Application of DEM to Micro-Mechanical Theory for Large Deformations of Granular Media

Abstract

Abstract : A constitutive theory is developed for granular material undergoing arbitrarily large deformations. A three-dimensional discrete element model (DEM) was developed to simulate granular material. The computational efficiency of the DEM was improved to allow for modeling of large particle systems. The need for large particle simulations was to develop on ability to model laboratory experiments on a one-to-one basis so that the discrete elements model could be evaluated against real soils. A comparison was made between laboratory experiments involving very large discontinuous deformations in sand and numerical simulations using large-scale DEM computation. The magnitude of the simulation provided a unique opportunity to assess the validity of the DEM, based on experimental results. The agreement between the experimental and simulated particle motions in the plowing experiment indicates that details not captured by the simplistic particle interaction model may not be relevant in statistically large assemblies. Once it was established that the discrete element method provided a reasonable model for real granular material, an averaging scheme was developed to convert properties local to the particles (e.g., mass, momentum) into continuum attributes (e.g., density, velocity gradients). From this averaging scheme, a new constitutive law was developed to model large deformation of granular material.