墩墙混凝土结构水管冷却分析

针对水闸闸墩、渡槽槽壁、地涵边墙、船闸边墙和导流墙等水工墩墙型混凝土结构在施工期经常会防不胜防地出现裂缝的现象,在理论上探讨了这种裂缝产生和扩展的机理,认为墩墙混凝土的基础温差、内外温差和收缩变形是裂缝出现的主要原因,尤其是刚施工不久混凝土墩墙的裂缝主要是由结构内外温差应力和自生体积变形应力所致。因此,施工期采用冷却水管降低墩墙内部温度和减小内外温差是防止裂缝出现的极有效的积极的温控措施之一。借助于水管冷却混凝土温度场的理论严密算法,详细仿真计算分析了某个水闸闸墩施工期的现场水管冷却试验及其温控防裂效果,并给出某些应用水管冷却措施时的建议。

ANALYSIS OF WATER-PIPE COOLING IN THIN-WALLED CONCRETE STRUCTURES

The appearances of cracking in concrete during the constructions of pier-wall structures, such as in sluices, aqueducts, culverts under floor, ship lock, overflow guidance wall and so on, are common and difficult to prevent. This paper aims at the mechanism and propagation course of the cracking. The basic difference of the temperature, the internal and external temperature difference and the shrinkage deformation of concrete are considered as the main factors influencing the phenomena. The cracking in concrete at early age is especially caused by the temperature differences. Therefore, the water-pipe cooling technique is an effective measure to decrease the temperature in the internal center of the structures. In doing so, the difference of the internal and surface temperatures is reduced and the appearance of cracking is avoided. A numerical algorithm is proposed in the paper to solve the resultant thermal problems including water-pipe cooling. An in-situ test about the influence and effectiveness of the present measure for prevention from cracking in piers of a sluice is studied. Some suggestions about to the application of water-pipe cooling to concrete structures are given.