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Titolo:
A two-phase model for compaction and damage 3. Applications to shear localization and plate boundary formation
Autore:
Bercovici, D; Ricard, Y; Schubert, G;
Indirizzi:
Ecole Normale Super Lyon, Lab Sci Terre, F-69364 Lyon 07, France Ecole Normale Super Lyon Lyon France 07 i Terre, F-69364 Lyon 07, France Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA Univ Calif Los Angeles Los Angeles CA USA 90095 Los Angeles, CA 90095 USA Univ Hawaii Manoa, Dept Geol & Geophys, Honolulu, HI 96822 USA Univ HawaiiManoa Honolulu HI USA 96822 & Geophys, Honolulu, HI 96822 USA
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B5, volume: 106, anno: 2001,
pagine: 8925 - 8939
SICI:
0148-0227(20010510)106:B5<8925:ATMFCA>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
LITHOSPHERE-MANTLE FLOW; DEFORMABLE POROUS-MEDIA; DYNAMIC FRACTURE; SELF-LUBRICATION; TOROIDAL MOTION; INSTABILITY; GENERATION; CONVECTION; MECHANICS; SOLIDS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
57
Recensione:
Indirizzi per estratti:
Indirizzo: Bercovici, D Yale Univ, Dept Geol & Geophys, POB 208109, New Haven, CT 06520 USA Yale Univ POB 208109 New Haven CT USA 06520 ven, CT 06520 USA
Citazione:
D. Bercovici et al., "A two-phase model for compaction and damage 3. Applications to shear localization and plate boundary formation", J GEO R-SOL, 106(B5), 2001, pp. 8925-8939

Abstract

A new two-phase theory employing a nonequilibrium relation between interfacial surface energy, pressure, and viscous deformation [Bercovici et al., this issue] provides a model for damage (void generation and microcracking) and thus a continuum description of weakening, failure, and shear localization. Here we demonstrate applications of the theory to shear localization with simple shear flow calculations in which one phase (the matrix, representing, for example, silicate) is much stronger (more viscous) than the otherphase (the fluid). This calculation is motivated as a simple model of plate boundary formation in a shear zone. Even without shear the two phases eventually separate due to gradients in surface tension. However, the influence of shear on phase separation is manifest in several ways. As shear velocity increases, the separation rate of the phases increases, demonstrating a basic feedback mechanism: Accumulation of the fluid phase causes focused weak zones on which shear concentrates, causing more damage and void generation and thus greater accumulation of fluid. Beyond a critical shear velocity, phase separation undergoes intense acceleration and focusing, leading to a "tear localization" in which the porosity becomes nearly singular in space and grows rapidly like a tear or crack. At an even higher value of shear velocity, phase separation is inhibited such that shear localization gives way to defocusing of weak zones suggestive of uniform microcracking and failure throughout the layer. Our two-phase damage theory thus predicts a widevariety of shear localization and failure behavior with a continuum model. Applications of the theory to various fields, such as granular dynamics, metallurgy, and tectonic plate boundary formation are numerous.

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Documento generato il 22/01/20 alle ore 13:15:41