Low frequency vibration mitigation performance of a phononic crystal-enhanced floating slab track

The low-frequency environmental vibrations induced by subway trains have attracted widespread attentions due to their detrimental effects on human health and precision instruments. Based on the theory of phononic crystals, a novel phononic crystal-enhanced floating slab track (PCFST) is proposed as an enhancement to the conventional steel spring floating slab track (SSFST), by introducing an elastic wave bandgap to elevate the low-frequency vibration mitigation performance. A periodic half-track model is established and subsequently solved by the spectral element method, elucidating the bandgap characteristics of the PCFST. Then, a coupled dynamic model of the vehicle-PCFST-foundation system is built to calculate the vibration responses of the track-foundation system under train loads, providing insights into the PCFST vibration mitigation performance. Furthermore, a laboratory hammer-impact test of the scaled PCFST model is conducted. The results indicate that the resonators in the PCFST contribute a bending wave bandgap of 10-15.28 Hz to the SSFST. The PCFST significantly improves the vibration mitigation performance at center frequencies within 8-16 Hz, and effectually addresses the vibration amplification issue associated with the low-frequency resonance of the floating slab. The accuracy of the simulation results and the effectiveness of the PCFST are corroborated by a scaled PCFST model test.