Specimen generation approaches for DEM simulations.

Discrete Element Method (DEM) simulations ofelement tests cam provide significant insight into the micro-mechanics of soil response. It is well established that soil behaviour is strongly dependant on the initial density. Generation of particulate assemblies for three-dimensional DEM analyses must therefore allow for void ratio control. In this paper, different specimen generation approaches for DEM analyses are discussed. A methodology for the generation of assemblies of spherical particles with a specified initial density and stress state is presented. The effects of the different preparation methods on the specimen fabric are then considered in detail. For isotropic consolidation, it is shown that varying the coefficient of inter-particle friction allows control of the specimen void ratio at a specified confining stress. Simulations of anisotropic consolidation, from an initial isotropic stress state, to a final state where sigma(3) = K(0)sigma(1) indicated that the specimen void ratio and fabric are relatively insensitive to the intermediate stress path, provided an intermediate stress along the K(0) line was attained.

Evolution of soil fabric and its interpretation using different methods.

Different methods to study the evolution of fabric anisotropy are presented. DEM simulations on assemblies of spheres subjected to different stress paths using a three-dimensional periodic cell are used for the analysis of these methods. The links between soil fabric and macro-scale behaviour are also discussed.