Abstract: A 1D constitutive model was formulated based on the hyperbola equation,the modified Masing rule,and the over-stress visco-plasticity theory.The specific features of the model included the relatively comprehensive capacity,nonlinear rheology and the simplicity in identifying model parameters.It was easy to incorporate the model into existing finite element codes.The model could also be degenerated into a time-independent one to simulate the nonlinear cyclic properties of geosynthetic reinforcements,so that it might be easily used for dynamic analysis.Experimental results on several geogrids were employed to evaluate the constitutive model.