溪洛渡导流洞衬砌混凝土温控防裂研究

溪洛渡水电站导流洞衬砌混凝土在施工初期出现了部分裂缝,在弹性徐变温度应力计算原理基础上,采用ANSYS有限元程序,模拟实际施工过程,对导流洞衬砌混凝土温度和温度应力进行了三维有限元仿真分析。根据计算分析结果,认为衬砌结构产生裂缝的原因主要有混凝土温升高、温降快、养护措施不当、洞内气温过低、围岩强约束等,最后提出了满足温控防裂要求的温度控制措施和方案。提出的优化配合比、洒水养护、分缝分块以及冬季封洞保温等温控措施,在导流洞衬砌混凝土后期施工中得到采用,有效地防止了裂缝的进一步发展。

Temperature Control and Crack Prevention for the Lining Concrete of Diversion Tunnel of Xiluodu Project

In the early construction period of lining concrete for the diversion tunnel of Xiluodu Hydropower Station, some cracks were found in the lining concrete. In view of this, ANSYS was employed to simulate the temperature and thermal stress of lining concrete based on the principle of elastic creep thermal stress calculation. According to the calculation result, the main causes of cracks were analyzed as follows large hydration heat and quick temperature decrease, improper surface curing measure, low temperature in the tunnel in winter, and strong restrain of surrounding rock. Moreover, measures of temperature control and crack prevention were proposed as follows to adjust concrete’s design age and optimize concrete mix ratio; to immediately spray water for concrete curing; to properly determine concrete grouting blocks; to seal the hole for thermal insulation in winter, etc. These measures were applied in the later stage of concrete construction and has effectively prevented further cracks.