锚杆支护组合构件与金属网匹配性试验研究

Experimental study on matching between rock bolt support composite components and metal mesh

  • 摘要: 鉴于金属网与组合构件的力学匹配性不足易引发网丝滑移、应力集中及峰后承载骤降造成支护失效等问题。采用自主研发的金属网静载试验系统对3类金属网与不同类型组合构件进行匹配性测试,得到了3类金属网在垂直载荷作用下的支护强度、刚度及变形破坏方式;提出了5类匹配性指标,系统分析了金属网与锚杆支护组合构件之间的匹配关系;借助有限元数值模拟软件分析了支护系统的应力分布特征,从应力分布特征角度进一步阐述了二者之间的匹配关系。结果表明:金属网支护系统的载荷−位移曲线呈现3阶段特征:初始载荷传递阶段表现为下凹上升趋势,网丝变形阶段呈现近似线性增长,结构破坏阶段则伴随波动和承载能力逐步下降,不同金属网因结构差异导致各阶段速率和破坏模式显著分化。组合构件的加入,可显著改变载荷−位移曲线各阶段的阈值点与增速。锚杆组合构件通过约束网丝滑移和优化载荷传递路径,显著提升支护系统的刚度和承载稳定性,其中W型钢带对钢筋网和经纬网的强化效果优于钢筋托梁,而菱形网则更依赖组合构件的延展性适配。组合构件改变支护系统破坏模式与位置,锚杆支护组合构件通过抑制金属网网丝与托盘直接接触,使剪切应力降低40%~55%,破坏位置由托盘转移至网兜底部,显著降低峰后失效风险。护表宽度与变形跨度关联性明确,W型钢带通过减小变形跨度(护表宽度增加30%),使支护强度提升18%~28%,但需优化钢带边缘连接以避免局部剪切应力集中。

     

    Abstract: In view of the problems—such as wire slippage, stress concentration, and abrupt post-peak bearing capacity drop leading to support failure—caused by insufficient mechanical compatibility between metal mesh and combined components, a self-developed static loading test system for metal mesh was used to conduct compatibility tests on three types of metal mesh with different combined components. The support strength, stiffness, and deformation and failure modes of the three types of metal mesh under vertical loading were obtained. Five matching indices were proposed, and the matching relationship between metal mesh and bolt-support combined components was systematically analyzed. The stress distribution characteristics of the support system were further investigated using finite element numerical simulation software, thereby clarifying the matching relationship from the perspective of stress distribution. The results show that the load–displacement curves of the metal mesh support system exhibit three distinct stages: the initial load transfer stage displays a concave upward trend; the wire deformation stage shows approximately linear growth; and the structural failure stage is accompanied by fluctuations and a gradual decline in bearing capacity. Owing to their structural differences, various metal meshes exhibit significant differentiation in the rate and failure mode of each stage. The introduction of combined components markedly alters the threshold points and growth rates of each stage of the load–displacement curve. Bolt combined components significantly enhance the stiffness and bearing stability of the support system by constraining wire slippage and optimizing load transfer paths. Specifically, W-shaped steel strips provide better reinforcement for steel bar mesh and welded wire mesh than rebar beams, whereas diamond mesh relies more on the ductility compatibility of the combined components. The combined components also change the failure mode and location of the support system. By inhibiting direct contact between the metal mesh wires and the bearing plate, bolt-support combined components reduce shear stress by 40%–55%, shifting the failure location from the bearing plate to the bottom of the mesh bag, thereby significantly lowering the risk of post-peak failure. There is a clear correlation between surface protection width and deformation span. By reducing the deformation span (with a 30% increase in surface protection width), W-shaped steel strips improve support strength by 18%–28%; however, the edge connections of the steel strip must be optimized to avoid local shear stress concentration.

     

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