GEOMATERIALS: CONTINUUM OR DISCONTINUUM, THAT IS THE QUESTION

Different numerical models within the framework of computational mate- rial mechanics will be presented allowing completely diverse insights into the material behaviour at the mesoscopic level. In order to obtain an anisotropic damage evolution in a natural and conceptually simple way geomaterials are modelled as a discrete granular particle assembly composed of convex polygons that are linked together by simple beams accounting for cohesive effects. An internal length scale is incorporated intrinsically into the model by a statistically controlled particle generation process. Compression simula- tions with different boundary conditions are used to verify the qualitative application of the model. A transition from a continuous to a discontinuous state of the material results as a naturally output of the simulation. The continuous approach presented in the sec- ond part is based on the microplane concept allowing for directional dependent stiffness degradation at the material point level. Different concepts regarding the enhancement of the microplane formulation are outlined. Among these are versions for elasto-damage, elasto-plasticity and their combination on the one hand and a gradient enhancement on the other hand. Finally, a comparison of both, discrete and continuous models, namely the discrete element model and the continuous elastic microplane model, shows some re- markable similarties between both schemes. This allows a schematic comparison noting the corresponding inter-relations between both models.

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