Seismic metamaterial barriers for ground vibration mitigation in railways considering the train-track-soil dynamic interactions

With the rapid development of high speed rail system, ground vibration mitigation solutions are desperately needed. Based on the concepts of phononic crystals, seismic metamaterial, which is a novel vibration mitigation method, can theoretically yield excellent performance in shielding dynamic propagation waves in broad frequency bands. However, the application of seismic metamaterials in railway-induced vibration mitigation is a recent and ongoing topic. Therefore, this study aims to create new contribution towards a better understanding into the mitigation effects by seismic metamaterials for railway-induced ground vibrations. The seismic metamaterials are made of an array of concrete inclusions in this study. The dispersion theory for seismic metamaterials is proposed for analyzing the theoretical band gaps. A 3D coupled train-track-soil interaction model is also developed based on the multi-body simulation principle, finite element theory, and perfectly matched layers method using LS-DYNA. The dimensions of seismic metamaterials are determined based on the dominant frequencies of vibration accelerations in natural ground. When the seismic metamaterials are adopted in railway ground, the vibration responses are investigated in both time and frequency domains to illustrate the mitigation effects. Finally, the numbers of inclusions, initial distances, and train speeds are changed to investigate their influences on shielding effects. The insight from this study provides a new and better understanding of attenuating ground vibrations using seismic metamaterials in high speed railways.