Rheology of granular materials composed of crushable particles

Area of Science:

• Physics
• Materials Science
• Geophysics

Background:

• Granular materials exhibit complex behaviors under stress.
• Particle breakage significantly influences bulk material properties.
• Understanding crushable particle dynamics is crucial for various applications.

Purpose of the Study:

• Investigate the effects of particle breakage on sheared granular materials.
• Analyze the evolution of particle size distribution and its impact on material behavior.
• Determine factors controlling crushing rate and shear strength.

Main Methods:

• Contact dynamics simulations.
• Bonded-cell model for particle breakage.
• Biaxial shearing under constant relative cohesion.

Main Results:

• Breakage is inhomogeneous, with some particles shattering and others remaining intact.
• Particle size distribution shifts, showing power-law behavior for intermediate sizes.
• Dense shear bands form, reducing dilatancy and altering stress-strain curves.
• Crushing rate depends on confining pressure; shear strength is linked to contact and force anisotropies.

Conclusions:

• The initial particle size distribution influences the final state, but fragmentation erases memory for intermediate sizes.
• Growing polydispersity due to breakage leads to reduced dilatancy and monotonic stress-strain evolution.
• Shear strength is largely independent of internal cohesion due to compensating effects of force and contact anisotropies.