Research On Pavement Temperature Field At Entrance And Exit Section Of Highway Tunnel In Qinling Mountains

Long tunnels majority lie in mountainous area highway，the meteorological condition ofmountainous area is different from flat area and it has complex effects on pavementtemperature field at entrance and exit section of tunnel. The differences between theenvironment factor of entrance and exit section of tunnel lead to great differences betweenpavement temperature field of entrance and exit section, furthermore, the pavementtemperature field at entrance and exit section appears to be in transient state. The research onthe pavement temperature field at entrance and exit section is seldom at present. This articleprovide a design reference to transition section of pavement according to the study of thermalregime characteristics of pavement at entrance and exit section of tunnel.Based on the climate characteristic and its influence of Qinling Mountains onpavement,this research establish temperature field model to study pavement temperature fieldat entrance and exit section of tunnel and its influencing factor. Providing a determinationmethod to longitudinaltransition section of temperature fieldthrough the analysis on thedistribution character of pavement temperature field. At the same time, analyzed the variationcharacteristics of pavement temperature field at transition section of highway tunnel underdifferent pavement structure on that basis, also provided directions and references forpavement structure at entrance and exit section of highway tunnel. The research revealed that:Seasonal change has great influence on temperature longitudinal distribution trend of tunneland the temperature and temperature gradient also existanunstable change.The unstablesection length grows as the pavement depth increases, the unstable section length in winter islonger than its in summer at the same structural layer. According to the longitudinaldistribution of characteristics of temperature field, we set the longitudinal unstable section ofroad surfacein winter as the longitudinal transition section of temperature. Set the winterlongitudinal unstable section of temperature gradientstructural layer where C40concrete slablies in as the longitudinal transition section of temperaturegradient. In some cases, if thepavement thickness is stable, simply change the structure material won’t have influence on the length of the longitudinal transition section of temperature and temperaturegradient, but itwill influence its distribution character. When the amplitude of variation of the pavementthicknessexceeds14cm, the length of longitudinal unstable section of temperature andtemperaturegradient will extend.Using composite surface course inside tunnel, combined basecourse or composite surface course outside the tunnel can effectively reduce the temperaturedifference of the longitudinal transition section of temperature, and play a warming effect onthe road surface. Considering reducing temperature gradient in the concrete slab, usingcombined base course or composite surface course outside the tunnel has good effect.