针对大同矿区石炭系特厚煤层综放工作面周期性发生液压支架立柱大幅下缩甚至压死支架的工程技术难题,采用理论分析与现场实测的方法,研究特厚煤层开采远场覆岩结构失稳机理。提出了远场"三角板"结构运动影响特厚煤层开采工作面矿压的理念,建立了远场关键层"横OX"破断形成的"三角板"结构力学模型,确定了该"三角板"结构滑落失稳和回转变形失稳的理论判据;结合同忻煤矿现场实例,预计了远场关键层"横O-X"破断"三角板"结构块体的几何尺寸,并分析了此"三角板"的走向长度及回转程度对其自身结构稳定性的影响,结果表明"三角板"的走向长度和回转程度越大时该结构越容易失稳。同忻煤矿8202工作面临空侧回风平巷超前段底臌变形特征间接验证了远场关键层发生"横O-X"破断的规律。据此提出超前预裂远近场关键层以及在"三角板"结构下工作面实行快速推进等防治措施。

To overcome the problems of sharp decrease of hydraulic support’s prop and even emerging support crush- ing disaster periodically when the fully-mechanized top coal caving mining method is applied for mining the Carbonif- erous super-thick coal seam in Datong mining area,the methods of theoretical analysis and field measurement were used to study the mechanism of the instability of strata structure in far field for super-thick coal seam mining. The hy- pothesis that the movement of the “triangle plate” structure in far field impacts the mine pressure in super-thick coal seam working faces was proposed,and the “triangle plate” structural mechanics model for far field key strata broken in the shape of “horizontal O-X” for super-thick coal seam mining was established. Combining the field measurement in Tongxin coalfield,the geometrical parameters for the broken blocks of “triangle plate” structure for far field key strata broken in the shape of “horizontal O-X” were predicted,and the influence of its strike length and rotation degree on the structural stability was analyzed. The results show that this structure was easy to break when a big strike length and a heavy rotation degree of “triangle plate” existed. The floor heave deformation behavior of advancing segments in tail- gate on the side of free face of 8202 working face,Tongxin coalfield,indicated the breakage rule for the “horizontal O- X” breakage of far-field key strata indirectly. Based on the influential mechanism of the “ triangle plate” structure in far field on the mine pressure in working faces,the precautions of presplitting the far field key strata in advance and mining quickly under the “triangle plate” structure were addressed. The research work can provide a reference to the safe and high-efficiency mining and strong mine pressure controlling of faces with large mining height in super-thick coal seams.