Study On Leak Detection Of Pipeline Based On Ground-penetrating Radar

The municipal water supply pipe network in China suffers from serious leakage for a long time,the leakage of water each year is equivalent to the annual amount of water transferred through the middle route of the South-to-North Water Diversion Project.Leakage of pipe network not only leads to waste of water resources,but also causes secondary disasters such as urban water supply crisis,traffic interruption and secondary pollution of pipe network.Therefore,The Action Plan for Prevention and Treatment of Water Pollution deliberated and adopted by the central government set the goal of "controlling the leakage rate of urban water supply pipe network within 10%by 2020".The severe reality of pipe network leakage and the great difference from government goal make the research of leakage detection become the focus of scientific research.Ground penetrating radar(GPR)is a detection method for buried objects,which is fast,nondestructive,high resolution in depth direction and not easily disturbed by external environment.While the research on leakage detection of buried pipeline is rare at present,its clear detection principle and efficient operation advantages make it a potential nondestructive testing method.In this research project,the theory and technology of leakage detection of water supply pipe based on ground-penetrating radar are systematically developed.The main contents are as follows:1.Radar data acquisition.Build the experimental platform and use sand as the medium to lay pipes of different diameters and materials as well as bury interfering stones to simulate various working conditions.Then utilize radar antennas with different frequencies of 500MHz and 800MHz for detection under all kinds of working conditions to obtain two types of profiles,which are along the direction of the pipeline and perpendicular to the direction of the pipeline.2.Routine radar data analysis.Analyze the two types of measured radar profiles to find out the anomalies in the images and analyze the reasons for the occurrence of anomalies,so as to judge the position of the leakage points in the pipeline network and summarize the characteristics of the images of the pipe network leakage.Finally,compare the leak detection performance of the two kinds of profiles3.Radar 3D data volume analysis.By using interpolation method,transform the two-dimensional radar data along the pipeline direction of each working condition into a three-dimensional radar data volume,in which the profiles of three directions are analyzed and the leakage characteristics are summarized.Finally,analyze the advantages of 3D data volume in leakage detection compared to 2D radar image.4.Radar data attribute analysis.Based on the 3D radar data volume,we have analyzed the radar attribute for the working conditions that the leakage signal in the experiment is not obvious,and also probe into the feasibility of the radar attribute analysis in the field of pipeline network leakage.The research findings in this paper are as follows:1.The establishment of 3d data volume that solves the problem that the radar detection along the pipeline direction cannot determine the specific position of pipeline and other interference from the images,and also enables us to analyze the position of pipeline leakage points on the time section by using the radar images of three directions.2.It is able to strengthen leakage signal by using radar attribute analysis,instantaneous amplitude related attributes works best,instantaneous phase related attributes take second place and instantaneous frequency related attributes is the worst.3.T his paper finds out the difference between the signals formed by pipeline network leakage and rock interference in radar images.More specificially,the leakage diffraction wave coincides with the pipeline signal,and the influence range is large as well as the shape is generally round,which will cause the pipeline signal interruption.In addition,the stone signal does not coincide with the pipeline signal,and the influence range is small generally not more than 1 meter.Typically,the shape is irregular,which does not cause the pipeline signal interruption.