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Coal Engineering ›› 2026, Vol. 58 ›› Issue (6): 77-85.doi: 10.11799/ce202606011

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Mechanical response and weakening characteristics of coal-rock in an isolated working face under hard strata #br#

  

  • Received:2025-09-26 Revised:2025-12-04 Online:2026-06-15 Published:2026-06-24
  • Contact: wang xiangye E-mail:wangxiangye@cctegxian.com

Abstract:

The mining of isolated island working face under deep cover with overlying hard strata is prone to severe strata pressure behavior, threatening coal mine safety. This study, based on the 3206 isolated island working face at Shanxi Tiandi Wangpo Coal Mine, employs a combined methodology of theoretical analysis, numerical model-ing, and field measurement. A mechanical model of the coal-rock mass loading before and after mining was established. The deformation characteristics and stress transfer evolution laws before and after the weakening of the hard strata were comparatively analyzed, and the effectiveness of hydraulic fracturing treatment was val-idated through field measurements. The results indicate that the isolated panel is subjected to a high static load from its self-weight and the transferred load from the adjacent goafs on both sides, superimposed by a dynamic load equivalent to twice the static load step variation before and after the fracturing of the hard strata, leading to a high dynamic response in the stope. When the panel advanced into the initial fracturing zone after strata weakening, the extent and degree of strata failure were limited, and the pre-splitting effect was not significant. Upon advancing into the fully fractured zone, the overall plastic failure range of the strata increased, the failure modes diversified, and the failure intensity deepened. The vertical displacement at the working face rapidly increased to 5.31 m. A larger tensile stress zone developed in the roof above the goaf, while the stress concen-tration in the front coal body decreased to 24.4 MPa, a reduction of 3.17% compared to the pre-weakening condition. The stress concentration zone shifted forward into the rock mass. As mining progressed, the front hard strata broke and caved in a timely manner, preventing large area

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