Study On Defect Detection Method Of Hydraulic C Oncrete Based On Ultrasonic CT Technology

Concrete is the most important structural material in water Conservancy project.In the process of using concrete components,there are often some structural defects.How to accurately determine the internal quality of concrete members is very important.In recent years,ultrasonic CT technology has been introduced into the field of nondestructive testing of concrete,which can be used to express the internal quality of concrete detection profile in the form of images.Therefore,the factors affecting the ultrasonic CT imaging of hydraulic concrete,the weak surface inside the hydraulic concrete,the ultrasonic CT detection of the construction cold seam and the wavelet analysis of the ultrasonic CT detection signal of the concrete defect are studied in this paper.The main research contents and results of this paper are as follows:(1)The main factors affecting ultrasonic CT imaging were analyzed.The physical models with different types of defects were tested by non-metallic ultrasonic detection analyzer,and the effects of detection system,line distribution density,mesh partition and multiple defects on CT imaging were analyzed.The results show that the inversion effect of the four side perspective detection system is the best,and the inversion effect of the perspective detection system on both sides is the worst,and with the increasing density of the line,the effect of image reconstruction becomes better,and when the inversion grid division is roughly the same as the actual test mesh division,the inversion effect is the best;Will have an impact on the imaging of a single defect,resulting in a large defect pseudo-image,poor inversion effect,and,in the same specimen,there are many defects,the worse the inversion effect.(2)Experimental study on the influencing factors of ultrasonic CT detection of internal defects in hydraulic concrete.The influence of the detection system,the distribution density of the measuring line,the mesh division of the inversion,the multiple defects of the specimen and the effect of different mixture ratio concrete on CT imaging are studied.The results show that the inversion effect of four side perspective detection system is the best,and the inversion effect of the perspective detection system on both sides is the worst.The effect of CT image inversion becomes better with the increase of line density,and when the inversion grid division is roughly the same as the actual test mesh division,the inversion effect is the best;when there are many defects in the specimen,it will affect the imaging of a single defect,and the greater the strength of the concrete,the greater the initial wave velocity of the ultrasonic wave,Lead to poor results of ultrasonic CT inversion.(3)Aiming at the characteristics of ultrasonic detection signal,the small wavelet function of wavelet multiresolution analysis is determined as sym6 wavelet base function,decomposition scale location 4 is carried out,and the results of small wave multiresolution analysis of sym6 wavelet base function and haar6 wavelet base function are interpreted.It is determined that the Penalize threshold rule is used to denoising the ultrasonic detection signal.The effectiveness of Wavelet denoising is proved by the inversion of the original ultrasonic signal and the ultrasound signal after wavelet analysis.