Safety speed threshold of high-speed train running on bridges under seismic excitation of different soil types

Abstract

This study investigates the safety speed threshold of high-speed train running on bridges under seismic excitation of different soil types. In this paper, a train-track-bridge shaking table scale model test was conducted, and the train-track-bridge spatial coupling dynamics model was established. The reliability of the numerical model was verified by the tests. Afterward, the effects of transverse seismic excitation of different soil types on the train’s running safety were investigated, and the train’s safety speed thresholds were obtained. The results indicated that the dynamic response of the train-track-bridge system and the train’s running safety indices have an obvious increasing trend with the increase of peak ground acceleration and train’s running speed, and there are significant differences in the impact of different soil types. For the train-track-bridge system and the selected seismic records in this paper, the speed thresholds under different seismic fortification intensities were obtained based on the evaluation indices for the running safety of train. Among the four soil types, the safety speed threshold of soil type IV is lowest. The main frequency of soil type IV record is closer to that of the CRH380A train, resulting in severe rolling vibration of the train, and the offload factor has exceeded the limit when the speed is 50 km/h under the Loma seismic records with 8-degree seismic precautionary intensity.