  • Xin Chang,
  • Jianbo Wu,
  • Xin Zhou,
  • Joseph F. Labuz

摘要

During deep excavation of coal resources, high geostress and complex hydrogeological conditions exacerbate the probability of hydrodynamic disasters. To investigate the failure mechanism of water-bearing coal and its associated geophysical response, uniaxial compression tests were conducted on coal samples with varying water saturation levels. The influence of moisture content on mechanical behavior and energy dissipation was analyzed, and the synergistic response of pressure-stimulated current (PSC) and acoustic emission (AE) was examined. Using correlation integral, the clustering fractal structures of microcracks in both time and space domains were quantitatively studied during the progressive failure process. Finally, the water–coal interaction mechanism and the effects of moisture were discussed from a microscopic perspective. The results indicated that as the applied stress increases, the occurrence of high-amplitude AE events rises, along with an increasing trend in PSC signals. The AE ringing count, cumulative energy, and PSC strength reach their peaks when water-bearing coal is loaded near catastrophic failure, at which point the stored elastic energy is rapidly released due to extensive microcrack propagation. An increase in water content leads to a gradual decline in compressive strength and the rate of energy dissipation. However, both the peak value and the increasing rate of PSC become larger, showing an opposite trend to AE signals. Load-dependent AE and PSC signals in water-bearing coal exhibit clustering fractal structures and power-law self-similarity, and the three fractal dimensions consistently display an overall downward trend as catastrophic failure approach. Moisture in loaded coal can mitigate stress concentration by dissolving clay minerals and shifting the failure mode of coal samples from oblique failure to axial splitting failure. This leads to a greater prevalence of intergranular fractures during crack propagation, as observed by scanning electron microscopy. The water–coal interaction mechanism is supported by the relative amplitude/average frequency results, which show that tensile cracks dominate the failure process, while the proportion of shear cracks decreases with increasing water content. These findings hold significant engineering value and offer crucial insights for the prevention and management of hydrological hazards in coal mining operations and provide theoretical support for enhancing the geological safety of coal mining engineering.