Fracturing of ductile anisotropic multilayers: influence of material strength

Enrique Gomez Rivas, Albert Griera, Maria-Gema Llorens

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Abstract

Fractures in rocks deformed under dominant ductile conditions typically form simultaneously with viscous flow. Material strength plays a fundamental role during fracture development in such systems, since fracture propagation can be strongly reduced if the material accommodates most of the deformation by viscous flow. Additionally, the degree and nature of anisotropy can influence the orientation and type of resulting fractures. In this study, four plasticine multilayer models have been deformed under coaxial boundary conditions to investigate the influence of strength and anisotropy on the formation of fracture networks. The experiments were made of different mixtures and had two types of anisotropy: composite and composite-intrinsic. The transition from non-localised deformation to systems where fracture networks control deformation accommodation is determined by the ability of the material to dissipate the external work and relax the elastic strain during loading either by viscous flow or by coeval flow and failure. Tension cracks grow in experiments with composite anisotropy, giving rise to a network of shear fractures when they collapse and coalesce with progressive deformation. The presence of an additional intrinsic anisotropy enhances the direct nucleation of shear fractures, the propagation and final length of which depend on the rigidity of the medium. Material strength increases the fracture maximum displacement (dmax) to fracture length (L) ratio, and the resulting values are significantly higher than those from fractures in elastic–brittle rocks. This can be related to the low propagation rates of fractures in rocks undergoing ductile deformation.
Original languageEnglish
Pages (from-to)497-514
Number of pages18
JournalSolid earth
Volume6
Early online date19 May 2015
DOIs
Publication statusPublished - 19 May 2015

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fracturing
strength (mechanics)
Strength of materials
Multilayers
mechanical properties
rocks
anisotropy
viscous flow
shear stress
Anisotropy
Viscous flow
fracture network
composite materials
Rocks
rock
propagation
strength of materials
fracture propagation
Composite materials
ductile deformation

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Fracturing of ductile anisotropic multilayers : influence of material strength. / Gomez Rivas, Enrique; Griera, Albert; Llorens, Maria-Gema.

In: Solid earth, Vol. 6, 19.05.2015, p. 497-514.

Research output: Contribution to journalArticle

Gomez Rivas, Enrique ; Griera, Albert ; Llorens, Maria-Gema. / Fracturing of ductile anisotropic multilayers : influence of material strength. In: Solid earth. 2015 ; Vol. 6. pp. 497-514.
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