Capabilities and Limitations of Cross Hole Ultrasonic Testing of Piles

Abstract

This paper describes an attempt to quantify flaw detectability in cross hole ultrasonic testing of piles. To this end we constructed a bored pile with access tubes and three pre-fabricated flaws, and then tested it with the CHUM ultrasonic instrument. We analyzed the results and presented them in the conventional one-dimensional format, as well as in two- and three-dimensional tomographic images. We then compared the results with those of a finite element model which showed similar effect of the flaws. We concluded that a flaw is usually detectable by this method only if its size exceeds one-third of the access tube spacing. In addition, the use of advanced tomographic techniques may enhance flaw detectability.