A Study Of Urban Sewer Inspection,Assessment And Related Factors

In recent years,problems of Chinese urban sewer pipes become more and more serious.However,due to the comolexity and particularity of sewer pipes,inspection and assessment one pipe's defect level is the critical work in sewer pipe management system.This study used QV and CCTV detection system on 28.7 km of sewer pipes in a typical southern city in China,15 common defects and their classification methods were defined in the evaluation systems and analyzed the correlation between pipe damages and related factors.Then,the rules of groundwater inflection were studied through the self-made sewer pipes simulation device with 3 damage types.Severl conclution are bellow:?1?13 kinds of defection were found and quantified in those 28.7 km sewer pipes,can be grouped into 5 types: depfrmation,joint problem,break/corrosion,obstruction and leakage,by acquiring quantitative information from sewer inspection,each pipe was classified into 4 type: slight,moderate,sever,emergent,the evaluation results were indicated by a Sewer Defect Index.In this study,the proportion of this 4 type pipes is: 69.1%,13.8%,4.6%,12.5%;?2?Through the comparative method to study the relation of pipe defection,pipe evaluation results with 5 factors: length,diameter,pipe age,hydraulic gradient and pipe material,the reults show that the rate of defection of 5 type problems all have obvious relationship with those factors,but defection degree is not so obvious,pipe age,diameter and pipe material have obvious relationship with the Sewer Defect Index;?3?Analyzed the data of 11 kinds of defects,3 types of pipe performance and 7 kinds of factors by CCA,in this way,several canonical correlation varibales were founded with the most essential information: break/ collapse and other defects and pipe age,diameter,3 types of pipe performance have significant positive correlation with pipe length,diameter;?4?3 kind of damage conditions test included leakage,break and displaced joint,the water level included 150 mm,200 mm,250 mm.In this test,the rate of infiltration ranged from 5.4 mL ? h cm to 27.6 mL ? h.Proposed a estimation method of infiltration,then estimate infiltration rate of 651 m sewer pipes in a south city ranged from 1.133 m³·d^-1 to 2.936 m³·d^-1,if there is no measure to respire the damage,the rate of infiltration ranged from 413.5 m³·a^-1 to 1071.6 m³·a^-1.