A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Duct inspection using scanning impact-echo
Duct localization using impact-echo (IE) has been found to be a useful tool in situations where the ducts are inside a slab. The thickness of the slab should be small enough to be measurable using IE. A thickness of more than 500mm should be avoided in order to identify the backside echo unambiguously. Geometry effects interfere with true IE-signals in plate-like objects of limited size. On these objects, it must be verified through scanning measurements that geometry effects do not interfere with the interpretation of a signal. Using the backside echo as a reference, tendon ducts can be located by the frequency shift indicating an apparent greater thickness of the slab containing the duct. This frequency shift must be measured against a reference point with known dimensions. The concrete cover of the duct cannot be measured with precision; a direct signal from the duct was not found in every test case. Even when such a signal is identified, the basic IE-formula will provide a cover that is too large. The modified IE-formula (Sansalone and Street 1997) described in the test case here resulted in a cover that is too small. There have been indications that imperfect duct grouting is detected by a large shift of the backside echo and through 'side bands' in B-scans across such ducts. This observation may only be valid in a well-defined test case. It was not observed in other test scenarios described in this study. When IE should be used as the exclusive test method for the investigation of the grouting condition of ducts, the validity of these tests must be verified for the given test scenario. Scanning impact-echo (SIE) has proven to be suitable for the verification of IE for a given test situation. The data manipulation applied to a full set of SIE data makes it very easy to evaluate a given measurement task. B- and C-scan type data representations are helpful for engineers to understanding the data. Impact-echo can reliably be used for quality assurance of concrete tunnel liners. In Germany, mandatory testing was introduced for new tunnels (Bundesanstalt für Straßenwesen 2001). Additional research is needed before impact-echo can be reliably used for testing tendon ducts on a regular basis.
Duct inspection using scanning impact-echo
Duct localization using impact-echo (IE) has been found to be a useful tool in situations where the ducts are inside a slab. The thickness of the slab should be small enough to be measurable using IE. A thickness of more than 500mm should be avoided in order to identify the backside echo unambiguously. Geometry effects interfere with true IE-signals in plate-like objects of limited size. On these objects, it must be verified through scanning measurements that geometry effects do not interfere with the interpretation of a signal. Using the backside echo as a reference, tendon ducts can be located by the frequency shift indicating an apparent greater thickness of the slab containing the duct. This frequency shift must be measured against a reference point with known dimensions. The concrete cover of the duct cannot be measured with precision; a direct signal from the duct was not found in every test case. Even when such a signal is identified, the basic IE-formula will provide a cover that is too large. The modified IE-formula (Sansalone and Street 1997) described in the test case here resulted in a cover that is too small. There have been indications that imperfect duct grouting is detected by a large shift of the backside echo and through 'side bands' in B-scans across such ducts. This observation may only be valid in a well-defined test case. It was not observed in other test scenarios described in this study. When IE should be used as the exclusive test method for the investigation of the grouting condition of ducts, the validity of these tests must be verified for the given test scenario. Scanning impact-echo (SIE) has proven to be suitable for the verification of IE for a given test situation. The data manipulation applied to a full set of SIE data makes it very easy to evaluate a given measurement task. B- and C-scan type data representations are helpful for engineers to understanding the data. Impact-echo can reliably be used for quality assurance of concrete tunnel liners. In Germany, mandatory testing was introduced for new tunnels (Bundesanstalt für Straßenwesen 2001). Additional research is needed before impact-echo can be reliably used for testing tendon ducts on a regular basis.
Duct inspection using scanning impact-echo
Prüfung von Kabelkanälen mittels Schlag-Echo-Abtastung
Wiggenhauser, H. (author)
2003
13 Seiten, 8 Bilder, 1 Tabelle, 10 Quellen
Conference paper
Storage medium
English
zerstörungsfreie Prüfung , Schlagprüfung , Spannbeton , Ortung , Abtastung , B-Bild , C-Bild , Kabelkanal
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