大体积混凝土底板施工的综合防裂技术

大体积混凝土体积庞大,混凝土浇筑后释放出大量水化热,由于体积较大,聚集在混凝土内部的热量不易散发,混凝土内部温度较高,造成混凝土内外温差较大.由于约束的影响,在混凝土的升降温过程中会引起混凝土内部温度应力剧烈变化而导致混凝土结构产生有害裂缝,施工难度较大.结合南京某综合大楼基础底板大体积混凝土工程施工实例,施工前用有限元分析模拟大体积混凝土温度场,根据分析结果制定施工方案,优化混凝土配合比.现场埋设了温度监控点,施工中根据监控信息随时调整养护方案,从而做到信息化施工.实践证明理论分析得出的温度变化规律与实测结果基本符合,采取的施工方案安全可靠,上述综合防裂技术措施的应用确保了该工程大体积混凝土防裂目标的实现.

The Finite Element Analysis of Simulation Example on Mass Concrete Construction

The dimension of the mass concrete is very huge. After the concrete is poured, a great deal of cement heat of hydration is given off. The heat quantity congregated in the concrete can not emit easily because of the huge dimension and the rapid rise in the temperature of inside mass concrete, so the temperature difference between internal and external concrete is very great. In the course of the rise and drop of the temperature, the temperature stress inside concrete changes greatly because of the restriction, which induces the deleterious crack to come into being and the construction of the mass concrete to be difficult. This article incorporates with a practice for mass concrete construction of the raft foundation of the comprehensive building in Nanjing. The temperature field of the mass concrete is analyzed and simulated by the finite element method before construction, and the construction project and the optimized mixture proportion are made according of the result. The purpose of the informative construction is achieved that the temperature monitoring places are disposed and the maintain project is adjusted at any moment according to the monitoring information. The practice proves that the temperature variety rule achieved by theoretic analysis is about the same as testing result, the construction project adopted is safe and credible. The application of the above technique measures assures the successful construction.