Tunnel detection using radio imaging method at the Otay Mesa site
- RIMtech, Westminster, CO (United States)
The authors demonstrated that Radio Imaging Method (RIM) surface-to-surface, borehole-to-surface, and borehole-to-borehole sensing technologies at the Otay Mesa test site east of San Diego, California could detect and delineate a horizontal 4 {times} 6-foot (cross-section) tunnel buried at a depth of approximately 45 feet. Utilizing monochromatic, continuous wave electromagnetic signals from a magnetic dipole source operating in the range between 22 kHz and 15 MHz, the authors confirmed the effectiveness of two general approaches: (1) mapping the electrical conductivity contrast between the country rock (sandstone) and the tunnel (i.e. the void and surrounding desiccation fractures) and (2) locating a cable (i.e. conductor) within and running the length of the tunnel from its induced, secondary radiation. Surface-to-surface RIM, utilizing a gradiometer receiver, mapped the two-dimensional, plan view location of the tunnel. Borehole-to-surface delineated both the depth and plan view location of the tunnel. Borehole-to-borehole RIM delineated the depth of the tunnel.
- OSTI ID:
- 207938
- Report Number(s):
- CONF-940449-; ISBN 0-8194-1521-9; TRN: IM9616%%266
- Resource Relation:
- Conference: Society of Photo-Optical Instrumentation Engineers conference on intelligent information systems, Orlando, FL (United States), 4-8 Apr 1994; Other Information: PBD: 1994; Related Information: Is Part Of Aerial surveillance sensing including obscured and underground object detection; Cindrich, E.; Del Grande, N.K.; Gowrinathan, S.; Johnson, P.B.; Shanley, J.F. [eds.]; PB: 443 p.; Proceedings/SPIE, Volume 2217
- Country of Publication:
- United States
- Language:
- English
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