Micromechanical investigation of geogrid-reinforced granular soil

Geogrids are widely used as a soil reinforcement technique in many engineering applications, however a detailed study of the mutual interaction between these structures and the granular soil is complex and generally faced only with specific laboratory tests. In the last decades, the recourse to numerical methodologies has experienced large growth, and among the different methods, the discrete element method (DEM) has proven its reliability in understanding both the micro and macro aspects of the soil-geogrid interaction. In this study, 3D discrete element simulations of pull-out tests are performed. The shape of the numerical geogrid and the contact properties of its elements are calibrated using the results of laboratory tests referring to a real PET woven geogrid. The geogrid mechanical properties investigated control its strength and stiffness. Their role and influence on pullout behaviour are investigated in different soil conditions regarding the confinement stress, the soil particle size and shape. The granular soil is modelled using both spheres and clumps to simulate different fine-graded gravels.