早龄期混凝土温度场分布的细观数值仿真分析

在细观层次上,将混凝土看作由粗骨料、砂浆及二者界面过渡区组成的三相复合材料,提出了适用于热量传输分析的细观格构网络模型。假定仅有砂浆相在水化过程中释放热量,根据伽略金加权余数法和有限差分法,建立了混凝土各相组分的热传导控制方程及其离散形式。基于所建立的细观格构网络模型,并考虑混凝土在早龄期的"热-化学"耦合作用,开展了混凝土温度场分布的时变数值仿真研究,分析了骨料预冷和边界条件对早龄期混凝土内部温度场分布的影响。与已有试验结果对比表明,所建立的细观格构网络模型能够较准确地模拟混凝土绝热温升的变化规律。

Mesoscale numerical simulation analysis for temperature distribution in early-age concrete

The mesoscale lattice network model,in which concrete is treated as three-phase composite ma-terial consisting of coarse aggregate,mortar and interfacial transition zone (ITZ) between the aggregate and the mortar matrix, is developed to analyze heat transport process in concrete. In terms of the Galerkin-method of Weighted Residuals and Finite Difference method,a heat conduction equation as well as its dis-crete form for the concrete ingredients,i.e. aggregate,mortar and ITZ,has been established assuming that mortar is the main heat source during the hydration process. A time-varying numerical simulation of the temperature distribution and the temperature fields affected by the aggregate pre-cooling and boundary condi-tions for early-age concrete is carried out by means of the mesoscale lattice network model, in which the thermal-chemical coupling mechanism has been taken into account. The results indicate that the mesoscale lattice network model can be effectively used to predict the adiabatic temperature rise within the early-age concrete.