複數連續小波轉換評估基樁長度之試驗研究

EXPERIMENTAL STUDY OF COMPLEX CONTINUOUS WAVELET TRANSFORM FOR EVALUATING PILE LENGTH

倪勝火(Sheng-Huoo Ni) ； 李吉龍(Ji-Lung Li) ； 楊子彤(Zih-Tong Yang)

《中國土木水利工程學刊》 30卷1期 (2018/03) Pp. 29-36

https://doi.org/10.6652/JoCICHE.201803_30(1).0003

摘要

本文透過現地實體原型基樁之音波回音法試驗，使用複數連續小波轉換(CCWT)法，求取應力波於基樁之傳播時間，以評估基樁樁長。經試驗五根不同長度及材料之基樁的結果顯示，藉著CCWT之相角時頻關係圖，可明確判斷應力波於基樁之傳播之往返時間，求得基樁之樁長，而其誤差均在約4%以內。因此，本文建議將音波回音法所得之訊號應用CCWT分析處理，相較於傳統之時域分析，不僅可提供於不同頻帶下之高解析度的結果，更能夠由相位時頻圖清楚判釋反射訊號的時間，減少人為判斷反射振波到達時間之誤差，有效求得樁長及提升評估之準確性，增進音波回音法於基樁非破壞檢測之實用性。

關鍵字

基樁 ； 非破壞檢測 ； 音波回音法 ； 複數連續小波轉換

並列摘要

The sonic echo method of prototype piles is used to obtain the propagation time of the stress wave in the pile and to evaluate the pile length by using complex continuous wavelet transform (CCWT) method in this paper. The experimental testing results show that the phase-time-frequency diagram obtained by the CCWT analysis can clearly determine the travel time of stress wave in the five different lengths and materials of piles. Then, the pile length can simply be calculated. The errors are less than about 4%. Therefore, this paper suggests the signal obtained from sonic echo method should be applied to the processing of the CCWT analysis. Compared to the traditional time domain analysis, it not only provides the result of high resolution in different frequency bands but also clearly interprets the arrival time point of the reflected signal by the phase angle-time-frequency diagram. This will indirectly reduce the wave arrival time error of human judgment. It obtains the pile length effectively, enhances the accuracy of evaluation, and improves the practicability of the sonic echo method in the field of non-destructive testing.

並列關鍵字

pile ； nondestructive test ； sonic echo test ； complex continuous wavelet transform