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<p>To elucidate the energy evolution during coal damage under deep fluidized-mining-induced stress paths and the post-failure three-dimensional fracture network characteristics, this study performed equivalent mining-induced stress-path tests for three typical scenarios: looped mining mode of fluidized mining with backfill (BC), longwall mining without coal pillars (BD), and looped mining mode of fluidized mining without backfill (BE). Quantitative analysis integrated energy decomposition with post-failure X-ray CT-based three-dimensional reconstruction. As the mining mode transitions from BC to BE, peak-bearing capacity and pre-peak volumetric dilation increase markedly. The peak major principal stress under BE is about 17% higher than that under BC, and failure shifts from stable through-going shear failure to abrupt brittle instability. BC exhibits a prolonged pre-peak energy-storage stage with a gradual increase in dissipation, whereas BE shows higher pre-peak elastic energy storage and concentrated pre-peak energy dissipation within a narrower strain interval. CT characterization indicates that, with increasing disturbance intensity, the fractal dimension increases from about 2.08 to 2.28, and the volume proportion of meso- and micro-scale fractures rises from about 1.7% to 9.2%; fracture volume fraction and equivalent aperture also increase. Overall, BC can reduce the risk of sudden instability by suppressing concentrated pre-peak energy release and fracture network complexity. In contrast, BE enhances instantaneous bearing capacity, but tends to induce a highly connected multiscale fracture network, increasing dynamic-instability risk.</p>

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Energy Evolution and CT-Quantified 3D Fractures in Coal-Rock under Fluidized Mining Stress Paths

  • 期刊论文

  • 发表日期：

    2026年5月26日

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  • Honghao Yuan,
  • Jianfeng Liu,
  • Jinbin Wei,
  • Yifan Tang,
  • Danli Li

摘要

To elucidate the energy evolution during coal damage under deep fluidized-mining-induced stress paths and the post-failure three-dimensional fracture network characteristics, this study performed equivalent mining-induced stress-path tests for three typical scenarios: looped mining mode of fluidized mining with backfill (BC), longwall mining without coal pillars (BD), and looped mining mode of fluidized mining without backfill (BE). Quantitative analysis integrated energy decomposition with post-failure X-ray CT-based three-dimensional reconstruction. As the mining mode transitions from BC to BE, peak-bearing capacity and pre-peak volumetric dilation increase markedly. The peak major principal stress under BE is about 17% higher than that under BC, and failure shifts from stable through-going shear failure to abrupt brittle instability. BC exhibits a prolonged pre-peak energy-storage stage with a gradual increase in dissipation, whereas BE shows higher pre-peak elastic energy storage and concentrated pre-peak energy dissipation within a narrower strain interval. CT characterization indicates that, with increasing disturbance intensity, the fractal dimension increases from about 2.08 to 2.28, and the volume proportion of meso- and micro-scale fractures rises from about 1.7% to 9.2%; fracture volume fraction and equivalent aperture also increase. Overall, BC can reduce the risk of sudden instability by suppressing concentrated pre-peak energy release and fracture network complexity. In contrast, BE enhances instantaneous bearing capacity, but tends to induce a highly connected multiscale fracture network, increasing dynamic-instability risk.