Analysis For The Couple Problem Of Time And Temperature Field When Paving Hot Mixture Asphalt In Long Tunnel

As the great western development of deepening, the scale of mountainous highway construction has been rapid development. Because the tunnel will be able to reduce substantially the totel length of road, improve operation efficiency, save the land resources, protect the environment etc, the scale of the long tunnel on the highway projects, especially of high-grade highways, is getting bigger, and grown tunnel asphalt pavement construction problems facing also become more outstanding. However, when paving hot mixture asphalt (HMA) in tunnel, it can release a lot of heat and harmful gas will cause construction environmental of the tunnel degradation, serious impact of construction machinery and construction workers normal construction. Therefore, internal temperature field variation law with time of paving asphalt mixture in tunnel has been concern as the academic community, and its research results can provide reference for construction environment optimization.This paper is based on the theory of heat transfer and the three dimensional finite element numerical simulation model, simulation dynamic process of paving hot mixture asphalt in tunnel and further analysis air temperature field distribution pattern of the tunnel, the research content of this paper mainly includes the following:(1) According to the law of conservation of energy, through the UDF of FLUENT, with heat flux in the form of model of HMA elements assignment, in order to simulation dynamic process of paving hot mixture asphalt in tunnel and examine the effect.(2) Through finite element numerical simulation software, to explore the different conditions, the horizontal and vertical air temperature field distribution pattern. Longitudinal temperature distribution characteristics:when the longitudinal slope of tunnel is zero, air longitudinal temperature distribution shows "hourglass" shape, the hot air flow from both tunnel hole, temperature relatively high regional occurred in the length midpoint nearby; When the longitudinal slope of tunnel is not zero, tunnel of hot air mainly flow from elevation higher hole, air temperature is relative taller area to uphill direction deflection.Temperature distribution characteristics of cross-section of tunnel:when the longitudinal slope of tunnel is zero, the temperature of cross-section of higher temperature area in already paving section, increases with the distance from the pavement, and decreases with increasing distance from the center axis of symmetry; the temperature of Already paving section within (not including high temperature area), decreases with the increasing of the height from the pavement within a certain height from the pavement, and increases with the increasing of the height from the pavement outside a certain range from pavement.(3) By changing the speed of paving, the longitudinal slope of the tunnel and spreading thickness different working conditions, the temperature contrast analysis of construction work area, the research on the influencing construction personnel and construction machines working environment temperature factors. The results indicate that within the confines of the code, the change of the speed of paving HMA (2m/min-6m/min) has little influence on the temperature of construction circumstance; The change of spreading thickness(4cm-7cm) deeply influence the temperature of the construction circumstance, therefore, thin layer concrete more conducive to the construction; The effect of the change of the longitudinal slope(≤3%) on air temperature field distribution is obvious, but minimal on the temperature of construction circumstance.