CRITICAL SPEED AND DYNAMIC RESPONSE OF HIGH-SPEED RAILWAY IN BALLASTLESS TRACK

The current requirements for train speed are getting higher and higher. When the train increases to the critical speed, it will cause resonance of track and substructure, which will adversely affect the train driving safety. At present, ballastless track is widely used in high-speed railway, and the vibration characteristics is different from ballasted track. Based on 2.5D finite element method, this paper establishes the vehicle-track-subgrade coupling model to analyze the critical speed of ballastless track under different foundation conditions. The relationship between critical speed and shear wave velocity of homogenous and layered subsoil is obtained through parametric analysis. The results show that the critical speed of ballastless track under homogenous subsoil depends on the Rayleigh wave velocity of subgrade. Besides, the presence of subgrade can improve the critical speed to be greater than the Rayleigh wave speed of homogenous subsoil. Moreover, the critical speed of ballastless track under layered subsoil is influenced by the shear wave speed ratio of adjacent soil layers. Finally, the proposed empirical formula is of guiding significance for the construction of ballastless track.