Modeling cyclic behavior of unbound aggregates using two-surface plasticity theory

Various empirical rutting models have been proposed to predict the permanent deformation of aggregate base/subbase layers in pavements. Nevertheless, an analytical model is required for large-scale finite element simulation of the pavement structure. A two-surface plasticity theory is used to predict the long-term cyclic behavior and provide path-dependent material responses of aggregates. The deviatoric stresses for each aggregate were determined based on the shear stress ratio and the shear strength properties at source and engineering gradations. The proposed rutting model was optimized and validated via repeated load triaxial tests using 11 aggregates. The numerical results demonstrate that the proposed model accurately describes aggregates with low-level permanent strain and thus enables the yield surface, long-term shear strain, and path-dependent resilient modulus to be assessed. Overall, the proposed physics-based modeling approach can help understand and predict the deformation behavior of aggregates subjected to moving-wheel loads.