BOREHOLE RADAR - A NEW TECHNIQUE FOR INVESTIGATION OF LARGE ROCK VOLUMES. LARGE ROCK CAVERNS - PROCEEDINGS OF THE INTERNATIONAL SYMPOSIUM, HELSINKI, FINLAND, 25-28 AUGUST 1986. VOLUME 2

A borehole pulse radar system has been developed as a part of the international Stripa project with the objective to identify and characterize fracture zones at considerable distances from the borehole. The radar uses very short pulses of electromagnetic energy, which are transmitted and received by dipole antennas inserted into the boreholes. The system uses center frequencies of 20-60 mHz corresponding to wavelengths of a few meters in rock. Reflection measurements have been used to identify fracture zones and determine their position and orientation. The zones often cause strong and well defined reflections originating from the resistivity change at the edges of the zones. The exact orientation of the zones can be determined by combining data from several boreholes. During measurements at Stripa reflections from fracture zones have been observed more than 100 m from the borehole. The borehole radar system has also been used in crosshole configurations to collect data suitable for tomographic analysis. A tomographic inversion, using either traveltime or amplitude data, will give information on the extent of fracture zones in the plane spanned by the boreholes as well as a quantitative estimate of the electrical properties of the zones. Reflections have also been registered in crosshole surveys and have been analysed together with single hole reflection data to describe the inhomogeneities in a large rock volume. Radar measurements have been performed at a number of sites and found to be a very efficient instrument for locating and characterizing fracture zones. For the covering abstract of the symposium see IRRD 810647. (Author/TRRL)

  • Availability:
  • Corporate Authors:

    Pergamon Press, Incorporated

    Headington Hill Hall
    Oxford OX30BW,    
  • Authors:
    • Olsson, O
    • Forslund, O
    • Lundmark, L
    • Sanberg, E
    • Falk, L
  • Publication Date: 1987

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00476294
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-08-034078-4
  • Files: ITRD, TRIS
  • Created Date: Sep 30 1988 12:00AM