Anisotropic breakage mechanics

From stored energy to yielding in transversely isotropic granular rocks

Ferdinando Marinelli, Giuseppe Buscarnera*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The microstructure of geological solids is affected by their deposition history, which generates complex systems of grain contacts and damage patterns able to induce mechanical anisotropy. This paper aims to disclose the connection between energy storage and the yield surface of cross-anisotropic granular rocks, with the goal to simplify the representation of their mechanical anisotropy. For this purpose, a reformulation of Continuum Breakage Mechanics (CBM) is proposed to introduce material symmetries associated with energy storage processes. It is shown that, due to the thermodynamic consistency of the selected approach, the energy release resulting from comminution is influenced by the anisotropic characteristics of the elastic energy potential. As a result, the model is able to capture naturally and without additional fitting parameters the dependence of the yielding envelope on the relative orientation between bedding planes and loading direction. The performance of the new CBM model has been tested by performing parametric analyses which elucidate the role of cross-anisotropic elastic properties on the yield surface of a granular rock. Furthermore, its accuracy has been assessed against laboratory results available for two sandstones exhibiting dependence of the yield stress on the orientation of the bedding planes. Despite the simplicity of the selected model, the results emphasize that the proposed approach captures the salient features of the deformation response of anisotropic granular rocks, thereby disclosing an intimate connection between grain-scale energy release and cataclastic yielding which greatly simplifies the mathematical description of intrinsic inelastic anisotropy.

Original languageEnglish (US)
Pages (from-to)1-18
Number of pages18
JournalJournal of the Mechanics and Physics of Solids
Volume129
DOIs
StatePublished - Aug 1 2019

Fingerprint

continuum mechanics
Mechanics
Anisotropy
Rocks
rocks
energy storage
Energy storage
anisotropy
comminution
Comminution
sandstones
Potential energy
Sandstone
complex systems
Yield stress
energy
Large scale systems
envelopes
elastic properties
potential energy

Keywords

  • Bedding planes
  • Breakage mechanics
  • Granular rocks
  • Porous rocks
  • Yielding
  • intrinsic anisotropy

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

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title = "Anisotropic breakage mechanics: From stored energy to yielding in transversely isotropic granular rocks",
abstract = "The microstructure of geological solids is affected by their deposition history, which generates complex systems of grain contacts and damage patterns able to induce mechanical anisotropy. This paper aims to disclose the connection between energy storage and the yield surface of cross-anisotropic granular rocks, with the goal to simplify the representation of their mechanical anisotropy. For this purpose, a reformulation of Continuum Breakage Mechanics (CBM) is proposed to introduce material symmetries associated with energy storage processes. It is shown that, due to the thermodynamic consistency of the selected approach, the energy release resulting from comminution is influenced by the anisotropic characteristics of the elastic energy potential. As a result, the model is able to capture naturally and without additional fitting parameters the dependence of the yielding envelope on the relative orientation between bedding planes and loading direction. The performance of the new CBM model has been tested by performing parametric analyses which elucidate the role of cross-anisotropic elastic properties on the yield surface of a granular rock. Furthermore, its accuracy has been assessed against laboratory results available for two sandstones exhibiting dependence of the yield stress on the orientation of the bedding planes. Despite the simplicity of the selected model, the results emphasize that the proposed approach captures the salient features of the deformation response of anisotropic granular rocks, thereby disclosing an intimate connection between grain-scale energy release and cataclastic yielding which greatly simplifies the mathematical description of intrinsic inelastic anisotropy.",
keywords = "Bedding planes, Breakage mechanics, Granular rocks, Porous rocks, Yielding, intrinsic anisotropy",
author = "Ferdinando Marinelli and Giuseppe Buscarnera",
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language = "English (US)",
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T2 - From stored energy to yielding in transversely isotropic granular rocks

AU - Marinelli, Ferdinando

AU - Buscarnera, Giuseppe

PY - 2019/8/1

Y1 - 2019/8/1

N2 - The microstructure of geological solids is affected by their deposition history, which generates complex systems of grain contacts and damage patterns able to induce mechanical anisotropy. This paper aims to disclose the connection between energy storage and the yield surface of cross-anisotropic granular rocks, with the goal to simplify the representation of their mechanical anisotropy. For this purpose, a reformulation of Continuum Breakage Mechanics (CBM) is proposed to introduce material symmetries associated with energy storage processes. It is shown that, due to the thermodynamic consistency of the selected approach, the energy release resulting from comminution is influenced by the anisotropic characteristics of the elastic energy potential. As a result, the model is able to capture naturally and without additional fitting parameters the dependence of the yielding envelope on the relative orientation between bedding planes and loading direction. The performance of the new CBM model has been tested by performing parametric analyses which elucidate the role of cross-anisotropic elastic properties on the yield surface of a granular rock. Furthermore, its accuracy has been assessed against laboratory results available for two sandstones exhibiting dependence of the yield stress on the orientation of the bedding planes. Despite the simplicity of the selected model, the results emphasize that the proposed approach captures the salient features of the deformation response of anisotropic granular rocks, thereby disclosing an intimate connection between grain-scale energy release and cataclastic yielding which greatly simplifies the mathematical description of intrinsic inelastic anisotropy.

AB - The microstructure of geological solids is affected by their deposition history, which generates complex systems of grain contacts and damage patterns able to induce mechanical anisotropy. This paper aims to disclose the connection between energy storage and the yield surface of cross-anisotropic granular rocks, with the goal to simplify the representation of their mechanical anisotropy. For this purpose, a reformulation of Continuum Breakage Mechanics (CBM) is proposed to introduce material symmetries associated with energy storage processes. It is shown that, due to the thermodynamic consistency of the selected approach, the energy release resulting from comminution is influenced by the anisotropic characteristics of the elastic energy potential. As a result, the model is able to capture naturally and without additional fitting parameters the dependence of the yielding envelope on the relative orientation between bedding planes and loading direction. The performance of the new CBM model has been tested by performing parametric analyses which elucidate the role of cross-anisotropic elastic properties on the yield surface of a granular rock. Furthermore, its accuracy has been assessed against laboratory results available for two sandstones exhibiting dependence of the yield stress on the orientation of the bedding planes. Despite the simplicity of the selected model, the results emphasize that the proposed approach captures the salient features of the deformation response of anisotropic granular rocks, thereby disclosing an intimate connection between grain-scale energy release and cataclastic yielding which greatly simplifies the mathematical description of intrinsic inelastic anisotropy.

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