Recommendations for Numerical Rail Substructure Modeling Considering Nonlinear Elastic Behavior

This paper considers the problem of modeling railway track substructure. The most commonly used methodology for designing the railway substructure cross section does not considerably differ from that proposed in the 1980s. For the bearing capacity of the subgrade, the currently used design methodology implicitly meets one objective: the stresses transmitted to the subgrade must be compatible with its bearing capacity. The bearing capacity depends on the qualities and thicknesses of the soils that compose the subgrade, from the formation layer to the lower layers. In addition, railway administrations have included additional recommendations based on their experience. During the last decade, finite-element models (FEM) have been shown to be a very useful tool for designing cross sections. These models are often very complex and require a very high computational time to be solved. To reduce this complexity and computational time while remaining faithful to the reality to be modeled, this paper proposes some recommendations to develop a parameterized numerical model in three dimensions within the elastic nonlinear range under the static load of a given railway section. To adequately reproduce the real behavior of materials (elastoplastic) and the contact surfaces between very different materials adequately, artifices to use the model in the elastic range are propsed. In addition, the goodness of this design is analyzed using multilayer numerical models. This model may be a very useful tool for analyzing the behavior of different types of railway cross sections. (C) 2013 American Society of Civil Engineers.