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<p>Deep tunnel excavation and mining operations are commonly subjected to the coupled effects of high in-situ stresses and blasting loads, under which the pre-existing static stress state can markedly govern blasting-induced rock breakage and excavation efficiency. Meanwhile, in complex blasting and excavation settings, robust delineation of the post-blast-damaged zone and quantitative characterization of its geometric complexity remain challenging. To clarify how confinement regulates blast-induced damage in rock, this study conducted blasting experiments on granite under a series of confining-stress conditions. First, a 3D point-cloud-based damage-identification approach was developed to extract the damaged region under complex surface backgrounds and to provide high-quality image data for subsequent analyses. Second, a “Dynamic selection method based on ddual-criterion and edge penalization” (DS-DCEP) was established to determine the scale-free interval for fractal-dimension estimation, thereby improving the accuracy and stability of fractal characterization. On this basis, the blast-induced damaged zones were subjected to fractal analysis. The results show that confinement significantly alters the damage distribution pattern and evolution path by regulating the stress field around the blasthole: uniaxial confinement strengthens damage directionality, asymmetric biaxial confinement promotes localized damage concentration and more pronounced anisotropy, whereas elevated equal biaxial confinement markedly suppresses damage expansion, leading to a convergent and relatively homogenized damage distribution. Moreover, the fractal dimension, as a key quantitative descriptor of damage complexity, not only captures the geometric attributes of rock damage but also reveals the intrinsic distinction between damage extent and complexity, offering unique advantages for anisotropy assessment and failure-mechanism identification. Overall, this work establishes a damage-identification and fractal-characterization framework for complex scenarios, elucidates the confinement-dependent evolution of blasting damage and anisotropy, and provides quantitative support for parameter optimization and safety assessment in deep blasting engineering.</p>

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A Novel Damage Recognition and Adaptive Scale-Free Interval Approach for Fractal Characterization of Blasting Damage in Granite

  • 期刊论文

  • 发表日期：

    2026年5月23日

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  • Jiazheng Gao,
  • Yongsheng He,
  • Yeqing Chen,
  • Zhenqing Wang,
  • Chunhai Li,
  • Gangwei Mei

摘要

Deep tunnel excavation and mining operations are commonly subjected to the coupled effects of high in-situ stresses and blasting loads, under which the pre-existing static stress state can markedly govern blasting-induced rock breakage and excavation efficiency. Meanwhile, in complex blasting and excavation settings, robust delineation of the post-blast-damaged zone and quantitative characterization of its geometric complexity remain challenging. To clarify how confinement regulates blast-induced damage in rock, this study conducted blasting experiments on granite under a series of confining-stress conditions. First, a 3D point-cloud-based damage-identification approach was developed to extract the damaged region under complex surface backgrounds and to provide high-quality image data for subsequent analyses. Second, a “Dynamic selection method based on ddual-criterion and edge penalization” (DS-DCEP) was established to determine the scale-free interval for fractal-dimension estimation, thereby improving the accuracy and stability of fractal characterization. On this basis, the blast-induced damaged zones were subjected to fractal analysis. The results show that confinement significantly alters the damage distribution pattern and evolution path by regulating the stress field around the blasthole: uniaxial confinement strengthens damage directionality, asymmetric biaxial confinement promotes localized damage concentration and more pronounced anisotropy, whereas elevated equal biaxial confinement markedly suppresses damage expansion, leading to a convergent and relatively homogenized damage distribution. Moreover, the fractal dimension, as a key quantitative descriptor of damage complexity, not only captures the geometric attributes of rock damage but also reveals the intrinsic distinction between damage extent and complexity, offering unique advantages for anisotropy assessment and failure-mechanism identification. Overall, this work establishes a damage-identification and fractal-characterization framework for complex scenarios, elucidates the confinement-dependent evolution of blasting damage and anisotropy, and provides quantitative support for parameter optimization and safety assessment in deep blasting engineering.