港珠澳大桥138号钢桥塔整体段翻身技术

Techniques to Turn Monolithic Section of Steel Pylon No.138 for Hongkong-Zhuhai-Macao Bridge

港珠澳大桥138号钢桥塔为"海豚"形全钢结构,外形尺寸为18.9m×19.7m×105.0m,重达2 560t,采用桥位2台浮吊进行竖转提升。受航道限制,钢桥塔安装前,需在工厂内进行180°翻身,将主塔柱在下、副塔柱在上的姿态转化为副塔柱在下、主塔柱在上。翻身施工包括卸船、翻身和装船3个环节。采用2台2 000t轨道式龙门吊抬吊,配合使用扁担梁、框形吊架和栓接吊耳进行卸船,通过L形吊架和垫梁进行2个90°空翻完成180°翻身,翻身之后直接装船绑扎。主要吊具采用Q690D高强钢。整个作业过程中,对钢桥塔、吊具和龙门吊进行了应力和位移的监控,保证了翻身过程受控。

The Steel pylon No.138 is a dolphin-shaped steel structure,having the dimension of18.9 mby 19.7 m,105.0 min height.The pylon weighed up to 2 560 t,which were designed to be vertically turned and lifted by two floating cranes on site.Restrained by the shipping channel,the steel pylon,which was laid with the secondary pylon column above the main pylon column,had to experience a 180 degree turn in the factory before its in-situ installation,to allow the main pylon column located above the secondary pylon column.The turning process involved three key operations:unloading the pylon from the boat,turning the pylon and loading the pylon to the boat again.Two rail type gantry cranes with a capacity of 2 000 teach were used to lift the pylon,aided by the spreader beam,lifting frames and bolted lifting lugs to unload the pylon from the boat.Then,the pylon was turned by two times,each time 90 degree,to complete its 180 degree turn-around.And the pylon was loaded to the boat for banding after turning.The main lifting devices are made of Q690 Dhigh-strength steel.The stresses and displacements of the pylon,lifting devices and gantry cranes were monitored and controlled during the whole process,to ensure the turning operation under control.