塔梁墩固结体系斜拉桥整体顶升关键技术

昆山市吴淞江大桥主桥为2×101 m的塔梁墩固结体系斜拉桥,为满足升级到Ⅲ级航道的通航要求,需将全桥整体顶升抬高1.87 m。该桥采用整体同步顶升方案施工,其中两侧引桥先采用断柱顶升法施工,主桥后采用抬梁顶升法施工。在主桥整体顶升中,首先在主墩墩底以上1 m处施工托换结构(由抬梁和抱柱梁组成),并将原桥墩内部空心部位用C50灌浆料填充密实;托换结构施工后,安装液压自锁式千斤顶和跟随千斤顶,同步进行主墩及过渡墩墩柱切割;墩柱切割后将主墩处主梁放置在托换结构上,过渡墩处主梁直接放置千斤顶上,通过PLC同步控制系统顶升桥梁至设计标高;最后,对主墩及过渡墩墩柱进行接高及加粗,完成1.87 m接高区段墩柱连接。

Key Integral Jack-up Technique for Cable-Stayed Bridge with Fixed Pylon-Girder-Pier System

The main bridge of Wusong River Bridge in Kunshan City is a cable-stayed bridge with two equal spans of 101 m,and is also a fixed pylon-girder-pier system.To meet the demand of upgrading the navigation channel to GradeⅢ,the overall bridge had to be raised by 1.87 m.An integral and synchronized jack-up scheme was employed,in which the approach bridges on the two sides are raised by cutting off piers and jacking up,but the main bridge is raised by jacking up the girder.In the integral jack-up of the main bridge,the underpinning structure,comprising lifting beams and girdling beams,was installed at the location of 1 m distance from the main pier base,and the cavity of the original pier was filled with C50 mortar.After the construction of the underpinning structure,the hydraulic jacks capable of self-locking and follow-up jacks were installed.The shafts of main and transition piers were cut simultaneously,after which,the main girder over the main piers was placed on the underpinning structure,whereas the main girder over the transition piers was directly placed on jacks and subsequently jacked up to the design elevation by PLC synchronous control system.At last,the shafts of the main and transition piers were lengthened and thickened,to complete the connection of the 1.87 m lengthened section with the existing pier sections.