大洞径全圆针梁衬砌台车底拱混凝土表面气泡消减措施探讨

Discussion on the Measures to Reduce Air Bubbles on the Concrete Surface of the Bottom Arch of the Large Diameter Full Circle Needle Beam Lining Trolley

全圆模板浇筑易导致底拱表面气泡水纹集中,影响衬砌混凝土外观质量。结合叶巴滩水电站大洞径全圆针梁台车衬砌混凝土施工,分析大洞径全圆针梁台车底拱混凝土气泡水纹的产生原因和影响因素,明确底拱120°范围是质量控制重点,并从混凝土配合比优化与拌和参数控制、台车结构调整和性能改进、模板质量要求和处理措施等方面进行探讨,总结了降低用水量、控制坍落度、优选脱模剂、强化振捣措施、增设排气引水孔、提高模板表面光洁度等系列方法,成功解决底拱混凝土表面气泡水纹问题,为同类工程混凝土气泡水纹消减提供思路。

Full circle formwork pouring can easily lead to the concentration of bubbles and water marks on the surface of the bottom arch,which affects the appearance quality of the lining concrete.This article combines the construction of the lining concrete of the large diameter full circle needle beam trolley at the Yebatan Hydropower Project,analyzes the causes and influencing factors of the concrete bubble and water marks on the bottom arch of the large diameter full circle needle beam trolley,clarifies that the 120°range of the bottom arch is the focus of quality control,and explores the optimization of concrete mix proportion and mixing parameter control,structural adjustment and performance improvement of the trolley,quality requirements and treatment measures of the formwork,summarizes a series of methods such as reducing water consumption,controlling slump,selecting demolding agents,strengthening vibration measures,adding exhaust water holes,and improving the surface smoothness of the formwork.It successfully solves the problem of bubble and water marks on the surface of the bottom arch concrete,providing ideas for the reduction of concrete bubble and water marks in similar engineering projects.