扩胀-摩擦式吸能防冲锚索及其力学特性

Expansion friction energy absorption anti impact cable and its mechanical characteristics

  • 摘要: 冲击危险巷道围岩冲击大变形造成锚固支护材料过载失效已成为深部煤矿巷道支护技术中亟待解决的工程难题。针对传统钢绞线锚索难以适应围岩冲击作用而出现的过载拉断问题,基于金属圆管扩胀塑性变形及摩擦耗能原理,研发了一种扩胀-摩擦式吸能防冲锚索。采用塑性力学理论开展了吸能防冲锚索吸能原理解析分析,并结合正交模拟试验讨论了吸能装置结构尺寸及材料属性对吸能阻力的影响规律及敏感性,得到了影响吸能防冲锚索吸能阻力的主控因素。研究结果表明:吸能防冲锚索的吸能装置在让位吸能过程中,吸能装置吸能总阻力可分为扩胀变形阻力和滑动摩擦阻力两部分。吸能套管壁厚、膨胀比、屈强比、摩擦系数以及扩径台锥角对扩胀变形阻力、滑动摩擦阻力的影响规律存在显著差异,吸能套管屈强比增加会导致吸能总阻力降低,扩径台锥角越大,降低速度越快;滑动摩擦阻力对吸能套管膨胀比变化较为敏感,而扩胀变形阻力对扩径台锥角变化极为敏感,增大扩径台锥角可迅速降低滑动摩擦阻力,增大扩胀变形阻力,从而改变二者在吸能总阻力中的占比;扩径台锥角相同时滑动摩擦阻力对吸能套管膨胀比的敏感性显著大于扩胀变形阻力;摩擦系数直接影响滑动摩擦阻力,而对扩胀变形阻力没有影响。6因素5水平正交模拟试验结果表明:影响吸能总阻力的因素主次顺序为吸能套管壁厚、扩径台锥角、吸能套管屈强比、挤压圆台高度、吸能套管膨胀比以及摩擦系数,吸能总阻力数值模拟与理论计算结果的相对误差在10%以下,吸能套管壁厚、膨胀比、屈强比、摩擦系数以及扩径台锥角,对吸能总阻力的影响趋势与理论分析基本一致。理论解析、数值模拟与实验结果具有较高的吻合程度,证实了吸能防冲锚索解析模型、数值模型的正确性,可作为吸能防冲锚索结构设计的理论依据。通过调整吸能装置的材料及结构参数,可以实现吸能阻力在300~500kN之间的调整,以匹配不同型号钢绞线。

     

    Abstract: The failure of support materials caused by roadway rock burst has become a major engineering problem that needs to be solved urgently in mine roadway support. In considering that the ordinary cables are difficult to adapt to impact dynamic loads and the engineering problems such as structural deformation and fracture, based on the principle of plastic deformation of metal cylinder and frictional energy absorption, an expansion and friction energy absorption anti impact cable are designed. The theory of plastic mechanics is used to carry out the analytical analysis of the energy absorption principle of the energy absorption anti impact cable, and combined with the orthogonal simulation experiment, the influence law and sensitivity of the structural size and material properties of the energy absorption device on the energy absorption resistance are discussed. The main controlling factor that affects the energy absorption resistance of the energy absorption anti impact cable are obtained. The results show that during the energy absorption process of the energy absorption device of the energy absorption anti impact cable, the total energy absorption resistance of the energy absorption device can be divided into two parts: the expansion deformation resistance and the sliding friction resistance. There are significant differences in the influence of wall thickness, expansion ratio, yield to tensile strength ratio of the energy absorption tube, friction coefficient, and cone angle of the expansion cone on the expansion deformation resistance and sliding friction resistance of the energy absorption tube. The increase in the yield to tensile strength radio of the energy absorption tube will result in the total energy absorption resistance decreases, the larger the cone angle of the expansion cone, the faster the reduction speed. The sliding friction resistance is more sensitive to the changes in the expansion ratio of the energy absorption tube, while the expansion resistance is extremely sensitive to the changes in the cone angle of the expansion cone. Increasing the cone angle of the expansion cone can quickly reduce the sliding friction resistance and increase the deformation resistance of the expansion, thereby changing the proportion of the two in the total energy absorption resistance. Then the cone angle of the expansion cone is the same, the sensitivity of the sliding friction resistance to the expansion ratio of the energy absorption cube is significantly greater than the expansion deformation resistance. The friction coefficient directly affects the sliding friction resistance, but has no effect on the expansion deformation resistance. Six factors and five horizontal orthogonal simulation experiment results show that the primary and secondary order of factors affecting the total energy absorption resistance are energy absorption tube wall thickness, expansion cone angle, energy absorption tube yield ratio, extruded truncated cone height, energy absorption tube expansion ratio and friction coefficient. The relative error between the numerical simulation and theoretical calculation results of the total energy absorption resistance is less than 10%. The influence trend of the energy absorption tube wall thickness, expansion ratio, yield to tensile strength radio, friction coefficient and cone angle of the expansion cone on the total energy absorption resistance is basically consistent with the theoretical analysis. The results of theoretical analysis, numerical simulation and experiment have a high degree of agreement, which confirms the correctness of the analytical analysis model and numerical model of the energy absorption anti impact cable, which can be used as the theoretical basis for the design of the energy absorption anti impact cable structure. By adjusting the material and structural parameters of the energy absorption device, the energy absorption resistance can be adjusted between 300 kN and 500 kN to match different types of steel strands.

     

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