Abstract
Railway GBN impact has raised increasing concerns due to underground transportation expansion. Reducing train speed or replacing standard baseplates with high resilient ones are adopted for GBN control. Both mitigations are not satisfactory considering the installation difficulty and limited performance, e.g., only ~3dB noise reduction for 30% train speed reduction. On the other hand, FST (Floating Slab Track) are commonly used. In many cases, to accommodate the FST, tunnel diameter is enlarged for the TBM (Tunnel Boring Machine) tunnel section. Also, rail dampers are used for air-borne noise control, but never used for GBN control due to its relatively small mass. P2 resonance is a main cause of railway GBN. It is a simple harmonic motion of a lump mass (wheel and rail combined) oscillating on top of resilient baseplates. Laboratory test was conducted with a 6m fastened rail and a ~450kg mass to simulate train wheel and track system. A retrofit rail damper with TMD (Tuned Mass Damping) oscillators was tested. The mass of TMD oscillators along the rail with ~2m effective length of P2 resonance is more than 10% of the wheel. Around 7dB vibration reduction was recorded at the rail and floor when allowing the TMD oscillation.
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