首页|Non-destructive testing of full-length bonded rock bolts based on HHT signal analysis
Non-destructive testing of full-length bonded rock bolts based on HHT signal analysis
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NSTL
Elsevier
Full-length bonded rock bolts are commonly used in mining, tunneling and slope engineering because of their simple design and resistance to corrosion. However, the length of a rock bolt and grouting quality do not often meet the required design standards in practice because of the concealment and complexity of bolt construction. Non-destructive testing is preferred when testing a rock bolt's quality because of the convenience, low cost and wide detection range. In this paper, a signal analysis method for the non-destructive sound wave testing of full-length bonded rock bolts is presented, which is based on the Hilbert-Huang transform (HHT). First, we introduce the HHT analysis method to calculate the bolt length and identify defect locations based on sound wave reflection test signals, which includes decomposing the test signal via empirical mode decomposition (EMD), selecting the intrinsic mode functions (IMF) using the Pearson Correlation Index (PCI) and calculating the instantaneous phase and frequency via the Hilbert transform (HT). Second, six model tests are conducted using different grouting defects and bolt protruding lengths to verify the effectiveness of the HHT analysis method. Lastly, the influence of the bolt protruding length on the test signal, identification of multiple reflections from defects, bolt end and protruding end, and mode mixing from EMD are discussed. The HHT analysis method can identify the bolt length and grouting defect locations from signals that contain noise at multiple reflected interfaces. The reflection from the long protruding end creates an irregular test signal with many frequency peaks on the spectrum. The reflections from defects barely change the original signal because they are low energy, which cannot be adequately resolved using existing methods. The HHT analysis method can identify reflections from the long protruding end of the bolt and multiple reflections from grouting defects based on mutations in the instantaneous
Rock boltNon-destructive testingSound wave reflection testHilbert-Huang transformFast Fourier transform
Liu, C. S.、Shi, Z. M.、Liu, L.、Peng, M.、Liu, C. C.、Tao, F. J.
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Wuhan Changsheng Engn Explorat Technol Dev Co Ltd, Wuhan 430312, Hubei, Peoples R China
Tongji Univ, Dept Geotech Engn, Minist Educ, Key Lab Geotech & Underground Engn, Shanghai 200092, Peoples R China
Tongji Univ, Inst Acoust, Dept Phys Sci & Engn, Shanghai 200092, Peoples R China
NSTL
Elsevier
