An ultrasonic P-wave borehole system was developed as a nondestructive testing (NDT) technique to evaluate the
length of embedded bridge foundation elements. The system is designed to be lowered within a PVC-cased
borehole. Ultrasonic P-waves are transmitted into the soil and the corresponding reflection signals are plotted to
generate an image of the foundation. This paper summarizes the suite of laboratory tests that were performed as part
of the development of this system. A large soil model was constructed in the laboratory and multiple objects
composed of steel, timber, concrete, and various plastics were embedded throughout different cross sections of the
model. The effects of borehole construction were mimicked by varying the thickness of the PVC and the presence of
a grout layer. The results show that under ideal conditions the system is capable of recording reflection signals from
objects embedded in 0.9 m of soil. Moreover, the system can detect object edges to within approximately 5% of
their true locations.
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