Environmental noise and vibration characteristics of rubber-spring floating slab track.

The floating slab track is considered one of the most effective track structures to reduce the adverse effects of underground railway noise and vibration. This paper reports a new type of rubber-spring float track (RSFS), which adopts a well-designed rubber-spring vibration isolator and is conceptually designed as a float track structure. The dynamic performance of different track structures, namely RSFS track, fixed slab track, and transition section, were studied. Vibration response of the car body and the track structure was obtained. Internal noise from the train and external noise near the tracks were also recorded. The results show that the measured track structures can ensure the safety of train operation. Compared with the fixed plate track, the RSFS track has a good vibration isolation effect, and the RMS vibration reduction at the tunnel wall was 15.1 dB. However, it amplifies the vibration above the isolation layer and slightly increases the internal noise of the train. RSFS track structure should be evaluated comprehensively before implementation. In addition, the track stiffness has a significant impact on the vibration level of the track, thus affecting the vibration isolation effect. The noise distribution inside the train is not uniform and is not sensitive to the stiffness of the track structure. Due to the uncertainty of train-induced vibration, a probabilistic framework is needed to evaluate or predict the train-induced environmental vibrations.