Numerical study and in-situ measurement of temperature features of asphalt supporting layer in slab track system

Abstract

Recently, asphalt supporting layer (ASL) has been adopted as a novel technology to waterproof subgrade and increase stability of slab track in China. Asphalt concrete is a typical thermal sensitive material and its mechanical properties are very susceptible to temperature conditions, which makes it very brittle at low temperature and easy to suffer from deformation at high temperature. Therefore, it is essential to investigate the temperature features of ASL in slab track during its service life. In this paper, the temperature distribution within ASL was studied by combining field recorded data and numerical simulation, and the effects of meteorological factors including air temperature, solar radiation, and wind speed were numerically studied with emphasis. The results show that the temperature within ASL distributed non-uniformly along the cross section of ASL, and the temperature of the area directly underneath the track slab was much more stable than other areas exposed to the air. The variation of meteorological factors including air temperatures, solar radiation and wind speed has significant effects on the temperature of ASL, but it takes hours for the change of meteorological factors to be seen within ASL. There is alinear relation between the change of ASL temperature and the variation of air temperature and solar radiation incident, but the influence of wind speed decreases with the increasing of wind speed. Meanwhile, the temperature of ASL is moresusceptible to solar radiation and wind speed in summer, and it is more easily affected by air temperature in summer.