| Summary: | 碩士 === 國立成功大學 === 土木工程學系 === 106 === In recent years, the technique of wavelet transform has been widely used in signal processing in different fields, including non-destructive testing(NDT) of pile foundations. In addition, using time-frequency analysis to analyse time-domain data, from sonic echo(SE) method, can also evaluate the pile integrity effectively. The purpose of this study is about using complex continuous wavelet transform(CCWT) to estimate the pile length and impedance changes of large-scale and in-situ piles, ratio of slenderness are 20, 32.5, 40, by analyzing the time-frequency analysis. In order to increase the accuracy, conceiving a set of standard processes to find the most appropriate analysis frequency and parameter of function for the piles.
The results show that using the most suitable complex wavelet function for analysis can effectively evaluate different types of foundation piles, the analysis results are almost equal, and the overall pile length error results are less than 5%. Beside, the phase angle diagram can compensate for the disadvantage that the phase spectrogram cannot see the tiny reflected signals.
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