<p>Affected by the depositional environment, coal seams in the weathered and oxidized zone and their overlying strata are characterized by developed fractures and poor self-stability, leading to difficulties in roadway and working face roof management. This paper analyzes the failure characteristics of coal-rock masses in this zone. Combined with model tests and numerical simulation methods, it investigates the stress distribution status, deformation-failure characteristics, and movement-fracture laws of the overlying strata in a fully mechanized top-coal caving working face. The results indicate: (1) Weathering and oxidation significantly degrade strength and increase plastic deformation in coal-rock masses; (2) Under mining-induced disturbance, overlying strata stress is released from the in-situ state and sharply reduced, forming stress concentration zones ahead of the coal wall and at face ends; (3) During mining, fractures propagating upwards from the coal wall trigger rib spalling and top-coal collapse, forming combined cantilever and articulated rock beam structures. The overlying strata sequentially undergo four deformation-failure stages: “bed separation, immediate roof fracture, main roof fracture, and high-level strata collapse”. The research findings can provide a basis for the safe mining of fully mechanized top-coal caving faces in weathered and oxidized coal.</p>

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Research on movement and fracture laws of overlying strata in fully mechanized top-coal caving faces within shallow-buried weathered and oxidized zones

  • Mao-lin Tian,
  • Cheng Yang,
  • Shao-jie Chen,
  • Da-wei Yin,
  • Yuan Zhou,
  • An-fu Zhang,
  • Jia-bao Wang

摘要

Affected by the depositional environment, coal seams in the weathered and oxidized zone and their overlying strata are characterized by developed fractures and poor self-stability, leading to difficulties in roadway and working face roof management. This paper analyzes the failure characteristics of coal-rock masses in this zone. Combined with model tests and numerical simulation methods, it investigates the stress distribution status, deformation-failure characteristics, and movement-fracture laws of the overlying strata in a fully mechanized top-coal caving working face. The results indicate: (1) Weathering and oxidation significantly degrade strength and increase plastic deformation in coal-rock masses; (2) Under mining-induced disturbance, overlying strata stress is released from the in-situ state and sharply reduced, forming stress concentration zones ahead of the coal wall and at face ends; (3) During mining, fractures propagating upwards from the coal wall trigger rib spalling and top-coal collapse, forming combined cantilever and articulated rock beam structures. The overlying strata sequentially undergo four deformation-failure stages: “bed separation, immediate roof fracture, main roof fracture, and high-level strata collapse”. The research findings can provide a basis for the safe mining of fully mechanized top-coal caving faces in weathered and oxidized coal.