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Cohesion‐Induced Stabilization in Stick‐Slip Dynamics of Weakly Wet, Sheared Granular Fault Gouge
Author(s) -
Dorostkar Omid,
Guyer Robert A.,
Johnson Paul A.,
Marone Chris,
Carmeliet Jan
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2017jb015171
Subject(s) - cohesion (chemistry) , discrete element method , fault gouge , granular material , slip (aerodynamics) , granular layer , materials science , compaction , granular matter , geotechnical engineering , mechanics , fault (geology) , composite material , geology , physics , thermodynamics , quantum mechanics , cerebellum , neuroscience , seismology , biology
We use three‐dimensional discrete element calculations to study stick‐slip dynamics in a weakly wet granular layer designed to simulate fault gouge. The granular gouge is constituted by 8,000 spherical particles with a polydisperse size distribution. At very low liquid content, liquids impose cohesive and viscous forces on particles. Our simulations show that by increasing the liquid content, friction increases and granular layer shows higher recurrence time between slip events. We also observe that slip events exhibit larger friction drop and layer compaction in wet system compared to dry. We demonstrate that a small volume of liquid induces cohesive forces between wet particles that are responsible for an increase in coordination number leading to a more stable arrangement of particles. This stabilization is evidenced with 2 orders of magnitude lower particle kinetic energy in wet system during stick phase. Similar to previous experimental studies, we observe enhanced frictional strength for wet granular layers. In experiments, the physicochemical processes are believed to be the main reason for such behavior; we show, however, that at low confining stresses, the hydromechanical effects of induced cohesion are sufficient for observed behavior. Our simulations illuminate the role of particle interactions and demonstrate the conditions under which induced cohesion plays a significant role in fault zone processes, including slip initiation, weakening, and failure.