Microscale Normal Compression Behaviors of Clay Aggregates: A Coarse-Grained Molecular Dynamics Study

Area of Science:

• Geotechnical Engineering
• Materials Science
• Computational Physics

Background:

• Micromechanical experiments and molecular dynamics simulations have limitations in capturing clay aggregate compression.
• Understanding clay aggregate deformation is crucial for geotechnical applications and material science.

Purpose of the Study:

• To simulate the normal compression of clay aggregates under varying conditions.
• To elucidate the evolution of deformation and stresses based on particle orientation and stack distribution.

Main Methods:

• Utilized a Gay-Berne potential model for simulation.
• Investigated effects of vertical pressure, particle number, loading methods, and environments (vacuum vs. atmosphere).
• Analyzed variations in particle orientation and stack distribution.

Main Results:

• Vertical pressure and loading environment significantly affect deformation and void ratio changes.
• Deformation under constant pressure loading exceeded that under step loading.
• In the 40-100 MPa range, void ratios were consistent across loading conditions due to mechanical force dominance.
• Horizontal stress decreased in a vacuum due to stack movement; lateral pressure coefficients (k) were higher in an atmosphere.
• Increased initial loading pressure led to more large stacks and significant anisotropy in a vacuum.

Conclusions:

• Clay aggregate compression is governed by particle stacking and orientation, influenced by pressure and environment.
• The findings provide insights into the mechanisms of clay aggregate deformation and stress evolution.
• This simulation work aids in explaining experimental observations of long-term clay aggregate ripening.