State of Practice for Quality Assurance in Drilled Foundations

Drilled foundation elements are increasingly being used for deep foundation support. The trend is for larger diameter elements carrying much higher loads. Many of these drilled foundations are cast under slurry, making inspection very difficult. Many legacy non-destructive testing (NDT) methods aren’t well suited for the inspection needs of modern drilled foundation elements. To satisfy the design intent, the as-built shaft shape, shaft vertical alignment, shaft base cleanliness, cage alignment, concrete cover, and concrete integrity are all important. Additionally, there is a need to prove the capacity of these highly loaded bored piles.  Several test methods are available to check these design considerations. Many current test methods are unable to provide all the information needed or don’t address all design considerations. There have been several recent advances in drilled shaft/bored pile quality control instrumentation. These recent advances in drilled shaft quality control methods offer owners, engineers, and contractors innovative and powerful tools for quality control and quality assurance of drilled foundations. This paper discusses recent advances in quality control methods for drilled shafts and presents field data where these technologies have been successfully used for evaluation of drilled shaft/bored piles.