青藏铁路多年冻土地区混凝土双片式T型梁日温差变化规律

Daily temperature difference of concrete double T beam in permafrost regions along Qinghai—Tibet railway

针对青藏铁路多年冻土地区混凝土双片式T型梁日温差进行现场试验与理论分析。开发适合青藏高原恶劣气候环境的气温梁温自动采集存储系统,对青藏铁路典型地区(沱沱河、扎加藏布)的混凝土双片式T型梁体表面温度进行1 a的连续测试;建立双片式T型梁体日照温度场二维非稳态有限元分析模型,结合现场实测数据,分析与系统采样时刻相应的梁体截面温度分布,获得测试期间内的梁体日温差。研究结果表明:沱沱河地区梁体最大日温差为10.2℃;扎加藏布地区梁体最大日温差为17.8℃,其中大于规范值(15℃)的时间为20 d,占样本总数的5.31%,主要出现在每年11月至第2年3月之间。研究成果对于青藏铁路多年冻土地区桥上无缝线路的设计和养护维修具有重要参考价值。

A set of on-the-spot test and theoretical analysis in daily temperature difference of concrete double T beam in permafrost regions of Qinghai--Tibet railway were carried out. An automatic collection and storage system for air and beam temperature was developed which was suitable for the bad weather conditions of Qinghai--Tibet Plateau. The surface temperature of concrete double T beam was continuously tested for 1 a in the typical regions of Qinghai--Tibet railway, such as Tuotuohe, Zhajizangbu, and so on. A two-dimensional unsteady simulation model of double T beam solar radiation temperature field was established by using the finite element method. The beam section temperature distribution of the corresponding testing moment was analyzed with the measured data, based on which the daily temperature differences were obtained. The results show that the maximum daily temperature differences of beam are 10.2℃ and 17.8℃ respectively in Tuotuohe and Zhajiazangbu. In Zhajiazangbu, there are 20 d of daily temperature differences greater than the standard value （15 ℃）, which accounts for 5.31% of the total number of samples, and it mainly appears from November to March of next year. The research results are significant for the design and maintenance of continuously welded rail track on bridge in permafrost regions of Qinghai--Tibet railway.