FE simulation of viscous behavior of geogrid-reinforced sand under laboratory-scale plane-strain-compression testing

A nonlinear finite element method (FEM) analysis technique is developed to simulate the viscous behavior of geogrid-reinforced sand during loading. In the FEM simulations, the viscous properties of sand and polymer geogrid are described in the framework of a unified nonlinear three-component elasto-viscoplastic model. The results from the plane-stain-compression (PSC) tests on the geogrid-reinforced sand specimen with the dimension of 96 × 62 × 120 mm are simulated using the developed elasto-viscoplastic FEM technique. In the PSC tests, the strain rate was changed step-by-step as well as the creep and stress relaxation tests were performed during monotonic loading (ML) at a constant strain rate. Both creep and stress relaxation tests lasted for 3 h. The FEM simulated average stress ratio-vertical strain-time relationships of geogrid-reinforced sand are compared with the measured ones from the PSC tests. The strain during creep loading stage is also simulated by the FEM. It is shown that the developed FEM analysis technique can simulate the stress-strain behavior of geogrid-reinforced sand well, especially for rate-dependent behavior, creep deformation and stress relaxation. The constraining effects due to the tensile reinforcing of geogrid layers can be observed clearly in the FEM simulation results.