Modeling cyclic behavior of geosynthetics using mathematical functions combined with Masing rule and bounding surface plasticity

Abstract

In the numerical analysis of geosynthetic-reinforced soil structures subjected to earthquake loadings, the constitutive model for the geosynthetic reinforcement is important, because it affects the accuracy of numerical simulations. Two different approaches for modeling the monotonic and cyclic behavior of geosynthetic reinforcements are discussed in this paper: a nonlinear mathematical function combined with the modified Masing rule, and bounding surface plasticity. The Masing rule was modified so that it can simulate the hysteretic behavior of geosynthetics under cyclic loading, including the decrease in the residual strain rate with the number of loading cycles (cyclic strain-hardening). For the bounding surface model, different bounding lines were defined for primary loading, unloading, and reloading. An exponential function was used as the bounding line for primary loading in order to capture the stiffening behavior of some geosynthetics. Constitutive models were proposed based on the two approaches for different types of geosynthetic. Experimental results for six geogrids were used to verify the proposed models, and it was shown that they were able to capture the nonlinear and hysteretic behavior of the corresponding geosynthetics. It was shown that the approach utilizing a mathematical function combined with the modified Masing rule is simple and straightforward. Bounding surface plasticity provides an approach that is more rational for simulating the cyclic behavior of geosynthetics, especially for the case of irregular earthquake loading.