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Mathematical Problems in Engineering
Volume 2017, Article ID 7920649, 13 pages
Research Article

A New Approach of Waveform Interpretation Applied in Nondestructive Testing of Defects in Rock Bolts Based on Mode Identification

1College of Resources & Civil Engineering, Northeastern University, Shenyang 110819, China
2Department of Civil Engineering, Ryerson University, Toronto, ON, Canada

Correspondence should be addressed to Tianhong Yang; nc.ude.uen.liam@gnohnaitgnay

Received 7 December 2016; Accepted 9 February 2017; Published 5 March 2017

Academic Editor: Mitsuhiro Okayasu

Copyright © 2017 Xiaoyang Rong et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Due to the characteristics of dispersion of guided waves, the waveforms recorded in ultrasonic nondestructive testing (NDT) of rock bolts are complicated to interpret. With a goal to increase the inspection sensitivity and accuracy in NDT of rock bolts, an approach of waveform interpretation based on wave modes identification is developed. The numerical simulation of full rock bolt and rock bolts with grout defect by Finite Element Method (FEM) is applied to illustrate the approach; it is found that the sensitive and low attenuation wave modes exist. Laboratory tests on full rock bolt and rock bolt with grout loss using NDT are conducted to evaluate the efficacy of the approach of waveform interpretation. In addition to that, a parametric study was conducted on rock bolt models with different sectional defect size. Based on the waveform interpretation, the mode-based reflection coefficient is proposed to evaluate the sensitivity of wave modes to the defect size of sectional area. It is found that the sensitivity of the wave mode does not change with the defect sectional area, and the amplitude depends on the size of the defect.