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Characterization of pore structure and strain localization in Majella limestone by X-ray computed tomography and digital image correlation

Ji, Yuntao; Hall, Stephen LU ; Baud, Patrick and Wong, Teng-fong (2015) In Geophysical Journal International 200(2). p.699-717
Abstract
Standard techniques for computed tomography imaging are not directly applicable to a carbonate rock because of the geometric complexity of its pore space. In this study, we first characterized the pore structure in Majella limestone with 30 per cent porosity. Microtomography data acquired on this rock was partitioned into three distinct domains: macropores, solid grains, and an intermediate domain made up of voxels of solid embedded with micropores below the resolution. A morphological analysis of the microtomography images shows that in Majella limestone both the solid and intermediate domains are interconnected in a manner similar to that reported previously in a less porous limestone. We however show that the macroporosity in Majella... (More)
Standard techniques for computed tomography imaging are not directly applicable to a carbonate rock because of the geometric complexity of its pore space. In this study, we first characterized the pore structure in Majella limestone with 30 per cent porosity. Microtomography data acquired on this rock was partitioned into three distinct domains: macropores, solid grains, and an intermediate domain made up of voxels of solid embedded with micropores below the resolution. A morphological analysis of the microtomography images shows that in Majella limestone both the solid and intermediate domains are interconnected in a manner similar to that reported previously in a less porous limestone. We however show that the macroporosity in Majella limestone is fundamentally different, in that it has a percolative backbone which may contribute significantly to its permeability. We then applied for the first time 3-D-volumetric digital image correlation (DIC) to characterize the mode of mechanical failure in this limestone. Samples were triaxially deformed over a wide range of confining pressures. Tomography imaging was performed on these samples before and after deformation. Inelastic compaction was observed at all tested pressures associated with both brittle and ductile behaviors. Our DIC analysis reveals the structure of compacting shear bands in Majella limestone deformed in the transitional regime. It also indicates an increase of geometric complexity with increasing confinement-from a planar shear band, to a curvilinear band, and ultimately to a diffuse multiplicity of bands, before shear localization is inhibited as the failure mode completes the transition to delocalized cataclastic flow. (Less)
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author
organization
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Contribution to journal
publication status
published
subject
keywords
Microstructures, Permeability and porosity, Creep and deformation, Elasticity and anelasticity
in
Geophysical Journal International
volume
200
issue
2
pages
699 - 717
publisher
Wiley-Blackwell
external identifiers
  • wos:000350042400001
ISSN
0956-540X
DOI
10.1093/gji/ggu414
language
English
LU publication?
yes
id
75a8586c-0e37-4cf3-bf8d-b19b993533cb (old id 5305621)
date added to LUP
2015-04-23 16:33:43
date last changed
2016-04-15 14:00:04
@article{75a8586c-0e37-4cf3-bf8d-b19b993533cb,
  abstract     = {Standard techniques for computed tomography imaging are not directly applicable to a carbonate rock because of the geometric complexity of its pore space. In this study, we first characterized the pore structure in Majella limestone with 30 per cent porosity. Microtomography data acquired on this rock was partitioned into three distinct domains: macropores, solid grains, and an intermediate domain made up of voxels of solid embedded with micropores below the resolution. A morphological analysis of the microtomography images shows that in Majella limestone both the solid and intermediate domains are interconnected in a manner similar to that reported previously in a less porous limestone. We however show that the macroporosity in Majella limestone is fundamentally different, in that it has a percolative backbone which may contribute significantly to its permeability. We then applied for the first time 3-D-volumetric digital image correlation (DIC) to characterize the mode of mechanical failure in this limestone. Samples were triaxially deformed over a wide range of confining pressures. Tomography imaging was performed on these samples before and after deformation. Inelastic compaction was observed at all tested pressures associated with both brittle and ductile behaviors. Our DIC analysis reveals the structure of compacting shear bands in Majella limestone deformed in the transitional regime. It also indicates an increase of geometric complexity with increasing confinement-from a planar shear band, to a curvilinear band, and ultimately to a diffuse multiplicity of bands, before shear localization is inhibited as the failure mode completes the transition to delocalized cataclastic flow.},
  author       = {Ji, Yuntao and Hall, Stephen and Baud, Patrick and Wong, Teng-fong},
  issn         = {0956-540X},
  keyword      = {Microstructures,Permeability and porosity,Creep and deformation,Elasticity and anelasticity},
  language     = {eng},
  number       = {2},
  pages        = {699--717},
  publisher    = {Wiley-Blackwell},
  series       = {Geophysical Journal International},
  title        = {Characterization of pore structure and strain localization in Majella limestone by X-ray computed tomography and digital image correlation},
  url          = {http://dx.doi.org/10.1093/gji/ggu414},
  volume       = {200},
  year         = {2015},
}