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<p>To address the critical challenges in characterizing the dynamic responses and identifying the instability precursors of sandstone under repetitive impacts, this study establishes a comprehensive experimental framework. Multi-gradient cyclic impact testing (50–160&#xa0;cm drop heights) was implemented to simultaneously monitor the dynamic mechanical responses and acoustic emission (AE) signals. Through an integrated analysis of the impact mechanical parameters, power-law statistics of the AE absolute energy, damage stage classification, and <i>b-</i>value/<i>S-</i>value correlation, we reveal the intrinsic relationship between the impact rate, damage progression, and instability precursors. The experimental results demonstrate the following: (1) exponential relationships exist between the impact height and both the peak impact force and time-to-peak in sandstone; (2) under moderate strain rates, the absolute energy probability density of acoustic emissions follows a power-law distribution, with the power-law index correlating with the impact height under equivalent impact cycles; (3) damage evolution manifests through three characteristic stages, showing a negative linear correlation between the bmin values and impact rate; and (4) damage instability exhibits coupled precursors featuring a synchronous <i>b-</i>value surge and <i>S-</i>value collapse. The developed <i>b</i>–<i>S</i> dual-parameter criterion enables precise identification of damage acceleration thresholds. These findings provide new laboratory evidence for dynamic disaster monitoring in rock engineering applications.</p>

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Multifaceted characteristics of acoustic emission damage and precursor indicators of instability in sandstone under cyclic impact loading

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年6月5日

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  • Xu Hong,
  • Chao Pan,
  • Yujun Zuo,
  • Shujian Li,
  • Juncai Cao,
  • Qiang Liu,
  • Lin Yan,
  • Xuefeng Li,
  • Tengfei Han

摘要

To address the critical challenges in characterizing the dynamic responses and identifying the instability precursors of sandstone under repetitive impacts, this study establishes a comprehensive experimental framework. Multi-gradient cyclic impact testing (50–160 cm drop heights) was implemented to simultaneously monitor the dynamic mechanical responses and acoustic emission (AE) signals. Through an integrated analysis of the impact mechanical parameters, power-law statistics of the AE absolute energy, damage stage classification, and b-value/S-value correlation, we reveal the intrinsic relationship between the impact rate, damage progression, and instability precursors. The experimental results demonstrate the following: (1) exponential relationships exist between the impact height and both the peak impact force and time-to-peak in sandstone; (2) under moderate strain rates, the absolute energy probability density of acoustic emissions follows a power-law distribution, with the power-law index correlating with the impact height under equivalent impact cycles; (3) damage evolution manifests through three characteristic stages, showing a negative linear correlation between the bmin values and impact rate; and (4) damage instability exhibits coupled precursors featuring a synchronous b-value surge and S-value collapse. The developed b–S dual-parameter criterion enables precise identification of damage acceleration thresholds. These findings provide new laboratory evidence for dynamic disaster monitoring in rock engineering applications.