Geoscience Reference
In-Depth Information
9.2. Introduction
Macroscopic models used within the field of continuum mechanics are still the
most rational tools for modeling the behavior of constructions, though with the steady
development of computational methods, micromechanical models are becoming a
viable alternative for analyzing the phenomena governing the behavior of soils. For
any given problem, the quality of the numerical simulation depends on not only the
selection of the physical model and the methods of identifying its parameters, but also
the numerical process of integrating and solving the model's equations, which should
satisfy the concerns of efficiency and rapidity.
Jean Biarez was one of the first in France to recognize the potential of the finite
element method. In the 1970s, he encouraged a certain number of his students, namely
Denis Aubry, Philippe Descrois, and Jean-Claude Hujeux to study this new method.
Under the dynamic direction of Biarez, the laboratory of soil, structure and material
mechanics (LMSSMat) at
Ecole Centrale de Paris
(ECP) acquired a rich and
unparalleled experience in studying soil behavior. The ECP elastoplastic model, best
known as the “Hujeux model”, came out of the research studies of those days. Even
today, it is one of the most efficient models available, especially for modeling cyclic
loading.
A family of models incorporating the same basic mechanisms but serving different
purposes now exists. At first, the multimechanism and cyclic version of the model
presented by J.C. Hujeux [HUJ 85] introduced the notion of domain of behavior. After
years of research in both mechanics and numerical modeling, the
GEFDyn
software
was completed under the supervision of Denis Aubry [AUB 86, AUB 96]. Since then,
other versions of this model have been developed, such as:
- multimechanism elasto-visco-plastic model incorporating the work of Kodaissi
[AUB 91, KOD 83];
- model for asphalt concrete [AUB 87, MOD 89b];
- elastoplastic cyclic interface model [AUB 90];
- elastoplastic model for unsaturated soils [ABO 92, ABO 95, MOD 94a,
MOD 94b, MOD 96];
- thermo-elasto-plastic or thermo-elasto-viscoplastic model [LAL 95, MOD 97];
- thermo-elasto-plastic model for unsaturated soils [MOD 95];
- elastoplastic model with damage mechanism [MOD 03];
- plastic model with oriented criteria [MOD 03, PIC 91, VOS 01].
The ECP elastoplastic model is based on a relatively simple formulation that
nevertheless manages to describe the elementary mechanisms of soil behavior. The
particular advantage of this model is that it has already been used over decades
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