Damage Localization of Piles Based on Complex Continuous Wavelet Transform: Numerical Example and Experimental Verification

Abstract

A new signal processing method called complex continuous wavelet transform (CCWT) is introduced in this paper to localize pile damage because it clearly reveals inherent characteristics of response signals. In this method, CCWT is first performed on the response signal to obtain the wavelet coefficient matrix. The resultant coefficients are then employed to calculate phase angles at different frequency bands with an aim of pile damage localization. However, the CCWT method is only demonstrated via laboratory tests on pile specimens, and its application on actual piles has not been examined. Moreover, various factors such as pile-soil interaction need to be considered when the CCWT method is applied on actual piles. To address these issues, a numerical example of 3D finite element pile model followed by a parameter analysis and an experimental verification on an actual pile are investigated. The results demonstrate that the CCWT method is capable of localizing pile damage under different damage scenarios. However, there are still some interference points in the grayscale images of phase angles and the reduction of interference points needs to be addressed by mutual verification with other pile damage detection methods and engineering experience.

Wavelet Analysis for Evaluating the Length of Precast Spliced Piles Using Low Strain Integrity Testing

“…To increase the reliability of low strain integrity testing, in [29][30][31][32][33][34], it was proposed to use the complex continuous wavelet transform to perform a time-frequency analysis of the recorded signals. CCWT converts the studied signal f (t) ∈ L 2 (R) into a function of two variables a, b ∈ R, a > 0:…”

“…Wavelet analysis for low strain integrity testing of piles was introduced by Addison and Watson [26,27]. The technique was further developed in the papers [28][29][30][31][32], in which the advantages of analyzing the phase of the complex continuous wavelet transform (CCWT) are shown using synthetic and experimental data. In [33], an improved algorithm for pile defect localization based on automatic extraction of abnormal values of wavelet coefficients followed by the analysis of wavelet spectrum phase sections was presented.…”