港珠澳大桥承台墩身工厂化预制施工技术

Construction Techniques for Factory Precasting of Pile Caps and Pier Shafts of Hong Kong-Zhuhai-Macao Bridge

港珠澳大桥浅水区非通航孔桥采用浅埋式预制墩台结构，墩高19．143～42．974m，承台尺寸为15．6m×11．4m×4．5m；预制承台及其底节墩身最高18．5m，最重2370t；墩身采用矩形空心墩结构；承台及墩身分别采用C45、C50混凝土。该桥承台、墩身采用整体预制施工，在自动化钢筋加工车间利用数控钢筋弯曲机加工钢筋，经验收合格后运输至场内指定位置进行钢筋绑扎、安装，承台钢筋绑扎后整体横移至预制台座上，墩身钢筋通过龙门吊机整体吊装插入承台钢筋，安装模板，进行承台、墩身的一次性整体浇筑，待混凝土达到设计强度后拆除模板，将承台、墩身横移至存放台座完成预制。目前，已完成32个桥墩的承台、墩身的工厂化预制施工，施工质量良好。

The pile caps and piers for the non-navigable span bridge of the Hong Kong-Zhu- hai-Macao Bridge over the shallow water area are the shallowly embedded precast structures. The height of the piers ranges from 19. 143 m to 42. 974 m and the dimensions of a pile cap is 15.6 m × 11.4 m×4.5 m. The maximum height of the pile cap plus the bottom segment of the pier shaft is 18.5 m and the maximum weight is 2 370 t. All the piers of the bridge are the rectangular hol- low structures and the concrete used for the pile caps and pier shafts is respectively of C45 and C50. The pile caps and pier shafts were integrally precast. In the workshop of automatic rein- forcement processing, the reinforcement were processed by the computer numerical control （CNC） bending machines. After the processed reinforcement were inspected and accepted, the reinforcement were transported to the designated places in the factory where the reinforcement were then bound and installed. The bound reinforcement for the pile caps were integrally and transversely shifted onto the precasting beds while the reinforcement for the pier shafts were inte- grally lifted and inserted into the reinforcement of the pile caps by the gantry crane. The form- work for the pile caps and pier shafts were installed and the concrete for the pile caps and pier shafts was cast in integrity in one time. After the concrete reached the designed strength, the formwork were stripped and the precast pile caps and pier shafts were shifted to their storage beds. Presently, the construction of the 32 pile caps and pier shafts has been completed and the construction quality is so far so good.