虎门二桥坭洲水道桥主索鞍吊装施工技术

Hoisting and Installation Construction Technology for Main Cable Saddle of Nizhou Waterway Bridge of Second Humen Bridge

虎门二桥坭洲水道桥为主跨1 688m的不对称双塔钢箱梁悬索桥,全桥共4套主索鞍总成,主索鞍鞍体为铸焊结构,由2个半鞍体通过高强度螺栓锁合而成,半鞍体重达125t,安装在256.4m高的塔顶主鞍室内。主索鞍采用"桥塔承台顶面转放平台移运+塔顶门架承载+连续提升液压千斤顶垂直起吊+重物移运器纵移"的方式吊装。施工时,首先采用塔顶门架起吊系统吊装格栅及反力架,精确定位后浇筑格栅反力架混凝土,然后利用塔顶门架起吊系统吊装上、下承板,最后采用塔顶门架起吊系统分别吊装2个半鞍体至塔顶,利用高强度螺栓将2个半鞍体拼接成整体。在主桥上部结构安装过程中,根据主索鞍预偏监控指令,采用2个1 000t千斤顶逐步将其顶推到位,完成主索鞍的最终定位与安装。

The Nizhou Waterway Bridge of the Second Humen Bridge is an asymmetrical double-tower steel box girder suspension bridge with the main span of 1 688 m.The bridge consists of four main cable saddles,and the main cable saddles have a structure of cast welding that consists of two semi-saddles locked by high-strength bolts.The semi-saddles with the weight of 125 t are installed in the main saddle chamber at the top of a 256.4 m-high tower.The main cable saddles are hoisted by means of"transfer platform on the top of bridge pylon cap+support by portal frame on pylon top+vertical hoist by a hydraulic jack with continuous lifting+longitudinal translation by transporter".During the construction,the grid reaction frame is hoisted by a hoisting system on the tower top,and concrete grout is poured into the grid reaction frame after being precisely positioned;then the upper and lower supporting plates are hoisted by the hoisting system on the tower top;finally,two semi-saddles are hoisted to the top of the tower by the hoisting system on the tower top and joined together by the high-strength bolts.During the installation of the superstructure of the main bridge,according to the pre-deflection monitoring instructions,the main saddles are gradually pushed in place by two 1 000 t jacks,thus final positioning and installation of the main saddles are completed.