Research On Comprehensive Detection Of Complex Underground Pipelines In Old Urban Communities

Underground pipeline systems are an improtant part of urban infrastructure,and its safety,stability,reliability,and efficiency are essential for People's daily work and life.With the advancement of science and technology and the development of society,the pipe network systems in urban community of China has been continuously built and improved,and the underground pipe network are increasingly complex,which is mainly manifested in the variety of pipelines,high density,different pipeline materials,and chaotic underground distribution,which is more serious in the old urban communities.On the other hand,the age of the pipeline in old community is very old,resulting in a variety of failures,which needs to be temporarily rushed to repair.This requires the construction person to have an accurate understanding of the basic data such as the type,location and interrelation of different pipelines.However,due to various reasons such as technical limitations,design defects,non-standard construction,backward management and variation in major pipeline construction materials in different periods,as well as random moidifies in pipeline during emergency repairs,etc.,the lack of pipeline data or inaccurate pipeline information in the old communities are general.Therefore,it is imperative to comprehensively detect the pipelines in the old urban communities.This study takes the Taibai campus of Northwest University in Xi'an,Shaanxi province as the research area,investigates how to integrate a variety of detection methods to efficiently detect the underground pipeline system.Firstly,this study summarizes the difficulties faced in the old community pipelines detection,analyzes the characteristics of pipelines in urban old community and their impact on detection,suggests that and establishes the scheme of integrated interior work and field work detection.Secondly,in order to solve the real problems as the goal,this study presents two typical pipeline detection difficult areas,which include close cast iron pipe and different materials pipe.After comparing the advantages and disadvantages of different detection technologies for different pipelines with different materials and different distributions,a reasonable integrated scheme of multi-method detection was given,including acoustic detection method,electromagnetic induction method and geological radar method.Finally,the detection work is summarized.The main conclusions of this study are as follows:(1)for the old urban community,the three detection methods have their advantagesrespectively: acoustic detection method is advantageous in solving the problem of"connectivity between pipelines",electromagnetic induction method is preferred to"detection of metal pipelines",and geological radar method more effective at"detection of PVC pipelines and metal pipelines without exposed points".The threemethods can be used together and valided each other to solve the pipeline problemmore effectively.(2)When there is less pipeline data available in the exploration area,it is moreconducive to start the exploration work of the pipeline at the area with obviouspoints(exposed points,such as Wells).In the process of detection,more convenientdetection methods should be selected according to practical situations.When thedetection is difficult,it is necessary to comprehensively analyze the detectionresults of geological radar method,electromagnetic induction method,acousticdetection method and other methods.(3)In the condition of the different distribution of near-cast iron pipelines(same originor parallel),different detection methods are adopted to coordinate and cross-verifyeach other,which can effectively solve the detection problem of near-cast ironpipelines.For close-distance homogenous cast iron pipelines with densedistribution and complex trend,the detection scheme combining acoustic detectionmethod and electromagnetic induction method can be selected.The metal pipelinedetector is used to detect the direction and position information of the pipes,theacoustic detection method is used to determine the connectivity and connectionmode between the pipes,and the distribution of the pipes can be finally determinedby comprehensive analysis of the detection results.When the distance between thecenter of the close parallel cast iron pipe is less or equel than 0.03 m,the directionof each pipe can be detected with the metal pipeline detector.However,due to thesignal interference between adjacent pipelines,it is impossible to accuratelydistinguish and locate each pipeline at the place where the pipelines are parallel,soit is necessary to further solve this problem with the help of Ground PenetratingRadar(GPR).Because the volume of old residential area in China is very big,the study of pipeline detection of old urban communities is of great significance.In this study,the integrated process of detection,the formulation of detection scheme,the selection of detection method and parameters,and the solution of detection difficulties(such as short-distance cast iron pipeline and multi-material hybrid pipeline)give valuable references to detect underground pipes in similar communities.