Numerical modeling of liquefaction and lateral ground deformation including cyclic mobility and dilation response in soil systems

Recent laboratory and analytical studies have focused attention on the importance of cyclic mobility and dilation in dictating lateral deformation of many cohesion-less soils under cyclic loading conditions. Consequently, the main objective of this thesis was to develop an analytical computational procedure capable of modeling this phenomenon during dynamic earthquake excitation. For that purpose, a new soil constitutive model was developed. This model was based on the original framework of plasticity theory for frictional cohesionless soils presented by Prevost 1985. A Biot-type theory for solid-fluid coupled analyses after the works of Chan and Zienkiewicz was also numerically implemented. This coupled formulation and the developed constitutive model were implemented in a general purpose 2-D (plane strain and axisymmetric) finite element program.; Using this developed computer program, results of computational analyses to model two major centrifuge studies representing 1-D and 2-D spatial stress conditions are presented and thoroughly discussed. The computational model was calibrated by experimental laboratory and centrifuge testing data. Thereafter, the calibrated model was used to predict other dynamic experimental centrifuge results. Modeling the dilative material characteristics was shown to be critical in predicting appropriate cyclic lateral deformations, surface acceleration response, and pore water pressure buildup. Finally, it was demonstrated that the developed numerical algorithm is an extremely effective tool for assessment of lateral deformations and effectiveness of liquefaction countermeasure techniques. Calibration and prediction of seismic response at Lotung, Taiwan were also performed and is presented in detail. This study was undertaken to illustrate the capabilities and limitations of the developed methodology in an actual well documented seismic response situation.