特厚煤层强采动巷道顶板全锚索控制系统研究

Study on cables in roof controlling system to support the intensively dynamic pressure roadway in extra-thick coal seam

针对大采高综放强采动影响下特厚煤顶大断面煤巷出现剧烈变形的控制难题,综合现场调研、数值模拟、井下试验及现场实测方法,详细研究了特厚煤层强采动巷道变形特征,提出顶板全锚索控制系统,分析了新支护系统的组成结构、控制原理、锚索预应力分布与演化机理、支护效果。结果表明:1)特厚煤层强采动巷道大变形原因可概括为"三大一快"开采特征、强采动应力影响作用、顶煤与夹矸层物理力学性质差异大以及顶板支护强度不足,而其变形特征主要为顶板煤岩离层值大、受采动影响敏感系数高和顶板变形过程非均匀性;2)全锚索综合控制系统通过高预应力小孔径锚索与厚层高强度钢带综合作用形成双承载结构,能有效控制锚索锚固范围内顶板的离层和变形;3)全锚索支护过程中锚索长度,排距和预紧力不同参数值对顶煤中形成的叠合预应力带厚度、预应力扩散传递方向和范围影响显著。并详细介绍了井下运用全锚索系统控制特厚煤层大断面强采动巷道成功案例。

Aiming at controlling problems of intensive deformation of large cross-sectional roadway in extra-thick coal seam roof affected by the dynamic pressure during mining process. It adopts the method of fully-mechanized top coal caving with large mining height, combining with the field investigation, numerical simulation, field test and field monitoring. The deformation characteristics of the coal road- way in extra-thick coal seam affected by the intensively dynamic pressure are analyzed in detail. The Controlling System with Cables in Roof （CSCR） is put forward and the composition structure, controlling principle, pre-stress distribution and evolution mechanism of the roof cables, supporting effect are researched. The research results are as follows： 1） The induction factors of large deformation of road- way affected by the intensively dynamic pressure are mainly the influence of characteristics of the working face in extra-thick coal seam with ＂three large and one fast＂, intensively dynamic pressure, large difference of the physical and mechanical properties between the roof coal seam and parting, and the lack of the roof supporting strength. Besides, the deformation characteristics are summarized as large bedding separation between the coal seam and parting, high sensitive factor affected by the mining effect and the non-uniformity of the roof deformation process. 2） The CSCR could form two bearing structures in the thick coal seam, depending on the combining effect of the small diameter pre-stressed cable with high pre-tightening force and thick steel belt with high strength, which could effectively con- trol the bedding separation and deformation of the roof in the range of the cable supporting. 3） In the process of CSCR, the parameters of the cable length, distance between two rows and pre-tightening force have significant influence to the thickness of the pre-stress belt, transfer direction and range. A typical successful case of CSCR application to large and intensively dynamic roadway with extra-thick coal seam is introduced in detail.