LEAP-2017: Comparison of the Type-B Numerical Simulations with Centrifuge Test Results

This paper presents comparisons of 11 sets of Type-B numerical simulations with the results of a selected set of centrifuge tests conducted in the LEAP-2017 project. Time histories of accelerations, excess pore water pressures, and lateral displacement of the ground surface are compared to the results of nine centrifuge tests. A number of numerical simulations showed trends similar to those observed in the experiments. While achieving a close match to all measured responses (accelerations, pore pressures, and displacements) is quite challenging, the numerical simulations show promising capabilities that can be further improved with the availability of additional high-quality experimental results

Strain Space Multiple Mechanism Model for Clay Under Monotonic and Cyclic Loads

[The 6th International Conference on Earthquake Geotechnical Engineering (6ICEGE)] 1-4 November 2015; Christchurch, New Zealand.The strain space multiple mechanism model, originally developed for cyclic behavior of granular materials such as sand, is adapted for idealizing stress strain behavior of clay under monotonic and cyclic loads. The proposed model has advantages over the conventional elasto-plastic models of Cam-clay type in the facts that (1) arbitrary initial K0 state can be analyzed by static gravity analysis, (2) stress induced anisotropy (i.e. effect of initial shear) in the steady (critical) state can be analyzed based on Shibata’s dilatancy model (1963), (3) over-consolidated clay can be analyzed by defining the dilatancy at the steady state based on over-consolidation ratio, (4) strain rate effects for monotonic and cyclic shear can be analyzed based on Isotach/TESRA models proposed by Tatsuoka et al (2002) in the strain rate ranging from zero to infinity in addition to the conventional strain rate effects of secondary consolidation (creep) type. Performance of the proposed model is demonstrated through simulation of drained/undrained behavior of clay under monotonic and cyclic loading

Finite Deformation Analysis of Dynamic Behavior of Embankment on Liquefiable Sand Deposit Considering Pore Water Flow and Migration

[The 6th International Conference on Earthquake Geotechnical Engineering (6ICEGE)] 1-4 November 2015; Christchurch, New Zealand.To verify the applicability of a finite deformation analysis considering pore water flow using a strain space multiple mechanism model based on Total Lagrangian (TL) and Updated Lagrangian (UL) formulations, seismic response analyses are performed on the dynamic behavior of an embankment considering aftershocks after a main shock. Comparison between the experimental and analytical results indicated that the time history of excess pore water pressure was well simulated by considering the pore water drainage during computation. In addition, the results (e.g., the crest settlement, deformed configuration, and acceleration response) obtained in the finite deformation analyses based on both TL and UL formulations were in good agreement with the measurement. In conclusion, in order to accurately predict the behavior of embankment during and after large earthquakes, including aftershocks, it is required to take into account the effect of both geometrical nonlinearity and pore water flow and migration