Analysing Railway Substructure And Superstructure By Using Finite Element Methods And Dimensioning Of Track Components

Conventional railway’s substructure and superstructure system consists of natural soil, subgrade, sub-ballast, ballast, sleepers, fastening system and rails respectively and this structure is named as ballasted railway track. The combination of natural soil, subgrade and sub-ballast is called as railway substructure. On the other hand, the combination of ballast, sleepers, fastening system and rails is called as railway superstructure. In case of using concrete plates with steel wires instead of ballast layer, this structure is named as ballastless railway track or slab track. The rails can be laid or embedded on or into the concrete plates. The both of ballasted and ballastless railway tracks can be used for inner and intercity rail systems. In this study, rails and sleepers structure which are laid on ballast layer or concrete plate modelled and solved as two (2D) and three dimensional (3D) models using finite element methods as a beam on an elastic foundation. SAP2000 and PLAXIS programs were used as the final element program. The system is also modelled and solved with conventional (Winkler’s Model of Elastic Foundation) methods and the results were compared with each other. The results of displacements and moments along the beam were nearly found similar in both methods. The ballast layer modelled as a spring model, a plane element (2D) and a solid element (3D) in finite element methods. The modules of subgrade reaction were used in the spring model and the stress-strain modules were used in the plane and solid elements. After testing the accuracy of both conventional and finite element models, the complex railway superstructures were loaded and analysed under various passenger and freight trains. The superstructure and substructure components were dimensioned on the base of analyses results and successful results were obtained.