施工工艺对碾压混凝土坝温度应力的影响分析

Influence of construction technology on temperature stress of RCC dams

碾压混凝土坝由于其水泥用量小、绝热温升低的材料优点和施工简单、速度快的特点,受到了建设者的青睐。但混凝土温度裂缝是工程建设者长期关注的问题,它的产生影响着结构的外观,也影响着工程的质量和安全性。混凝土浇筑时间、浇筑层厚和层间间歇时间对结构的温度应力有重要影响,选择浇筑时间、改进浇筑层厚、控制间歇时间可以减小温度应力和开裂风险。以周宁抽水蓄能电站碾压混凝土大坝为例,借助三维有限单元法,对不同浇筑时间、浇筑层厚和间歇时间下的混凝土温度应力进行仿真计算。计算结果表明,层间间歇时间太短和浇筑层太薄不利于混凝土温控防裂,高温季节浇筑强约束区混凝土会增大开裂风险。

RCC dams are favored because of the advantages of small cement consumption,low adiabatic temperature rise as well as simple and rapid construction.But the thermal crack of concrete is a long concerned problem,which not only affects the external appearance of dams,but also affects the projects'quality and security.Pouring time,layer thickness and pouring interval have important influence on the temperature stress of dam structure.Optimal pouring time,improved layer thickness and well-controlled pouring interval can reduce temperature stress and minimize cracking risk.Taking RCC dam of Zhouning pumped storage power station as an example,the temperature stress of concrete with different pouring time,layer thickness and pouring interval was simulated by use of three-dimensional finite element method.The results show that too short pouring interval and too thin layer are not helpful to the temperature control and crack prevention,and pouring concrete in strong restraint zone in high temperature season will increase the cracking risk.