Reversible griffith crack: a viable model for dilatancy

Journal Article · Wed Dec 10 04:00:00 EST 1980 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB085iB12p07101· OSTI ID:7064025

Holcomb, D J; Stevens, J L

Previous work (paper I) on the mechanism of dilatancy has outlined the deficiencies of the sliding crack model. We have developed a new model, based on reversible Griffith crakcs, that is in accord with experimental results to data. These results can be summarized as follows: (1) dilatant rock exhibits volume increases at sufficiently high increasing and differential stress, (2) there is substantial hysteresis in physical properties between increasing and decreasing stress, (3) examination of stressed and unstressed samples, using a scanning electron microscope, reveals stress-induced cracks that are preferentially oriented with the crack plane close to the maximum compressive stress axis, (4) few shear cracks (required by the sliding crack model) are observed, and (5) dilatant rock exhibits 'memory' of the maximum differential stress since the last complete unloading. When returned to this stress state, the physical properties return to their previous values but at other stress states there is large hysteresis between loading and unloading. A classical Griffith crack exhibits all of these properties if it is postulated to be reversible. That is, below a critical stress, the crack closes in an unstable mode and healing occurs. This behavior requires close registration of the crack faces.

• Research Organization: Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964
• OSTI ID: 7064025
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 85:B13; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
CRACKS
DILATOMETRY
HYSTERESIS
MECHANICAL PROPERTIES
MECHANICS
ROCK MECHANICS
ROCKS
SHEAR
STRAIN RATE
STRESSES
TENSILE PROPERTIES
THERMAL ANALYSIS