沉管预制大体积混凝土季节性温控技术研究

Research on Seasonal Temperature Control Technology of Precast Large Volume Concrete for Immersed Pipes

沉管预制过程中大体积混凝土浇筑产生的水化热反应会导致不均匀温度应力的产生,极易形成温度裂缝且将严重影响沉管结构的抗渗性能。混凝土浇筑易受环境影响,为避免沉管混凝土浇筑后内表温差过大,研究沉管大体积混凝土浇筑在不同季节下温度场发展规律十分有必要。文章采用数值模拟和现场监测分析方法对不同季节下沉管大体积混凝土温度场规律和温控技术进行研究,结果表明:数值计模拟结果与现场监测结果大致吻合,夏季与冬季管节混凝土温升规律大致相同,即先快速增大后缓速减小,温峰出现在底板中隔墙倒角处,最大内外温差峰值出现在顶板中隔墙倒角处。基于上述分析提出了分阶段式温控措施,实施后混凝土内表温差下降了28%。

The heat of hydration reaction generated by the bulk concrete placement in the precast process of the immersed pipe will lead to the generation of uneven temperature stresses,which will easily form temperature cracks and will seriously affect the impermeability of the immersed pipe structure.Concrete placement is easily influenced by the environment,and in order to avoid excessive temperature difference between the inner surface of the concrete after placement,it is necessary to study the development of the temperature field in different seasons for large volume concrete placement of immersed pipes.The paper adopts numerical simulation and field monitoring analysis method to study the temperature field law and temperature control technology of immersed pipe mass concrete under different seasons,the results show that:the numerical meter simulation results and field monitoring results roughly match,the temperature rise law of pipe section concrete in summer and winter is roughly the same,the first rapid increase and then slow decrease,the temperature peak appears in the bottom plate in the diaphragm wall chamfer,the maximum internal and external temperature difference peak appears in the top plate in the maximum temperature difference between inside and outside peaks at the chamfer of the diaphragm wall in the top slab.Based on the above analysis,the phased temperature control measures were proposed,and the temperature difference between the inner and outer surfaces decreased by 28% after implementation.