Improved Approach for Determining Pile Length of Group Pile Using Complex Continuous Wavelet Transform
This paper investigates the integrity test ability of the sonic echo (SE) test by using a field constructed group pile foundation. Due to the energy reflected stress wave is generally faded with wave travel path for the testing of a pile with pile cap, a signal process techniques were generally used to enhance the signal interested. The purpose of this paper is to study an improved signal processing approach to detect the pile length of a pile with pile cap. This paper utilized the amplitude and phase message of complex continuous wavelet transform to determine pile length of pile foundations by analyzing the time-frequency-phase angle diagram in the different frequency band. Two- pile group and four-pile group pile were tested. Six piles with different types of defects were installed and tested to verify the proposed approach in this study. The results show that complex continuous wavelet transform is able not only to provide high-resolution results in different frequency bands but also to simplify the identification of the reflection of defects using 3D phase spectrogram. The location of reflected stress wave of pile toe can then be determined using phase diagram.
This study was supported by the Ministry of Science and Technology under Grant No. MOST 105-2221-E-006-044, Taiwan, R.O.C. The authors would like to express their special thanks to all other participants in this project.
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