Diameter Test Of Pile By Ultrasonic Tset Method And Applied Research On CT Technology

Ultrasonic testing technologies use high frequency ultrasonic wave,which length is small,so the ultrasonic testing method has high resolution,it can reflect the defects sensitively.The detection method determines the quality of the pile mainly through sound,amplitude,frequency,wave-form.At present,the application of this method mainly makes qualitative analysis on the defects of the pile by the time-domain signal,but the analysis of frequency-domain signal is very little.This paper makes qualitative and quantitative analysis of the pile's quality,based on the comprehensive analysis of time-domain signal and frequency-domain signal.ANSYS/LS-DYNA is used to simulate the model piles with different diameters,the simulation tests are carried out by oblique and single hole test,analyzing the time-domain and frequency-domain signal data synthetically by MATLAB,calculating the diameter of model pile,also calculating the expanding diameter of model pile in the test base and the expanding engineering-pile.The errors of diameter calculation of the model pile and the test pile are within 10%.Building model used to ultrasonic sector testing by ANSYS,doing the experiment of pile in the test base,the time data are analyzed by MATLAB,then the CT velocity nephogram of pile is inversed through ART and SIRT algorithm,the results of the location and size of defect are similar to design.In the inversion process,using different grid size and different initial value selection method,through the comparison between inversion results,it is found that the accuracy of the inversion is higher when choosing the smaller grid size,the two different ways of selecting the value of wave slow almost have no effects on results,and the use of mean filtering method is aimed to reduce the impact of image noise.The program of ultrasonic testing technologies with live velocity nephogram is prepared,through the data processing of testing,we can see that the program model can reflect the position and approximate size of the pile defect,the results are consistent with the CT inversion program.The result of this program is relatively rough,because the line is given a certain width in the process of the program,so the defect area is prism in the velocity nephogram.The biggest advantage of the program is fast calculation,and the quality results of the pile scene can be inversed quickly,accurately and intuitively.