Drainage Network To Change The Expansion Of Computer Aided Design

With the progress of urbanization and the enlargement of city scale in China, the optimal design on rehabilitation and extension of urban drainage networks poses a key task to the water and wastewater engineers. The rehabilitation and extension project of combined sewer system in Xingsha Economic and Technological Development Zone, Changsha, is taken as a case study in this thesis. In order to simulate as exactly as possible the actual sit ation of the flow in combined sewer during storm, the unsteady flow simulation is used to check the capability of the existing drainage networks to carry storm water and find out the overloaded pipes. Genetic Algorithms (GAs), which were applied widely in engineering in recent years, is used in the design of this rehabilitation and extension project. GAs is a strong robust global searching algorithm. It is not based on objective function gradient estimates, but directly targets at the code in certain form of the variable. They may be used to solve nonlinear problems such as the drainage networks?optimization and reach discrete pipe diameters. After comparing the simulation experiment results of different programs where varies of operation parameters are combined, the program, which consists of population size 100, character coding, elitism strategy, adaptive crossover and mutation rates, could converge the most rapidly in the optimal solution. Finally, the designed optimal sewer system is checked on its hydraulic reliability.