DETECTION OF UNDERGROUND CAVITIES BY ELECTRO-MAGNETIC METHOD BETWEEN THE SOIL SURFACE AND THE BOREHOLE
DETECTION DES CAVITES SOUTERRAINES PAR UNE METHODE ELECTROMAGNETIQUE ENTRE SURFACE ET FORAGE
The method described led to the detection of a cavity which, because of its depth and size, could not be investigated by other known geophysical techniques. This method carries out an electrical investigation of the ground round a borehole by means of two electrodes which are located on the surface and are transmitting an alternative current of constant amplitude; they are placed at a variable distance from the axis of the borehole and from 2 electrodes measuring the vertical component of the resulting electric field; they are lowered in the borehole at a variable depth. Details are given of the results of a small-scale model study and of in-situ measurements. Data interpretation is outlined. The method appears to be a reliable low-cost technique for use in the investigation of limited areas such as foundations or for detecting a cavity in the vicinity of a control borehole after investigations have been conducted with other methods. /TRRL/
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Corporate Authors:
Laboratoire Central des Ponts et Chausees (LCPC)
Boulevard Lefebvre 58
Paris Cedex 15, France F-75732 -
Authors:
- Gabillard, R
- Dubus, J P
- Bavandi, R
- Rat, M
- Lagabrielle, R
- Publication Date: 1977-11-12
Language
- French
Media Info
- Features: Figures; References;
- Pagination: p. 68-73
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Serial:
- Bulletin de Liaison des Lab des Ponts et Chaussees
- Issue Number: 92
- Publisher: Laboratoire Central des Ponts et Chausees (LCPC)
Subject/Index Terms
- TRT Terms: Boreholes; Costs; Detection and identification; Detectors; Electricity; Electrodes; Electromagnetism; Field tests; Geophysics; Granular soils; Holes; Magnetic properties; Mathematical models; Measurement; Methodology; Underground structures
- Uncontrolled Terms: Cavities; Models; Site investigation; Subterranean
- Old TRIS Terms: Insitu methods; Underground
- ITRD Terms: 5711: Bore hole; 5738: Cavity; 6954: Electricity; 5742: Geophysics; 6936: Magnetism; 9102: Method; 6205: Model (not math); 5722: Site investigation; 4372: Subterranean
- Subject Areas: Bridges and other structures; Finance; Geotechnology; Highways; I41: General Soil Surveys;
Filing Info
- Accession Number: 00195642
- Record Type: Publication
- Source Agency: Transport and Road Research Laboratory (TRRL)
- Files: ITRD, TRIS
- Created Date: Aug 15 1979 12:00AM