Dynamic responses of flexible multi-layered pavement subjected to vehicle loads

Based on the field test data, vehicle load are simplified as a semi-sinusoidal rectangular distributed load, the expression of vehicle load are obtained by considering the dynamic component of load caused by pavement roughness. By regarding the flexible pavement structure as a three dimensional multi layered system, the dynamic responses of the pavement subjected to the semi-sinusoidal moving load are studied. The governing equations of motion are solved by employing the potential function decomposition and the Fourier transform technique. Considering the mixed boundary condition at the upper surface, the fixed boundary condition at the lowest surface and that the stress and displacement at the interface of the layers are continuous, the theoretical solutions of the components of the responses are deduced with the exact stiffness matrix method. Numerical results are obtained by using FFT algorithm and the calculation results are consistent with ones of laboratory test. The influence of different parameters such as load speed, pavement structural combination and the properties of base layer and subgrade on the responses are carefully discussed. The theory developed herein may be used as a preliminary reference in flexible pavement engineering design.