EVALUATION OF THE PORTABLE BOREHOLE DEFLECTOMETER

THE BOREHOLE DEFLECTOMETER WAS EVALUATED TO DETERMINE ITS USEFULNESS IN THE RESEARCH STUDY REBOUND IN MATERIALS IN HIGHWAY CUTS. THE RESULTS INDICATE THAT THE DEVICE IS SUITABLE FOR DETERMINING MOVEMENTS ALONG WELL DEFINED PLANES WITHIN A SOIL MASS. IT IS LESS CAPABLE IN DETERMINING A GRADUAL DISTRIBUTED MOVEMENT ALONG A BOREHOLE. THIS IS BECAUSE THE DEFLECTOMETER ONLY DETECTS DIFFERENTIAL DEFLECTIONS WITHIN THE LENGTH OF THE MEASURING PROBE AND DOES NOT ACCUMULATE DEFLECTION OVER THE LENGTH OF THE HOLE. THE INSTRUMENT IS ENTIRELY DEPENDENT ON THE RELATIVE MOVEMENTS OF THE PORTIONS OF THE JOINTED PROBE, AND DOES NOT HAVE A MEANS OF EXTERNAL REFERENCE SUCH AS A GRAVITY PENDULUM. IT IS, THEREFORE, INSENSITIVE TO GENERAL ROTATIONAL MOVEMENTS OF THE SOIL MASS IN WHICH THE BOREHOLE IS LOCATED, WHICH A PENDULUM TYPE SUBSURFACE DEVICE COULD DETECT. NEITHER TYPE INSTRUMENT, OF COURSE, CAN DISCERN PLANE TRANSLATORY MOVEMENTS OF THE ENTIRE SOIL MASS. THE DEFLECTOMETER IS WELL CONSTRUCTED, AND SEEMS TO BE SATISFACTORILY STABLE OVER A PERIOD OF TIME. HOWEVER, FACILITIES SHOULD BE LOCALLY AVAILABLE TO CALIBRATE THE UNIT AGAINST KNOWN DEFLECTIONS. THE INSTRUMENT IS SOMEWHAT AWKWARD AND CUMBERSOME TO USE IN THE FORM SUPPLIED FOR THIS PROGRAM. /AUTHOR/

  • Corporate Authors:

    California Division of Highways

    Bridge Department
    Sacramento, CA  USA  05914

    Bureau of Public Roads /US

    400 7th Street, SW
    Washington, DC  USA  20590
  • Authors:
    • Smith, T W
    • Smith, R E
    • Cortright, D J
  • Publication Date: 1968-4

Subject/Index Terms

Filing Info

  • Accession Number: 00228632
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS
  • Created Date: Aug 15 2004 2:08AM