桥梁承台大体积混凝土施工水化热分析及温控研究

Research on the Hydration Heat Analysis and Temperature Control in Mass Concrete Construction of the Bridge Platform

以某多跨连续梁桥大体积混凝土承台温控作业为例,采用有限元软件对承台浇筑后的水化热释放情况进行数值模拟分析,根据分析结果有针对性地进行承台冷却水管及测温元件的布置。对承台浇筑后连续14 d的实际温度变化监测结果显示:大体积混凝土承台浇筑完成后,水化热在承台中同一测温层无论是沿顺桥向还是承台对角线方向都表现出靠近平面中心温度高,向外温度逐渐降低并且在靠近外表面位置温度急剧降低的分布特征;水化热在承台中不同层同一水平位置测点的竖向温度都表现出中间位置高\,接近上下表面位置处低及温度最高点靠近下部的分布特征;大量水化热在混凝土浇筑完成后前4天放出;内外温差超过20℃可能导致承台开裂,浇筑完成后的前几天要特别注意控制内外温差。

Taking the temperature control operation of mass concrete cap of a multi-span continuous beam bridge as an example,finite element software was used to simulate and analyze the release of hydration heat after pouring of the cap.According to the analysis results,the layout of cooling water pipes and temperature measuring elements on the cap is carried out.The monitoring results of the actual temperature change of the cap for 14 consecutive days after pouring show that:After the pouring of mass concrete caps,the hydration heat in the same temperature measuring layer in the cap shows high temperature near the center of the plane no matter along the direction of the bridge or the diagonal direction of the cap.The distribution characteristics shows gradually decreasing outward temperature and sharply decreasing temperature near the outer surface.The vertical temperature of the measuring point at the same horizontal position of different layers in the platform shows a high temperature atcenter position,low temperature near the upper and lower surfaces.And the distribution characteristics shows the highest temperature is near the lower part.A large amount of hydration heat is released 4 d before the completion of concrete pouring.The temperature difference between inside and outside exceeding 20℃may cause the cap cracking,therefore,special attention should be paid to control the temperature difference between inside and outside a few days before the completion of pouring.