Seismic site response of layered saturated sand: comparison of finite element simulations with centrifuge test results

Abstract

A numerical model based on the finite element framework was developed to predict the seismic response of saturated sand under free-field conditions. The finite element framework used a non-linear coupled hypoplastic model based on the u-p formulation to simulate the behaviour of the saturated sand. The u-p coupled constitutive model was implemented as a user-defined routine in commercial ABAQUS explicit 6.14. Results of centrifuge experiments simulating seismic site response of a layered saturated sand system were used to validate the numerical results. The centrifuge test consisted of a three-layered saturated sand system subjected to one-dimensional seismic shaking at the base. The test set-up was equipped with accelerometers, pore pressure transducers, and LVDTs at various levels. Most of the constitutive models used to date for predicting the seismic response of saturated sands have underestimated volumetric strains even after choosing material parameters subjected to rigorous calibration measures. The hypoplastic model with intergranular strains calibrated against monotonic triaxial test results was able to effectively capture the volumetric strains, reasons for which are discussed in this paper. The comparison of the numerical results to centrifuge test data illustrates the capabilities of the developed u-p hypoplastic formulation to perform pore fluid analysis of saturated sand in ABAQUS explicit, which inherently lacks this feature.

Investigation of the effects of cyclic lateral load characteristics on monopiles in saturated sandy soils using hypoplastic material model

“…Ottawa sand with a relative density (D r ) of %75, a maximum void ratio of 0.800, and a minimum void ratio of 0.608 was used for model preparation for the test. Basic hypoplastic material properties of Ottawa sand from Niemunis and Herle 25 and intergranular strain parameters from Nagula et al 33 are given in Table 1.…”

“…T A B L E 1 Ottawa sand hypoplastic material parameters. 25,33 Parameters F I G U R E 3 Prototype FEA model and place of the pore pressure transducers.…”

Numerical Modeling of a Pile Group Subjected to Seismic Loading Using the Hypoplasticity Model

“…In order to validate the program's capabilities in modeling the hypoplasticity problem, the findings from experimental, numerical (Open Sees, SANI SAND model), and PLAXIS 3D hypoplasticity analysis were compared. The problem involved a comparison between the results obtained from the experimental and numerical research performed by [22][23][24] and the results obtained from PLAXIS 3D. The problem includes conducting a number of centrifugal tests to assess the interaction between the soil and the structure of layered liquefiable soil deposits and the seismic site response.…”