Investigating The Multi-objective Design And Resilience Of Urban Drainage Design Problems

In recent years,with the development of urbanization and changes in climate and others,all kinds of cities across the country have experienced frequent flooding,which has had tremendous impact on people's production and life.Therefore,the problem of urban flooding has seriously restricted the sustainable development of cities and the construction of ecological civilization in China.There are many reasons for the waterlogging,among which the design of storm sewer network is one of the most important ones.The pipeline is an important factor in the system and it accounts for the largest proportion of the total investment,so there is a large space for optimization.Reasonable layout of the pipeline network and selection of pipe diameters have great significance for urban flood control.Based on the hydraulic model of storm sewer network,this master's thesis puts forward an optimization function based on average fullness and cost in order to achieve multi-objective optimization design of storm sewer network.At the same time,based on the multi-objective Pareto fronts,the theory and technical method of storm sewer network resilience analysis based on spatial difference of rainfall are innovatively proposed to determine the optimal design scheme of storm sewer network.The research content of this paper can be divided into the following four parts.First of all,this thesis studies the engineering-based design method(EBDM)and SWMM modeling.On the basis of the original API interface functions,in order to facilitate the acquisition of basic information such as SWMM file nodes and pipes,some API interface functions are added.At the same time,the function development based on the original SWMM program makes it possible to calculate a complete design by inputting any INP file and setting the design depth of pipes.Case 1 is designed according to full pipe flow by EBDM and simulated in SWMM,it can be concluded that although the solution generated by EBDM cannot fully satisfy the design criteria when considering the rainfall process line,its results can be used as approximate optimal solutions and the result of the solution is fully consistent with the decision space function constraint.Secondly,the multi-objective optimization algorithm is studied,and the Borg algorithm is applied to the multi-objective optimization of storm sewer network for the first time.The mathematical model of the optimization algorithm is established and the flow chart of Borg algorithm optimization is given.The approximate optimal solution generated by EBDM is used as the initial solution for the optimization of the Borg methods.Compared with the traditional optimization design method(that is,the initial solution determined by not providing the EBDM method)the efficiency of finding the optimal solution is significantly improved,and the optimization effect is more obvious in the large storm sewer network.In addition to improving efficiency,the Pareto fronts coverage and qualities are also significantly better than the results of traditional optimization methods.In the optimization process,another innovation of this master's thesis is to put forward the constraints of increasing engineering feasibility in decision space to ensure that the upstream pipeline is not larger than the downstream pipeline diameter,thus improving the engineering practicability of the optimization scheme.Finally,starting from the spatial heterogeneity of rainfall,this paper proposes a simulation method of normal distribution of rainfall space to carry out the resilience analysis of urban storm sewer network based on spatial inhomogeneity of rainfall to determine the optimal storm sewer network design.