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/

• 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
• 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