SCANNED ACOUSTICAL HOLOGRAPHY FOR GEOLOGICAL PREDICTION IN ADVANCE OF RAPID UNDERGROUND EXCAVATION. PHASE II

A large circular scanner, five feet in diameter, was activated in January 1976. The system employs microcomputers for determining the reference wave phase angles in real-time. Holograms were made and reconstructed in less than ten minutes. The quality of the hologram is excellent and the laser reconstructions (reconstructed images) are of good quality showing good resolution and good image definition. A variety of "roughness" features were modeled on a variety of objects immersed in a large water tank. These features simulate properties that will be encountered when actual geologic conditions are examined. Also developed were a variety of new image enhancement techniques essential for the success of the effort when real-world situations were encountered. Plans for an actual field demonstration of the system in rock are proceeding. A variety of new prototype designs for data gathering, data storage, data processing and display techniques were also completed. The authors predict that implementation of a large tunnel boring machine with an acoustic holography system will be highly successful.

• Supplemental Notes:
  • See also PB-245 147.
• Corporate Authors:

  Massachusetts Institute of Technology

  Department of Civil Engineering, 77 Massachusetts Avenue
  Cambridge, MA  United States  02139

  National Science Foundation

  1800 G Street, NW
  Washington, DC  United States  20550
• Authors:
  • Price, T O
  • Fitzpatrick, G L
  • Brennan, J M
• Publication Date: 1976-5

Media Info

• Pagination: 59 p.

Subject/Index Terms

• TRT Terms: Acoustic detectors; Acoustic signature; Acoustics; Excavation; Excavation and tunneling; Forecasting; Geological events; Geological surveying; Geophysical prospecting; Holography; Lasers; Physical properties; Rocks; Scanners; Surveying; Surveys; Tunneling; Tunneling machines
• Old TRIS Terms: Acoustic detection; Excavation technology; Geological conditions; Geophysical surveys; Rapid excavation; Rock properties; Scanning; Underground surveying; Underground surveys
• Subject Areas: Bridges and other structures; Construction; Geotechnology; Highways;

Filing Info

• Accession Number: 00150947
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: NSF/RA-760297 Intrm Rpt.
• Contract Numbers: NSF-APR75-16376
• Files: TRIS
• Created Date: Mar 30 1977 12:00AM