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<p>The initial mining period in thick-hard roof working faces frequently induces large-scale suspended roof hazards, while the design of roof-cutting parameters lacks robust theoretical foundations. This study established a mechanical model for combined roof-cutting structures, analyzed the influence mechanisms of key parameters on roof caving, and developed a parameter design methodology based on fracture coalescence. Guided by this methodology, a combined roof-cutting technical scheme was designed and implemented to evaluate its effectiveness in roof management and rockburst prevention. Results demonstrate that increasing borehole spacing <i>D</i> significantly enhances shear resistance within non-coalesced fracture zones, thereby inhibiting caving. Conversely, expanding the blast-induced radial fracture range <i>r</i> and abrasive water jet radial fracture range <i>d</i> reduces shear strength and increases the weakened area, while decreasing the spacing between abrasive water jet fracturing stages <i>H</i> improves fracture network connectivity through increased axial weakening surfaces. Both approaches promote caving. Consequently, a parameter optimization principle was established to maximize r and d while minimizing <i>D</i> and <i>H</i>, based on fracture coalescence criteria. Parameter experiments and theoretical derivations yielded theoretical thresholds of 13.18 m for blast hole spacing and 6.92 m for abrasive water jet fracturing stage spacing. A combined roof-cutting scheme for the initial caving stage was subsequently engineered and field-implemented. Post-operation observations behind hydraulic supports confirmed complete roof collapse after 16 m of mining advance, with roof fracture energy released as low-frequency, low-energy events, while the initial caving span was controlled at 39 m. These outcomes confirm the successful mitigation of large-scale roof hanging during thick-hard roof initial mining, reduced rockburst risks, and validated reliability of the roof-cutting parameter design. This research provides a theoretical foundation for managing roof hazards under similar mining conditions and offers technical guidance for safe coal extraction beneath thick-hard roof strata.</p>

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Design Method of Combined Cutting Parameters for Thick-Hard Roof Working Face and Analysis on Rockburst Prevention Effectiveness

  • 期刊论文

  • 发表日期：

    2026年5月18日

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  • Anliang Lu,
  • Zhenlei Li,
  • Chao Zhou,
  • Yu Zhou,
  • Xueqiu He,
  • Dazhao Song,
  • Hongping Li

摘要

The initial mining period in thick-hard roof working faces frequently induces large-scale suspended roof hazards, while the design of roof-cutting parameters lacks robust theoretical foundations. This study established a mechanical model for combined roof-cutting structures, analyzed the influence mechanisms of key parameters on roof caving, and developed a parameter design methodology based on fracture coalescence. Guided by this methodology, a combined roof-cutting technical scheme was designed and implemented to evaluate its effectiveness in roof management and rockburst prevention. Results demonstrate that increasing borehole spacing D significantly enhances shear resistance within non-coalesced fracture zones, thereby inhibiting caving. Conversely, expanding the blast-induced radial fracture range r and abrasive water jet radial fracture range d reduces shear strength and increases the weakened area, while decreasing the spacing between abrasive water jet fracturing stages H improves fracture network connectivity through increased axial weakening surfaces. Both approaches promote caving. Consequently, a parameter optimization principle was established to maximize r and d while minimizing D and H, based on fracture coalescence criteria. Parameter experiments and theoretical derivations yielded theoretical thresholds of 13.18 m for blast hole spacing and 6.92 m for abrasive water jet fracturing stage spacing. A combined roof-cutting scheme for the initial caving stage was subsequently engineered and field-implemented. Post-operation observations behind hydraulic supports confirmed complete roof collapse after 16 m of mining advance, with roof fracture energy released as low-frequency, low-energy events, while the initial caving span was controlled at 39 m. These outcomes confirm the successful mitigation of large-scale roof hanging during thick-hard roof initial mining, reduced rockburst risks, and validated reliability of the roof-cutting parameter design. This research provides a theoretical foundation for managing roof hazards under similar mining conditions and offers technical guidance for safe coal extraction beneath thick-hard roof strata.