Guided Wave Technology In Water Conservancy Project Pipeline Damage Detection Research On Application

The pipeline was an important part of the hydraulic structures, which was widely used inagricultural irrigation, water conservancy. Most pipelines’ working environment was very adverse.In the process of long-distance transmission, dued to the external load, aging pipes, corrosion andother reasons that lead to the Pipeline leak, and resulting in a serious waste of water resources.Therefore, the damage detection and damage localization of the Water-filled pipes had veryimportant theoretical significance and practical value. Traditional detection methods must scan thepipeline point-by-point and the detection speed was slow, inefficient, expensive and lessanti-interference ability and accuracy. And some tiny, hidden damage likely to cause a miscarriageor missing of justice. So it was difficult to widely used in the detection of the long-distance pipeline.Guided wave detection technology had many advantages such as high detection efficiency, longdetection distance, fast speed and the sound field throughout the entire wall thickness. So guidedwave detection technology was widely used in the pipeline non-destructive testing. Since thelow-frequency guided wave was without dispersion, and with fast group velocity, not susceptible tothe interference of the other modal signal, more suitable for the detection of multiple types ofdefects in the long-distance pipeline, so this thesis mainly studied the application of low-frequencywave guide to detect damage to the long-distance pipeline, and comparative analysis the differentworking conditions, laid the foundation for the realization of the long-distance pipeline damagedetection.In order to verify the feasibility of the low-frequency wave guide to detect the pipeline, thisthesis used Matlab software to solve the dispersion equation, calculated and drew the dispersioncurves, and analysised its dispersion characteristics. The study showed that in the low frequencyband of0~20KHz, the group velocity of mode L (0，1) was fastest. And in the band of0~10KHz,its group velocity was essentially unchanged. The phase velocity was also essentially unchanged,so it was suitable for the detection of a long distance of the pipe. Thus it proved the feasibility ofthe application of low-frequency guided wave detection of pipeline.In order to verify the reliability of the method of the Ansys numerical simulation, this thesisdid Ansys numerical simulation of the pipeline by two damage conditions the no damage pipelineand single defect injury pipeline, and compared the results with the same size, the same injurystatus pipeline in the laboratory test. The results showed that the wave velocity, the shape of thewave and the judgment of the defect position calculated by Ansys simulation were consistent withthe experimental results of the laboratory and consistent with the actual situation, thus it verifiedthe feasibility of the Ansys numerical simulation methods, and the obtained data was accurate and conclusions were reliable.In order to study the detection effect of the axial defects, circumferential defects, radial defectsand the double defects of the pipeline by the low frequency guided wave, this thesis used Ansyssoftware, did the numerical simulation by exerting symmetrical instantaneous exciting force to thetwelve nodes at the end of the pipeline. Explored several basic modals inspiring by such incentive,analysised the degree of sensitivity and the detection effect of the pipeline defects by this detectionmethod. The results showed that L (0，1) mode guided wave had good recognition effect of thecircumferential defect, radial defects and the double defects, but it was insensitive to the axialdefects.Finally, this thesis analysised the inadequacies of the existing work, pointed out the limitationsof the guided wave detection and further research direction.