Abstract：Propagation characteristics of high frequency longitudinal axisymmetric modes in full-length-bonding bolt are studied. For the same mode in bolt，its attenuation and velocity vary greatly with frequency range. In theory，there is high order longitudinal mode above 1 MHz whose axial displacement concentrates in the middle of bolt. Its attenuation is the smallest，and its energy velocity is the fastest in all modes at the special high frequency. This indicates that the high order low loss longitudinal mode can be used to inspect full-length-bonding bolt. At the same time，the experiments about diameter 22 mm，1m length bolt without defect embedded in grout detected using ultrasonic guided wave are carried out. The scope of inspection frequency is between 1.13 MHz and 2.85 MHz. The velocity and amplitude curves of first end reflection with frequency are made. The experiment curves are consistent with those dispersion curves of theory. Besides，the experiment that the bolt with one defect embedded in grout detected by guided waves also is carried out. This indicates that ultrasonic guided waves can be used to inspect the length of bolt and confirm the location of defect. Finally，site inspection for diameter 18 mm，2 m length bolt is performed. The inspection results show that the guided waves technology is available for the nondestructive testing of full-length-bonding bolts.
