Study On Evaluation Theories Of Underground Drainage Pipelines

The function of urban underground drainage pipelineis to transport sewage andtimely exclude rainwater, which is a crucial role in urban living and infrastructure.But now the operational management of underground drainage system is not perfect,so that the drainage system failure lead to a series of accidents, such as roadsubsidence, sewer spills,urban waterlogging and so on. In order to prevent suchdisasters, an efficient systemforsewer monitoring, evaluation, maintenance andrepair should be established.At present, pipeline defect detection and evaluationmethod is relatively simple in China. Technical specification for inspection andevaluation of urban sewer is formulated in2012. But this specification just list theimage evaluation techniques that only reflect the surface state of the pipeline Whileignoring the actual intensity. Thus the value of its guidance is greatly reduced.This paper analyzed the current development of domestic underground drainagepipeline and evaluation theory in the firstplace. Then based on the research andanalysisof the running state of sewers, give a definition of pipe deterioration forin-servicesewer pipe.Thenthis paper summarized the factors affecting pipedeterioration and divided pipe deterioration into the structure deterioration andhydraulic deterioration.For structure deterioration process of pipeline, the paper discussed theinteraction force between the pipeline loadsand the soil pipe based on Marston theoryof loads. When the phenomenon of soil around the pipe loss occurs due toconstruction, the pipeline subsidence is likely to appear. Therefore, by discussing thestandard of pipeline subsidence, the paper analyzed the model of elastic foundationbeam to simulation pipeline sedimentation, and proposed different methods ofsubsidence calculation for rigid pipes and flexible pipes. In addition since the higherproportion of pipeline failure due to Pipe joint damage, this paper also analyzed themechanical properties of rigid interface and flexible interface that may be changed inthe soil movement. Finally, taking into account the phenomenon of soil loss around the pipe, which lead to pipeline suspending, the paperalso discussed this phenomenonpartly.For the hydraulic deterioration of pipelines, the general assessment includesphysical and statistical model, but because this study failed to obtain sufficientanalytical data and limited by the scope of the professional research, this paper onlygave out some statistical analysis, then compared homogeneous Poisson processmodel, the process of updating the model, the non-homogeneous Poisson processmodel and progressive multiple regression models.