Elastic surface wave attenuation in layered soil by metastructures

Seismic metastructures are able to effectively attenuate or convert elastic surface waves, attracting increasing attention in different areas such as civil engineering. However, the effects of the source depth and layered characteristics of viscous soil on metastructures for elastic surface wave reduction with Bragg bandgap mechanism remain challenging, which are the key issues for practical applications. In this work, we calculate the dispersion and transmission of metastructures in layered soil and confirm that the metastructures can effectively attenuate the elastic surface waves within the bandgaps. Then, the influence of the embedded depth of the metastructures, the depth of the vibrating source, layered characteristics of viscous soil on the surface vibration reduction are further discussed. It is found that surface vibration attenuation is enhanced by increasing the embedded depth of the metastructures and the density of the first layer. The width of the bandgap increases with the introduction of soil viscosity. On the contrary, the surface vibration attenuation decreases if the vibrating source is placed at a certain depth which requires the bandgap of bulk waves of the metastructures. This study of the seismic metastructures in layered soil provides a guidance in surface vibration reduction in practice.