IDENTIFICATION OF DYNAMIC PROPERTIES OF OII LANDFILL

The performance of landfills during strong earthquake shaking is a mat ter of considerable concern and deserves to be studied more extensivel y. 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 landf ill materials behaved as essentially a linear viscoelastic material, s howing a negligible reduction in shear modulus with shear strain ampli tude. The damping responsible for energy dissipation was found to depe nd on frequencies between 0.1 and 10 Hz. The physical origins of this frequency-dependent damping are not yet clearly understood. The result s of this study are useful in analyzing the dynamic response of landfi lls and cap systems during small to moderate-size earthquakes. The pre sent analysis is simplified because there were only two recording inst ruments at the On landfill. It is recommended that researchers deploy more held instruments at this and other landfills to document their dy namic response during future earthquakes, and develop large-scale labo ratory tests to determine landfill material properties under large sta tic and dynamic strains.