Influence of Subgrade Freezing and Thawing on Vertical Deformation of Asphalt Pavement

The severe freezing and thawing in seasonally frozen soils is one of the main reasons for frost heave and thaw settlement of subgrade, which leads to cracks and other serious diseases of asphalt pavement. To study the impact of freezing and thawing of subgrades on the pavement structure, an on-site investigation of the asphalt pavement diseases in Tibet, China was conducted, and a 1:5 mock-up for laboratory tests and a finite element model were designed. The temperature and humidity of the subgrade and the stress and vertical deformation of the pavement were analyzed. It was found that the moisture content of the subgrade had a significant impact on the cracking of asphalt pavement, and the vertical displacement of pavement increased by about 0.6 mm when the moisture content increased by 5 %. If there were initial cracks in the semirigid base, the maximum principal stress of the asphalt surface layer was 2.1 times more than that without cracks, which could easily lead to serious diseases in asphalt pavement. The flexible base had a good deformation coordination, which reduced the damage of the frost heave to the asphalt pavement, thereby preventing cracks on the asphalt pavement. The research results provided a theoretical direction for the analysis of frost heave characteristics and a basis for the optimum design of pavement structures in cold regions.