铁路预应力混凝土槽形梁施工水化热的实测与分析

摘要

Based on the field test results of hydration heat temperature in the process of concrete casting of railway trough girder,the time-history curve of temperature variation was presented in this paper.The peak temperature and the law of temperature difference were obtained under the influence of hydration heat on the different parts of beam after concrete casting.Analysis results show that the maximum temperature of hydration heat of trough girder is 72.5℃,which appears in the lower part of the web.The maximum temperature of each measuring point of the web is greater than that of the bottom plate,and the time to reach the maximum temperature is also different.The vertical temperature difference of the web is above 20℃ and the vertical temperature difference of the bottom plate is 9℃.The temperature of measuring points on the bottom of the plate and the surface of the web were dropped to the ambient temperature after concrete casting over 80 h.According to the variation law of hydration heat temperature,the measures for controlling hydration heat of concrete from four aspects were put forward,including material ratio,concrete casting process,construction maintenance and stage.%根据铁路混凝土槽形梁浇筑时水化热温度的现场测试结果,绘制了温度变化的时程曲线,得到预应力混凝土浇筑后梁体不同部位在水化热影响下的温度峰值及温差变化规律.分析结果表明:槽形梁混凝土水化热的最高温度达到了72.5℃,最高温度出现在腹板的中下部;腹板各测点的最高温度均大于底板各测点的最高温度,且达到最高温度所用的时间也有所差异;腹板部位的竖向温差均在20℃以上,而底板竖向温差为9℃;腹板表面测点和底板各测点在混凝土浇筑完毕80 h后降至环境温度.根据水化热温度的变化规律,从材料配比、混凝土浇筑工艺、施工养护、施工阶段4方面提出了控制混凝土水化热的措施.