橡胶垫层吸能缓冲构件对锚杆支护系统抗冲击性能的影响机理

Impact resistance performance of rockbolt system with(out) rubber cushion energy absorbing and buffering components

  • 摘要: 冲击危险巷道的防冲支护实践表明,锚杆支护系统中安装吸能缓冲构件可显著改善其抗冲击性能。以橡胶垫层作为吸能缓冲构件,采用自主研制的冲击试验平台开展了吸能缓冲构件对多锚杆支护系统抗冲击性能影响机理的试验研究。通过对有、无吸能垫层两种工况下锚杆支护系统进行冲击加载试验,得到锚杆变形、载荷、吸能及围岩破碎特征等参量的响应特征,定量阐释了吸能缓冲构件对支护系统抗冲击性能的影响机制。研究表明:锚杆支护系统经历冲击作用时,锚杆载荷的动态响应早于变形,且安装吸能缓冲构件时锚杆载荷、变形及响应“时−速”均显著降低,表明吸能缓冲构件能够改善锚杆支护系统的抗冲击性能;吸能缓冲构件通过塑性变形消耗部分冲击能量,降低支护系统中主要构件的吸能需求,锚杆吸能速率降低是能量吸收量降低与响应时间延长双重作用的结果;吸能缓冲构件有利于均衡锚杆群受力,与各支护构件协同承载,进而提升支护系统的抗冲击性能,支护系统各冲击响应指标的标准差显著降低,其中锚杆吸能速率降低尤为明显,降幅达77.89%;安装吸能缓冲构件,围岩破坏程度,围岩裂隙迹线长度、分形维数及质量损失比等定量指标显著降低,吸能缓冲构件防冲作用表现在抑制裂隙扩展、张开及防止破裂后碎块分离弹射2个方面。研究成果可为冲击危险巷道锚杆支护系统的优化设计提供有益参考。

     

    Abstract: The practice of impact resistance support in dangerous roadways has shown that energy absorbing and buffering components can improve the impact resistance performance of rockbolt support systems. A rubber cushion layer was used as an energy absorbing and buffering component, and an impact test platform was used to conduct impact loading on rockbolt support systems with and without energy absorbing cushion layers. The response characteristics of parameters such as rockbolt deformation, load, energy absorption, and surrounding rock fragmentation are compared to reveal the impact mechanism of energy absorbing buffer components on the impact resistance performance of rockbolt support systems. Experimental studies have shown that: (1) when the rockbolt support system experiences impact, the dynamic response of the rockbolt load is earlier than the deformation, and the rockbolt load, deformation, and response "time velocity" are significantly reduced when installing buffer components, indicating that buffer components can improve the impact resistance performance of the rockbolt support system; (2) The buffer components consume some impact energy through plastic deformation, thereby reducing the energy absorption demand of the main components in the support system; (3) Buffer components are conducive to achieving balanced stress distribution of rockbolt, cooperating with various support components to enhance the impact resistance performance of the support system, and significantly reducing the standard deviation of impact response indicators; (4) When installing buffer components, the degree of rock damage is significantly reduced, and indicators such as the length of rock crack traces, fractal dimension, and quality loss ratio are significantly reduced. The research results can provide reference for the optimization design of support systems for impact dangerous tunnels.

     

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