Constitutive modeling approaches for cross-anisotropic porous rocks

G. Buscarnera, F. Marinelli, G. Shahin

Research output: Contribution to conferencePaperpeer-review

1 Scopus citations

Abstract

Simulating the anisotropy of rock properties is a major challenge for geomechanical modeling. Despite numerous techniques that have been proposed to account for the orientation of the material reference system with respect to the loading directions, such methods often involve a major increase in the number of model parameters, especially if the anisotropy influences both elastic and plastic properties. In this paper, two approaches to model the mechanical behavior of cross-anisotropic porous rocks are examined. The first approach relies on a tensorial projector used in conjunction with standard strain-hardening plasticity. It is illustrated how such projector is able to map the stress conditions into a modified stress space, thus distorting the yield surface and inducing the dependence of yielding on the direction of sample coring. Afterwards, a novel energy-based approach to replicate such mapping effects is discussed. The methodology relies on the Breakage Mechanics theory, i.e. a constitutive framework expressing the yielding of granular rocks in terms of a strain energy threshold associated with the release of the elastic energy stored in the brittle grains constituting its skeleton. It is shown that energy-based yielding produces the same benefits of a tensorial projection without the need of introducing additional model parameters, but solely relying on the directional properties of the elastic stiffness tensor. The capabilities and performance of both approaches with respect to data available for a porous rock are outlined, discussing their relative merits and providing guidelines for the formulation of constitutive laws able to reduce the number of model parameters by relying on more detailed insights on the microscopic causes of inelasticity.

Original languageEnglish (US)
StatePublished - 2020
Event54th U.S. Rock Mechanics/Geomechanics Symposium - Virtual, Online
Duration: Jun 28 2020Jul 1 2020

Conference

Conference54th U.S. Rock Mechanics/Geomechanics Symposium
CityVirtual, Online
Period6/28/207/1/20

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Geotechnical Engineering and Engineering Geology

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