Physical modeling and analysis of site liquefaction subjected to biaxial dynamic excitations

The paper presents a series of centrifuge tests of level sites consisting of a granular soil deposit, with and without an embedded structure subjected to various biaxial and uniaxial base excitations. The tests were conducted at RPI NEES centrifuge facility to assess the dynamic response characteristics of level deposits and soil-structure interaction (SSI) under multidimensional conditions. Synthetic sinusoidal waves were used as base excitations to test soil models under biaxial and uniaxial shaking. A dense array of accelerometers was used to monitor the deposit response along with pore water pressure transducers. One uniaxial test and two biaxial shaking tests were conducted on three similar soil models, to study the effect of multidirectional shaking on the generation of soil liquefaction for dense deposits. The observed acceleration and pore pressure are used along with non-parametric identification procedures to evaluate the corresponding dynamic shear stress–strain histories. The measured results along with the obtained time histories are used to shed light on the mechanisms of liquefaction occurring through the stratum under multiaxial shaking. It also shows the effect of soil relative density on soil behavior when subjected to biaxial shaking. The soil–structure interaction test showed significant differences in soil behavior at different locations beneath the footing when subjected to biaxial shaking. This difference is associated with coupling in stress–strain in both experiments compared to the more known uniaxial soil behavior.