基于气象条件的客运专线简支箱梁日照温度场研究

Study on Temperature Fields of Simply-supported Box Girder under Solar Radiation in Passenger Dedicated Lines Based on Meteorological Conditions

分析日照作用下混凝土箱梁与环境的热交换机理,结合桥位气象条件,采用瞬态热流边界模拟日照温度条件、计算客运专线简支箱梁温度场,采用实测数据对该方法进行验证。以我国客运专线采用的无砟轨道32m标准跨径简支箱梁为工程背景,分析基于气象条件的客运专线标准跨径简支箱梁日照温度场分布特征,探讨大气透明度系数、覆盖层厚度及混凝土表面吸收率等参数对箱梁温度场的影响。研究表明:箱梁日照温度边界可采用瞬态热流边界进行模拟,计算渡越时间约为84h;箱梁最值温度与大气透明度系数正相关,且对顶板温度的影响最大;梁顶覆盖层能有效减小梁顶的温度变化幅度;提高混凝土表面的光洁度或采用浅色涂层以减小混凝土表面吸收率,可有效降低箱梁的温度变化幅度。

The heat transferring mechanism between concrete box girder under solar action and environment was analyzed.Considering meteorological conditions of bridge site,transient heat flux boundaries were applied to simulate the sunshine temperature and to calculate the temperature field of simply-supported box girder of passenger dedicated line ( PDL).The results were verified with the measured data.Based on the 32 m standard span ballastless simply-supported box girder used by the PDL in China,the distribution law of the temperature field of the PDL ’ s simply-supported box girder under solar radiation was analyzed based on meteorological conditions.The influence of atmospheric transparency coefficient,thickness of coverage and concrete surface absorption coefficient on the temperature field of the box girder was studied.The analysis shows that the box girder ’ s sunshine temperature boundaries can be simulated as transient heat flux,and the transition time is 84 hours.The highest and lowest temperatures of the box girder and atmospheric transparency coefficient have positive correlation,while the effect on top slab is most distinct.Meanwhile,the coverage on the girder top can effectively reduce the top slab ’ s temperature amplitude of variation.Increasing the smoothness of concrete surface or using light-colored coating, to reduce the concrete surface absorption can effectively reduce the girder ’ s temperature amplitude of variation.