Defect Detection (Available only in Geo/Environmental Special Issue)

by Tracy Brettmann, P.E., (M.ASCE), Berkel & Company Contractors, Inc., Houston, TX,
Larry Olson, P.E., (M.ASCE), Principal Engineer and President; Olson Engineering, Inc., Golden, CO,


Serial Information: Civil Engineering—ASCE, 1996, Vol. 66, Issue 7, Pg. 2A-6A


Document Type: Feature article

Abstract: Sonic integrity logging technology can detect flaws in deep foundations more reliably and at less cost than conventional boring techniques. These non-destructive test tools are being used for cast-in-place foundations with concrete drilled shafts and for auger pressure grouted piles. Surface reflection methods are those where testing is done from the top of the foundations, and downhole logging is where the testing is done along the full length of the foundation, using cast-in-place access tubes. Sonic echo and impulse response methods are described (surface reflection). The downhole logging methods are gamma logging and sonic logging, particularly crosshole sonic logging and advantages of each approach is described. The newest methods described are crosshole tomography and singlehole sonic logging on fresh grout for immediate quality assurance of grout placement. In the latter case, construction flaws can be corrected as soon as detected instead of after the project is complete. Case histories of these various methods are included.

Subject Headings: Nondestructive tests | Cast in place | Reflection | Foundations | Defects

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