Dynamic Shakedown Analysis of Flexible Pavements under Rolling and Sliding Contact Considering Moving Speed

Pavement subjected to the traffic load above shakedown limit is predicted to exhibit accumulated plastic strains that eventually lead to failure within the pavement system. Shakedown theory is a valid approach to estimating the critical shakedown load level. In this study, a dynamic shakedown method for computing the shakedown limit of pavement is presented based on the lower-bound theorem of shakedown. To this end, a combined Finite element-Infinite element (FE-IE) method is utilized to calculate the dynamic elastic stress field due to rolling and sliding contact between wheel and pavement surface considering the effect of moving speed. The rolling and sliding contact is approximated by a moving Hertz distribution load, which is performed through moving vertical and horizontal body forces simultaneously modeled by thin-layered element above the pavement surface. Shakedown limits for both uniform and two-layered pavement system at various moving speeds have been investigated, respectively. It is found that the shakedown limit decreases with the increasing moving speed and then turns to increase when the moving speed exceeds the Rayleigh wave speed. This dynamic effect is more profound when the horizontal force is small. The influence of horizontal force on shakedown limit at various moving speed is also discussed. Eventually, the impact of frictional coefficient and material properties on shakedown limit for two-layered pavement is also investigated as can then be applied to the optimal pavement design.