Mechanical responses of asphalt pavements under moving loads.

[Objective] Asphalt pavement structural layers experience stress and strain under mobile loads generated by vehicles. Exceedance of the material limit of strain or stress in a structural layer leads to fractures or damage, ultimately causing pavement cracking. Therefore, it is very important to clarify whether the strain in each structural layer can be coordinated and whether the stress remains below the limit value. This clarification is essential for ensuring the structural integrity of the pavement and prolonging its service life, making it a key issue in the design of pavement structural layer combinations. [Methods] To solve this issue, this study establishes a three-dimensional model of the pavement structure using the large-scale finite-element software ABAQUS and applies a moving rectangular load in the pavement model to simulate the dynamic response of the actual pavement under the action of moving vehicle loads. Based on the finite-element calculation results, this study analyzes the changes in stress, strain, and displacement of the upper layer, middle surface layer, lower layer, base layer, and sub-base layer of an asphalt pavement under the action of moving loads. Moreover, the effects of axle load, temperature, and vehicle speed on the vertical displacement, stress, and strain of each layer are systematically studied, providing a foundation for pavement design. [Results and Conclusions] The test results indicate that when the moving load is directly above the observation point, the vertical displacement, stress, and strain reach their peak values, which gradually decrease with increasing pavement depth. Moreover, the vertical displacements of the asphalt pavement layers under moving loads were most affected by axle loads, followed by temperature, and least affected by temperature. In addition, the slopes of the curves decrease with increasing pavement depth. Compared with vehicle speed, the effects of axle load and temperature change on the vertical displacement of the pavement are more significant. Furthermore, the vertical and shear stresses in the layers of the asphalt pavement under moving loads increase with increasing axle load, temperature, and vehicle speed and decrease with increasing pavement depth. The effect of axle load changes on stresses is more pronounced than that of vehicle speed and temperature. In addition, the trends of vertical and shear strains and stresses are similar for all layers of asphalt pavement. The stress and strain conditions within the pavement structure are complex. In the design process, controlling the most unfavorable stress and strain in each structural layer is essential to meet the design requirements. [ABSTRACT FROM AUTHOR]