This paper investigates the issue of particle size scaling when modeling the mechanical behavior of granular materials using both finite and discrete element methods (FEA and DEM). Geomaterials have a complex mechanical behavior due to the nature of the microfabric structure composed of individual particles. The microfabric structure of the geomaterial dictates its macro level mechanical behavior.

Researchers at Caterpillar have been using FEA and DEM extensively to model different earthmoving operations. Each of these methods has its own limitations and applications. To apply FEA or DEM for analyzing earthmoving operations the model must reproduce the mechanical behavior of the granular material. In practice this macro level mechanical behavior is not achieved by modeling the exact physics of the microfabric structure but rather by approximating the macro physics and using finite elements or discrete elements that are larger than the physical grain size. The fundamental issues that drive the need for up-scaling in FEA and DEM are discussed in this paper.

Numerical simulations using DEM and FEA showed good agreement with the experimental results and have been used to study scaling issues. The intent is to establish a reliable scaling technique that can, to some extent, bridge the length scales from micro to macro levels.