FILTERING AND FOCALISATION FIELD PROCEDURES FOR THE ELECTROMAGNETIC DETECTION OF UNDERGROUND QUARRIES

PROCEDES DE FILTRAGE ET DE FOCALISATION DE CHAMP POUR LA DETECTION ELECTROMAGNETIQUE DES CARRIERES SOUTERRAINES

The electromagnetic detection, from the surface, of subterranean quarries by classical methods becomes difficult when the depth involved is greater than 10 M and when the thickness and the conductivity of the surface layers are irregular. The problem is studied in two stages: first using successive approximations, the characteristics of various courses of a stratified medium are identified, and the quarries are then detected by observations of the variations in the conductivity of one of the lower courses. Use of a computer is necessary. The chances of detecting quarries are considerably improved by a method of focalisation of the field, developed by the authors: interpretation by computer is thus eliminated. The novel aspect is an auxiliary transmitter which cancels out the currents induced by the main transmitter in the upper layers. The theoretical and experimental results demonstrate that the probability of detecting quarries by this method is four times greater than by a classical method. (TRRL)

  • Corporate Authors:

    European Association of Exploration Geophysicists

    30 Carel van Bylandtlaan
    The Hague,   Netherlands 
  • Authors:
    • Dubus, J P
    • Clicque, D
    • Baudet, J
    • Gabillard, R
  • Publication Date: 1978-6

Language

  • French

Media Info

  • Features: Figures; References;
  • Pagination: p. 407-420
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00309224
  • Record Type: Publication
  • Source Agency: Laboratoire Central des Ponts et Chausees (LCPC)
  • Files: ITRD, TRIS
  • Created Date: May 21 1980 12:00AM