Pile Length Estimate of Impulse Response Testing with Guided Wave Approach

Abstract

The constant velocity one-dimensional wave theory has been commonly used to determine the pile lengths from the impulse response testing results for several years. In this paper, the three-dimensional guided wave theory was introduced to extract more information from the impulse response spectra on five concrete piles. Combined with resonance concept, this guided wave-based approach was developed to simply and efficiently identify the length estimates with 3% or less errors, similar to those of the conventional one-dimensional wave-based approach. Moreover, the guided wave theory provides more individual resonant frequencies insight over that of the one-dimensional wave theory. All the experimental phase velocities at their corresponding resonant frequencies have a good consistency with the guided wave prediction curve at frequencies up to 5000 Hz. The resulting scattering also presents a slightly decrease trend with frequency. The overall analysis indicates that the guided wave theory can give more useful information than that of the one-dimensional wave theory. In future, one can use this inverse computation approach to evaluate unknown pile lengths.