Multiscale interactions of elastic anisotropy in unsaturated clayey rocks using a homogenization model

The microstructure of a geomaterial plays a significant role in determining its macroscale properties. Most clay rocks have an anisotropic microstructure due to preferential orientation of the pores and mineral grains, which results in transversely isotropic mechanical properties. Their anisotropic...

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Bibliographic Details
Published in:Acta geotechnica 2023-05, Vol.18 (5), p.2289-2307
Main Authors: Ip, Sabrina C. Y., Borja, Ronaldo I.
Format: Article
Language:English
Subjects:
Anisotropy
Clay
Clay minerals
Complex Fluids and Microfluidics
Elastic anisotropy
Elastic properties
Elasticity
Engineering
Evolution
Foundations
Geoengineering
Geotechnical Engineering & Applied Earth Sciences
Homogenization
Hydraulics
Mechanical properties
Microstructure
Research Paper
Rock
Rocks
Saturation
Soft and Granular Matter
Soil Science & Conservation
Solid Mechanics
Stiffness
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Summary:The microstructure of a geomaterial plays a significant role in determining its macroscale properties. Most clay rocks have an anisotropic microstructure due to preferential orientation of the pores and mineral grains, which results in transversely isotropic mechanical properties. Their anisotropic microstructure is complex and spans multiple orders of magnitudes. The interactions between anisotropy at different scales in these rocks can give rise to emerging properties such as saturation-dependent elastic anisotropy. In this study, we develop a homogenization model with three levels of upscaling to capture the multiscale interactions of elastic anisotropy in unsaturated clay rocks. The model provides an enriched description of the elastic behavior of clay rocks during changes in the degree of saturation by bridging the nano-, micro- and macroscale microstructures. Stress-point simulations are presented to demonstrate the interactions between anisotropy at different spatial scales that result in the elastic behavior of clay rocks observed in the literature, including constant anisotropy, evolving anisotropy and a rotation of the principal orientation of anisotropy. The results highlight that constant and evolving elastic anisotropy can originate from the same microstructural features that either neutralize or enhance one another. Overall, the proposed model offers a quantitative link between anisotropy at multiple scales in clay rocks and its macroscopic anisotropic stiffness.
ISSN:1861-1125
1861-1133
DOI:10.1007/s11440-022-01784-2