Post-yield Strength and Dilatancy Evolution Across the Brittle–Ductile Transition in Indiana Limestone

An extensive uniaxial and triaxial compression testing programme was performed on Indiana Limestone to assess its behaviour across the brittle–ductile transition. Particular attention has been paid to the post-yield evolution of strength and dilatancy. Specimens tested at σ 3  = 30 MPa displayed a f...

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Bibliographic Details
Published in:Rock mechanics and rock engineering 2017-07, Vol.50 (7), p.1691-1710
Main Authors: Walton, G., Hedayat, A., Kim, E., Labrie, D.
Format: Article
Language:English
Subjects:
Alloys
Axial strain
Brittleness
Civil Engineering
Compression
Compression tests
Dilatancy
Ductile-brittle transition
Ductility
Earth and Environmental Science
Earth Sciences
Evolution
Evolutionary biology
Fracture mechanics
Friction
Geophysics/Geodesy
Limestone
Localization
Nonlinear systems
Nonlinearity
Original Paper
Rocks
Sedimentary geology
Shear
Shear strain
Strain
Strength
Volumetric strain
Yield strength
Yield stress
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Summary:An extensive uniaxial and triaxial compression testing programme was performed on Indiana Limestone to assess its behaviour across the brittle–ductile transition. Particular attention has been paid to the post-yield evolution of strength and dilatancy. Specimens tested at σ 3  = 30 MPa displayed a fully ductile failure mechanism, whereas specimens tested at σ 3  = 15 MPa and σ 3  = 20 MPa displayed transitional mechanisms, which were neither fully brittle nor fully ductile. Based on an examination of failure localization and dilatancy characteristics, the stress at which crack volumetric strain begins to increase was found to be an indicator of individual specimen ductility. In contrast to less porous rocks, the reversal of total volumetric strain did not coincide with the onset of axial strain nonlinearity under unconfined conditions. With respect to post-yield strength, a major change in the rate of friction mobilization relative to plastic shear strain was observed across the brittle–ductile transition. The dilatancy of the specimens was also found to undergo a major change, with the plastic shear strains to mobilization of peak dilatancy in the ductile regime being approximately one order of magnitude higher than in the brittle regime.
ISSN:0723-2632
1434-453X
DOI:10.1007/s00603-017-1195-1