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<p>Rock mass engineering, such as pillars, in inclined ore beds, is affected by the inclination of the seam, which is subject to combined compression and shear loads. At the same time, these rock mass engineering also contains flaws. This study innovatively extends traditional uniaxial loading to compressive–shear combined loading conditions to systematically investigate the effects of a 10° loading angle (Loading path simulating a 10° seam dip angle) and full-range fissure angles (0°–180°) on the mechanical behavior and crack propagation mechanisms of flawed yellow sandstone. Through combined compression–shear experiments integrated with real-time DIC monitoring of crack evolution, analyzing crack-dominated macroscopic mechanical responses. Based on fracture mechanics theory, expressions for the crack-tip stress field and fracture toughness are derived, quantifying the dual effects of loading angle and fissure angle from these two dimensions. The results demonstrate that flaws exert a strength-reducing effect on the compressive strength of rocks. When the dip direction of the loading angle and the fissure angle are the same (0° &lt; <i>α</i> &lt; 90°), the peak load first decreases, then increases, and finally decreases as the fissure angle increases. The loading angle dominates wing crack propagation and the final failure mode. When the dip direction of the loading angle and the fissure angle are opposite (90° &lt; <i>α</i> &lt; 180°), as the fissure angle increases, the peak load first decreases and then slightly rises. The loading angle controls crack initiation and early propagation, while the fissure angle determines the crack path and macroscopic failure mode, leading to a shear-dominated tensile–shear composite failure. Across the entire range of fissure angles, the peak load is highest at a fissure angle of 75°(43.73 kN) and lowest at 165°(22.13 kN). The derived expressions for the stress field and fracture toughness at the crack tip well reveal the crack propagation path and failure mode. The research has important guiding significance for underground engineering in rocks with fissures in inclined strata.</p>

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Mechanical Behavior and Crack Propagation Mechanism of Sandstone Containing a Pre-existing Flaw Under Combined Compression–Shear Loading

  • 期刊论文

  • 发表日期：

    2025年9月26日

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  • Lanxin Liu,
  • Binyu Luo,
  • Yicheng Ye,
  • Yuan Su,
  • Dazhong Li,
  • Wenwu Yi

摘要

Rock mass engineering, such as pillars, in inclined ore beds, is affected by the inclination of the seam, which is subject to combined compression and shear loads. At the same time, these rock mass engineering also contains flaws. This study innovatively extends traditional uniaxial loading to compressive–shear combined loading conditions to systematically investigate the effects of a 10° loading angle (Loading path simulating a 10° seam dip angle) and full-range fissure angles (0°–180°) on the mechanical behavior and crack propagation mechanisms of flawed yellow sandstone. Through combined compression–shear experiments integrated with real-time DIC monitoring of crack evolution, analyzing crack-dominated macroscopic mechanical responses. Based on fracture mechanics theory, expressions for the crack-tip stress field and fracture toughness are derived, quantifying the dual effects of loading angle and fissure angle from these two dimensions. The results demonstrate that flaws exert a strength-reducing effect on the compressive strength of rocks. When the dip direction of the loading angle and the fissure angle are the same (0° < α < 90°), the peak load first decreases, then increases, and finally decreases as the fissure angle increases. The loading angle dominates wing crack propagation and the final failure mode. When the dip direction of the loading angle and the fissure angle are opposite (90° < α < 180°), as the fissure angle increases, the peak load first decreases and then slightly rises. The loading angle controls crack initiation and early propagation, while the fissure angle determines the crack path and macroscopic failure mode, leading to a shear-dominated tensile–shear composite failure. Across the entire range of fissure angles, the peak load is highest at a fissure angle of 75°(43.73 kN) and lowest at 165°(22.13 kN). The derived expressions for the stress field and fracture toughness at the crack tip well reveal the crack propagation path and failure mode. The research has important guiding significance for underground engineering in rocks with fissures in inclined strata.