The Study On Optimal Design To Rehabilitation And Extension Of Drainage Pipe Network

With the progress of urbanization and the enlargement of city scale in china, Nowadays the drainage pipe network in cities has couldn't satisfy the needs of urban's development, and this project has attached more and more importance to the designers of drainage pipe network. So it has actual meanings to reconstruct and extend the drainage pipe network in cities. The rehabilitation and extension project of drainage pipe network in an Economic and Technological Development Zone, Zhejiang province, is taken as a case study in this thesis to the optimal design of the rehabilitation and extension in drainage pipe network. Achieveing a satisfy result.Finding out the overloaded pipes by checking the capability of the existing drainage pipe network to carry storm water. Second, this thesis ascertains the optimum parameters in the cost functions and the storm intensity equation. The storm intensity equation is a fundamental equation of designing storm water pipelines. Combining the characters of an Economic and Technological Development Zone and basing on the current searching methods, it selects a proper storm intensity equation suitable for this area in Zhejiang province. Cost function is generally the object of drainage optimal model. They are non-linear functions. Whether or not their parameters are appropriate, they will affect the design reliability of drainage pipe network. The parameters of the drainage pipe network can be obtained by using statistical software SPSS. It shows that statistical software SPSS is simple for operation, flexible, and have accurate result.Optimizing pipe parameter when the plane disposal of pipeline has been fixed is an important content to the optimal design of the drainage pipe network. This thesis will mainly study the second aspect. It is a typical combined optimum question to the optimum design on rehabilitation and extension of the fixed drainage pipeline system. Genetic Algorithms (GA), which was applied widely in engineering in recent years, is used in the design of this rehabilitation and extension project. GA is suitable for the problem of the multitude parameter's optimization. It is a strong robust global searching algorithm. It is not based on objective function gradient estimates, butdirectly targets at the code in certain form of the variable. They may be used to solve nonlinear problems such as the drainage pipe network's optimization and reach discrete pipe diameters. And the proposed algorithms are the best algorithms and can obtain the global optimal results.The designed optimal on rehabilitation and extension of drainage pipeline system is checked on its hydraulic reliability. The result shows this method is suitable for engineering practice.