高速铁路简支箱梁日照温差的变化规律

Temperature Difference Variation Law of Simply-supported Box Girders on High Speed Railway Under Solar Radiation

考虑日照条件下混凝土箱梁热流密度边界的时变特征,建立高速铁路简支箱梁温度场参数化仿真分析模型,研究高速铁路标准跨径简支箱梁温差的分布特征及控制措施。结果表明:箱梁最大正、负温差均沿厚度方向呈负指数分布,最大正温差在数值上大于负温差;随着大气透明度系数的提高,箱梁顶板和底板的正、负温差及腹板的负温差增大,而腹板正温差随之减小;箱梁温差与混凝土短波辐射吸收率成正相关,涂刷浅色涂料和提高混凝土表面光洁度可有效减小箱梁温差;昼夜气温差对箱梁温差分布影响显著,日温差越大箱梁各个部位温差越大;增大梁顶覆盖层厚度可一定程度上降低箱梁顶板温差。

Considering the time-varying characteristics of heat f lux boundary of concrete box girder under solar radiation,a parametric simulation model of temperature f ield of simply-supported box girder on high speed railway was established to study the distribution characteristics and control measures of temperature difference of standard span simply-supported box girder on high speed railway.The results show that the maximum positive and negative temperature differences of box girder are negatively exponentially distributed along the thickness direction,and the maximum positive temperature difference is greater than the negative temperature difference in numerical value.With the increase of atmospheric transparency coeff icient ,the positive and negative temperature differences of top and bottom decks of box girder and the negative temperature difference of web increase,while the positive temperature difference of web decreases.The temperature difference of box girder is positively correlated with the absorptivity of shortwave radiation.The temperature difference of box girder can be effectively reduced by applying light-colored paint and improving the surface f inish of concrete.The temperature difference between day and night has a signif icant effect on the temperature difference distribution of box girder.The larger the temperature difference between day and night,the greater the temperature difference of each part of box girder.The temperature difference of top deck of box girder can be reduced to a certain extent by increasing the thickness of overburden.