Identification of Dynamic Properties of OII Landfill

Abstract

The performance of landfills during strong earthquake shaking is a matter of considerable concern and deserves to be studied more extensively. This paper investigates the dynamic properties of the OII landfill materials 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 materials behaved as essentially a linear viscoelastic material, showing 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. The physical origins of this frequency-dependent damping are not yet clearly understood. The results of this study are useful in analyzing the dynamic response of landfills and cap systems during small to moderate-size earthquakes. The present analysis is simplified because there were only two recording instruments at the OII landfill. It is recommended that researchers deploy more field instruments at this and other landfills to document their dynamic response during future earthquakes, and develop large-scale laboratory tests to determine landfill material properties under large static and dynamic strains.