Coarse-Grained Molecular Dynamics Approach to Simulating Clay Behavior

A unique simulation was developed within the large-scale atomic/molecular massively parallel simulator (LAMMPS) open source molecular dynamics environment to model kaolinite clay during one-dimensional consolidation. The simulation was composed of a coarse grained representation of the mineral with long-range and short-range interaction potentials. Additionally, the simulation allows for the edge to-edge and edge-to-face attractions to develop through use of two subparticle types. Periodic simulation boundaries were created and thus allowed for consolidation to proceed without any wall effects distorting the resulting fabric. By following the parallel processing paradigm of the LAMMPS code, the number of particles simulated was limited only by the hardware on which the simulation was run. The results of the simulation showed remarkable consistency with previous published studies over all the void ratios explored and the transition from over-consolidated to normally consolidated behavior was captured. Fabric analysis showed that reorientation occurred during unloading and subsequent loading and followed a nonlinear path in virgin compression. Additionally, the median spacing between particles was determined, and particle contact was found to coincide with a stiffness change during consolidation. (C) 2015 American Society of Civil Engineers.