On the micromechanics of slip events in sheared, fluid‐saturated fault gouge. Issue 12 (28th June 2017)

• Record Type: Journal Article
• Authors: Dorostkar, Omid; Guyer, Robert A.; Johnson, Paul A.; Marone, Chris; Carmeliet, Jan
• Is Part Of: Geophysical research letters. Volume 44:Issue 12(2017)
• Page Start: 6101
• Page End: 6108
• Publication Date: 2017-06-28
• Subjects: slip micromechanics -- earthquake physics -- sheared granular materials -- CFD‐DEM -- depositional wedge -- saturated fault gouge; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL073768
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: We used a three‐dimensional discrete element method coupled with computational fluid dynamics to study the poromechanical properties of dry and fluid‐saturated granular fault gouge. The granular layer was sheared under dry conditions to establish a steady state condition of stick‐slip dynamic failure, and then fluid was introduced to study its effect on subsequent failure events. The fluid‐saturated case showed increased stick‐slip recurrence time and larger slip events compared to the dry case. Particle motion induces fluid flow with local pressure variation, which in turn leads to high particle kinetic energy during slip due to increased drag forces from fluid on particles. The presence of fluid during the stick phase of loading promotes a more stable configuration evidenced by higher particle coordination number. Our coupled fluid‐particle simulations provide grain‐scale information that improves understanding of slip instabilities and illuminates details of phenomenological, macroscale observations. Key Points: We study hydromechanical coupling mechanisms in granular fault gouge undergoing particle rearrangements and fluid flow during failure Fluid flow and the spatiotemporal distribution of effective pressure affect particle arrangement Comparison of dry versus fluid‐saturated cases shows that fluids tend to stabilize shear and increase the recurrence time of slip events