Method for Cognizing Deficient Pile Based on Discrete Symmetry Wavelet Transform
Xiang Fang · Journal of Kunming University of Science and Technology · 2006
Amplitude change is the main characteristic for pile signal detection by Reflection Wave Method(RWM).If the reflected signal is weak,the traditional data processing methods are difficult to identify the deficiency of pile,such as time-domain analysis or frequency-domain analysis.Whereas wavelet analysis which has local time-frequency characteristics can deal with weak signal perfectly;signals mixed with impulse signal which is regarded as deficiency in pile by Wavelet Transform(WT),here,wavelet is secondary B spline wavelet.And the procedure is proposed to detect deficiency in pile.Two examples are illustrated in this paper:one numerical example has an explicit mathematic expression with a minute change in amplitude at certain position,and the minute change is detected by the proposed method;the other example is that the singularity of a practical engineering signal of a concrete pile is identified,using the tested low-strain dynamic data in pile to estimate the time of deficiency appearance by discrete wavelet analysis,then evaluating the deficiency position with the assumption invariable wave velocity in pile.Considering characteristics of various piles,the example pile has four isolations.So the proposed method is valid for cognizing deficient pile.