VIBRATION ISOLATION PERFORMANCE OF FLOATING SLAB TRACK SYSTEM

Floating slab track system is one of the most effective measures for mitigating ground-borne vibration induced by metro trains, while it is only effective in reducing medium and high frequencies above 2 times the resonance frequency of the track. Therefore, it is important to expand the vibration isolation range and improve the vibration isolation performance of floating slab track. In this paper, a double-beam model on rigid foundation subject to a harmonic moving load is employed to assess vibration isolation performance of floating slab system with various parameters. Both of the rails and the track are assumed to act as infinitely long double Euler-Bernoulli beam on elastic foundation. Rail pads and the slab bearings are represented by continuous layers with uniform stiffness and damping constant. The evaluated parameters include structural parameters (such as mass of slab) and dynamic parameters (such as stiffness, damping of bearing, etc.). The result demonstrates that decreasing stiffness and increasing damping factor can conspicuously reduce the force transmission to improve the vibration isolation effectiveness, while the increasing mass has no obvious effect for low frequency excitation. Increasing slab mass and decreasing bearing stiffness can reduce the resonance frequency of floating slab track to expand the vibration isolation range. Under the security and stability conditions of traffic operation, reasonable ranges of parameters are given to provide reference for design.