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频繁动载扰动下锚固结构损伤破坏的模型试验研究

Model experimental study on damage and failure of anchored structures under frequent dynamic loading disturbance

  • 摘要: 频繁的动载扰动对巷道锚固围岩的稳定性构成严重威胁,易导致支护结构的渐进性损伤与破坏。针对多次动载作用下锚固结构的瞬时力学响应特征与累积破坏机制尚不清楚的问题,基于自主研发的动载巷道冲击地压模拟试验系统,构建了适用于巷道物理模型试验的锚杆支护精细化模拟方法,开展了动载扰动巷道的物理模型试验,系统研究了动载扰动下锚固结构的瞬时力学响应与破坏机制。试验结果表明,动载扰动瞬间锚杆轴力经历剧烈震荡、小幅震荡和相对稳定3个阶段。动载应力波引起顶板与帮部锚固围岩的非协调变形,导致不同部位锚杆轴力呈现差异化演化特征:顶板锚杆轴力呈现“先下降—后上升—再震荡”的趋势,帮部锚杆以压缩应力为主,轴力呈现“先上升—后震荡”的变化规律,阐明了动载扰动下锚固结构内的应力传递与转化机制。在多次动载扰动作用下,锚杆轴力的瞬时震荡峰值与稳定值均表现出同步性变化特征,整体呈现“波动增长—急剧上升—稳定下降”的演变规律。研究进一步发现,震荡效应是导致锚固结构损伤的关键因素,频繁动载扰动会加剧震荡效应,最终促使锚固结构发生性能衰减与失效,揭示了多次动载扰动下锚固结构“损伤累积—突变破坏”的失稳机制。基于上述研究成果,提出了针对性支护优化策略,包括提升锚杆螺纹结构强度与锚固基体性能,以及锚杆与让压支架协同支护模式,为动载扰动巷道的支护防控提供了理论依据与指导。

     

    Abstract: Frequent dynamic disturbances pose a significant challenge to the stability of anchored surrounding rock in deep underground roadways, often resulting in progressive damage to the support structures. Addressing the unclear instantaneous mechanical response characteristics and cumulative failure mechanisms of anchorage structures under frequent dynamic loading.A physical model experiment was conducted using a self-developed experimental system designed to simulate dynamic loading in underground roadways. A refined anchorage simulation method, tailored for roadway model tests, was established to investigate the mechanical behavior of anchored structures subjected to dynamic disturbances. The experiments revealed the instantaneous mechanical response characteristics and failure mechanisms of the anchorage system under dynamic loading. The results demonstrate that the axial force of anchor bolts undergoes three distinct stages—severe oscillation, mild fluctuation, and relative stabilization—immediately following a dynamic disturbance. Stress waves induce incompatible deformation between the roof and sidewall anchored zones, resulting in different axial force evolution patterns: the roof anchor bolts exhibit a decreasing-increasing-fluctuating trend, while the sidewall anchor bolts predominantly experience compression, with axial force increasing and then oscillating. These findings clarify the stress transfer and transformation mechanisms within the anchorage system during dynamic loading. Under repeated disturbances, the peak and stabilized axial forces of the anchor bolts exhibit synchronized trends, characterized by cyclic growth, rapid escalation, and eventual decline. The oscillatory effect was identified as a key contributor to anchorage damage, with frequent dynamic loading accelerating oscillation-induced deterioration and ultimately triggering sudden failures through a damage accumulation process. Based on these insights, targeted support strategies are proposed, including enhancing the mechanical strength of anchor threads and the anchorage matrix, as well as employing synergistic support with yielding components. These recommendations provide theoretical basis and guidance for the support and control of dynamic load disturbance roadways.

     

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