大体积混凝土筏板基础温度场的精确控制

Accurate Control of Temperature Field of Mass Concrete Raft Foundation

在深基坑开挖后的饱和土地层上浇筑混凝土筏板,浇筑与养护的过程中,由于水化热导致的温度剧烈升高,导致产生温缩裂缝隐患的工程问题的风险是无法避免的。着重研究某工程在施工前所处临近地铁施工导致土体含水率大幅度浮动情况下温度场的变化环境,并进行温度场控制方案的模拟,在确保工程安全的前提下对方案再度进行优化。通过理论计算与有限元模拟分析,同时考虑到混凝土浇筑筏板都有其唯一性,针对本工程的大体积筏板进行特有的混凝土水化热温控措施设计,能够在保障筏板强度的同时抑制因内外温差过大导致的混凝土裂缝。对热能传导原理及混凝土破坏原因进行分析,通过有限元模拟分析大体积混凝土筏板基础温度场,提出针对深基坑开挖后在饱和土上浇筑混凝土筏板水化热的有效精确话冷却方法与成本控制措施,在有效降温同时节能减碳。研究成果为相似的混凝土筏板工程温控技术契合碳中和、碳达标方针政策提供有效参考。

The risk of potential thermal shrinkage cracking caused by the significant increase in temperature due to hydration heat during the pouring and curing process of the concrete raft on the saturated soil layer after deep excavation cannot be avoided.Emphasis was focused on the study of the variation of temperature field under the condition of significant fluctuation of soil moisture content caused by the nearby subway construction before the construction of a certain project.The simulation of temperature field control scheme was conducted,and the scheme was optimized on the premise of ensuring project safety.Through theoretical calculations and finite element simulation analysis,considering the uniqueness of the concrete pouring raft,a specific design of concrete hydration heat temperature control measures for the large-volume raft of this project was proposed,which can guarantee the strength of the raft and restrain the cracking of concrete caused by excessive temperature difference inside and outside.The principles of heat conduction and the causes of concrete failure was analyzed,the temperature field of large-volume concrete raft foundation was simulated and analyzed using finite element method,and an effective and precise cooling method was proposed for the hydration heat of pouring concrete raft on saturated soil after deep excavation,as well as cost control measures,to achieve effective cooling and energy saving and carbon reduction.The research results provide effective references for similar concrete raft projects in terms of temperature control technology to meet the carbon neutrality and carbon target policy.