Reliability of Underwater Acoustic Imaging and Underwater Ultrasonic Testing

One of the most difficult locations to inspect infrastructure is under the water’s surface. The two most frequently used underwater nondestructive evaluation (NDE) technologies include underwater acoustic imaging and underwater ultrasonic testing. The ability to observe the submerged surroundings and underwater infrastructure (e.g., bridge foundations, bulkheads, earth retaining walls, embankments, marine facilities, etc.) with acoustic surface imaging provides tremendous value. Additionally, ultrasonic testing of concrete, steel, and timber members can provide tangible data on the remaining thickness/internal integrity of these materials. But the reliability of these technologies could be questioned if proper practices are not followed since there is limited reliability research and few standards. Underwater acoustic imaging reduces risks in many situations by providing geomatic metrology insight about the submerged elements. Underwater acoustic imaging can enhance underwater observations and provide high resolution 2-D and 3-D imagery documentation at any time; but its greatest value is most often demonstrated during extreme flood events when divers are unable to collect any information due to the hazardous conditions. Recent research data from the University of Wisconsin – Milwaukee is discussed in this paper, as well as the reasonableness of expectations when using underwater technologies. This paper provides lessons learned for using acoustic imaging and ultrasonic testing in the subsurface marine environment. Information is provided on obtaining high quality 2-D and 3-D acoustic images as well as meaningful ultrasonic testing thickness data. Knowledgeable equipment selection and appropriate qualifications are recommended for both underwater acoustic imaging and ultrasonic testing.

References
1. Atherton, M., Echoes and Images: The Encyclopedia of Side-Scan and Scanning Sonar Operations, Oyster Ink Publications, 2011, Vancouver, BC, Canada. 2. Browne, T., and Forsyth, R., “Underwater Inspection of Bridge Substructures Using Underwater Imaging Technology”, TPF-5(131) Literature Review Report, FHWA, Washington, DC, 2012. 3. Browne, T., “Underwater Acoustic Imaging Devices for Portable Scour Monitoring”, ICSE Conference, 2010. 4. Browne, T., “Improvement of Underwater Bridge Inspection Documentation with Innovative Sonar Technology”, FHWA Bridge Engineering Conference, Orlando, FL, 2010. 5. Browne, T., and Strock, T., “Overview and Comparison of Nationwide Underwater Bridge Inspection Practices”, Journal of the Transportation Research Board, 2009. 6. Evans, James A., “Acoustical Imaging Cameras for the Inspection and Condition Assessment of Hydraulic Structures”, U.S. Army Corps of Engineers ERDC/CHL CHETN-IX-23, Washington, DC, August 2010. 7. Federal Highway Administration, “Technical Advisory-Revisions to the National Bridge Inspection Standards (NBIS)”, T5140.21, U.S. Dept. of Transportation, Washington, DC, September 1988. 8. Federal Highway Administration-Technical Resource Center Atlanta Memo by Cynthia Nurmi, 2009. 9. Federal Highway Administration, Underwater Bridge Inspection Manual—FHWA-NHI-10-027, U.S. Dept. of Transportation, Washington, DC, 2010. 10. Hite, J.E., “Detection and Evaluation of Scour Protection for Navigation Dams”, U.S. Army Corps of Engineers Navigation Systems Research Program ERDC/CHL TR-08-14, Washington, DC, August 2008. 11. Jones, Jenny, “Scanning Method Yields Fast, Accurate Underwater Surveys”, Civil Engineering Magazine, pp. 38-39, July 2010.
Metrics
Usage Shares
Total Views
65 Page Views
Total Shares
0 Tweets
65
0 PDF Downloads
0
0 Facebook Shares
Total Usage
65