大体积膨胀混凝土水化热实验与数值模拟研究

Experimental and Numerical Simulation Study on Hydration Heat of Expansive Mass Concrete

摘要:

针对某质子治疗中心项目的大体积膨胀混凝土水化热问题，以大体积膨胀混凝土为研究对象，通过模型实验和MIDAS/FEA有限元仿真，研究了大体积膨胀混凝土的水化热反应过程，得出混凝土浇筑后温度场和应变场情况。结果表明：在水化热反应过程中，混凝土终凝后温度变化分为急剧升温、缓慢升温和降温三个阶段，当混凝土入模温度为30 ℃以下时，混凝土浇注后的中心温度最高达到65.1 ℃；混凝土的应变变化为应变增长、应变降低和趋于稳定三个阶段，距离中心越远应变越低，最大应变达到370 μm，通过在混凝土中掺加SY-G型高性能膨胀抗裂剂补偿混凝土的收缩，避免了混凝土产生危害性裂缝，满足了工程抗裂要求；此外，有限元的水化热分析结果与实验结果非常吻合，表明有限元数值分析对大体积混凝土水化热反应的温度场变化有较好的预测效果，但应变结果与实验存在一定的误差，绝对误差为18.9%。

Abstract:

This paper is positioned on the hydration heat problem of expansive mass concrete used in the construction of a proton oncology hospital. Taking expansive mass concrete as the research object， experimental and numerical simulation study on hydration heat reaction of expansive mass concrete were performed. The temperature distribution and strain of the expansive mass concrete were obtained from the model test and MIDAS finite element simulation. Results showed that there are three stages in the heat hydration process of the concrete， which are rapid heating， slow heating and cooling. The highest central temperature of the concrete after pouring is 65.1 ^oC when the concrete molding temperature is lower than 30 ^oC. The strain variation of concrete includes increasing stage， decreasing stage and stabilization stage， and the highest strain of the concrete is 370 μm. By using SY-G expansion agent， the shrinkage of concrete can be compensated and hence the cracks due to the shrinkage of concrete are avoided. In addition， FE results of the temperature of hydration heat have good agreement with the test results， indicating that FE has a good prediction on the temperature variation of concrete caused by hydration heat. But there is a certain absolute error between the strain results and the experiment， and the absolute error is 18.9%.