Study On Optimization Design And Safety Evaluation About Urban Drainage System In The Case Of Abrupt Rainstorm

The construction of public security facilities is vigorously promoted in ourcountry. As an important content in it, the construction of municipal drainage pipelinehas very important strategic significance. Currently, the situation that urban drainagepipe network in our country are aging and silted up generally and depend on thedrainage design system of gravity flow alone does not match the reality of globalclimate changing abnormal and rainfall large and concentrated, it is imminent forusing the new emergency drainage mode with "gravity flow+pressure flow" todesign and explore in the case of abrupt rainstorm in order to minimize disasterswhich their bring urban people’s. The design pattern with "gravity flow+pressureflow" is that drainage is changed into depending on power and energy provided bypumps preferentially and its gravity complementally from gravity simply in the past tospeed up the drainage of urban drainage pipe network and ensure cities are notflooded and the safety of the people’s life and property is not affected by the threat offlood.Urban drainage system in a certain city district of Harbin in the case of abruptrainstorm is as the research object in this paper, on the basis of in-depth study for thesubject that Jilin University youth science and technology innovation fund "Study onDrainage Pipe Network Optimization in the Case of Abrupt Rainstorm"(No.:450060487502), through design and discourse for urban storm drainage pipe systemusing the new design pattern with "gravity flow+pressure flow" to compositeemergency drainage, the following results can be got:(1) The computational formulas of pressure drop and mechanical energy power required of urban storm drainage pipe system are derived, and the parameters areselected reasonably, thus pressure drop and mechanical energy power required ofurban storm drainage pipe system are obtained.(2) The equation and outcome of maximum internal intensity of pressure andinternal pressure and average internal intensity of pressure along the drainage unitlongitudinal length of drainage pipe is obtained, and balance equation of state on forceof water in the drainage unit pipeline acted as the research object is built, and thecomputational formula and outcome of circumferential force and axial force andradial force of drainage unit pipeline are obtained, thus the constitutive (stress-strain) relation of urban storm drainage pipeline is inferred and analyzed.(3) The calculation formula and outcome as well as analysis of soil pressure ofpipeline top and lateral earth pressure as well as the average lateral earth pressure onurban storm drainage pipeline are obtained, and the calculation formula and outcomeas well as analysis of average storm scour force and top friction force, two sidesfriction, bottom friction, and total friction force between pipeline and the surroundingsoil are obtained respectively, thus the conclusion that urban storm drainage pipelineis safe in the anti-scour aspect is obtained.(4) The overall structure of urban storm drainage pipeline system is designed andits facilities are configured reasonably, and the central water level informationprocessing software is designed systematically using Visual Basic programminglanguage to realize two big functions and has passed the test successfully.(5) It is ascertained that fuzzy comprehensive analysis method into fuzzymathematics is as the mathematical model of safety evaluation about the pipeline, andmethods and steps of fuzzy comprehensive evaluation on pipe network security aregiven, and factor sets, evaluation sets and evaluation of classification of pipe networksecurity are ascertained, and a series of membership functions of safety evaluation onurban storm drainage pipeline system are deduced and thus the fuzzy evaluationmatrixR r ij n mof safety evaluation on the pipeline is obtained, and indexweights of fuzzy comprehensive evaluation are calculated, and multiplication is done for fuzzy matrix of comprehensive evaluation, finally the greatest possible evaluationresults of comprehensive evaluation is obtained.(6) Finally, study on optimization design and safety evaluation about urbandrainage system in the case of abrupt rainstorm is summarized in the paper, and somemeasures and suggestions are put forward to improve security of urban storm drainagepipeline and make it safe.