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Detection of cavities around concrete sewage pipelines using impact-echo method

Title
Detection of cavities around concrete sewage pipelines using impact-echo method
Author
박두희
Keywords
Impact-echo; Cavity; Sewage pipeline; Sustained duration
Issue Date
2017-05
Publisher
PERGAMON-ELSEVIER SCIENCE LTD
Citation
TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY, v. 65, page. 1-11
Abstract
Impact-echo method has been successfully used to detect flaws in concrete and to evaluate the state of grout bonding in tunnels. It has not yet been used to detect underground cavities formed by leakage of pipelines, which is becoming a major problem in many urban environments. We perform model and field tests to evaluate whether the impact-echo method can be used to detect cavities around concrete sewage pipelines. Fourier spectrum was used to determine the resonant frequency and the short time Fourier transform was used to determine the temporal variation of the resonant frequency component. Results show that the presence of cavity cannot be reliably predicted from the wave time history or Fourier spectrum. The spectrogram is demonstrated to be a better indicator for detecting the presence of a cavity. The cavity induces a longer tail in the spectrogram because of a higher impedance contrast and a lower attenuation. We propose a new quantitative index based on the resonant frequency and the spectrogram, denoted as the sustained duration. Both model and field tests demonstrate that the cavity in wet soils can be successfully detected using the proposed index. (C) 2017 Elsevier Ltd. All rights reserved.
URI
https://www.sciencedirect.com/science/article/pii/S0886779816302395?via%3Dihubhttps://repository.hanyang.ac.kr/handle/20.500.11754/114154
ISSN
0886-7798
DOI
10.1016/j.tust.2017.02.002
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > CIVIL AND ENVIRONMENTAL ENGINEERING(건설환경공학과) > Articles
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