Study On Optimal Design To Rehabilitation And Extension Of Drainage Network System In Mishan

Drainage network system is an important part of urban infrastructure, which isresponsible for discharging domestic sewage, industrial wastewater and rainfall intomunicipal sewage treatment plant or a nearby river. Whether the designing fordrainage network is reasonable or not directly affects the level of development ofthe city, affects people’s living environment, to some extent, it is like a businesscard of the city. Meanwhile, the cost of drainage network system takes up nearly80percent of an entire drainage project. Therefore, the optimal design for urbandrainage network system not only has social significance, but also economicallysignificant.Due to historical reasons, the penetration rate of drainage network system inChina is not very high compared with developed countries. With the rapid economicdevelopment, the coverage of the existing pipe network can not meet therequirements of the urban drainage any more. Because of the lack of investment indrainage network system, unreasonable design and construction, bad constructionquality, unsound routine maintenance and some other reasons, China’s drainagenetwork system is in urgent need of effective improvement.According to this thesis, Mishan drainage network expansion project is set asthe object to study the optimal design of drainage network system. Mishan is asmall city located in Northeast China, due to the rapid economic development inrecent years, the existing drainage network has been unable to meet the needs of theurban drainage. Therefore, it is a necessity to take actions in drainage networksystem renovation and expansion. Taken the current status of drainage network inMishan and the technical and economic factors into consideration, it is advisablethat the combined system is applied in the old district of Mishan, and a triagesystem is applied in the new urban district.After the decision of Mishan’s drainage system, traditional algorithm andgenetic algorithm were used to calculate and optimize the renovation and expansionof Mishan’s drainage network, and get two different programs. Through thetechnical and economic comparison of the two programs, the program produced bythe genetic algorithm is deemed as the final plan.According to the optimal design for Mishan’s drainage network, the geneticalgorithm showed its superiority compared to the traditional method. Sometimes,however, the genetic algorithm also has its limitations. And the traditional algorithmshows its convenience in the aid of computer software (Hongye GPS). Looking tothe future of drainage network design, the traditional algorithm and genetic algorithm should be applied in combination to find the most optimal result.