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To investigate the influence of pavement roughness on the dynamic stresses under traffic vehicles, a pavement resting on a layered poroelastic half-space is studied. The shape of pavement roughness is treated as a sine function of irregularity while the vehicle is modeled as a quarter-vehicle vibration system with two degrees of freedom (DOF). Based on the Biot's dynamic poroelastic theory, the time domain solutions of the homogeneous poroelastic half-space are obtained by Fourier transforms and inverse Fourier transforms. The time domain solutions of the layered poroelastic half-space are then presented using the transfer-matrix method. By regarding the top layer as a thin-plate and using the Kirchhoff's hypotheses, the vertical displacement and stress of the thin plate are calculated. The time domain solutions of the rigid pavement-layered poroelastic ground system are obtained based on the compatibility condition at the interface of the pavement-ground system. The dynamic effects of the load velocity, the wave length and the thickness of the plate are discussed, respectively. It is found that the roughness of the top plate significantly affects the dynamic stress response in the poroelastic layers when the vehicle velocity is below a critical value. In addition, the dynamic impact coefficient depends on the wave length of the roughness as well as the amplitude. The dynamic stress response caused by the roughness of pavement is evident and different from the dynamic stress response caused by vehicle weight. This study is intended to provide potential guidance for the design of a rigid pavement system.

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.