Stick-slip failure in a sheared granular layer: effect of confining stres
Abstract
We model laboratory earthquakes in a biaxial shear apparatus using the Shear-Transformation-Zone (STZ) theory of dense granular flow. The theory is based on the observation that slip events in a granular layer are attributed to grain rearrangement at soft spots called STZ's, which can be characterized according to principles of statistical physics. We model lab data on granular shear using STZ theory and document direct connections between the STZ approach and rate-and-state friction. We discuss the stability transition from stable shear to stick-slip failure and show that stick-slip is predicted by STZ when the applied shear load exceeds a threshold value that is modulated by elastic stiffness and frictional rheology. As in the experiment, the recurrence time of large events decreases with the load applied normal to the fault zone. We show that STZ theory mimics fault zone dilation during the stick phase of stick-slip motion, consistent with lab observations. We discuss how the STZ model can be extended to encompass a wider array of phenomena such as slow slip and triggered slip.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMMR41D2716L
- Keywords:
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- 3902 Creep and deformation;
- MINERAL PHYSICSDE: 7209 Earthquake dynamics;
- SEISMOLOGYDE: 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGYDE: 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS