基于细观模型的泵送混凝土温度场演化机理研究

Temperature Field Evolution Mechanism of Pumped Concrete Based on Meso Model

针对泵送混凝土绝热温升高、不同批次混凝土配合比及热学特性参数离散性大的问题,本文基于混凝土细观模型,通过物理试验及数值试验探讨了骨料形状、体积分数及骨料预冷等对泵送混凝土早期内部温度场的影响机理.砂浆绝热温升模型采用基于水化度的指数双曲线型,其相关参数依据试验值反演获得;混凝土细观模型由碎石骨料、砂浆及界面层构成,仅考虑砂浆的放热作用.结果表明:骨料形状差异对温度场影响较小;前期温升速率及最终温升值与碎石骨料投放量成反比;骨料粒径和数量影响温度场的时空分布;采取骨料预冷后混凝土前期温升速率显著减小且最终温升值显著降低.研究成果为实际工程宏观热学特性参数的快速确定以及温度场演化机理研究提供了研究工具.

Aiming at the problems of high adiabatic temperature rise of pumping concrete,large discreteness of mix proportion and thermal characteristic parameters of different batches of concrete.Based on the meso-scale model of concrete,this paper discusses the influence mechanism of aggregate shape,volume fraction and aggregate precooling on the early internal temperature field of pumping concrete through physical and numerical experiments.The exponential hyperbolic model based on hydration degree was used for describing the adiabatic temperature rise of mortar,and the relevant parameters were obtained from the experimental data;the meso model of concrete was composed of crushed stone aggregate,mortar and their interfaces,and only the exothermic effect of mortar was considered.The analysis results show that the aggregate shape difference has little effect on the temperature field.The early temperature rise rate and final temperature rise are inversely proportional to the amount of gravel aggregate;the particle size and quantity of aggregate affect the spatial and temporal distribution of temperature field;the early temperature rise rate of concrete decreases significantly and the final temperature rise decreases significantly after aggregate precooling.The research results provide a research tool for the rapid determination of macroscopic thermal characteristic parameters and the study of temperature field evolution mechanism in practical engineering.