Multi-objective Optimization of Ballastless Track of Urban Express Line Based on NSGA-Ⅱ Genetic Algorithm
In order to study the lightweight economy of ballastless track structure and the coordinated optimization design of train rapid operation safety,a vehicle-track spatial coupling model is established by using the multi-body dynamics software Universal Mechanical.The dynamic response of wheel-rail system caused by the change of track slab length,width,thickness,elastic modulus,fastener stiffness and fastener spacing when the D-type motor train passes through the city at a speed of 160 km/h is analyzed in detail.The response surface model of rail vertical displacement of ballastless track of urban express line is obtained by response surface experiment.The optimal parameter combination is obtained by multi-objective optimization of NAGA-Ⅱ genetic algorithm.The results show that through the single factor test,the significant factors affecting the vertical displacement of the rail are fastener spacing,fastener stiffness and track slab length.It is suggested that the vertical displacement of rail should be taken as the key evaluation index in the design of ballastless track structure of urban express line.The primary and secondary order of the influences of design variables on the mechanical properties of ballastless track of urban express line are fastener spacing,fastener stiffness,track slab length,track slab width,track slab thickness and track slab elastic modulus.The recommended design parameters are fastener system stiffness 25 kN/mm,fastener spacing 0.625 m,track slab length 4.9 m,track slab width 2.8 m,track slab thickness 0.26 m and concrete grade C40.
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