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<p>The role of structural planes (SPs) in inducing rockburst is crucial, but the precise mechanism of how the stiff SPs influence rockburst remains unclear. To address this, triaxial loading and double-face unloading rockburst tests were performed on sandstone specimens with stiff SPs exhibiting strong cementation (by epoxy resin) and five different dip angles (<i>β</i> = 0°, 30°, 45°, 60°, 90°). The rockburst stress, energy consumption, failure mode, and acoustic emission (AE) characteristics were analyzed to assess the impact of <i>β</i> on rockburst. In particular, the stress release characteristics were evaluated based on the spatial distribution of b-values from the AE events. The results reveal that the rockburst stress initially decreases and then increases as <i>β</i> increases, with <i>β</i> = 45° representing an inflection point. The maximum principal stress drop rate and fragments’ ejection velocity (0–3.4&#xa0;m/s) exhibit a similar evolution pattern: they first decrease as <i>β</i> increases and then increase. Among the specimens with different <i>β</i> angles, those with <i>β</i> = 0° and 60° display the greatest and weakest rockburst intensities, respectively. The main failure patterns include splitting, buckling, and shear fractures, with specimens having <i>β</i> = 45° exhibiting the least failure degree (slight splitting). Additionally, the SPs affect stress release characteristics: microcracks with weak stress release are present in the upper SPs rock for <i>β</i> angles less than 45°, whereas stress release in the rock below the SP (including the free face) are weakest for <i>β</i> = 60°. Finally, a model based on the K-Nearest Neighbors method was developed using AE entropy (an AE parameter based on Shannon’s entropy) to predict the rockburst stress. The model performs well, especially for predicting stress before the peak (including peak).</p>

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Experimental Investigation on the Influence Mechanism of the Dip Angle of the Stiff Structural Planes with Strong Cementation on Double-Face Unloading Rockburst

  • 期刊论文

  • 发表日期：

    2025年4月1日

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  • Fuqiang Ren,
  • Jinze Gu,
  • Chun Zhu,
  • Xiaoshuang Li,
  • Dongqiao Liu,
  • Bingbing Chen,
  • Jun Lu

摘要

The role of structural planes (SPs) in inducing rockburst is crucial, but the precise mechanism of how the stiff SPs influence rockburst remains unclear. To address this, triaxial loading and double-face unloading rockburst tests were performed on sandstone specimens with stiff SPs exhibiting strong cementation (by epoxy resin) and five different dip angles (β = 0°, 30°, 45°, 60°, 90°). The rockburst stress, energy consumption, failure mode, and acoustic emission (AE) characteristics were analyzed to assess the impact of β on rockburst. In particular, the stress release characteristics were evaluated based on the spatial distribution of b-values from the AE events. The results reveal that the rockburst stress initially decreases and then increases as β increases, with β = 45° representing an inflection point. The maximum principal stress drop rate and fragments’ ejection velocity (0–3.4 m/s) exhibit a similar evolution pattern: they first decrease as β increases and then increase. Among the specimens with different β angles, those with β = 0° and 60° display the greatest and weakest rockburst intensities, respectively. The main failure patterns include splitting, buckling, and shear fractures, with specimens having β = 45° exhibiting the least failure degree (slight splitting). Additionally, the SPs affect stress release characteristics: microcracks with weak stress release are present in the upper SPs rock for β angles less than 45°, whereas stress release in the rock below the SP (including the free face) are weakest for β = 60°. Finally, a model based on the K-Nearest Neighbors method was developed using AE entropy (an AE parameter based on Shannon’s entropy) to predict the rockburst stress. The model performs well, especially for predicting stress before the peak (including peak).