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<p>The mechanical behavior and damage evolution of weathered granite under cyclic impact loading are examined using scanning electron microscopy (SEM), split Hopkinson pressure bar (SHPB) cyclic impact tests, and fractal analysis. Granite specimens under exposure to different degrees of weathering conditions (slightly weathered, moderately weathered, and highly weathered) are characterized to quantify microcrack structures, dynamic mechanical responses, and failure features. The relationship between fractal characteristics and damage evolution is also evaluated. Results indicate that weathering significantly increases the complexity of the microcrack network. The fractal dimension of microcracks obtained using the two-dimensional box-counting method increases from 1.72 for slightly weathered granite to 1.95 for highly weathered granite. Under cyclic impact loading, increasing weathering exposure leads to faster attenuation of peak stress, greater residual strain, and a reduced strain rebound effect. The dynamic elastic modulus progressively degrades with the number of impacts, with degradation exceeding 50% in highly weathered specimens. The cumulative damage variable increases nonlinearly with weathering damage. Slightly weathered and moderately weathered samples exhibit a three-stage damage evolution process (compaction–stabilization–rapid growth), whereas highly weathered granite directly enters the rapid damage growth stage due to the development of secondary cracks. In addition, the fractal dimension of fragments increases with the degree of weathering. Both the microcrack fractal dimension and the fragment fractal dimension show strong linear correlations with weathering damage, indicating that mesoscopic fractal characteristics provide effective indicators for predicting macroscopic damage and failure.</p>

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Evolution of cyclic impact damage in weathered granite based on dual-scale fractal analysis

  • 期刊论文

  • 发表日期：

    2026年4月15日

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  • Jianli Cao,
  • Gang Wang,
  • Hangli Gong,
  • Leibo Song,
  • Zhihai He,
  • Bolong Liu

摘要

The mechanical behavior and damage evolution of weathered granite under cyclic impact loading are examined using scanning electron microscopy (SEM), split Hopkinson pressure bar (SHPB) cyclic impact tests, and fractal analysis. Granite specimens under exposure to different degrees of weathering conditions (slightly weathered, moderately weathered, and highly weathered) are characterized to quantify microcrack structures, dynamic mechanical responses, and failure features. The relationship between fractal characteristics and damage evolution is also evaluated. Results indicate that weathering significantly increases the complexity of the microcrack network. The fractal dimension of microcracks obtained using the two-dimensional box-counting method increases from 1.72 for slightly weathered granite to 1.95 for highly weathered granite. Under cyclic impact loading, increasing weathering exposure leads to faster attenuation of peak stress, greater residual strain, and a reduced strain rebound effect. The dynamic elastic modulus progressively degrades with the number of impacts, with degradation exceeding 50% in highly weathered specimens. The cumulative damage variable increases nonlinearly with weathering damage. Slightly weathered and moderately weathered samples exhibit a three-stage damage evolution process (compaction–stabilization–rapid growth), whereas highly weathered granite directly enters the rapid damage growth stage due to the development of secondary cracks. In addition, the fractal dimension of fragments increases with the degree of weathering. Both the microcrack fractal dimension and the fragment fractal dimension show strong linear correlations with weathering damage, indicating that mesoscopic fractal characteristics provide effective indicators for predicting macroscopic damage and failure.