Finite Element Modelling of geogrids in stabilisation function - Comparison study

Finite element methods (FEM) are commonly used in geotechnical designs. These methods become particularly valuable when complex multistage scenarios with a variety of interactions need to be considered. Many advanced constitutive models describing soil behaviour exist. However, features in FEM software to model geogrids are often limited to elements that are represented as elastoplastic membranes that interact with the surrounding aggregate through an interface element. These methods, using limited parameters, are more suited to modelling the reinforcement function of geosynthetics. Since ISO 10318-1:2015+A1:2018 was published, a new function of geogrids was introduced: stabilisation. Stabilisation relies on the interlock between the geosynthetic and the granular material which confines the granular aggregate. This generates very small strains within the geosynthetic product. In addition, the confinement of the granular material, due to the stabilisation effect, influences beyond the thin layer of interface into the aggregate. The aim of this paper is to examine and assess the traditional feature that is available in popular FEM software Plaxis and compare it to the Tensar Soil Stabilised (TSS) constitutive model – a user defined soil model (USDM) available in software such Plaxis, Abaqus, Flac or Cesar. The TSS model aims to more accurately represent the geogrid and aggregate interaction by modelling the composite behaviour of the two materials.