动力扰动下全长黏结锚杆的力学响应特性

Mechanical response characteristics of full grouted rock bolts subjected to dynamic loading

深部岩体工程中,锚杆在围岩变形后处于高承载应力状态,受到爆破振动、矿震等动载荷作用后极易失效,因此,亟待研究动力扰动下锚杆的力学响应机制。基于SHPB试验平台,自行研发了一套研究锚杆动力响应的试验装置,开展动力扰动下全长黏结锚杆的力学响应特性研究。结果表明:初始动载荷作用下锚杆滑移量随着入射能的增加而增加,锚杆中应力波的波峰值随着传播距离的增加而逐渐减小,当应力波传播至锚杆最里端时,应力波峰值衰减较大;第2次动载荷后锚杆SG1处与SG2处应力波峰值差明显比第1次减小,表明动载荷下锚固界面从锚杆外端开始损伤;锚杆失效与锚固界面损伤有关,锚杆承载后初次受到动载荷的影响导致锚固界面产生损伤,损伤锚固段又受到外部载荷(如二次冲击、岩体挤压)作用时会进一步劣化,其不能抵抗围岩的变形而失效。研究结果为揭示锚杆支护失效行为,采取合理的设计与施工提供新的思路。

Since the rockbolt is in the state of high bearing stress after the deformation of surrounding rock, it is easily to fail due to blasting vibration, earthquake and other dynamic loads in the deep rock mass engineering. Therefore, it is urgent to study the mechanical response mechanism of the bolt under dynamic disturbance. Based on the SHPB system, a set of testing equipment was developed for studying the dynamic response of bolts. Then the mechanical response characteristics of full-length bonded bolts were investigated under dynamic disturbance. The slippage of bolt increased with the increase of the incident energy at initial dynamic load,and the peak value of stress wave decreased with the increase of propagation distance. When the stress wave propagated to the farthest end of bolt, the peak value of stress wave decreased greatly. After the second dynamic load, the peak difference of stress wave between strain gauge SG1 and strain gauge SG2 was obviously smaller than that at the first time. This result indicates that the anchorage interface begins to damage from the outside of the anchor under the dynamic load. The failure of the anchor is related to the damage of the anchor interface. The anchorage interface is damaged after the first time loading. Then the damaged anchor bolt will be further deteriorated by the external load(such as secondary impact and rock mass extrusion). As a result, it can not resist the deformation of surrounding rock and fail. The research results provide new ideas for revealing the failure behavior of the supporting bolt and adopting the reasonable design and construction.