The Research Of Hydraulic Calculation Of Urban Rainwater Pipe Networks Based On Reliability

The rainwater pipe network is one of the urban important infrastructures, and the current design method is the definite value design method, lacking the consideration of reliability of draining off water. In fact, the variables involved in the course of designing and adoptive calculation models, etc. have uncertainty. In the design, these uncertain factors should be considered, the variables should be regarded as the random variables, and the probability limit state design method based on reliability theory should be adopted.The task of the urban rainwater pipe network system is to gather and get rid of surface runoff caused by rainfall in time and dependably, thus creating a comfortable and safe existence and production environment for the city. However, in recent years, waterlogging has taken place in various degree in a great deal of cities (such as Beijing , Shanghai, Nanjing , Chengdu ) and caused the enormous economic losses to people. The cause of waterlogging except that draining equipment and management system can not catch up with paces of economic development and urbanization process, it is a main reason too that the reliability of the existing drainage pipeline networks is low. So studying reliability of rainwater pipe network and adopting probability limit state design method based on reliability theory to design rainwater pipe network have important actual meanings.The uncertainty in the rainwater pipe network design is analysed in this thesis at first. Then to an existing rainwater pipe network, JC method, Monte-Carlo method and genetic algorithms (GA) method are adopted to calculate the reliability of every single section of pipelines, bound estimation method is adopted to calculate the reliability of the whole of rainwater pipe network system. The result of calculation shows that the reliability of the rainwater pipe network designed with definite value design method is low. Then the expected reliability indexes of rainwater pipe network are put forward, and the partial factors of corresponding to them are calculated. Finally, the probability limit state hydraulic calculation of rainwater pipe network is carried on with expected reliability index method and partial factor expression method for example.