深部大采高沿空留巷围岩结构沉降破坏与控制

为了解决深部沿空留巷围岩控制难题,选取邢东矿(埋深850 m)1126大采高工作面沿空留巷为研究对象。采用UDEC模拟分析关键块B不同下沉量围岩的响应特征。结果表明:1实体煤帮偏应力峰值和位置与关键块B下沉量呈线性关系增大且向深部转移;2实体煤帮深部变形对关键块B下沉量的响应较弱,愈靠近煤帮表面其敏感性越强,深浅部围岩位移有明显拐点;3顶板下沉量、帮变形量与关键块B下沉量呈正指数关系;4随关键块B下沉,实体煤帮的破坏形式经历了从不稳定三角块滑落→X共轭破坏→双X共轭破坏过程。认为:1巷旁采空区充填可有效限制关键块C下沉对块体B的带动作用;2钢管混凝土支架可适应关键块B的下沉特征,具有较强的抗压缩和弯曲特性;3高性能、高预紧力锚杆可更好地提高锚固体承载和抵御变形能力;4顶桁架锚索可以锚固在关键块B上,锚固基础稳固可靠;帮锚索可以穿越帮潜在滑移面,锚固在位移拐点内的锚固区内,限制帮结构性滑移。基于此提出了巷旁采空区充填+钢管混凝土支架+顶桁架、帮锚索+高强高预紧力锚杆联合控制方案;沿空留巷完成30 d后围岩趋于稳定,顶底板和两帮最大相对移近量分别为613 mm和374 mm,实现了深部大采高沿空留巷围岩的有效控制。

Subsidence broken of deep gob-side entry retaining surrounding rock structure with large mining height and its control

In order to solve the surrounding rock control problems in deep gob-side entry retaining, the working face 1126 with large mining height of Xingdong mine (850 m occurrence depth) was taken as research subject. Then, by means of UDEC simulation, we analyze surrounding rock response character with different subsidence amounts of key block B. Analysis result shows that: ①the deviatoric stress peak value of coal sides and its position have linear relationship with subsidence amount of key block B, and they transfer to deep part; ②deformation in deep part of coal sides has weak response to subsidence amount of key block B, and the closer to coal side surface, the more sensibility the coal sides has, therefore, there is an obvious inflection between the deep and shallow surrounding rock displacement; ③the roof subsidence amount and sides deformation amount have positive exponential relationship with the subsidence of key block B; ④along with key block B settling, broken form of coal sides experiences the following progress: unstable triangular block slide →X conjugate broken →double X conjugate broken. Therefore, some conclusions are made as follows: ①the roadside gob backfilling in can effectively limit the driving effect from key block C to block B; ②steel-concrete support can adapt subsidence feature of key block B well and has strong compression resistance and bending character; ③the high performance and high pre-stressed anchor can better improve the load capacity and deformation resistance ability of anchoring body; ④the roof truss anchor cable can be anchored in key block B that has solid and reliable anchoring basis, and, side cable can be anchored the area within the displacement inflection by passing through potential slip surface in order to restrict the side structural slip. Based on the above analysis, a collaborative control program was put forward which consists of roadside gob backfilling, steel-concrete support, roof truss anchor cable, side cable and high strength and high pre-stressed anchor. Thirty days after the entry retained, surrounding rock deformation tends to be stable. In addition, the relative displacement amount of roof and floor is 613 mm, and the other one of two sides is 374 mm, which achieves the effective control of gob-side retaining entry surrounding rock in deep mining with large mining height.