Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings (2013) / Chapter Skim
Currently Skimming:
Pages 18-29
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 18... ...
18 C h a p t e r 3 an Investigation for Detecting Delaminations, Voids, and Water Intrusion Introduction As indicated in Chapter 2, this investigation used several NDT techniques -- the ultrasonic linear array system, air-coupled GPR, ground-coupled GPR, thermal camera, and the portable seismic property analyzer -- to detect defects in concrete, shotcrete, and steel test specimens. Ultrasonic Tomography The results of the ultrasonic tomography testing are contained in Appendices M and N
|
From page 19... ...
19 the surface, and the final specimen had a 1-sq-ft water-filled void placed 8 in. from the surface.
|
From page 20... ...
20 heterogeneity of the shotcrete slabs, the contour maps of the variations in average USW modulus and dominant IE frequency exhibited reasonable uniformity for intact slabs (both concrete and shotcrete)
|
From page 21... ...
21 SPACETEC Pilot Project The research team conducted the SPACETEC pilot project in the Chesapeake Channel Tunnel during the night of April 11–12, 2011. The TS3 scanner was installed on the roof at the rear of the inspection vehicle, providing an undisturbed 360° measurement.
|
From page 22... ...
22 The following findings are of particular interest for this study: • GPR horn antenna data provided good quality structural information from the concrete tunnel but could not be used in the shotcrete tunnel where steel fibers were used in the shotcrete. The GPR data provided useful information on structures behind the tunnel linings.
|
From page 23... ...
23 peaks or troughs in the dielectric value are observed. The team noted that the data analysis could indicate lining interfaces and lining thickness estimates; however, actual defects within or behind the tunnel lining could not be readily determined from the analysis.
|
From page 24... ...
24 fully debonded and partially bonded areas within a single map based on the color distribution. It is not, however, able to measure the thickness of the delaminations directly.
|
From page 25... ...
25 tunnel testing using ultrasonic tomography are contained in Appendices M and N Portable Seismic Property Analyzer The UTEP team used the PSPA, which can perform IE and USW tests simultaneously.
|
From page 26... ...
26 Figure 3.9. PSPA results on a defective area in the Chesapeake Channel Tunnel.
|
From page 27... ...
27 project were mounted on an automated scanning device that BAM developed. Figure 3.11 shows the BAM scanner with the ultrasonic echo device.
|
From page 28... ...
28 Figure 3.12. Surface dielectric versus surface rating (using Chesapeake Channel Tunnel results)
|
From page 29... ...
29 Table 3.3. Surface Rating Based on Distress Observed Distress Observed Surface Rating Cracks, no staining 0 Cracks, light staining 1 Cracks, light staining, and light calcium carbonate deposits 2 Cracks, moderate calcium carbonate deposits and staining 3 Cracks, moderate calcium carbonate deposits and staining; potential spalling (<2 in.)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.