This report presents the results of six large-scale centrifuge model tests that were performed to study the effects of relative density and thickness of the sand layer on the amount of settlement and lateral spreading of liquefied soils. The models included a “river” channel with clay flood banks underlain by layers of
loose and dense sand of variable thickness, and a bridge abutment surcharge on one of the banks. Each model was subjected to three or four significant ground motion events, and the measurements of acceleration, pore water pressure, settlement, and lateral movements are presented. Data from approximately 70 sensors and all shaking events are available via the Internet in well-documented data reports. A Deformation Index (DI), which combines the influences of depth, density, and layer thickness, was found to correlate reasonably well with liquefaction-induced settlements and lateral deformations. It was found that a thick, medium-dense sand layer may present more severe liquefaction consequences than thin, loose layers. Finite element simulations, using SUMDES and OpenSEES, are compared with the experimental results, and the capability of these programs to simulate the results of centrifuge test results are discussed. The increase of soil permeability during liquefaction seems to be an important problem that is not well modeled in analyses, but analytical procedures seem promising overall.
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