Force fabric and macroscopic friction in two-dimensional granular materials

Area of Science:

• Physics
• Materials Science
• Geophysics

Background:

• Granular materials exhibit complex macroscopic behaviors arising from microscopic interactions.
• Understanding the relationship between local grain friction and bulk frictional properties is essential for predicting material flow and stability.

Purpose of the Study:

• To develop and test a model linking local grain-grain friction and force texture to macroscopic friction in granular piles.
• To investigate the role of slide planes and contact force geometry in determining emergent frictional values.

Main Methods:

• A theoretical model was developed based on the angular distribution of contact forces and slide plane roughness.
• A state-of-the-art two-dimensional granular pile model was simulated under gravity and uniaxial stress.
• The model was validated against simulation data, fitting a single parameter related to slide plane roughness.

Main Results:

• The model successfully relates local contact force distributions to macroscopic friction angles.
• The fitted parameter, dependent on slide plane roughness, was found to be crucial for model accuracy.
• Simulation results confirmed the model's ability to predict emergent frictional behavior.

Conclusions:

• Local grain-grain friction and force geometry are key determinants of macroscopic friction in granular piles.
• The proposed model provides a framework for predicting bulk frictional properties from micro-scale characteristics.
• This work advances the understanding of force transmission and failure mechanisms in granular materials.