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

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.