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<p>Inclined ore pillars in submarine mining operations frequently face severe instability risks due to the complex coupled effects of compression-shear stress and long-term seawater erosion, which significantly alter the physical and chemical integrity of the rock mass. To systematically investigate the mechanical deterioration and energy evolution mechanisms under these challenging environmental conditions, coupled compression-shear tests were conducted on red sandstone specimens with varying inclination angles (0°, 3°, 6°, 9°) and partial seawater immersion heights (0&#xa0;mm to 100&#xa0;mm), supplemented by detailed scanning electron microscopy (SEM) analysis. Experimental results reveal that increasing immersion height significantly degrades mechanical properties, reducing peak stress by 33.4%–38.5% and elastic modulus by 18.9%–23.3% across all inclination groups. A steeper inclination angle further exacerbates this degradation by introducing additional shear stress components that accelerate the fracturing process. Energy analysis indicates that while input and elastic strain energies decrease, dissipated energy increases following a distinct quadratic function with immersion height, reflecting a substantial reduction in the rock’s energy storage capacity. Notably, quantitative assessments demonstrate that seawater immersion plays a dominant role in mitigating rockburst proneness compared to the inclination effect. Microstructural observations confirm that seawater-induced pore enlargement and the chemical dissolution of inter-granular cementing materials induce a gradual transition from brittle tensile splitting to a ductile mixed tensile-shear failure mode. These findings provide critical theoretical insights and data support for assessing the long-term stability and optimizing the support design of subsea engineering structures.</p>

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Failure behavior and energy evolution of sandstone under coupled compression-shear loading and partial seawater immersion: Effects of immersion height and inclination angle

  • 期刊论文

  • 发表日期：

    2026年3月30日

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  • Tengfei Li,
  • Kang Peng,
  • Yuanmin Wang,
  • Song Luo,
  • Ze Xi

摘要

Inclined ore pillars in submarine mining operations frequently face severe instability risks due to the complex coupled effects of compression-shear stress and long-term seawater erosion, which significantly alter the physical and chemical integrity of the rock mass. To systematically investigate the mechanical deterioration and energy evolution mechanisms under these challenging environmental conditions, coupled compression-shear tests were conducted on red sandstone specimens with varying inclination angles (0°, 3°, 6°, 9°) and partial seawater immersion heights (0 mm to 100 mm), supplemented by detailed scanning electron microscopy (SEM) analysis. Experimental results reveal that increasing immersion height significantly degrades mechanical properties, reducing peak stress by 33.4%–38.5% and elastic modulus by 18.9%–23.3% across all inclination groups. A steeper inclination angle further exacerbates this degradation by introducing additional shear stress components that accelerate the fracturing process. Energy analysis indicates that while input and elastic strain energies decrease, dissipated energy increases following a distinct quadratic function with immersion height, reflecting a substantial reduction in the rock’s energy storage capacity. Notably, quantitative assessments demonstrate that seawater immersion plays a dominant role in mitigating rockburst proneness compared to the inclination effect. Microstructural observations confirm that seawater-induced pore enlargement and the chemical dissolution of inter-granular cementing materials induce a gradual transition from brittle tensile splitting to a ductile mixed tensile-shear failure mode. These findings provide critical theoretical insights and data support for assessing the long-term stability and optimizing the support design of subsea engineering structures.