Field Tests on Vibration Response of Ballastless Subgrade under Excitation of High Speed Train in China

By conducting field dynamic tests on a ballastless track-subgrade system located in the Milestone JJK86+274 of Beijing-Tianjin Intercity Dedicated Passenger Line in China, vibration velocities and their distributions of the center and the edge of slab track, the concrete roadbed edge, and the subgrade surface were measured under excitation of a high-speed train at the highest speed of 344 km/h in the world. The relationship between the maximum vibration velocity of slab track and train speed was also obtained. The results of the dynamic tests expand findings of the behavior of the ballastless track system on high-speed railway in Germany. An S-shaped growth curve along with a fitting formula are derived and can be used to describe the correlation between the maximum vibration velocity V_d and train speed V. This paper provides a useful reference for evaluation, prediction and control on dynamic response of ballastless subgrade, high safety, high stability and high comfort for the running of high-speed trains in the future.