为定量探究循环冲击下锚杆支护系统动态响应特征, 采用自主研制的冲击试验平台对锚杆支护系统进行5 000 J能量循环冲击, 并同步跟踪锚杆杆体变形、载荷、吸能及围岩破碎特征等参数信息。试验结果表明: 随循环冲击次数的增加, 杆体响应时间差先快速降低再缓慢增大, 杆体载荷和能量吸收特征参数均先增大后下降, 三者均在第2次冲击时达到极值; 循环冲击下锚杆杆体晶格结构被拉伸, 导致杆体抗变形能力增强, 因此等能量冲击下杆体峰值变形量呈降低趋势, 但杆体变形速率在第2次冲击时达到最大值; 首次冲击使围岩层间空隙压实, 完整性提高, 承载能力增强; 第2次冲击时, 杆体载荷、变形及吸能特征等各项参数达到最大值; 越靠近巷道表面的围岩, 破碎程度越高, 裂隙分布越复杂, 与现场实测结果相吻合。研究成果可为优化动载巷道支护设计提供参考。

Low to medium energy frequent impact disturbances have characteristics of high frequency and strong disturbances, which seriously threaten the long-term stability of roadways. Using a self-developed impact testing system, cycle impact of 5 000 J in energy was conducted on the rock bolt support system, and the parameters, such as rock bolt deformation, load, energy absorption, and rock fragmentation characteristics are synchronously monitored to quantitatively explore the dynamic response characteristics of the rock bolt support system. The results show that the response time of rock bolt first decreases rapidly and then gradually extends with cyclic impact. The load and energy absorption characteristic parameters of rock bolt first increase and then decrease. The response time of rock bolt, load and energy absorption characteristic parameter reach their extremes during the second impact. Under the cyclic impact, the lattice structure of the rock bolt is stretched, resulting in an enhanced deformation resistance of the rock bolt. Therefore, under equal energy impact, the peak deformation of the rock bolt decreases, but the deformation rate of the rock bolt reaches its maximum during the second impact. The first impact causes the closure of primary micro defects in the surrounding rock of the roadway, improving the integrity and enhancing the bearing capacity of surrounding rock. However, the second impact leads to the maximum of various parameters of rock bolts, such as bolt deformation, and characteristic parameters of energy absorption. The closer the surrounding rock is to the surface of the roadway, the higher the degree of fragmentation, and the more complex the distribution of cracks, which is consistent with the mine-site monitoring results.