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<p>To reveal the macro-microscopic fatigue cumulative damage law of granite under cyclic impact loading in deep mining with “three highs and one disturbance” stress, and overcome the defect that existing studies deviate from real in-situ conditions, granite from Linglong Gold Mine, Zhaoyuan, Shandong was taken as the research object. Based on in-situ stress measurements, two gradient confining pressures were set. Three-dimensional cyclic impact tests were performed via split Hopkinson pressure bar (SHPB) at 0.4, 0.5 and 0.6&#xa0;MPa impact pressures, combined with nuclear magnetic resonance (NMR) to analyze pore evolution and damage characteristics. Granite impact failure undergoes four stages: elastic deformation, yielding with microcrack initiation, crack propagation and damage accumulation, and final failure. With rising impact cycles, peak dynamic strength and elastic modulus decay, while peak dynamic strain and dissipated energy density rise, with dissipated energy accelerating sharply before failure. Confining pressure improves initial dynamic strength; higher impact pressure brings higher initial strength but severer strength decay. Damage variables increase with impact cycles and pressure, closely correlated with energy dissipation. NMR results show post-impact micropore proportion decreases, mesopore and macropore proportions rise significantly, pores evolve to larger sizes, and confining pressure affects pore structure variation amplitude. Rock failure is dominated by shear cracks or complex modes, related to stress state and mineral properties. This work clarifies the macro-microscopic damage evolution mechanism of granite under 3D stress, providing theoretical and technical support for deep mine support design, disaster warning and safety assessment.</p>

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Cumulative macro-microscopic fatigue damage of hard rock under three-dimensional cyclic impact loading

  • 期刊论文

  • 发表日期：

    2026年4月10日

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  • Yunfeng Wu,
  • Changhong Li,
  • Peng Li,
  • Yu Wang,
  • Dan Ma,
  • Erhui Zhang,
  • Changkun Sun,
  • Prabhat Man Singh Basnet

摘要

To reveal the macro-microscopic fatigue cumulative damage law of granite under cyclic impact loading in deep mining with “three highs and one disturbance” stress, and overcome the defect that existing studies deviate from real in-situ conditions, granite from Linglong Gold Mine, Zhaoyuan, Shandong was taken as the research object. Based on in-situ stress measurements, two gradient confining pressures were set. Three-dimensional cyclic impact tests were performed via split Hopkinson pressure bar (SHPB) at 0.4, 0.5 and 0.6 MPa impact pressures, combined with nuclear magnetic resonance (NMR) to analyze pore evolution and damage characteristics. Granite impact failure undergoes four stages: elastic deformation, yielding with microcrack initiation, crack propagation and damage accumulation, and final failure. With rising impact cycles, peak dynamic strength and elastic modulus decay, while peak dynamic strain and dissipated energy density rise, with dissipated energy accelerating sharply before failure. Confining pressure improves initial dynamic strength; higher impact pressure brings higher initial strength but severer strength decay. Damage variables increase with impact cycles and pressure, closely correlated with energy dissipation. NMR results show post-impact micropore proportion decreases, mesopore and macropore proportions rise significantly, pores evolve to larger sizes, and confining pressure affects pore structure variation amplitude. Rock failure is dominated by shear cracks or complex modes, related to stress state and mineral properties. This work clarifies the macro-microscopic damage evolution mechanism of granite under 3D stress, providing theoretical and technical support for deep mine support design, disaster warning and safety assessment.