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<p>This study investigates the mechanical properties and fractal failure patterns of coral reef limestone (CRL) under impact loading. Static mechanical tests and split Hopkinson pressure bar (SHPB) dynamic impact experiments were performed on four types of CRL specimens. Multi-scale characterization techniques, including scanning electron microscopy (SEM) and X-ray computed tomography (CT), were employed to analyze the dynamic mechanical behavior and meso-porous structure of CRL. The results reveal significant heterogeneity in CRL: porous-type CRL, dominated by biogenic aragonite, fails along primary pores, while dense-type CRL, primarily composed of metamorphic calcite, destabilizes along secondary pores and weakly cemented interfaces. CRL exhibits significant strain rate dependence, with dynamic compressive strength and the dynamic increase factor (<i>DIF</i>) increasing linearly with strain rate. The dynamic strength of CRL is highly sensitive to both fractal dimension and strain rate, and its fragmentation fractal dimension demonstrates a positive correlation with energy dissipation density. At medium to high strain rates, dense CRLs primarily show brittle splitting failure, with cracks extending through the skeleton, while loose CRLs mainly undergo pulverization failure through perforation propagation. These findings provide a scientific basis for the rational utilization of CRL in island underground engineering and offer critical insights for optimizing structural safety and engineering design.</p>

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Analysis of the mechanical behavior and fractal damage features of coral reef limestone under impact loading

  • 期刊论文

  • 发表日期：

    2025年4月7日

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  • Bowen Cheng,
  • Shuai Zhang,
  • Qian Dong,
  • Ming Chang,
  • Junhong Huang

摘要

This study investigates the mechanical properties and fractal failure patterns of coral reef limestone (CRL) under impact loading. Static mechanical tests and split Hopkinson pressure bar (SHPB) dynamic impact experiments were performed on four types of CRL specimens. Multi-scale characterization techniques, including scanning electron microscopy (SEM) and X-ray computed tomography (CT), were employed to analyze the dynamic mechanical behavior and meso-porous structure of CRL. The results reveal significant heterogeneity in CRL: porous-type CRL, dominated by biogenic aragonite, fails along primary pores, while dense-type CRL, primarily composed of metamorphic calcite, destabilizes along secondary pores and weakly cemented interfaces. CRL exhibits significant strain rate dependence, with dynamic compressive strength and the dynamic increase factor (DIF) increasing linearly with strain rate. The dynamic strength of CRL is highly sensitive to both fractal dimension and strain rate, and its fragmentation fractal dimension demonstrates a positive correlation with energy dissipation density. At medium to high strain rates, dense CRLs primarily show brittle splitting failure, with cracks extending through the skeleton, while loose CRLs mainly undergo pulverization failure through perforation propagation. These findings provide a scientific basis for the rational utilization of CRL in island underground engineering and offer critical insights for optimizing structural safety and engineering design.