School of Mining Engineering, Taiyuan University of Technology

为检测锚杆实际有效锚固长度,得到锚固锚杆和自由锚杆中的高频超声导波传播规律,在1~15 MHz频率范围内对不同锚固锚杆试件进行频率扫描,并根据试验结果得到了群速度和频率之间的关系曲线。结果表明,激发频率为2.007~2.312和3.266~3.491 MHz时,导波在不同锚固质量的锚杆中传播速度几乎一致,且锚杆锚固质量对高频超声导波的传播速度影响很小,并据此得出在这个频率范围内可检测超声导波在自由锚杆中的传播速度,进而计算出锚杆的锚固长度。

In order to measure actual effective length of bolt, the propagation law of high frequency ultrasonic guided wave in anchored bolt and free bolt was obtai ned. A frequency scanning was conducted on different anchoring bolt specimens within 1 ~ 15 MHz frequency scope.A relationship curve between the group speed and frequency was obtained from the experiment results. The results showed the speeds of high- frequency ultrasonic guided waves in 2.007 ~ 2. 312 MHz and 3.266 ~ 3. 491 MHz were almost identical when spreading in rock bolts of different anchoring quality. That within some frequency scope, the bolt anchoring quality would have a le ss influence to the propagation speed of the high frequency ultrasonic guided wave. Thus within the frequency scope, the propagation speed of the ultrasonic guided wa ve in the free bolt could be detected and a length of the anchored bolt with the same material could be calculated.

国家自然科学基金资助项目(50774054)；