大体积混凝土底板水化热数值计算研究

Study of Numerical Calculation on Hydration Heat in Mass Concrete Slab

综合考虑对流边界条件、水泥水化放热、混凝土强度时变增强等因素,采用Midas有限元软件对厚度为3m的大体积混凝土底板水化热进行数值计算。通过算例分析表明:水泥水化反应初期,混凝土温度升高,表面受拉,内部受压,混凝土表面中心位置受到的拉应力最大;水化反应后期,混凝土降温收缩,外部混凝土由受拉变为受压,内部混凝土则由受压变为收缩受拉,混凝土内部收缩与外表面约束共同作用下将形成拉应力集中区。通过对算例优化设计,减少水泥用量并控制水泥水化热,降低了混凝土的开裂风险。

Mass concrete slab with a thickness of 3m is modeled by Midas to calculate the heat of hydration considering convective boundary,cement hydration and time-varying enhancement of concrete.The case study shows that,at the beginning of the cement hydration reaction,external concrete in tensile and internal concrete under pressure due to temperature rising in concrete. However,at late of the hydration reaction,external concrete under pressure and internal concrete in tensile because temperature fall down at this period. A tensile stress concentrated area is formed with the coaction of the internal shrink and external constraint. Optimal design is used to reduce the crack risk of concrete by reducing the cement content and the cement hydration heat.