Abstract
The performance of landfills during strong earthquake shaking is a matter of considerable concern that deserves to be studied more extensively than it has been. The dynamic properties of the Operating Industries Inc. (OII) landfill materials have been investigated using strong-motion recordings, available field measurements, and simplified physical models. Although the earthquakes recorded at the OII landfill generated shear strains as large as 0.08%, the landfill material behaved essentially as a linear viscoelastic material with a negligible reduction in shear modulus with shear strain amplitude. The damping responsible for energy dissipation was found to depend on frequencies between 0.1 and 10 Hz. This frequency-dependent damping is presumed to result from scattering of waves on heterogeneities within the landfill and diffusion of interstitial fluids. The results of this study are useful for analyzing the dynamic response of landfills and cap systems during low-to-moderate sized earthquakes. The analysis is simplified because there were only two recording instruments on the OII landfill. It is recommended that more field instruments be deployed on this and other landfills to document their dynamic response during future earthquakes, and to develop large-scale laboratory tests to determine landfill material properties under large dynamic strains.