特厚煤层大采高综放工作面覆岩结构及支架工作阻力研究

Analysis of overburden structure and support working resistance of working face in fully-mechanized top coal caving with large mining height in ultra thick coal seam

为了掌握特厚煤层大采高综放工作面的覆岩结构及支架合理工作阻力,以同忻煤矿8107工作面为研究对象,采用理论分析、现场观测的方法对特厚煤层大采高综放工作面覆岩的破断和组合形式进行了研究,建立了覆岩力学模型,得出了同忻煤矿8107工作面支架工作阻力计算式。结果表明:正常开采期间,大采高综放工作面直接顶易形成具有整体性的倒台阶组合悬臂梁结构,悬臂梁结构的破断、回转是支架—围岩互馈过程中的主要压力来源;来压期间,高位砌体梁结构与低位悬臂梁结构耦合形成"砌体梁—悬臂梁"结构,砌体梁结构的滑落失稳引起悬臂梁结构的协同回转,是大采高综放工作面强冲击来压的原因;实测8107工作面正常回采以及来压时支架工作阻力分别为26 MPa(9 750 k N)和40 MPa(15 000 k N),与理论计算结果较为吻合;8107工作面采用的ZF15000/27.5/42型四柱低位放顶煤支架能够满足生产需求。

In order to grasp the overburden structure and support working resistance of working face in fully-mechanized top coal caving with large mining height in ultra thick coal seam,this paper study the ultra thick coal seam in Tongxin coal mine. The fracture and combining form of the overburden strata in working face was researched using the methods of theoretical analysis and in-situ observation,and the mechanical model of overburden strata was also established,then the formula of support working resistance in 8107 working face was obtained. The results show that:In the period of normal mining,the immediate roof in working face of full-mechanized top coal caving with large height can easily form 'reverse step combination cantilever beam'which was a global body and the fracture and rotary of the'cantilever beams'was the main source of pressure in the mutual feedback between the support and the surrounding rock. In the period of periodic weighting the up 'masonry beam'and the down 'cantilever beams 'coupled with each other and formed new structure called 'masonry beam-cantilever beam',and the sliding instability of masonry beam resulted in the rotary of the'cantilever beams 'which was the reason that the intensive impact pressure appeared in working face in fully-mechanized top coal caving with large mining height. The actual measurement of support working resistance in 8107 working face were respectively 26 MPa(9 750 k N) in normal mining period and 40 MPa(15 000 k N) in periodic weighting period,which tallied with the theoretical calculation results. The ZF15000/27. 5/42 four bars low caving coal hydraulic support in 8107 working face can meet the production requirements.