A Discrete Elements Study of the Frictional Behavior of Fault Gouges

Area of Science:

• Geophysics
• Computational Rock Mechanics
• Tribology

Background:

• Fault gouge rheology is critical for understanding earthquake mechanics.
• Previous studies often simplify gouge particle characteristics and loading conditions.
• Simulating complex fault zone processes requires advanced computational methods.

Purpose of the Study:

• To investigate the frictional response of fault gouge under seismogenic zone conditions.
• To explore the influence of particle size, polydispersity, and shearing velocity on gouge behavior.
• To identify key parameters controlling shear band formation and frictional evolution.

Main Methods:

• Discrete element simulations (DEM) were employed.
• Monte-Carlo analyses were used to assess statistical effects.
• Simulations considered ultra-cataclastic flow and consolidated loading conditions.

Main Results:

• Local stick-slip events diminish with large-scale averaging.
• Frictional response is largely insensitive to particle position randomness and size distribution.
• Mean particle size dictates shear band formation and thickness.
• Friction evolution follows an exponential decay law dependent on particle size and slip distance.

Conclusions:

• Mean particle size is a dominant factor in fault gouge frictional behavior and shear band development.
• Shearing velocity plays a minor role under studied seismogenic conditions.
• Findings inform constitutive model development for continuum-based fault modeling and multiphysics analyses.