Finite element analyses of creep behaviors of non-reinforced and geogrid-reinforced sands

Based on the experimental results of creep tests under step loading in the plane strain compression,the creep behaviors of non-reinforced and geogrid-reinforced sands have been investigated.It is found that the creep deformation is affected by the initial stress level and the initial creep strain rate in a given creep loading stage.When monotonic loading is restarted from the end of each creep loading stage,the stress-strain relation shows a very high tangent stiffness.A nonlinear finite element analysis(FEA) incorporating the unified three-component elasto-viscoplastic constitutive model for both sands and geogrids is developed.The FEA can simulate the whole process including the monotonic loadings at a constant strain rate and the creep loading stages.By comparing the simulated results with the experimental results,it is shown that the developed elasto-viscoplastic FEA can simulate the creep behaviors of non-reinforced and geogrid-reinforced sands very well,especially for the high stiffness following a creep loading stage.