Non‐associative constitutive laws for low porosity rocks

Senseny, P.E.; Fossum, A.F.; Pfeifle, T.W.

doi:10.1002/nag.1610070110

Cited by 25 publications

(16 citation statements)

References 9 publications

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“…While the laboratory data do indicate dilatancy and therefore agree qualitatively with the theory, there is significant discrepancy between the magnitudes of the theoretically predicted and experimental values. This tendency for an associated flow rule to consistently overestimate the magnitude of dilatation at brittle failure has previously been noted in soil (Chen, 1984;Desai and Siriwardane, 1984) and in low-porosity rock (Senseny et al, 1983).…”

Section: Strain Hardening and Spatial Evolution Of Damagesupporting

confidence: 73%

Mechanical Compaction of Porous Sandstone

Wong

Baud

1999

Oil & Gas Science and Technology - Rev. IFP

102

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Résumé -Compaction mécanique des grès poreux -Pour de nombreux problèmes de tectonique et d'ingénierie de réservoir, la capacité à prévoir à la fois la fréquence, l'ampleur de la déformation inélas-tique et les ruptures repose sur une compréhension fondamentale de la phénoménologie et de la micromé-canique de compaction dans les roches-réservoirs. Cet article présente les résultats de recherches récentes sur la compaction mécanique des grès poreux. On insiste plus particulièrement sur la synthèse des données de laboratoire, la caractérisation microstructurale quantitative de l'endommagement, ainsi que sur les modèles théoriques basés sur un contact élastique et sur la mécanique de la rupture. Les attributs méca-niques de la compaction sur des échantillons initialement secs et saturés ont été étudiés sous des chargements hydrostatiques et non hydrostatiques dans une large gamme de pression. Les sujets spécifiques étu-diés ici incluent : la comparaison des données d'émission acoustique et mécanique avec une théorie de la plasticité ; le contrôle microstructural du début et du développement de la compaction ; l'écrouissage et l'évolution spatiale de l'endommagement lors de la compaction ; enfin, l'effet affaiblissant de l'eau sur le seuil de compaction et l'évolution de la porosité.Mots-clés : essais triaxiaux, porosité, émissions acoustiques, endommagement microstructural, compaction, dilatance. Abstract -Mechanical Compaction of Porous Sandstone -In many reservoir engineering and tectonic problems, the ability to predict both the occurrence and extent of inelastic deformation and failure hinges upon a fundamental understanding of the phenomenology and micromechanics of compaction in

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Section: Strain Hardening and Spatial Evolution Of Damagesupporting

confidence: 73%

Mechanical Compaction of Porous Sandstone

Wong

Baud

1999

Oil & Gas Science and Technology - Rev. IFP

102

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“…While Kayenta does support associativity at user request, many researchers report that normality tends to over-predict the amount of volumetric plastic strain [53]. Therefore, non-normality is supported in Kayenta as well.…”

Section: Advancing the Solution (Groundwork Discussion)mentioning

confidence: 97%

KAYENTA : theory and user's guide.

Brannon

Fossum

Strack

2009

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The physical foundations and domain of applicability of the Kayenta constitutive model are presented along with descriptions of the source code and user instructions. Kayenta, which is an outgrowth of the Sandia GeoModel, includes features and fitting functions appropriate to a broad class of materials including rocks, rock-like engineered materials (such as concretes and ceramics), and metals. Fundamentally, Kayenta is a computational framework for generalized plasticity models. As such, it includes a yield surface, but the term "yield" is generalized to include any form of inelastic material response including microcrack growth and pore collapse. Kayenta supports optional anisotropic elasticity associated with ubiquitous joint sets. Kayenta supports optional deformation-induced anisotropy through kinematic hardening (in which the initially isotropic yield surface is permitted to translate in deviatoric stress space to model Bauschinger effects). The governing equations are otherwise isotropic. Because Kayenta is a unification and generalization of simpler models, it can be run using as few as 2 parameters (for linear elasticity) to as many as 40 material and control parameters in the exceptionally rare case when all features are used. For high-strain-rate applications, Kayenta supports rate dependence through an overstress model. Isotropic damage is modeled through loss of stiffness and strength. We are grateful to our family members for their patience and support during the ongoing development of this model.

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“…Non-associative plastic flow has been observed for low-porosity rocks [21]. The frictional strength parameters B, h, and R typically overestimate the observed volumetric plastic deformation, warranting a non-associative model with L, /, and Q determined from experimental measurements of volumetric plastic deformation.…”

Section: Yield Functionmentioning

confidence: 92%

“…The next step is to multiply the second term in Eq. (21) by an elliptical cap function to account for yielding in compression.…”

Section: Yield Functionmentioning

confidence: 99%

Implicit numerical integration of a three-invariant, isotropic/kinematic hardening cap plasticity model for geomaterials

Foster

Regueiro

Fossum

et al. 2005

Computer Methods in Applied Mechanics and Engineering

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The mechanical constitutive behavior of geomaterials is quite complex, involving pressure-sensitive yielding, differences in strength in triaxial extension vs. compression, the Bauschinger effect, dependence on porosity, and other factors. Capturing these behaviors necessitates the use of fairly complicated and expensive non-linear material models. For elastically isotropic materials, such models usually involve three-invariant plasticity formulations. Spectral decomposition has been used to increase the efficiency of numerical simulation for such models for the isotropically hardening case. We modify the spectral decomposition technique to models that include kinematic hardening. Finally, we perform some numerical simulations to demonstrate quadratic convergence.

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Non‐associative constitutive laws for low porosity rocks

Cited by 25 publications

References 9 publications

Mechanical Compaction of Porous Sandstone

Mechanical Compaction of Porous Sandstone

KAYENTA : theory and user's guide.

Implicit numerical integration of a three-invariant, isotropic/kinematic hardening cap plasticity model for geomaterials

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