Study On The Optimization Method Of The Vertical Section Design Of Urban Rail Transit Lines

In recent years,the construction of urban rail transit in China has reached its peak.Vertical section design of urban rail transit line not only affects the project investment of the line,but also affects the operation cost in the future.In order to realize the sustainable development of urban rail transit system,reasonable setting of mileage and elevation of gradient-changing points of vertical section of urban rail transit,reducing the construction and operation costs,has gradually become the research focus of optimization design.Taking the underground line of urban rail transit as the research object,this paper constructs optimization models of V-shaped slope,one-way slope and W-shaped slope respectively,designs model solving algorithm based on adaptive genetic algorithm,and applies it to practical engineering cases.The main contents of this paper are as follows:(1)This paper summarizes and analyses the basic elements,basic slope types and influencing factors of the vertical section design of urban rail transit lines,and chooses earthwork cost and operation energy cost as evaluation indicators to measure the vertical section design scheme.The calculation model of earthwork cost of urban rail transit line varying with buried depth stage is established,the calculation method of earthwork cost in shield method and the calculation method of train energy cost in different planning stages are proposed.(2)An optimization model for V-shaped slope design is established,which takes the minimum sum of earthwork cost and train operation energy consumption cost as the optimization objective and the mileage and elevation of gradient-changing points as optimization variables.The constraints include the length and gradient of the main line and the station line,the combination of the horizontal and vertical lines,and the elevation control.Based on the platform of matlab,an adaptive genetic algorithm is designed to solve the model.Combined with the actual project case line,the V-shaped slope optimization scheme is obtained.Compared with the existing scheme,the total cost of the optimized scheme is reduced by about 5.46%.(3)Based on the optimization model of V-shaped slope and considering the technical characteristics of one-way slope,an optimization model of one-way slope design is constructed.The constraints include not only slope length,slope gradient and combination of the horizontal and vertical lines,but also the constraints of long slope section not coinciding with small radius curve and the adaptability of train braking.An algorithm for solving one-way slope design optimization model based on adaptive genetic algorithm is designed.Combining with the actual project case line,using the model algorithm proposed in this paper,the optimization schemes of "gentle slope+steep slope form" and "multi-gentle slope+steep slope combination form" are obtained respectively.Compared with the existing schemes,the total cost is reduced by 5.40%and 5.36%respectively.(4)Compared with V-shaped slope optimization model,the constraints include not only slope length,slope gradient,horizontal and vertical combination,elevation control,but also ventilation well and drainage pump house setting constraints.The adaptive genetic algorithm is used to solve the W-shaped slope optimization model.Combining with the actual case line,the optimization scheme of W-shaped slope design is obtained.Compared with the existing scheme,the total cost of the optimization scheme is reduced by 3.62%.