预应力钢筒混凝土管内壁环形裂缝的控制

Inner Annular Crack Control of Prestressed Concrete Cylinder Pipe

针对南水北调工程中预应力钢筒混凝土管(PCCP)内壁易出现的环形裂缝问题,通过分析环形裂缝的成因,探讨了不同的管道生产工艺对裂缝的影响,并提出了生产过程中控制裂缝的一些具体措施.结果表明:混凝土干缩和缠丝应力是产生内壁环形裂缝的主要原因,一般难以避免,但可以采取优化混凝土配合比、选取直径较小的钢丝、提高管芯混凝土缠丝强度,控制强度指标在45 MPa以上、加强管道内壁养护等措施降低裂缝出现的概率.

For the problem of prestressed concrete cylinder pipe（PCCP）lining ring crack in south-tonorth water transfer project,by analyzing the causes of cracks on ring,the influence of different pipe production technology on crack was discussed,and some measures to the crack control in the process of production was put forward.Results show that the shrinkage of concrete and wrapped wire stress are major cause of the lining ring crack,which are generally difficult to avoid,but we can take the measures to reduce the possibility of cracking：optimizatinng of the mix proportioning of the concrete,selecting smaller diameter steel wire,improving the concrete pipe core wrapped wire strength,controling index larger than 45 MPa,strengthening the internal curing and other measures.