Acoustic Transmission Method Signal Processing Research Of Pile Inspection

With the rapid development of engineering construction in our country, the pilefoundation is more and more widely used in a variety of basic engineering.The qualityof the pile is important to the building,and how to improve the reliability of piletesting has become an important issues of today’s construction engineering test.TheAcoustic Transmission Method is an important method of pile integrity testing,but asa kind of advanced detection methods its data processing methods are mostlytraditional time-frequency analysis. By a large number of bridge pile foundationtesting,the author found that there exist some inadequacies in pile quality assessmentmethod could easily lead miscarriage of justice or missing of defects.In this paperthe author proposed wavelet analysis and approximate entropy signal processingmethod to assess the quality of pile foundation.This article firstly describes the principles and methods of pile testing of acoustictransmission method,discusses the characteristics of the acoustic transmission signaland the assessment methods of Technical specification for inspection of Concretedefects by ultrasonic method.According to the complex frequency characteristics ofthe acoustic transmission signal,analyze the pile testing signals using waveletanalysis.The results show that under the wavelet decomposition, the amplitude ofdefect signal is attenuated in the high frequency band with a clutterwaveform.Wavelet analysis can capture the location of the pile testing signal singularperturbation from the microscopic point of view very quickly.In order toquantitatively evaluate the severity of the defects, and introduces the method ofapproximate entropy.From the entropy spectrum we can see that if the pile foundationand qualitative good the spectrum is smoothly while qualitative bad the spectrum fluctuate greatand present obvious" sawtooth".This method shows good effectivity in the practical pilefoundation inspection.The PSD multi-parameter is a macro method while wavelet analysis and approximateentropy signal processing method is a microscopic method.In practice, thecombination of the two methods can improve the detection effectiveness.