Analytical and numerical investigation of finite and infinite periodic lattices for mitigation of seismic waves in layered grounds

Abstract

This paper studies periodically arranged seismic barriers consisting of finite and infinite lattices to mitigate seismic surface waves in layered soils. Using Bloch-Flouquet theory, three different configurations of periodic barriers are examined. Rayleigh, Love, and shear surface waves are quantitatively identified using three conceptions: depth of energy, sagittal polarization ratio, and sound cone. The performed analyses suggest that if barriers increase the surface stiffness of existing ground, Rayleigh modes will be located above the sound cone, thus providing energy dissipating channels through bulk modes. Numerical modeling of finite barriers in time and frequency domains validates the concept of Rayleigh modes’ energy dissipation to bulk modes. The results indicate that the designed barriers effectively reduce the amplitude of surface seismic waves, thus mitigating damage from seismic events.