Can Meta-Soil Attenuate Seismic Waves?

Open Access
Gawelko, Lexi
Area of Honors:
Civil Engineering
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Parisa Shokouhi, Thesis Supervisor
  • Eric Todd Donnell, Honors Advisor
  • metamaterial
  • earthquake
  • civil engineering
  • resonator
Stable and resilient civil infrastructure is a key to public safety. However, current structures are vulnerable to damage resulting from excessive ground motion caused by earthquakes or underground explosions. Traditionally, structures are built to withstand ground motion, but this design approach is costly and the risk of failure during very large events remains high. A fundamentally different approach is found in controlling the ground motion itself through engineering the soil to act as an acoustic metamaterial. Acoustic metamaterials are composites, often with a periodic substructure, that have the ability to control the propagation of elastic waves through scattering or local resonance mechanisms. Recently, advances in the understanding of metamaterials have allowed the creation of stop bands in wave transmission around the resonator's natural frequency. A graded array of low-frequency acoustic metamaterials provides the possibility to create targeted band-stops, effectively filtering out destructive ground motion. Numerical modeling is used to inform future experimental design to study this phenomenon at laboratory scale. Local resonators are modeled as spheres with a heavy metal core and a thin elastic coating. A sensitivity analysis is performed in order to inform the design of improved resonators. Then, alternative resonators are modeled as spheres with a heavy metal core and elastic columns made of plastic. The geometry and material properties of the resonators are varied in numerical simulations to optimize the frequency range and width of the band gaps. Similar resonators could be incorporated at full scale to create a seismic shield around critical structures.