LABORATORY EFFORTS TO DEVELOP A BOREHOLE NONDESTRUCTIVE TESTING SYSTEM TO INSPECT IN SITU FOUNDATION ELEMENTS

Abstract

A nondestructive testing system was developed to evaluate foundations embedded in the subsurface. The system functions by generating elastic stress waves as it is lowered in a borehole alongside the foundation. Reflections from the foundation element are recorded and plotted to develop a high resolution image. The system is intended for inspection purposes of in-service foundation elements, particularly deep foundations for critical infrastructure. In this study, a large soil model was developed with a reduced-scale deep foundation element embedded within the model subsurface so that system performance could be evaluated. The foundation element features several anomalies, which replicate issues with foundation integrity in the field. The system was capable of differentiating between competent and anomalous sections of the foundation element. A summary of hardware components, system operation, and soil model construction/geometry is presented as well as the results from laboratory testing.