Dynamic Responses of Ballastless High-Speed Railway Due to Train Passage With Excitation of Uneven Trackbed Settlement

The ballastless slab track has been widely used in newly-developed high-speed railways in China as well as in other countries for its high stability and low maintenance. However, loss of track vertical alignment due to uneven trackbed settlement will bring adverse impact on train’s running safety and track serviceability. In this study, a train-track-trackbed coupling model has been proposed to investigate the dynamic responses of track structure with the excitation of trackbed settlement with varied patterns. To validate the proposed analysis model, comparisons with both the analytical solution and in- situ measures have been performed. The influences of train speeds, settlement trough amplitude and length are discussed based on this analysis model. It’s indicated that the dynamic responses of train vehicle and track structure increase with increasing in train speed and settlement amplitude within certain settlement length. By introducing the standards for train operation safety and riding comfort, a new trackbed settlement control criteria is proposed. The computation results indicate that the standard for train operation safety is found to be the dominating factor for uneven settlements with the length less than 10 m, while the standard for riding comfort dominates the settlement control criteria in other cases. To further facilitate the settlement control criteria in engineering practices, the ratio of settlement amplitude and settlement length (which is defined as deflection ratio) is adopted to depict the envelop curves for various settlement patterns.