The Analysis of High-Speed Railway Seismic-induced Track Geometric Irregularity

The high-speed railway in China passes through various seismic zones. As the track geometric irregularity is a critical aspect impacting train operation safety and traininduced vibration, it is meaningful to investigate the influence of earthquakes on the seismic-induced track geometric irregularity of high-speed railways. To determine the impact of earthquakes on track conditions, a complete study was conducted using various earthquake magnitude levels (3.0 to 7.0), varied limiting train speeds, and different track structural types (ballasted and ballastless track). The track quality index, long-wave irregularities, 10 m chord measurement, and vehicle vibration are analysed to suggest the change of track geometric irregularity and its influence after the earthquake. At the same time, the vehicle-track analysis model is used to calculate the difference in vehicle vibration under different seismic-induced track conditions. The vehicle acceleration, the rate of wheel load reduction, derailment coefficient indicators are investigated. These results imply that earthquakes have an impact on high-speed railways, causing track geometric irregularities to shift, which may contribute to increased vibration while trains are running. Compared to the ballasted track, whose normal speed is 250 km/h, the ballastless track, whose nominal speed is 350 km/h, was affected by the earthquake less. According to data, earthquakes have an influence on long waves greater than 1 m. While small and moderate earthquakes have a minor effect on railway safety, they do have an effect on train operating comfort because vehicle vibration is amplified as a result of the seismic-induced track geometric irregularity being worse.