SONAR PROBING AS A MINING AND TUNNELING TOOL
A 24 KHz sonar system is used to probe rock salt. This equipment, originally designed for water, has been modified to see into rocks. A study of coupling fluids was conducted and castor oil, glycerin, and UGL were tested as coupling fluids between the sonar transducer and the rock salt. The best is glycerin which couples a maximum of 80 percent of the sonar energy into the salt. Castor oil and UGL are about equal in coupling efficiency, but noticeably inferior to glycerin. Quarter-wave plates have been designed and built to increase the efficiency of sonar coupling to 100. A single test was unsuccessful. Energy reflected by a mismatch of acoustic impedances in getting the sonar energy into the salt, gives rise to reverberation in the transducer mount. A complete matching will solve both problems of efficient energy transfer and no reverberation. A theoretical analysis of the beamwidth in salt for both glycerin and castor oil revealed a difference in the beams with glycerin being more sensitive than castor oil for signals straight ahead, and less sensitive for signals off to an angle. This was experimentally verified. Thus, the use of two different fluids allows a change of the shape of the beam in the salt and helps to determine the direction of arrival of reflected signals.
Texas A&M University, College StationCollege of Geosciences
College Station, TX United States 77843
National Science FoundationApplied Science and Research Applications, 1800 G Street, NW
Washington, DC United States 20550
- Unterberger, R R
- Publication Date: 1978-6-1
- Pagination: 113 p.
- TRT Terms: Acoustic detectors; Couplers; Excavation and tunneling; Fluids; Geophones; Halite; Joining; Mining; Particle beams; Probes (Measuring devices); Reverberation; Signals; Sonar; Sonar transducers; Sound; Transducers; Vegetable oils
- Uncontrolled Terms: Glycerol
- Old TRIS Terms: Acoustic detection; Beams radiation; Castor oil; Probes; Sound signals; Underground mining; Underground surveys
- Subject Areas: Geotechnology; Highways;
- Accession Number: 00192030
- Record Type: Publication
- Source Agency: National Technical Information Service
- Report/Paper Numbers: NSF/RA-780172 Prog Rpt.
- Contract Numbers: NSF-APR76-21764
- Files: TRIS
- Created Date: Jul 11 1979 12:00AM