A distinct element method numerical investigation of compaction processes in highly porous cemented granular materials

In this paper, the results of an oedometric numerical test campaign, performed by means of a 3D Discrete Ele- ment Code on idealised cemented granular cylindrical specimens, are illustrated. The idealised microstructure taken into account is characterised by the following: (i) rigid grains bonded to one another; (ii) a high void ratio; and (iii) two different families of voids: the micro and the macro-voids. The compaction process developing within the specimens, as well as the localization along tabular zones of pure compressive deformation (compaction banding) that in some cases takes place, are discussed. The influ- ence on the evolution of this peculiar strain localization process of many microstructural/numerical parameters like material porosity, macro-void size, the constitutive relationship adopted for the bonds and the bond damage rate is analysed. Tests for different values of porosity were run. Below a certain porosity threshold value, the onset of mixed modes of localisation was detected whereas the increase in the macro-void size is observed to favour the onset of instability