Ballast Anisotropy and Discretization Effects on Train-Induced Responses: A Novel MultiSmartTrack Program

This study presents a new algorithm and computer program, MultiSmartTrack, developed for the analysis of layered railway track systems under static train loading. The framework couples the FEM for modeling the superstructure with Green’s function-based MultiSmart3D scheme in which the dual-variable and position method is used for simulating the layered substructure. While the proposed model is capable of accounting for transverse isotropy (or cross-anisotropy) in all soil layers, the present study emphasizes its influence on the ballast layer, in which anisotropic behavior is most pronounced. The effect of mesh discretization is examined, revealing its critical role in capturing local stress transfer and in reliable ballast safety evaluation. Furthermore, the program enables the computation of the damage index to assess ballast safety and identify zones prone to overstressing. Overall, the developed MultiSmartTrack model provides a versatile and efficient semianalytical tool for performance-based analysis, design, and maintenance planning of layered railway track systems.