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Finite-element analyses are performed of centrifuge tests consisting of untreated and drain-treated lateral spread sites, with the goal of evaluating the ability of numerical simulations to predict the response of sites improved with prefabricated vertical drains. Finite-element models of varying complexity are analyzed: a two-dimensional model of the full centrifuge test, a three-dimensional unit cell model around a single drain, and a two-dimensional unit cell model. All the finite-element models predict pore pressures consistent with the centrifuge tests. The deformation responses of the finite-element models show that unit cell analyses produce significantly larger deformations than those observed in the centrifuge. This result is caused by the fact that the centrifuge test geometry is not well represented by the infinite slope condition assumed in a unit cell. The full two-dimensional model predicts deformations that are more consistent with those of the centrifuge because it can capture the rotational mode of deformation experienced in the centrifuge. These results indicate that the expected mode of deformation should be considered when selecting the appropriate finite-element model to analyze a site. The simulations also show that constitutive models for liquefiable soils significantly overestimate the volumetric stiffness, which leads to inaccurate modeling of the diffusion process unless the model is appropriately modified. This issue is critical when simulating the performance of drain-treated sites. [ABSTRACT FROM AUTHOR]

Deep soil mixing (DSM) to form in-ground shear walls has been used to remediate against the potential effects of earthquake-induced liquefaction on many projects. A grid pattern of soil-cement walls act as a confined shear box, which can provide additional shear stiffness and strength for sites to withstand liquefaction. Current design practice for DSM grids commonly relies on the strain compatibility assumption, where the DSM walls and confined soil are assumed to experience the same shear strain. In this paper, the distributions of shear stresses and strains in liquefiable soil deposits treated with DSM grids are investigated using three-dimensional linear elastic finite-element analyses of unit cells. Parametric analyses are performed for a range of geometries, relative stiffness ratios, and dynamic loadings. These linear elastic results provide a baseline against which future nonlinear modeling results can be compared, but they are also sufficient for demonstrating that shear stress reductions are less than predicted by the assumption of shear strain compatibility. Modifications to the shear strain compatibility equation are presented, which improve its agreement with the results of these analyses. [ABSTRACT FROM AUTHOR]

Presents information on a study which analyzed steady cone penetration in clay using a novel finite-element procedure. Steady state deformation around cone penetrometer; Effects of stiffness and interface friction angle on cone factor; Effect of soil properties on strain paths.