Dynamic Characteristics Analysis of Prefabricated Floating Slab Track in Special Vibration Section

Research purposes: In order to meet the vibration reduction requirements of special sections of urban rail transit with a speed of 120 km/h, and to facilitate construction, maintenance and repair, a new fabricated floating slab track structure was proposed. Based on the finite element method and vehicle-track system coupling dynamics, the modal analysis, dynamic index evaluation and vibration reduction effect evaluation of the structure were carried out, and the effects of different slab lengths were compared and analyzed. Research conclusions:(1) When the length of floating slab is 3.55 m, 4.75 m and 5.95 m, the fundamental frequency of structure is 12~14 Hz. The increase of slab length will reduce the natural frequency, while has little influence on modal shape of each order. (2) The running safety, stability and track structure stability of 4.75 m and 5.95 m floating slab all meet the requirements. In order to meet the requirements of all dynamic response indexes, the steel spring supporting stiffness of the 3.55 m floating slab should be greater than 8.5 MN/m. (3) The root mean square differences of frequency division vibration level corresponding to the slab length of 3.55 m, 4.75 m and 5.95 m are 14.32 dB, 15.49 dB and 16.48 dB. The longer the floating slab is, the worse the vibration reduction effect at low frequency 1~5 Hz, but the better the vibration reduction effect at high frequency 20~125 Hz, which is more in line with the vibration reduction requirements of urban rail transit. In the specific structural design, the type of slab shall be reasonably selected according to the construction conditions and actual vibration reduction requirements in combination with the results of environmental impact assessment. (4) For the special vibration reduction section of urban rail transit, the research result can provide theoretical guidance for the selection and application of prefabricated floating slab track. © 2022, Editorial Department of Journal of Railway Engineering Society. All right reserved.