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Item type:Publication, Access status: with files , Seismic site response of layered saturated sand: comparison of finite element simulations with centrifuge test resultsA 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.Publicationtype: Journal ArticleScopus© Citations 5 137 204 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Numerical investigation of liquefaction mitigation potential with vibroflotation(2021-07); ; ; Vibroflotation is one type of ground improvement technique used for liquefaction mitigation in saturated sand. In order to study the feasibility of vibroflotation for liquefaction mitigation, two numerical models were created in the finite element framework. A nonlinear, coupled, hypoplastic u-p formulation was developed to simulate the behaviour of saturated sand. Numerical results were validated against on-field cone penetration test measurements after vibroflotation and centrifuge test simulating seismic site response of saturated sand. Seismic site response of saturated sand before and after vibroflotation was analysed. Saturated loose sand with fines and lower permeability underwent excess pore pressure generation, softening, and possibly liquefaction under seismic loading before vibroflotation. Sands with higher permeability were found to respond better to vibroflotation. The most effective degree of compaction was achieved in dry sands. Vibroflotation of saturated sand with fines ensured improved resistance against liquefaction whereas for coarse sands it led to complete eradication of the liquefaction.Publicationtype: Journal Article64