Abstract
The rheology of granular materials is largely dominated by geometrical constraints arising from steric exclusions and involving particle shapes and size distributions. This prevailing role of geometry permits one to simplify sometimes the dynamics in favor of a better description of the geometry or/and higher numerical efficiency. For example, a dense granular packing may be efficiently constructed by replacing the equations of dynamics by simple displacement rules satisfying the geometrical constraints. Such purely geometrical procedures can be much simpler and numerically faster than more realistic procedures employed in dynamic methods and quasistatic methods. The issue of the assembling methods is to construct configurations of particles as close as possible to a state of mechanical equilibrium with built-in packing properties. This can be, for example, a target packing fraction for a given particle size distribution. In the same way, the average connectivity of the particles (coordination number) and the anisotropy of the contact network are basic geometrical properties that control the mechanical response of a packing and may be built into a packing by an appropriate method. The homogeneity of the particle assembly in terms of packing fraction and connectivity is another important property which depends on the assembling rules. In this chapter, several basic assembling methods by simple geometrical rules will be introduced. As there is a close link between the particle size distribution (PSD) and texture of a granular packing, \index{particle size distribution} we also present a method for the generation of PSD and we discuss in detail their statistical representativity and influence on the packing properties.