Characteristics and analysis of the mechanical response inside the structure of asphalt pavement

Abstract

Listen

Translate article

Determining whether structural analysis method can objectively describe the real service status of pavements is the main issue in the design of asphalt pavements. Given the complexity and variety of pavement materials, the responses of pavement structures under vehicle load and environmental conditions exhibit clear nonlinear characteristics. Obtaining the structural mechanical response characteristics in the course of pavement service is not only the solution to one of the basic issues in the structural design of asphalt pavements, but also the key to ensure the scientific and reasonable analysis of pavement structures. To reveal the structural mechanical response characteristics and change the law of asphalt pavements and provide reliable data for the development of structural design methods that are suitable for the national conditions and highway construction characteristics in China, continuous follow-up observations of the mechanical responses of asphalt pavement structures, such as stress and strain, are conducted using RIOHTrack. The actual service environment and mechanical response law of asphalt pavement structures are obtained using sensor testing technology. The influence law of external factors, such as temperature and load, on the mechanical response behavior is analyzed and the temperature and load dependences of the true mechanical response are revealed. Results show that the structural mechanical response of asphalt pavements exhibits significant temperature and load dependence and that a nonlinear relationship exists between temperature and load. To ensure the rationality of pavement analysis, nonlinear mechanics theory requires consideration in the structural calculations. The stress and strain of asphalt pavements display alternating fluctuations in the annual cycle; the smallest and largest values of the stress and strain at the bottom of the asphalt layer are observed during winter and summer, respectively. For semi-rigid base asphalt pavements, the temperature monotonically affects the value of the mechanical response of the asphalt surface layer and does not change the direction of force. An exponential function can describe the relationship of strain and temperature, whereas the Boltzmann function can describe that of stress and temperature; the decision coefficient R 2 for both functions exceeds 0.94 and therefore indicates good correlation. For full-thick asphalt pavements, the temperature change causes an increase or decrease in the mechanical response values, and a change in direction, that is, compression state and tensile state can switch to each other. And the relationship curve between strain and temperature shows a pull conversion point and a zero strain line. In the depth direction, the compression-tensile conversion occurs between 24–36 cm, and as the temperature increases, the position of the compression-tensile conversion gradually moves down from the surface. The strain response significantly increases with the increase in load level and shows a clear trend of nonlinear change, especially at high temperature and overload. The actual structural mechanical response of the pavement needed to establish the asphalt pavement calculation system and analysis theory is obtained, which addresses the lack of systematic surface structural mechanical response observation test data due to the inability to perform full-scale tests before and provides the basic data for pavement design and analysis. Results can offer theoretical support for polishing the design and analysis methods for asphalt pavements.