Journal
ROCK MECHANICS AND ROCK ENGINEERING
Volume 45, Issue 1, Pages 21-33Publisher
SPRINGER WIEN
DOI: 10.1007/s00603-011-0195-9
Keywords
Opalinus Clay; Brittle failure; Clay shale; Frictional strength mobilization; Crack initiation
Funding
- Swiss Federal Nuclear Safety Inspectorate (ENSI)
Ask authors/readers for more resources
The brittle failure behavior of an over-consolidated clay shale (Opalinus Clay) in undrained rapid triaxial compression was studied. The confining stress levels were chosen to simulate the range of confining stresses relevant for underground excavations at the Mont Terri Underground Research Laboratory, and to investigate the transition from axial splitting failure to macroscopic shear failure. Micro-crack initiation was observed throughout the confining stress range utilized in this study at a differential stress of 2.1 MPa on average, which indicates that friction was not mobilized at this stage of brittle failure. The rupture stress was dependent on confinement indicating friction mobilization during the brittle failure process. With increasing confinement net volumetric strain decreased suggesting that dilation was suppressed, which is possibly related to a change in the failure mode. At confining stress levels <= 0.5 MPa specimen rupture was associated with axial splitting. With increasing confinement, transition to a macroscopic shearing mode was observed. Multi-stage triaxial tests consistently showed lower strengths than single-stage tests, demonstrating cumulative damage in the specimens. Both the Mohr-Coulomb and Hoek-Brown failure criteria could not satisfactorily fit the data over the entire confining stress range. A bi-linear or S-shaped failure criterion was found to satisfactorily fit the test data over the entire confinement range studied.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available