Research On Buried Pipeline Damage Identification Based On Ultrasonic Guided Waves

As the most important tool in the process of fluid transportation,pipeline is widely used in the transportation of oil,urban water,natural gas and other aspects,and plays a very important role in national production and national life.However,during the service of the long transportation pipeline,it is often in a complex external environment,such as rockfall impact,corrosion,debris flow and so on,which will cause local damage to the pipeline.If it cannot be predicted as soon as possible,it will cause fatal damage to the pipeline.Real-time health detection of local damage of the pipeline is an important measure to ensure its safe service.Ultrasonic guided wave technology has the advantages of high detection efficiency,low cost and convenient detection,so it is suitable for pipeline damage detection in complex environment.However,the propagation of ultrasonic guided wave in the pipeline is complex,showing the characteristics of multi-mode and dispersion,as well as the influence of external environmental noise,which will increase the ability to detect local small damage in the pipeline.In this paper,the damage of pipeline under different working conditions is identified from three aspects: dispersion theory,experimental research and numerical simulation.Through the positive and inverse piezoelectric effect of piezoelectric ceramic sensor and the propagation law of ultrasonic guided wave in pipeline,the feasibility of pipeline damage detection of ultrasonic guided wave is studied,which plays an important role in the healthy operation of long transportation pipeline.The main research contents and related results are as follows:(1)The basic classification and piezoelectric properties of piezoelectric materials are briefly introduced.at the same time,the applications of piezoelectric sensors and ultrasonic guided wave technology for pipeline damage detection are briefly introduced.(2)The propagation law of ultrasonic guided wave in pipeline is analyzed theoretically,the dispersion equation of ultrasonic guided wave in hollow pipeline,liquid-filled pipeline and liquid-filled buried pipeline is deduced,and its dispersion curve and propagation characteristics are obtained.The reference basis for selecting the mode and frequency range of the excited ultrasonic guided wave in the pipeline under different working conditions is obtained.(3)Choosing the appropriate ultrasonic guided wave frequency and excite the pipeline by Hanning window modulation.For hollow pipelines,liquid-filled pipelines and liquid-filled buried pipelines,single defects and multiple defects with different damage degrees in the direction of extending the circumference are set.According to the output voltage signal of the piezoelectric sensor,the feasibility of pipeline damage detection and the detection rules under different damage degrees are analyzed.(4)The model of liquid-filled buried pipeline is established by finite element software ABAQUS,the pipeline,soil and parameters are determined,different forms of multi-defects are set,and the interaction of water-pipeline coupling and pipe-soil coupling is defined at the same time.According to the guided wave frequency obtained from the test,the pipeline damage is detected by stimulating the simulated displacement load.On the basis of good agreement with the test results,the double defects of liquid-filled buried pipeline in different circumferential directions,different axial directions and different circumferential directions are accurately located.