Considering the fact that the creep properties of geogrids are fundamental and important factors on the long-term behavior of geogrid-reinforced earth structures

a series of comparative experimental tests of the creep properties of geogrids are conducted in the laboratory under different combinations of externally-applied load and environmental temperature. Based on the experimental results

comparative analyses are made to examine characteristics of isochronous load-strain curves

creep curves and relaxation curves of geogrids. Furthermore

a constitutive model based on viscoelasticity is proposed for geogrids and a rational procedure based on experimental tests is presented for defining the relevant parameters of the model. The proposed model is verified by comparing the prediction of the model and experimental results. It is shown that the viscoelasticity creep model can mainly display long-term behavior of geogrids.