Metabarriers for mitigating traffic-induced surface waves: Mechanism dependence on buried arrangements

Locally resonant metamaterials provide exceptional wave manipulation capabilities in the low-frequency regime. This study introduces a buried metabarrier, which can simultaneously harness both resonant and geometric scatterings, to attenuate surface Rayleigh waves at both low and high frequencies induced by traffic. In particular, how the buried arrangements of metabarriers influence their resonant- and geometric-scattering mechanisms is investigated by considering the metabarrier units buried vertically and horizontally in the ground. To this purpose, a numerical finite element model, which is verified through comparisons with existing studies, is developed to analyze the attenuation performance of the metabarrier. Using this model, we perform parametric studies to examine the effects of the material properties and dimensions of the metabarriers on their attenuation behavior. Due to resonant scattering, low-frequency Rayleigh waves are mainly reflected by the vertical metabarriers; in contrast, they are predominantly converted into refracted bulk waves by the horizontal metabarriers. Additionally, the geometric scattering of horizontal metabarriers yields Bragg effects, which can reflect more high-frequency Rayleigh waves and induce a partial mode conversion to transverse bulk waves. Our systematic investigations will, to some extent, facilitate the future design of a well-performing metabarrier attenuating broadband Rayleigh waves.