Dynamic response characteristics and vibration transmission mechanisms of the CRTS III slab track under high speed train loading

The CRTS III slab ballastless track is widely deployed in China’s high-speed railway projects and faces the issue of intensified track structure vibrations under train loads. To investigate the dynamic response characteristics and transmission patterns of the track structure as train speeds increase, field acceleration measurements and data analysis were conducted. The results indicate that, under conditions of good track smoothness, higher operational speeds significantly amplify track structure vibrations-a factor that must be considered in design. With increasing speed, the dominant frequencies of the rail and track slab increase significantly, high-frequency components become more prominent, and the spectral range broadens. Conversely, the base plate and sealing layer exhibit lower dominant frequencies along with weaking of high frequency components and shifting of acceleration frequencies to low frequency bands. As the velocity increases, vibrations within the track structure progressively concentrate in the rail, track slab, and base plate, while those in the sealing layer diminish. A strong vibration dissipation effect is observed between the rail and track whereas transmission loss between the base plate and the sealing layer remains limited due to their verified structural bonding. At frequencies above 250 Hz, increasing speeds lead to significant transmission losses between the track slab and base plate, with notable attenuation of high frequency vibrations. At a speed of 180 km/h, the transfer function amplitude from the rail to the track slab is greater, through its frequency distribution is more concentrated. At higher speeds, more high frequency components are transmitted to the track slab. Meanwhile, in the low-frequency range, vibration transmission from base plate to the sealing layer decreases, while phase correlation analysis indicates improved vibration coherence between them.