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<p>The complex fault structures at varying depths significantly impact the engineering stability of coal mining. This study focuses on intersecting faults as a representative complex geological feature by integrating large-scale true triaxial physical experiments, multi-software coupled numerical simulations, and engineering case studies from the Huainan Coalfield. The mechanical behavior and response mechanisms of intersecting fault zones under depth-driven effects are systematically elucidated. Furthermore, it provides engineering guidance for optimizing the stability of gas extraction boreholes in complex faulted zones. The results indicate that intersecting faults substantially disrupt the stress transmission paths in coal seams, thereby increasing the spatial heterogeneity of stress distribution. With increasing depth, the relative reduction in the maximum principal stress is monitored within specimen—compared to the applied loading stress—decreases from 19.1 to 13.5%, while the absolute stress reduction increases by approximately 0.27&#xa0;MPa for every 200&#xa0;m depth increment. Depth-driven stress increments dominate the strain evolution of coal seams, with the fault distance significantly influencing the direction and magnitude of strain adjustments. Furthermore, increasing depth intensifies the transitional displacement in fault zones, leading to pronounced increases in displacement gradients outside these zones. Faults with high dip angles exhibit more pronounced shear stress concentration at greater depths, particularly along the shear plane defined by the maximum horizontal and vertical principal stresses. By introducing the strength–stress ratio (SSR), the stability of gas extraction boreholes in intersecting fault zones was quantitatively analyzed, which reveals that plastic deformation areas expand extensively when boreholes traverse faults, thereby increasing instability risk. Therefore, optimizing borehole paths and support designs are crucial for construction safety. These findings provide a theoretical basis for analyzing the mechanical behavior of complex faulted coal seam systems and preventing associated hazards.</p>

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Engineering Stability and Response Mechanisms of Intersecting Fault Zones Under Depth-Driven Effects: Insights from the Huainan Coalfield, China

  • 期刊论文

  • 发表日期：

    2025年8月25日

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  • Chunhui Cheng,
  • Baocai Wang,
  • Qianting Hu,
  • Yongjiang Luo

摘要

The complex fault structures at varying depths significantly impact the engineering stability of coal mining. This study focuses on intersecting faults as a representative complex geological feature by integrating large-scale true triaxial physical experiments, multi-software coupled numerical simulations, and engineering case studies from the Huainan Coalfield. The mechanical behavior and response mechanisms of intersecting fault zones under depth-driven effects are systematically elucidated. Furthermore, it provides engineering guidance for optimizing the stability of gas extraction boreholes in complex faulted zones. The results indicate that intersecting faults substantially disrupt the stress transmission paths in coal seams, thereby increasing the spatial heterogeneity of stress distribution. With increasing depth, the relative reduction in the maximum principal stress is monitored within specimen—compared to the applied loading stress—decreases from 19.1 to 13.5%, while the absolute stress reduction increases by approximately 0.27 MPa for every 200 m depth increment. Depth-driven stress increments dominate the strain evolution of coal seams, with the fault distance significantly influencing the direction and magnitude of strain adjustments. Furthermore, increasing depth intensifies the transitional displacement in fault zones, leading to pronounced increases in displacement gradients outside these zones. Faults with high dip angles exhibit more pronounced shear stress concentration at greater depths, particularly along the shear plane defined by the maximum horizontal and vertical principal stresses. By introducing the strength–stress ratio (SSR), the stability of gas extraction boreholes in intersecting fault zones was quantitatively analyzed, which reveals that plastic deformation areas expand extensively when boreholes traverse faults, thereby increasing instability risk. Therefore, optimizing borehole paths and support designs are crucial for construction safety. These findings provide a theoretical basis for analyzing the mechanical behavior of complex faulted coal seam systems and preventing associated hazards.