Centrifugal Modeling of Soil Liquefaction Susceptibility

Abstract

Presented are the results of an experimental research program involving centrifugal model tests on a column of sand confined by a stack of teflon coated aluminum rings with a latex membrane between the sand and the rings. Dynamic centrifugal model testing was performed in a 1 m radius Schaevitz centrifuge using a piezoelectric shaker. A column of Monterey 0 grade sand contained in a stacked-ring apparatus modelled a sand layer. The sand layer was instrumented with pore pressure transducers at different depths and accelerometers at the base and top. The model was excited at the base with sinusoidal motions of various amplitudes and the excess pore water pressures and the ground surface accelerations were monitored. The principal objectives were to study the generation and dissipation of excess pore water pressures, and to estimate the threshold peak ground surface acceleration, and the threshold shear strain necessary for the initiation of excess pore water pressure. The influence of prior strain history on the generation of pore water pressure was an additional objective of this study. The study showed that the meaured time history of excess pore pressure generation and pore water pressure distribution with depth compared favorably with that predicted by the currently available numerical procedures using dynamic test results obtained on small elements of homogeneous sand. The study also showed the significance of the initial prior strain history on pore pressure development and the accuracy of the peak threshold acceleration and shear strain estimated from dynamic tests on small elements of homogeneous sand in cyclic triaxial tests.