Geogrid pull-out modelling using DEM

With the advancement of the use of synthetic reinforcements in geotechnics, a greater understanding of the mechanisms involved in soil-reinforcement interaction is the focus of major research centres on the subject. The topic of this study is the shearing behaviour at interfaces between granular materials and geogrids. The main objective is to provide a more fundamental understanding of some micromechanisms present in this type of interface, which in turn are important to optimize the design of such reinforcement. The numerical modelling of these reinforced structures must deal with the complexity of the material-reinforcement interaction problem; therefore, it requires specific numerical models whose formulations admit localized behaviours in the contacts as well as the granular nature of the material (e.g., soil, gravel, ballast). A robust and flexible way of modelling this problem is through the Discrete Element Method (DEM). The DEM proposes to model this granular nature by representing the soil as interacting constituent particles, whose behaviour is ruled by physical laws defined at the contact points. The numerical approach is desirable since it allows, in an articulated and relatively fast way, studying closely different regions of the interface, in order to identify factors and variables that are important for the problem. The purpose involves the DEM for a 3D modelling of a geogrid pull-out test to calculate the magnitude of forces in different elements of the geogrid (i.e., nodes, longitudinal and transverse members). Preparation of numerical samples has a particular importance in the final results of simulations. Thus, the numerical techniques used to obtain better geometry for the geogrid and a granular assembly with a representative grain rolling effect are also presented in this paper.