Stress interactions among arrays of tensile cracks in 3D: Implications for the nucleation of shear failure and the orientations of faults.
Abstract
In low porosity rocks it is widely believed that planes of shear failure nucleate through the interaction of arrays of smaller tensile microcracks. This model has been confirmed through laboratory rock deformation experiments and detailed microstructural analyses. In this contribution we use the Boundary Element Method (BEM) to model the interactions of arrays of tensile cracks, discretised as ellipsoidal voids in three dimensions (3D). We calculate the elastic stresses in the solid matrix surrounding the cracks resulting from an applied load and include the interaction effects of each crack upon all the others. We explore the role of variations in crack shape, size, position and orientation upon the total and locally perturbed stress fields. We calculate the average crack normal stress (CNS) acting over the area of each tensile crack, and then find the locus of the maximum value of this stress throughout the modelled volume. Following Reches & Lockner (1994) and Healy et al. (2006a, 2006b), we assert that planes of shear failure will most likely nucleate on surfaces parallel to the locus of maximum average CNS. These shear planes are oblique to all three principal stresses in the far field.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMMR43D0495H
- Keywords:
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- 5104 Fracture and flow;
- PHYSICAL PROPERTIES OF ROCKS;
- 7209 Earthquake dynamics;
- SEISMOLOGY;
- 8010 Fractures and faults;
- STRUCTURAL GEOLOGY;
- 8163 Rheology and friction of fault zones;
- TECTONOPHYSICS