Numerical investigation of the mechanical response of semi-rigid base asphalt pavement under traffic load and nonlinear temperature gradient effect

Abstract

The effectiveness of any pavement design based on the mechanistic procedure depends on the accuracy of the mechanical parameters used such as stresses and strains. Hence, an effective and realistic prediction of these parameters when traffic and environmental data are provided is a step towards the future design of more sustainable pavement structures. This study investigated the distribution of the mechanical parameters in three new semi-rigid pavement structures with typical functional and structural requirements, specially designed to withstand various distresses of semi-rigid pavements. The response of these pavements to the combined effect of the nonlinear thermal gradient and moving axle load was examined by means of an advanced 3D pavement FE modeling. The model integrated mechanical and thermophysical properties of each pavement material, studied the transient dynamic effect of wheels load, and employed transient heat transfer and implicit dynamic analysis. Field measurements of these experimental pavement structures at the RIOH-Track test site in Beijing, China, as well as relative climatic data were used to verify and validate the accuracy of the developed model. Comparison of the numerical and experimental results indicated that the developed model predicted accurately the characteristic non-linear distribution of temperature along with the pavement depth and the pavement response to the combined effect of the nonlinear temperature gradient and traffic load. The influence of three main factors affecting the distribution of the mechanical parameters, namely; the bonding conditions between the pavement’s layers, the vehicle speed and the axle load amplitude were evaluated. In addition, fatigue analysis of the asphalt layers and the semi-rigid layers was performed to evaluate the theoretical service life of each pavement structure. The findings of this study underscored that the non-linear temperature gradient, despite being often neglected in mechanistic modeling, is a key parameter for accurate prediction of the distribution of stresses and strains in pavement system. Moreover, the results indicate that the lowest traffic speed and the extra weight extension of the truck axle have an adverse effect on mechanical parameters. Furthermore, the improvement of contact conditions at the interface results in good performance. Overall, the conclusions obtained in this study provides a reference for the design of semi-rigid pavement structures.