Study On The Evaluation Of The Health Status And Optimization Of Repair Technology Of Urban Sewage Pipe Network

The sewage pipe network is an important part of the urban drainage system.With the development of urbanization and the improvement of people's living standards in China,the amount of sewage is increasing rapidly,the urban sewage pipe network is taking on more and more important tasks as well.This paper took the typical urban sewage pipe network as the research object,constructed the pipeline network health status risk prediction model and comprehensive evaluation model.According to the results,this paper formulated the pipeline inspection priority order and maintenance plan,optimized the pipeline repair technology in the end.The main research results include:(1)Based on Bayesian theory,a health risk prediction model and a comprehensive evaluation model for sewage network were constructed.Risk of pipeline health status predicted from two aspects: pipeline traits and social environmental factors by means of 8 indicators such as pipe diameter,pipe material,pipe age,interface mode and depth of soil cover etc.,the pipeline inspection sequence was determined according to the risk level.Pipeline traits,social environmental factors,structural conditions,and functional status were selected as the criteria layer,which contained 18 indicators to comprehensively evaluate the health status of the pipe network,and the results of the pipeline evaluation were classified into “health(Class I)and sub-health(Level II),illconditioned(level III),disease(level IV)” four levels.According to the different levels,the corresponding pipeline maintenance program were determined.(2)The optimal model of pipeline repair technology based on AHP-composite index evaluation was established.Four kinds of the most commonly used nonexcavation repair technologies at home and abroad as slip lining,cured-in-place pipe,lining,spiral winding were analyzed from three aspects: economic cost,social cost and environmental cost to select the optimal technology for the pipeline to be repaired.(3)The urban sewage pipe network in Suzhou was selected as an example,the risk prediction analysis of its health status showed that the risk level of pipelines in the study area is mainly II and III,accounting for 74% of the total pipelines,and the IV pipelines are the least.11.6% of the total.Through the analysis of CCTV test results,it is found that the structural defects of the pipeline are mainly deformation,rupture,undulation,disjoint and faulty,the second-level defects are mostly,and the functional defects are mainly obstacles,residual walls and broken dams,grade IV defects are mostly.The comprehensive evaluation results of the pipeline health status show that 44.2% of the pipelines in the study area are in the state of disease(class III)or disease(level IV);According to the preferred results of the pipeline repair technology to be repaired,the spiral winding method and The in-situ curing method is a repairing technology suitable for repairing most sewage pipes in the study area.