Evaluation and numerical modeling of defections and vertical displacement of rail systems supported by expanded polystyrene (EPS) geofoam embankments

This research seeks to develop a numerical method to evaluate the vertical rail deflection, sleeper (i.e., rail road tie), and embankment displacements for rail systems constructed atop Expanded Polystyrene (EPS) geofoam embankments. Such a model is needed for the design and safety evaluations of such systems. To achieve this purpose, laboratory testing of ballast material was performed in conjunction with the development and verification of two-dimensional (2D) and three-dimensional (3D) finite difference methods (FDM). These evaluations were done for multilayered rail systems undergoing deflections from typical locomotive and train car loadings. The proposed FDM approach and models were verified using case studies of: (1) an earthen rail embankment and FEM modeling of that embankment as presented in the literature and (2) an EPS-supported multilayered railway embankment system and field deflection measurement from Norway for a commuter rail system. The evaluation of these verification modeling examples show that the 3D FDM model can reasonably estimate the static vertical deflection associated with such systems subject to typical train loadings. However, more research is needed to measure the dynamic (i.e., rolling) train deflections and to develop evaluation methods for such systems constructed atop EPS-supported embankment.