Dynamic performance comparison of different types of ballastless tracks using vehicle-track-subgrade coupled dynamics model

This paper contributes to evaluate the dynamic performance of different types of ballastless tracks, including the CRTS II, CRTS III as well as CRTS DB, subjected to a moving high-speed railway vehicle. To this end, a vertically vehicle-track-subgrade coupled dynamics model appropriating for both the longitudinally connected-type track structure and the element slab-type track structure is constructed by introducing the Green's function method, so as to achieve a full characterization of the vehicle-track-subgrade system with accurate and efficient solutions. The time-spatial distributions of the displacement and velocity Green's functions of the track-subgrade system are analyzed to ascertain the values of the truncation parameters employed in the model. Numerical examples are presented to illustrate and compare the dynamic characteristics of the three types of track structures under various track irregularities, vehicle speeds, fastener stiffnesses and subgrade elastic moduli. It is shown that the discrepancy among different track structures exerts an ignorable influence on the vertical wheel-rail force, but its effect on the vertical displacement, acceleration and stress of the track-subgrade system is noteworthy. Besides, the attenuation characteristics of the track-subgrade system with respect to track depth are further investigated. It is concluded that the system displacement against the track depth presents an approximately linear attenuation, whereas the system stress reveals an approximately exponential attenuation.