Generalized Hoek-Brown elasto-plasticity and stress state estimation nearby faults

Nicolas Clausolles and Antoine Mazuyer and Richard Giot. ( 2016 )
in: 2016 RING Meeting, ASGA

Abstract

A fault can be described as a mechanical heterogeneity in a medium. Stress orientation and magnitude are disturbed nearby it. Faults could be modeled as a volume, with a fault core and a damage zone. Studies have shown that material properties evolve from the fault core to the edge of the damage zone. The goal of this paper is to compare the stress estimation in the core and the damage zone using two different behavior laws. The first one is elastic (Hooke’s law) and involves only two parameters. The second is elasto-plastic (Hoek-Brown criterion) and involves 4 parameters in addition to the elastic ones. We will especially focus on the implementation of the Hoek-Brown criterion algorithm which assumes isotropic media, linear elasticity and perfect plasticity. The algorithm is divided into two parts: the first one solves a static Finite Element problem by dividing and adding the boundary conditions by increments, and the second one is the stress state computation itself. The calculations are carried out using a return mapping scheme. In a first time the purely elastic response of the material is computed, and if the yielding criterion is exceeded, the stress state is returned to the criterion in a second time.

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BibTeX Reference

@INPROCEEDINGS{,
    author = { Clausolles, Nicolas and Mazuyer, Antoine and Giot, Richard },
     title = { Generalized Hoek-Brown elasto-plasticity and stress state estimation nearby faults },
 booktitle = { 2016 RING Meeting },
      year = { 2016 },
 publisher = { ASGA },
  abstract = { A fault can be described as a mechanical heterogeneity in a medium. Stress orientation and
magnitude are disturbed nearby it. Faults could be modeled as a volume, with a fault core and
a damage zone. Studies have shown that material properties evolve from the fault core to the
edge of the damage zone. The goal of this paper is to compare the stress estimation in the core
and the damage zone using two different behavior laws. The first one is elastic (Hooke’s law) and
involves only two parameters. The second is elasto-plastic (Hoek-Brown criterion) and involves
4 parameters in addition to the elastic ones. We will especially focus on the implementation of
the Hoek-Brown criterion algorithm which assumes isotropic media, linear elasticity and perfect
plasticity. The algorithm is divided into two parts: the first one solves a static Finite Element
problem by dividing and adding the boundary conditions by increments, and the second one is the
stress state computation itself. The calculations are carried out using a return mapping scheme.
In a first time the purely elastic response of the material is computed, and if the yielding criterion
is exceeded, the stress state is returned to the criterion in a second time. }
}