基于点阵式测量的混凝土箱梁水化热温度场原位试验

In-situ test on hydration heat temperature of box girder based on array measurement

在混凝土箱梁模型上布设479个温度测点,对箱梁在水化热期间的温度变化规律进行精密测量。通过德洛内三角网格算法,建立用于混凝土箱梁温度测量的温度传感器点阵,绘制箱梁全截面在水化热期间的温度场云图,进而分析混凝土箱梁的水化热温度发展规律。研究结果表明:箱梁的水化热温度场基本呈对称分布,其中腹板水化热温度变化最大,最高温度为64.8℃,顶板、底板与腹板的最大平均温升比值约为1∶1.1∶1.4;底板水化热温度最先达到峰值,为混凝土浇筑后11h;腹板的平均温度峰值出现在浇筑后12h;顶板温度峰值相对滞后,为混凝土浇筑后13h;箱梁各板沿厚度方向的水化热温度服从高斯分布形式;顶板、底板沿宽度方向水化热温度呈双峰对称分布,服从二项组合式的高斯分布模型,而腹板的水化热温度沿板高可认为常量。此外,文中给出了箱梁模型关键位置在水化热期间的温度数据,可用于指导混凝土箱梁水化热温度试验的测点布置,并且为箱梁的水化热温度控制和设计提供参考。

To investigate the evolution of hydration heat in concrete at early age, temperature fields of a box girder segment were measured by 479 thermocouples. Delaunay triangulation method was employed to establish a thermometry matrix, which made it possible to get accurate temperature fields in the process of hydration heat in box girder, and then the characteristic of temperature distribution was analyzed. The results show that the hydration temperature displays a symmetrical distribution across the vertical center axis of box girder segment.The maximum value of the hydration temperature is located in the box-girder web with a value of 64.8℃. The ratio of maximum hydration heat of tops, bottom flanges and webs of box girder is 1∶1.1∶1.4. The maximum hydration heat occurs within 11 hours after concrete casting in bottom flange, while it is 12 hours for the web and 13 hours for the top flange of box girder. The temperature variation in the thickness direction of plate follows an expression of Gaussian function, while the temperature variations in the width direction of top and bottom flanges follow a binomial expression of Gaussian function. In addition, the temperatures mainly keep in constant in height direction of box girder’s web. Groups of detailed temperature values are also provided during box girder’s hydration heat period, which can be referred in the measurement experiment of hydration temperature of concrete box girder. This work can also provide reference for the temperature control and design of box girder at the early age after concrete casting.