Boundary Effects of Pile Cap on the Integrity Testing of Group Piles

Abstract

Low-strain surface reflection pile integrity testing (PIT) methods have been successfully used for the quality assurance of newly-built individual piles. However, for existing piles with pile cap, previous studies have shown that the stress-wave reflected from the boundaries of pile cap may cause difficulties in determining their integrity. In this paper, the boundary effects of pile cap on the signal of PITs were studied by numerical simulation and tests on model piles. Feasibility of minimizing the boundary effects by embedded accelerometers was also investigated. Results from this study indicate that signals obtained from numerical simulation are similar to those obtained from tests performed on model piles. It also shows that boundary effects of pile cap on low strain pile integrity tests can be reduced by using embedded accelerometers, thus making it easier to assess the integrity of piles with a pile cap.