Many clay rocks have distinct bedding planes. Experimental studies have shown that their mechanical properties evolve with the degree of saturation (DOS), often with higher stiffness and strength after drying. For transversely isotropic rocks, the effects of saturation can differ between the bed-normal (BN) and bed-parallel (BP) directions, which gives rise to saturation-dependent stiffness and strength anisotropy. Accurate prediction of the mechanical behavior of clay rocks under partially saturated conditions requires numerical models that can capture the evolving elastic and plastic anisotropy with DOS. In this study, we present an anisotropy framework for coupled solid deformation-fluid flow in unsaturated elastoplastic media. Here we incorporate saturation-dependent strength anisotropy into an anisotropic modified Cam-Clay (MCC) model and consider the evolving anisotropy in both the elastic and plastic responses. The model was calibrated using experimental data from triaxial tests to demonstrate its capability in capturing strength anisotropy at various levels of saturation. Through numerical simulations, we demonstrate the role of evolving stiffness and strength anisotropy in the mechanical behavior of clay rocks. Plane strain simulations of triaxial compression tests were also conducted to demonstrate the impacts of material anisotropy and DOS on the mechanical and fluid flow responses.
Ip, Sabrina C.Y. and Borja, Ronaldo I.. "Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks." International Journal for Numerical and Analytical Methods in Geomechanics, vol. 46, no. 1, Nov. 2021. https://doi.org/10.1002/nag.3289
Ip, Sabrina C.Y., & Borja, Ronaldo I. (2021). Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks. International Journal for Numerical and Analytical Methods in Geomechanics, 46(1). https://doi.org/10.1002/nag.3289
Ip, Sabrina C.Y., and Borja, Ronaldo I., "Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks," International Journal for Numerical and Analytical Methods in Geomechanics 46, no. 1 (2021), https://doi.org/10.1002/nag.3289
@article{osti_1976362,
author = {Ip, Sabrina C.Y. and Borja, Ronaldo I.},
title = {Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks},
annote = {Many clay rocks have distinct bedding planes. Experimental studies have shown that their mechanical properties evolve with the degree of saturation (DOS), often with higher stiffness and strength after drying. For transversely isotropic rocks, the effects of saturation can differ between the bed-normal (BN) and bed-parallel (BP) directions, which gives rise to saturation-dependent stiffness and strength anisotropy. Accurate prediction of the mechanical behavior of clay rocks under partially saturated conditions requires numerical models that can capture the evolving elastic and plastic anisotropy with DOS. In this study, we present an anisotropy framework for coupled solid deformation-fluid flow in unsaturated elastoplastic media. Here we incorporate saturation-dependent strength anisotropy into an anisotropic modified Cam-Clay (MCC) model and consider the evolving anisotropy in both the elastic and plastic responses. The model was calibrated using experimental data from triaxial tests to demonstrate its capability in capturing strength anisotropy at various levels of saturation. Through numerical simulations, we demonstrate the role of evolving stiffness and strength anisotropy in the mechanical behavior of clay rocks. Plane strain simulations of triaxial compression tests were also conducted to demonstrate the impacts of material anisotropy and DOS on the mechanical and fluid flow responses.},
doi = {10.1002/nag.3289},
url = {https://www.osti.gov/biblio/1976362},
journal = {International Journal for Numerical and Analytical Methods in Geomechanics},
issn = {ISSN 0363-9061},
number = {1},
volume = {46},
place = {United States},
publisher = {Wiley},
year = {2021},
month = {11}}
National Science Foundation (NSF); USDOE; USDOE Office of Science (SC)
Grant/Contract Number:
FG02-03ER15454
OSTI ID:
1976362
Alternate ID(s):
OSTI ID: 1828613
Journal Information:
International Journal for Numerical and Analytical Methods in Geomechanics, Journal Name: International Journal for Numerical and Analytical Methods in Geomechanics Journal Issue: 1 Vol. 46; ISSN 0363-9061