DEM simulation of mechanical lab tests for coarse-grained granular material

Due to the characteristics of particulate systems, granular materials show a complex response if exposed to loads and deformations. In the past, intensive research was conducted to investigate this behaviour by use of laboratory testing coupled with continuum mechanical approaches, such as finite element method or finite different method. These continuum methods are incapable to investigate the behaviour at the particle-scale, and therefore, a detailed insight into the micromechanical response is not possible.
This study uses a 3-dimensional particle code (PFC^3D), which belongs to the group of Discrete Element Methods (DEM), for simulation of lab tests of coarse-grained granular material. The paper gives a short introduction into DEM and especially PFC^3D. Some conventional laboratory tests, i.e. repose test, dumping test, and oedometer test were performed for some selected coarse-grained materials and were modelled also with PFC^3D later on. For the numerical simulations spherical particles as well as clumps with specified grain size distribution and shape were used to create the numerical samples under consideration of appropriate porosity. The numerical loading process is performed by either moving walls and/or self-weight of particles under gravitation. The stress-deformation behaviour obtained by the experiments is compared with results obtained by corresponding numerical simulations. By matching the numerical results with those from the lab, the micro-parameters of the synthetic material are obtained. These calibrated micro-parameters can be employed for further modelling of practical problems (e.g. silo-problems, ballast problems for road constructions, foundation problems, stability of slopes, etc.). The simulation results have shown satisfying agreement with lab test result.

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