Title: On the micromechanics of slip events in sheared, fluid-saturated fault gouge

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.

Authors:

Dorostkar, Omid  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-7758-4919"

Guyer, Robert A. ^[2]; Johnson, Paul A.  ^[3];

• Search DOE PAGES for author "Johnson, Paul A."
• Search DOE PAGES for ORCID "0000-0002-0927-4003"

Marone, Chris  ^[4];

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• Search DOE PAGES for ORCID "0000-0002-4515-4500"

Carmeliet, Jan ^[5]

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+ Show Author Affiliations

1. Federal Inst. of Technology, Zurich (Switzerland). Dept. of Mechanical and Process Engineering; Swiss Federal Lab. for Materials Science and Technology (Empa), Dübendorf, (Switzerland); Federal Inst. of Technology, Zurich (Switzerland). Dept. of Civil, Environmental and Geomatic Engineering
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Nevada, Reno, NV (United States). Dept. of Physics
3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
4. Pennsylvania State Univ., University Park, PA (United States). Dept. of Geosciences
5. Federal Inst. of Technology, Zurich (Switzerland). Dept. of Mechanical and Process Engineering; Swiss Federal Lab. for Materials Science and Technology (Empa), Dübendorf, (Switzerland)

Publication Date:

Mon Jun 12 00:00:00 EDT 2017

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC), Basic Energy Sciences (BES); Federal Inst. of Technology (ETH), Zurich (Switzerland)

OSTI Identifier:

1469531

Report Number(s):

LA-UR-17-25964
Journal ID: ISSN 0094-8276

Grant/Contract Number:  

AC52-06NA25396

Resource Type:

Accepted Manuscript

Journal Name:

Geophysical Research Letters

Additional Journal Information:

Journal Volume: 44; Journal Issue: 12; Journal ID: ISSN 0094-8276

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Earth Sciences; slip micromechanics; earthquake physics; sheared granular materials; CFD‐DEM; depositional wedge; saturated fault gouge