The effect of stress-induced anisotropy on a model of brittle rock failure as localization of deformation

John W Rudnicki*

*Corresponding author for this work

Research output: Contribution to conferencePaperpeer-review

10 Scopus citations


In the axisymmetric compression test, rock samples, even those which are isotropic when unstressed, develop a transversely isotropic structure after a small amount of inelastic deformation due to the preferential growth of microcracks in the axial direction. To examine the effect of this developed anisotropy on faulting, conditions for the localization of deformation are derived for the most general form of stress strain relation for a material exhibiting transversely isotropic incremental response. This constitutive law involves six independent, incremental moduli. Expressions are derived for the predicted slope of the axial stress vs. axial strain curve at faulting and for the predicted fracture angle. Unfortunately, laboratory data are not sufficient to determine the values of all the incremental moduli, specifically, the moduli governing shearing parallel and transverse to the specimen axis. Nevertheless, for a plausible range of these moduli, the predicted fracture angle is relatively insensitive to their exact value and is shown to agree with experimentally observed values. If these shear moduli are interpreted as incremental elastic values, the results for the predicted slope at localization suggest that although stress-induced anisotropy may cause some reduction in the amount of postpeak deformation predicted for localization, it is not sufficient to cause localization to be predicted at peak load. However, it is possible that yield surface vertex effects may cause a further reduction of the amount of postpeak deformation prior to predicted localization.

Original languageEnglish (US)
StatePublished - 1977
Event18th U.S. Symposium on Rock Mechanics, USRMS 1977 - Golden, United States
Duration: Jun 22 1977Jun 24 1977


Other18th U.S. Symposium on Rock Mechanics, USRMS 1977
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology


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