Damage mechanism of track-bridge system and characterization of track irregularity under longitudinal seismic action

Abstract

Rational prediction of seismic-induced track irregularity is essential for evaluating the post-earthquake traffic capacity of high-speed railways. This study further presents damage evolution mechanisms for both regular and irregular bridge configurations, as well as the associated track regularity deterioration induced by longitudinal seismic excitation. A representation model for track regularity by adopting the null-phase distribution hypothesis of Gaussian pulse translation under stochastic seismic excitation is established. The results show that under longitudinal seismic action. The rail node vertical displacements on both sides of the pier, along with the seismic-induced track irregularity, exhibit antisymmetry about the pier centerline. The track irregularity reconstructed using the translational Gaussian pulse method can closely reproduce original seismic-induced track irregularity. The target seismic-induced track irregularity can effectively envelop the samples of track irregularities generated under various seismic conditions. The random-pier-height structure can be equivalently treated as a uniform-pier-height structure with the same height as its tallest pier. The target irregularity constructed can provide a reference for calculating the post-earthquake train speed threshold.