现浇箱梁支架蓄水预压法的应用

Application of Water Storage Preloading Method to Scaffolding of Cast-in-Situ Box Girder

重庆中渡长江大桥北岸引桥上部结构采用现浇连续箱梁结构,现浇箱梁施工采用贝雷梁钢管支架。为保证支架的安全性、消除支架和地基的非弹性变形,施工前需对支架进行预压。通过对现浇箱梁各种预压方案的比较,最终选用蓄水预压法。蓄水预压前应先对钢管支架进行检查验收,合格后进行模板铺设,并在模板内铺设防水篷布,确保防水篷布粘结牢固后进行逐级抽水加载预压,并对支架进行沉降观测。预压后支架沉降满足要求,浇筑的箱梁成品外观线形优美。

The superstructure of the north approach bridge of Zhongdu Changjiang River Bridge in Chongqing is the cast-in-situ continuous box girder structure.The structure was constructed by the bailey truss and steel pipe scaffolding.To ensure the safety of the scaffolding,eliminate the non-elastic deformation of the scaffolding and the supporting ground,the scaffolding should be preloaded before it was put into use in the construction.Through comparison of the different preloading methods for the scaffolding,the water storage preloading method was finally chosen.Before the scaffolding was preloaded by the water storage method,the steel pipe scaffolding was firstly checked and after the scaffolding was proved to be qualified,the formwork was set up on the scaffolding,the water-proof canvas was laid inside the formwork and the canvas was made sure to be tight bound with the formwork.The water was then gradually pumped in and the loading of the water was applied and at the same time,the settlement amount of the scaffolding was observed.The scaffolding could meet the requirements after the preloading and geometric shapes of the cast-in-situ box girder were elegant as well.