on the strength of transversely isotropic rocks

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Ronaldo I. Borja Stanford University March 29, 2019 On the strength of transversely isotropic rocks

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PowerPoint PresentationMarch 29, 2019
A serendipitous meeting with Enrique
STAMS 2019
Borja, R. I. and Alarcón, E., “A mathematical framework for finite strain elastoplastic con- solidation, Part 1: Balance laws, variational formulation, and linearization,” Computer Methods in Applied Mechanics and Engineering, Vol. 122, Nos. 1-2, 1995, pp. 145-171.
Borja, R.I., Tamagnini, C. and Alarcón, E., “Finite strain elastoplastic consolidation, Part 2: Finite element implementation and numerical examples,” Computer Methods in Applied Mechanics and Engineering, Vol. 159, Nos. 1-2, 1998, pp. 103-122.
Borja, R. I. and Alarcón, E., “Un marco matemático para la consolidación elastoplástica con deformaciones finitas,” Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería, Vol. 11, No. 3, 1995, pp. 345-381
Borja, R. I., Tamagnini, C. and Alarcón, E., “Consolidación elastoplástica con deformaciones finitas: implementación con elementos finitos y ejemplos numéricos,” Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería, Vol. 15, No. 2, 1999, pp. 269-296.
Una fructífera colaboración
Outline of presentation
Part 1: Dual porosity/dual permeability theory (Borja and Choo, CMAME, 2016)
Part 2: Transversely isotropic rocks, (Semnani et al., IJNAMG 2016, Zhao et al., IJNAMG 2018)
Integration of Parts 1 and 2: US Department of Energy project, in progress.
Double porosity
Double porosity
Double porosity
Double porosity
Double porosity
neutron tomography
Double porosity
neutron tomography
Double porosity
• macropores • micropores
Double porosity
• macropores • micropores
double porosity
Double porosity
Mechanisms considered
Double porosity
Mechanisms considered
Double porosity
Mechanisms considered
Double porosity
Mechanisms considered
Double porosity
Double porosity
Theoretical basis
Effective stress equation (Borja & Koliji, JMPS, 2009)
• For each pore scale, take the weighted sum of the pore air and pore water pressures with the local saturations taken as the weights.
• Take the sum of the mean pore pressures at each pore scale with the pore fractions taken as the weights.
Overall mean pore pressure:
Effective stress equation (Borja & Koliji, JMPS, 2009)
• For fully saturated media, take the weighted sum of the pore pressures with the pore fractions taken as the weights.
• Need a finite deformation formulation to track the evolution of the ore fractions.
Overall mean pore pressure:
Constitutive laws
• Mechanical constitutive law in terms of effective stress – modified Cam-Clay
Internal energy equation
Internal energy equation
Internal energy equation
Internal energy equation
Model validation
4 MPa
1.5 MPa
Model validation
4 MPa
1.5 MPa
One-dimensional consolidation
Waste
Multiphysics processes:
Motivations – transversely isotropic rocks
Anisotropy
Anisotropy
Transverse isotropy
Variation of the compressive strength with orientation of bedding plane (After Crook et al., 2002)
Evidence of anisotropy in the laboratory
• Material symmetry group
Transverse isotropy
not linearly independent
• Alternative stress tensor
• Alternative stress tensor
• Flow rule
Anisotropic thermoplasticity
Semnani et al. (2016)
Anisotropic thermoplasticity
• Isothermal and adiabatic, at theta = 45o and 40 MPa confining pressure, Zhao et al. (2018)
• Isothermal, at 40 MPa confining pressure, Zhao et al. (2018)
• Lab data are from Niandou et al. (1997)
Anisotropic thermoplasticity
• Isothermal, at 40 MPa confining pressure, Zhao et al. (2018)
• Lab data from Tien et al. (2006)
Anisotropic thermoplasticity
Anisotropic thermoplasticity
Anisotropic thermoplasticity
Anisotropic thermoplasticity
Anisotropic thermoplasticity
Plane strain compression of OC Tournemire shale
• Simulations are for OCR = 50 at 1 MPa confining stress, Zhao et al. (2018)
Anisotropic thermoplasticity
Plane strain compression of OC Tournemire shale
• Simulations are for OCR = 50 at 1 MPa confining stress, Zhao et al. (2018)
Finite element simulations
smooth ends clamped ends
Smooth versus clamped ends shear band direction predicted by local bifurcation
Zhao et al. (2018)
Smooth versus clamped ends
Failure modes observed in synthetic transversely isotropic rock, Tien et al. (2006)
Zhao et al. (2018)
In progress . . .
• Transverse isotropy in fluid flow and non-Darcy flow, Zhang & Borja (2019). CMAME, in press.
• Creep in shale at submicron scale – bridging nanoscale to millimeter scale, Yin & Borja (2019). CMAME.
Acknowledgments
• Collaborators: Shabnam Semnani, Joshua White, Qing Yin, Yang Zhao.
• Funding provided by the U.S. Department of Energy under Award Number DE-FG02-03ER15454 and by the U.S. National Science Foundation under Award Number CMMI-1462231.
¡Gracias!
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