Effect of model container on dynamic shear stresses in a centrifuge model

Abstract

This study uses two-dimensional (2D) nonlinear dynamic analyses and one-dimensional (1D) inverse analyses of accelerations from virtual vertical arrays to examine the effect that a flexible shear beam model container has on the dynamic stresses that developed within centrifuge models of level saturated sand. The 2D dynamic analyses are performed using the finite difference program FLAC2D 9.0 with the user-defined constitutive model PM4Sand to obtain cyclic stress ratios on horizontal planes (CSR_xy) in the soil. The 1D inverse analyses, which assume 1D shear beam responses, are performed using virtual vertical array data extracted from the 2D dynamic models (i.e., horizontal nodal accelerations along columns) to also obtain cyclic stress ratios on horizontal planes (CSR_1D,Σma). Temporal and spatial differences between the CSR_1D,Σma and CSR_xy from the same analysis model provide a basis for estimating potential errors in the CSRs from either 1D dynamic or 1D inverse analyses of centrifuge array data. The 2D nonlinear dynamic and 1D inverse analysis methods are described, followed by results for three different centrifuge model scenarios. The container effects on cyclic stress ratios for this class of problem are summarized and discussed.