Physical Modeling and Analysis of Site Liquefaction Subjected Biaxial Dynamic Excitations

The paper presents a series of centrifuge tests of level sites consisting of a granular soil deposits subjected to various bi-axial and uniaxial base excitations. The tests were conducted at RPI NEES centrifuge facility to assess the dynamic response characteristics of level deposits under multidimensional conditions. Synthetic sinusoidal waves were used as base excitations to test dense 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 one biaxial shaking test were conducted on two 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 estimate the corresponding dynamic shear stress-strain histories. The measured results along with the obtained time histories are used to shed the light on the mechanisms of liquefaction occurring through the stratum under uniaxial shaking. It also shows the effect of soil relative density on soil behavior when subjected to biaxial shaking. This difference is evident in the coupling in stress-strain loops compared to the more known uniaxial soil behavior.