Research Of Old Pavement Overlay Mechanical Behaviors Considering The Property Of Cross-anisotropy

Placing a structural asphalt overlay on the top of an existing deteriorated pavement is a very popular method of its rehabilitation. It has been demonstrated that asphalt concrete(AC) is cross-anisotropic, and the anisotropic properties of AC has significant effects on pavement mechanical behavior. However, the effects of cross-anisotropic properties of AC on asphalt overlay is not yet clear, the mechanical behavior of asphalt overlay considering cross-anisotropic AC is investigates in this paper, trying to provide theoretical guidance for the asphalt overlay design.Under the project(51278188) "The anisotropic pavement structure mechanics behavior and its parameters intelligent inversion research" financed by National Natural Science Foundation, the analyses of mechanical behaviors of asphalt overlay placed on asphalt pavement and concrete pavement in different conditions are performed considering cross-anisotropic AC. This article launches the research from following aspects:(1) On the basis of the assumption of cross-anisotropic AC, the mechanical behavior of asphalt overlay placed on asphalt pavement and subsequent pavement performance predictions based on AI principle are investigated, with different parameters including vertical load, horizontal load, modulus gradients of AC induced by temperature field, and existing cracking on old asphalt pavement considered. It is showed that he cross-anisotropy of AC has great effects on the mechanical behavior of asphalt overlay placed on asphalt pavement.(2) Considering the rigidity and temperature-sensitive characteristic of concrete pavement, the load stresses, temperature stresses and the coupling stresses of the cross-anisotropic asphalt overlay placed on the jointed concrete pavement are analyzed. Moreover, the effects on interface conditions on the stresses of overlay are investigated. The results show that the cross-anisotropy of AC has great influence on the mechanical behavior of asphalt overlay placed on jointed concrete pavement.Through the analysis of the mechanical behavior of asphalt overly placed on asphalt pavement and concrete pavement considering cross-anisotropic AC, it can be concluded that the cross-anisotropy of AC has great effects on the mechanical behavior and pavement performance. The anticipated service performance and predictive pavement life will be much over estimated comparing to the actual, qin consequence of taking no account of the cross-anisotropy of AC. Therefore, the cross-anisotropy of AC should be considered in the design of asphalt overlay on asphalt pavement and concrete pavement.