Vibration source characteristics and vibration reduction mechanism of the novel rubber pad floating slab track in metro turnout areas

Abstract

The vibration issues induced by metro turnout areas have become increasingly prominent recently. The novel rubber pad floating slab track (RPFST) is a type of assembled vibration-reducing track with the feature of slab-pad composite structure. To investigate the vibration source characteristics and the mechanism of vibration energy attenuation among different structural layers of the novel RPFST when a metro train passes through the turnout area, a vehicle-turnout-tunnel rigid-flexible coupled dynamic model was established based on the finite element method. It not only reflects the unique wheel-rail contact relationships in turnout area but also represents the vibration transmission of the nonlinear structural components of the turnout. Results show that, compared to the ordinary monolithic track bed (OMTB), the vibration source in the turnout area equipped with the novel RPFST exhibits narrower frequency band distribution, lower vibration amplitude, and longer vibration attenuation time. The novel RPFST can reduce the dominant frequency of tunnel wall vibrations. The dominant frequency in the crossing panel is higher than in other sections. The vertical and lateral vibration spectra of the tunnel wall both exhibit the characteristic of two frequency peaks, with the vertical vibration amplitude being about 1.3 times that of the lateral direction. The novel RPFST significantly attenuates the mid-to-low frequency vibration energy above 25 Hz in the turnout area, reducing energy by around 80 % after passing through the rubber pad layer, with a transmission loss can reach 23 dB. Compared to the OMTB, the insertion loss of the novel RPFST in the switch panel, closure panel, and crossing panel is 8 dB, 13 dB, and 9 dB, respectively.