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Open AccessArticle

Non-Destructive Evaluation of Rock Bolt Grouting Quality by Analysis of Its Natural Frequencies

Faculty of Civil Engineering, University of Zagreb, 10000 Zagreb, Croatia
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Materials 2020, 13(2), 282; https://doi.org/10.3390/ma13020282
Received: 5 November 2019 / Revised: 1 January 2020 / Accepted: 6 January 2020 / Published: 8 January 2020
(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering)
Grouted rock bolts represent one of the most used elements for rock mass stabilization and reinforcement and the grouting quality has a crucial role in the load transfer mechanism. At the same time, the grouting quality as well as the grouting procedures are the least controlled in practice. This paper deals with the non-destructive investigation of grouting percentage through an analysis of the rock bolt’s natural frequencies after applying an artificial longitudinal impulse to its head by using a soft-steel hammer as a generator. A series of laboratory models, with different positions and percentages of the grouted section, simulating grouting defects, were tested. A comprehensive statistical analysis was conducted and a high correlation between the grouting percentage and the first three natural frequencies of rock bolt models has been established. After validation of FEM numerical models based on experimentally obtained values, a further analysis includes consideration of grout stiffness variation and its impact on natural frequencies of rock bolt. View Full-Text
Keywords: rock bolt; grouting quality; dynamic response; natural frequency; finite element method rock bolt; grouting quality; dynamic response; natural frequency; finite element method
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MDPI and ACS Style

Bačić, M.; Kovačević, M.S.; Jurić Kaćunić, D. Non-Destructive Evaluation of Rock Bolt Grouting Quality by Analysis of Its Natural Frequencies. Materials 2020, 13, 282.

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