混凝土箱梁早期温度测试与分析

Test and analysis of early temperature of concrete box girder

通过对长沙中低速磁浮混凝土箱梁水化热阶段温度分布的连续观测,研究了夏季和冬季两种外界环境温度下混凝土箱梁水化热温度场的时变规律,并提出适用于不同外界环境温度条件下的混凝土箱梁水化热温度荷载模式.结果表明:混凝土箱梁在早期温度变化期间会经历4～6d的温度升高和降低的阶段,并在混凝土浇注后的1～2d内达到其峰值温度.冬季与夏季相比,其箱梁水化热温度的升、降温速率、峰值温度以及水化热持续时间较短.在箱梁跨中截面顶板和底板厚度方向上,内表面测点温度均高于外表面测点温度,其温度峰值相差约3.1℃和5.2℃.在箱梁顶板和底板横向方向上,位于两侧的测点温度均明显低于位于顶板或底板中间的测点温度,温度峰值相差约8℃,平均温度相差5.4℃.通过实测箱梁内外温度,发现其内外温差最大值达到18.4℃,出现的时刻为混凝土浇注后的第49h.混凝土箱梁的水化热温度荷载模式与外界环境温度有关,但均可采用物理意义相同的正弦函数拟合.

According to the continuous observation of the temperature distribution in the hydration heat phase of Changsha medium and low-speed maglev concrete box girder,the time-varying regularity of the hydration heat temperature field of concrete box girder in summer and winter is studied.And a suitable hydration heat temperature load mode of concrete box girder for different environment temperature conditions is proposed.The analysis results reveal that during the construction period,the concrete box girder experienced a period of 4-6 days of rising and decreasing of hydration heat;the peak temperature is reached in the 1 to 2 days.The temperature of hydration heat of the box girder in winter is lower than that in summer.In the thickness of the roof and the bottom of the cross section of the box girder,the temperature of the measuring point on the inner surface is higher than that of the outside surface;the difference of peak temperature is about 3.1℃and 5.2℃.In the transverse direction of the roof and floor of the box girder,the temperature of the measuring points on both sides is obviously lower than the temperature at the middle point;the difference of peak temperature is about 8 ℃;and the average temperature difference is 5.4℃.And by measuring the temperature inside and outside of the box girder,it is found that the maximum temperature difference between inside and outside is 18.4 ℃;the moment of occurrence is the 49 hafter the concrete is created.The hydration heat temperature load mode of concrete box girder is related to the environmental temperature,but can be fitted the same physical meaning of sine function.