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Comparison of Constitutive Laws for Numerical Simulation of Soil Liquefaction Phenomenon

Iranmanesh, Mohammad Ali | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44842 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Pak, Ali
  7. Abstract:
  8. Liquefaction is one of the probable consequences of earthquake in soil layers of saturated loose sands. Various aspects of liquefaction have been investigated using different methods of field, laboratory, and numerical studies. Numerical simulation of liquefaction constitutes a major part of these researches. A proper constitutive law must be implemented in the numerical analysis for modeling the complicated behavior of saturated sands during dynamic loading. Simplicity of formulation, limited number of parameters and good performance are the main features of a proper constitutive law. In this study, Endochronic model for simulating liquefaction has been introduced. This model is implemented into the finite element program, PISA. The model is able to predict magnitude of the pore water pressure, coupled with advanced models such as critical state two-surface plasticity or simple models such as Mohr-Coulomb. Simulating cyclic simple shear and centrifuge tests showed acceptable performance of this model in predicting variation of pore water pressure. Also in this research, the performance of some plasticity models for liquefaction modeling has been compared. Among boundary surfaces models, a critical state two-surface plasticity model (Manzari & Dafalias, 1997), among nested surfaces models, (Elgamal et al., 2002), among classical plasticity models, densification model (Zienkiewicz, Chang & Hinton, 1978) and among generalized plasticity models, Pastor-Zienkiewicz model (Zienkiewicz, Huang & Pastor, 1993) have been chosen for this purpose. Comparison of the performance of the above mentioned constitutive laws in simulating model number 1 of VELACS project showed that Manzari & Dafalias(1997) from category of the boundary surfaces and after that the model used by Elgamal et al. (2002) from category of the nested surfaces models predict better results compare to the other constitutive laws
  9. Keywords:
  10. Liquefaction ; Numerical Modeling ; Behavioral Models ; Endochronic Theory

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