Locally resonant seismic metamaterial with an ultrawide and ultralow-frequency bandgap designed from gyroid-type triply periodic minimal surfaces

Abstract In this study, we propose a locally resonant seismic metamaterial (SM) inspired by gyroid-typed triply periodic minimal surfaces. This novel SM with a lattice constant of only 2.0 m achieves an ultrawide and ultralow-frequency bandgap of 0–47.05 Hz, covering the frequencies of typical seismic waves completely. Calculations for homogeneous half-space models show that the proposed SM with infinite units can absolutely isolate the surface waves and drive the P-and S-waves away from the surface of the earth. The efficiency of the SM attenuating seismic waves decreases markedly in layered formations with a cover layer of soft soil because the layer interface obstructs the P-and S-waves going away from the surface of the earth. This decrease in attenuation efficiency can be resolved by adjusting the height of the SM to correspond with or exceed the thickness of the cover layer. Furthermore, we conduct a 1/40 scaled-down experiment in the laboratory to validate the effectiveness of the proposed SM for attenuating seismic waves with ultralow frequencies. The ultra-low-frequency bandgap relies on TPMS-type structure characteristics of the SM, whose materials can be selected according to the engineering requirements. This study provides a new way for seismic wave shielding, which can promote the application of SM in practical engineering.