Dynamic response of ballasted High-Speed Railways: insights from experimental measurements and 3D nonlinear numerical modelling

High-Speed Railways provide efficient transportation but impose significant dynamic forces on ballasted tracks, accelerating ballast degradation and increasing maintenance demands. This study aims to understand and mitigate these effects by investigating the dynamic behavior of ballasted tracks under high-speed train passages. A field campaign conducted on the Madrid-Barcelona high-speed line involved comprehensive instrumentation of the Brihuega railway segment to capture dynamic responses. These data were used to calibrate and validate an advanced three-dimensional numerical model incorporating nonlinear material properties and Coulomb friction interfaces in an innovative approach. The validated model accurately replicated vertical displacements and revealed that elastic deformations are primarily confined to the railpads and ballast layer, with minimal impact on deeper layers. Non-linear Coulomb friction modeling introduced in the ballast/sub-ballast interface enhanced stress transfer simulations, confirming negligible sliding between these two layers. Decreasing railpad stiffness from 100 to 60 kN/mm reduced ballast stresses by 10 % and improved load distribution, promoting longer track service life, while increasing rail displacements and reducing overall track stiffness by 20 %. This study concludes that railpad stiffness optimization can balance track resilience and degradation mitigation, providing a sustainable approach to infrastructure management. The validated numerical model offers a versatile tool for simulating complex track behaviors, enabling predictions of unmeasurable parameters like stress paths in the track bed. Future work should address long-term loading effects and non-uniform track conditions, advancing track design and maintenance strategies for high-speed rail networks.