软岩巷道扩孔锚固机理及支护控制数值模拟研究

Numerical simulation study on bolting mechanism and support control of soft rock roadway

针对深部煤矿巷道应力复杂、软弱围岩变形较大的问题,提出一种端部扩孔锚固方法,通过理论模型及数值计算,分析了端部扩孔锚固界面应力分布、脱锚长度扩展及端面挤压应力分布;研究了不同锚固方式巷道围岩变形、应力集中特征。结果表明:相比于常规锚固,界面剪应力在拉拔端附近先增大后减小,且在扩孔起点处附近也存在一个峰值,整体分布形态上呈现双峰值特征;在相同拉拔荷载下,扩孔锚固脱锚长度明显减小;扩锚端面可提供一定挤压抗力,沿扩锚端面径向向外逐渐降低,随扩孔直径增大,挤压抗力明显上升;扩孔锚固巷道顶板变形量比常规锚固降低了36%,巷帮应力集中系数降低了37%;在保证相同巷道稳定性控制效果前提下,扩孔锚固排距可按1.3倍进行布置,有效降低了锚固施工量。

To solve the problem of complex stress and large deformation of soft surrounding rock in deep coal mine,a method of end-reaming anchor was put forward.Through theoretical analysis and numerical simulation,the stress distribution of end-reaming anchorage interface,the extension of de-bonding length and the distribution of end-face extrusion stress were analyzed.The deformation and stress concentration characteristics of roadway surrounding rock with different anchor modes were studied.The results show that compared with traditional anchor,the interface shear stress increases first and then decreases near the pullout end,and there is also a peak value at the starting point of reaming.The overall distribution is characterized by a double peak value.Under the same pullout force,the length of bolt de-bonding decreases obviously.The start face of the reaming anchor can provide certain extrusion resistant stress,which decreases gradually along the radial direction of the start face of the reaming anchor,and increases obviously with the increase of the diameter of the reaming hole.Compared with conventional anchoring,the roof deformation and stress concentration coefficient of roadway side decreased by 36%and 37%respectively.On the premise of ensuring the same stability control effect of roadway,the reaming anchorage row spacing can be arranged by 1.3 times,effectively reducing the amount of anchoring construction.