Time-frequency characteristics investigation and numerical reconstruction of seismic-induced track irregularity for high-speed railway bridge

Abstract

In recent years, the construction of high-speed railway has gradually extended to area with high seismic intensity. Seismic-induced track irregularity in high-speed railways is essential for evaluating high-speed railway safety upon earthquakes. Signals of seismic-induced track irregularity typically exhibit non-stationary characteristics, but research on the time–frequency characteristics of seismic-induced track irregularity on high-speed railways is currently limited. To ensure that high-speed train can continue to transport medical supplies and disaster rescuers after the earthquake, this study uses the simply supported beam bridge of the CRTS II ballastless track high-speed railway as the research object. It builds a sample database of post-earthquake residual track geometric irregularity based on the earthquake's randomness. In addition, this research investigates the effectiveness of different signal analysis methods, such as the Short time Fourier transform and wavelet transform, in reconstructing track geometric irregularity. A method of constructing the representative sample of seismic-induced track irregularity based on confidence level is proposed. The results indicated that: (1) Seismic-induced track irregularity in high-speed railway bridges is dominated by alignment irregularity; (2) The amplitude of the time–frequency spectrum for seismic-induced track irregularity in high-speed railway bridges decreases from low to high frequencies, and does not contain a significant high-frequency component; (3) Compared to Short time Fourier transform, wavelet transform is more effective in reconstructing post-earthquake track geometric irregularity; (4) Seismic-induced track geometric irregularity based on the wavelet transform can be a valuable indicator for evaluating the performance of a high-speed train on a bridge after an earthquake.