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Journal of the Southern African Institute of Mining and Metallurgy

On-line version ISSN 2411-9717
Print version ISSN 0038-223X

J. S. Afr. Inst. Min. Metall. vol.109 n.2 Johannesburg Feb. 2009




Rock bolt condition monitoring using ultrasonic guided waves



B.J. BuysI; P. S. HeynsI; P.W. LovedayII

IDynamic Systems Group, Department of Mechanical and Aeronautical Engineering, University of Pretoria
IISensor Science and Technology, Material Science and Manufacturing, CSIR




Rock bolt integrity is a critical issue for the mining industry because of its influence on the safety of mining operations. Guided ultrasonic wave testing of the defects associated with resinanchored rock bolts was investigated. Axisymmetrical and threedimensional finite element models were built, one of a partially encapsulated bolt and the other of a bolt with a simulated local corrosion crack. Experimental bolts were then installed in a testing block and typical responses were compared to finite element models of different defect scenarios.
Encouraging results were obtained for the smaller axisymmetrical and three-dimensional finite element models, as well as during the experimental investigation. It is recommended that software with energy-absorbing elements should be utilized to consider higher frequencies and longer bolts. Once the integrity of models such as these has been established, the models could in principle be used to train neural networks for use in commercial equipment to determine the integrity of the installed bolt.



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