Seismic metamaterials for energy attenuation of shear horizontal waves in transversely isotropic media

We study the energy attenuation of shear horizontal waves in a half-space with an overlying layer coupled with the interaction of seismic resonators. We focus on the material anisotropic effect of the layered media, allowing that both the top layer and the half-space are transversely isotropic. The anisotropy of the media is aimed to characterize the geological behavior of the earth due to sediment stratifications and, at the same time, could serve as additional flexibilities to interfere with the seismic metamaterials in different ways. Our objective is to explore possibilities of coupled interference so that, within a certain frequency range, the engineered internal structure of the resonators with suitable material composition can shield off much of the seismic wave energy for earthquake protection. Our results show that the two additional shear moduli will influence the dispersion behavior, including the two bounding shear velocities. With the inclusion of seismic resonators, we demonstrate that the displacement responses can be significantly reduced. A three-dimensional finite element simulation is conducted to demonstrate the effectiveness of seismic attenuation. Our study on the effect of soil material anisotropy will provide guidelines for a rational design of seismic metamaterials for shear horizontal waves.