A three-dimensional finite element approach for modeling biaxial geogrid with application to geogrid-reinforced soils

Understanding soil-geogrid interaction is essential for the analysis and design of geogrid-reinforced soil structures. A first step towards accurate modeling of this interaction is choosing a suitable material model for the geogrid that is capable of simulating tensile test results. The model must be able to capture the three-dimensional response of the geogrid considering its exact geometry. Modeling geogrid inclusion as a continuous sheet has proven to reasonably simulate the overall response of soil-geogrid systems; however, it does not explain the different sources of interaction between the geogrid layer and the surrounding soil. To understand the three-dimensional aspects of this complex interaction problem, a two-phase numerical investigation is developed in this study. The first phase focuses on the three-dimensional modeling of unconfined biaxial geogrid subjected to tensile loading. Applicability of the geogrid model in solving soil-structure interaction problems is then demonstrated, in the second phase, by investigating the response of a reinforced subgrade subjected to a square shaped surface loading. It is concluded that modeling the three-dimensional geogrid geometry is important to accurately capture the true response of geogrid under both confined and unconfined conditions. The modeling approach proposed in this study for the analysis of unconfined and soil-confined geogrid can be adapted for other reinforced soil applications. (C) 2016 Elsevier Ltd. All rights reserved.