自密实混凝土在窄口水库泄洪洞加固中的应用

Application of self-compacting concrete(SCC) in flood discharge tunnel reinforcement of Zhaikou Reservoir

河南窄口水库泄洪洞原为圆形无压洞,除险加固设计将其改为有压洞,设计最大水头60 m。由于衬砌厚度小、钢筋密集、振捣困难等原因,以致生产性试验段浇筑速度、浇筑质量等很难满足设计要求。经分析比较,确定采用具有高流动性、不离析、不泌水、均匀、稳定、简单振捣便能密实成型的C40W8自密实混凝土,施工期间通过持续改进浇筑方案,较好解决了混凝土入仓难、振捣难、模板上浮等难题。从混凝土力学性能检测、安全监测及充水运行检查情况来看,自密实混凝土强度及抗渗性完全能满足设计要求,泄洪洞运行情况良好。

The original flood discharge tunnel of Zhaikou Reservoir was free - flow tunnel with diameter of 3.5m, which is to be modified to pressure tunnel with maximum head of 60 m in the reinforcement engineering. Due to small lining thickness, dense steel bar distribution and difficult vibration, it was hard to meet the design requirements for grouting speed and quality during the trial production. After analysis and comparison, the C40 self - compacting concrete was adopted for its high liquidity, segregation -free, bleedingfree, stability, and uniformity, and the concrete could be compacted and formed by simple vibration. The continuous improvement of grouting scheme has well solved the difficulties of concrete placement, vibration, and template floating in the construction period. According to concrete mechanical properties test, safety monitoring and waterfilling operation check, the self - compacting concrete could completely meet the design requirements on strength and permeability, and the flood discharge tunnel has been in good condition since its operation.