Dynamic shakedown analysis of two-layered pavement under rolling-sliding contact

Shakedown theory provides a rational tool to predict the long-term plastic behavior of pavement subjected to repeated traffic loads. Lower-bound shakedown solutions have been proposed in recent years to estimate the shakedown limit load under which the failure of the pavement due to excessive permanent deformation will not occur. However, for such a problem when the tire-pavement interaction is characterized by rolling-sliding contact, the dynamic responses of pavement structures were not thoroughly explored. In this paper, a numerical method for computing the shakedown limit of pavement is presented based on the lower-bound shakedown theorem. A moving Hertzian contact with sliding friction is constructed in a finite element model with infinite element boundary to calculate the dynamic elastic stress field due to rolling and sliding contact between the pavement and vehicles with different moving speeds. Shakedown analysis for both uniform subgrade and two-layered pavement has been investigated. It is found that the shakedown limit decreases with increasing vehicle moving speed. The dynamic effects of moving speed become less significant as the contact friction coefficient increases. Both the speed and the friction coefficient can affect the location of critical failure point, which tends to transit from the top layer to the bottom layer with increasing speed or decreasing friction coefficient. Eventually, the influences of frictional coefficient and material properties on shakedown limit are also investigated and the characteristics of the distribution of critical residual stress is also discussed.