Research On Defect Identification Of Pile By CT Technology Based On Ultrasonic Transmission Method Of Foundation Pile

The ultrasonic transmission method of foundation pile belongs to the integrity test of pile.Because ultrasonic wave has characteristics of high frequency and low wavelength,it is sensitive to the defect of concrete structure when spreading through pile.The common ultrasonic transmission method is flat measurement which utilizes acoustic characteristics such as waveform,acoustic time and amplitude of bow wave to judge the pile quality.This thesis is based on the acoustic transmission detection technology and concrete tomography theory to study the feasibility of acoustic CT technique in foundation pile.Through theoretical research and comparative analysis,This paper has obtained the following theoretical achievements: ART and SIRT theories have been improved to improve inversion accuracy and inversion efficiency;Through applying the theory of simulated annealing algorithm to the inversion theory of CT technology of ultrasonic transmission method of foundation pile,inversion theory based on simulated annealing algorithm is obtained;Defect identification system theory has been proposed to obtain the theory of defect identification of pile by CT technology based on ultrasonic transmission method of foundation pile.The author carried out simulated sector scanning detection on the simulated piles,which have defectiveness,to get the acoustic time data.And scanning detection with acoustic transmission method was carried out on the test pile in the test site of HUST South 2nd teaching building,also to get the acoustic time data.These are called the forward process.On the other hand,ultrasonic CT inversion programs were wrote based on different theories to get the acoustic inversion image from the forward data,and studied and analyzed the inversion images.The author successfully wrote two suitable inversion procedures based on SIRT and the theory of simulated annealing algorithm.Finally,the program of defect identification of pile by CT technology based on ultrasonic transmission method of foundation pile was written.And this program can reflect pile defects more intuitively and accurately.