Experimental And Theoretical Prediction Study On Temperature Field Of Ballastless Track

As one structure exposed to the environment for a long time,the ballastless track structures bear not only the train load,but also the thermal load caused by the climatic variations.So far,although there have been some studies about the temperature field of the ballastless track,these theoretical results have so many assumptions,and the thermal parameters can not be adopted accurately.While the temperature tests of the track cost too much,and it is hard to monitor the extreme weather,these obtained empirical formulas also have weak theoretical basis.Based on the previous research,the climatic data and measured temperature values of the bi-block track were analyzed through spectrum analysis,and the relationships between the climatic factors and the track temperature were built.Then,these relationships were verified by thermodynamic principles,the thermal parameters were obtained by inversion analysis,and a widely applicable method prediction model of the ballastless track temperature was established.First of all,the heat exchange mechanism between the ballastless track and the environment was analyzed in this work,a temperature field test of the bi-block track was carried out to study the variation of meteorological parameters and the time-space distribution characteristics of the track temperature.And the relationship between the temperature of the concrete slab and the meteorological parameters was mainly analyzed.Secondly,on the basis of heat transfer principle,temperature of the concrete slab was analyzed theoretically,and the thermal diffusivity adoption of the reinforced concrete used in the track was also given.Then,a method formula to predict the track temperature was set up,the comparisons of the theoretical values and the experimental values in different areas show good agreement between them,which indicates that these predicted formulas can be used to calculate the track temperature field under high temperature weather accurately.Finally,through the method formula deduced in this work,the influence of the meteorological parameters on the track temperature was analyzed,and the track temperature distributions in typical times were calculated under different solar radiation,air temperature and wind speed.In addition,the track temperature distribution under extreme weather was also studied,these results can provide reference for the thermal loads used in the track design.