Research Of Mechanical Behaviors Of Cross-Anisotropy Pavement Structure

Road pavement structure system is relatively complex. Road pavement materials are various and complicated; the vehicle load and environment is complex. They almost make it impossible to understand the mechanical behaviors of road pavement structure. The structural component and shaping of subgrade and pavement materials result in the remarkable property of anisotropy, and under the load the mechanical behaviors of asphalt pavement structure layers are different. The characterization and analysis methods for isotropic and anisotropic materials are quite different. Cross anisotropy is considered for the purpose of simplification, and due to the experimental evidence. Therefore, cross-anisotropy model will be more reasonable, which is used to describe the mechanical behaviors of pavement structure layers. For the cross anisotropic case, the solid is considered to have significant differences only in vertical and horizontal directions due to the anisotropic compaction, aggregate orientation, restraint conditions, and gravity direction. In cross anisotropic elasticity, there are only five material constants.Based on cross-anisotropy of subgrade and pavement materials, this paper presents the mechanical behaviors of pavement structure layers under different load cases through finite element simulations. Under the project (51278188) financed by National Natural Science Foundation the main study is in the following aspects:(1) Established the cross-anisotropy three dimensions finite element model of pavement structure. Considering the cross-anisotropy of aggregate base and subgrade, studied on the mechanical behaviors of pavement structure under the vertical load. The study analyzed the effects of cross-anisotropy and mechanical analysis on pavement responses, including surface deflection, tensile strain and stress at the bottom of the HMA layer, tensile strain and stress at the bottom of the base layer, and compressive strain on top of the subgrade. And, analyzed the mechanical behaviors of cross-anisotropy aggregate base pavement structure under Horizontal and vertical loads. And then, evaluated the cross anisotropy of aggregate base and its effect on the estimated pavement life for rutting and fatigue cracking.(2) The tire ground shape was simplified to establish non-uniformly distributed load model; the study showed the mechanical behaviors of cross-anisotropy asphalt concrete and aggregate base pavement structure under non-uniformly distributed load. (3) A three-dimensional finite element model was developed to investigate the dynamic responses of asphalt pavement under impulsive loading similar to a falling weight deflectometer test. The study analyzed the effects of cross-anisotropic stress-dependent asphalt concrete, aggregate base, subgrade modulus and dynamic analysis on pavement responses.