大体积箱梁0、1号块混凝土浇筑温度控制

Temperature Control for Concrete Casting of No.0 and No.1 Blocks of Large Box Girder

为控制某桥桥墩上现浇0、1号块箱梁的内外温差,消除巨大温差引起的裂缝等结构安全隐患,以实际桥梁工程为背景,采用有限元软件对浇筑后的箱梁0、1号块瞬态温度场进行仿真分析,并在现场埋设温度传感器监测其温度场。结果表明:相对于顶板、腹板和底板,横隔板温度更高且最晚达到最大值(45℃);采用分层浇筑、埋设冷却水管等施工控制措施,各部件温度明显降低,结构内、外温差可以较好地控制在20℃以内,且拆模后未发现裂缝。

In order to control the difference of the temperature inside and outside the cast-in- situ No. 0 and No. 1 blocks of the box girder over bridge piers and reduce the potential risks of the structure induced by great temperature difference, such as the occurrence of cracks, a real bridge was cited as an example. The finite element software was adopted to carry out simulation analysis of the transient temperature field of the No. 0 and No. 1 blocks of the box girder after concrete casting, and temperature sensors were embedded to monitor the temperature field. The results of the analysis indicated that compared with the top slab, webs and the bottom slab, the tempera- ture in the diaphragms was higher and was the latest to reach the maximum value （45 ~C） ; when the concrete was cast in layers and cold water pipes were buried, the temperature of each compo- nent was apparently reduced, the difference of the temperature inside the structure and outside the structure could be well controlled to be less than 20℃, and after the formworks were dis- mantled, no cracks were found.