Surface waves attenuation using periodic buried soil-foam wave barriers

Using wave barriers is one of the effective measures for seismic wave attenuation. The barriers have different geometries and are arranged in periodic configurations. Considering the complex barrier behaviors and their miscellaneous characteristics, many research is conducted in recent years to find effective barriers. This paper proposes a new unit cell as a wave barrier to reduce the propagation of surface waves. Unlike the common practice in which harder and heavier materials are placed in the center and soil around it, the suggested unit cell consists of undisturbed soil as a core and a foam layer on both sides as a soft coating material. Firstly, a unit cell is considered in an infinite periodic lattice using solid-state physics concepts and periodic theories and is modeled using COMSOL Multiphysics FEM software. The dispersion curve can be obtained by changing the wave vector in the first irreducible Brillouin zone and calculating the corresponding eigenfrequencies. Then, the bandgaps are defined in the dispersion curves. Following that, because constructing an infinite lattice is impractical, a finite lattice of the unit cell is simulated to explore the unit cell efficiency in a more realistic setting. The time and frequency domain analyses are carried out using the finite lattices. The findings reveal that the proposed soil-foam unit cell with a height of four meters can effectively reduce the waves in the bandgap range in infinite and finite lattices. The obtained bandgap range is between 12.75 to 17.61 Hz.