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Coal Engineering ›› 2026, Vol. 58 ›› Issue (5): 193-201.doi: 10.11799/ce202605024

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Fracture propagation and evolution law of directional waterless fracturing in soft coal seams #br#

  

  • Received:2025-03-03 Revised:2025-04-16 Online:2026-05-15 Published:2026-05-27

Abstract:

Abstract:Addressing the issues of coal slime accumulation and water-blocking effects in hydraulic permeability enhancement technologies for high-stress soft coal seams, where newly formed fractures tend to close rapidly resulting in inefficient gas drainage, this study investigates the damage characteristics and fracture propagation patterns in soft coal subjected to directional expansion fracturing based on water-free fracturing technology. The research analyzes the relationship between fracture length and expansion force, along with fracture extension patterns under different guide borehole layout parameters. Experimental results demonstrate that multi-borehole fracturing achieves superior performance compared to single-borehole operations. Under 30 MPa expansion pressure, the developed fracture length reaches approximately 1.5 m. Optimized guide borehole arrangement at 1.3 m from the expansion hole significantly improves terminal fracture development.

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