Estimation of Rail Bed Modulus Based on Ballasted Railway Components Characteristics

Rail bed modulus is one of the main parameters in optimal track design which is determined based on components of ballasted railway tracks. Perception of track bed behavior in different conditionsand on substructure with complex characteristic has an important role in the rail system analyses. Technical and geometric characteristics of track may have a significant impact on rail bed modulus. Review of recent researches on railways in different countries indicates the importance of rail supporting system in rail analysis results. This paper studies the importance of change in rail bed components characteristics in determining track modulus as one of the parameters of rail system analysis and design. This study is divided into two parts including field tests and numerical analysis. To achieve this goal, ballasted railway tracks are modeled according to technical and geometrical characteristics. Then, model is calibrated using field test in order to confirm the validity of model, and it is analyzed by employing finite element method based on tracks components classification. Finally, some diagrams and tables are presented for different conditions of rail roads according to ballast layer thickness and the type of the subgrade in order to determine track modulus and control rail vertical deflection.