爆炸荷载下锚杆动态响应试验研究

 通过物理模型试验，研究集中装药爆炸荷载作用下临近工作面端锚锚杆的动态响应。利用黏贴在锚杆上的应变片，测得动载期间不同锚杆断面处和距工作面不同距离锚杆上的应变波，并对数据进行分析研究。模型试验结果表明：爆破引起锚杆的振动时间约为5 ms，初始应变波可以是拉伸波，也可以是压缩波；爆破过后锚杆存在残余变形，最大残余应变发生在锚尾的自由段，最大动态拉应变发生在锚杆中部的锚固段。将锚杆的总应变分解为轴向应变和弯曲应变后，发现临近工作面的锚杆在爆炸动载作用下的主要变形为弯曲变形，轴向变形相对较小；动载过后锚杆处于弯曲状态，随锚杆至工作面距离的增加弯曲应变波的频率和幅值下降明显。采用小波包理论分析爆破引起锚杆振动的频率分布，进一步证明弯曲应变波的频率与锚杆至工作面距离的增加而衰减的规律。与以往现场测试结果的比较表明，物理模型试验测得的应变波总体上反映了工程锚杆的动态响应。

EXPERIMENTAL INVESTIGATION ON DYNAMIC RESPONSE OF ROCKBOLT UNDER BLASTING LOAD

By physical model test，the response of end-anchored rockbolt close to working face is studied under blasting loading in mass charge. The dynamic strain measured from strain gauges mounted on rockbolts are obtained considering gauge?s locations on rockbolts and distances from working face. And then，the measured data are analyzed. The results show that：(1) Rockbolts vibration approximately ceases after duration of 5 ms. And the initial wave is either tensile wave or compressive wave. (2) After blasting，the residual deformations exist on the rockbolts. The maximum residual strain appears on the free segment of rockbolts? tail，while the maximum dynamic tensile strain appears on the anchoring segment of rockbolts? middle. When the total strain is divided into axial strain and bending strain，it is found that：(1) The main deformation of rockbolt close to working face under blasting load is bending deformation；and the axial deformation is small relatively. (2) The rockbolts are bending after blasting. And the frequency and magnitude of bending strain wave apparently decrease with the increase of distance. Based on wavelet packet theory，vibration frequency distribution of rockbolt caused by blasting is analyzed. The analysis also proves the attenuation law of vibration frequency of rockbolt. Comparison with previous field test results indicates that the strain waves measured in model test reflect the dynamic response of engineering rockbolts on the whole