Influences of dynamic material properties of slab track components on the train-track vibration interactions

Slab tracks or so-called ballastless tracks have been widely adopted for highspeed rail networks. Material properties of slab track components have significant influences on the serviceability performance of both high-speed trains and the slab tracks. In reality, the stiffness of rail pads and moduli of elasticity of concrete and CA mortar are quite different when they are determined by using either quasi-static or dynamic loading tests. Based on a critical literature review, most previous studies adopted some static material properties despite the fact that the actual loads from high-speed trains onto slab tracks are dynamic excitation. In addition, some studies simply adopted the dynamic stiffness of rail pads whilst ignored the dynamic effect on modulus of elasticity in their simulations. This study is thus aimed at highlighting the influence of the dynamic material properties on the train-track vibration interactions. A nonlinear 3D coupled vehicle-slab track model has been developed based on the multi-body simulation principle and finite element theory using LS-DYNA. This model has been validated by comparing its results with field test data together with other simulation results. A good agreement among the results has been found. The magnification effect on the dynamic modulus of elasticity under dynamic train loads has been determined firstly. The influences of material properties on the serviceability performance of the vehicle, the wheel-rail contact force, the vibration responses of the rail, concrete slab, and CA mortar have then been evaluated. The deviation coefficients of vibration responses of the vehicle and track under three types of material properties have been determined to emphasise the influences of the dynamic stiffness and modulus of elasticity. The insight from this study provides a new reference and recommendation for adopting suitable and realistic material properties of high-speed slab tracks in practice.