大跨度钢箱桁架拱桥拱肋架设施工技术

湖北香溪长江公路大桥为主跨519m(计算跨径)全推力中承式无铰钢桁架拱桥,主拱采用"缆索吊机+斜拉扣挂法"悬臂拼装架设。主拱肋分成桁片节段,在工厂加工制造预拼,船运至桥位处,进行缆索吊机吊装施工;拱脚段采用支架对预埋件进行定位,吊装至设计位置;再进行拱肋整体桁片节段吊装,拱肋整体桁片前4个节段安装完毕,封铰后,进行第一次体系转换,进行剩余节段的安装;合龙前,北岸最后一个节段(NS11)采用"倒栽葱"方式通过间隙;合龙段采用"配切+温度变化"来实现精确合龙;主拱合龙后,拆除扣锚索,完成第二次体系转换。

Erection Techniques for Arch Ring of Long-Span Steel Box Truss Arch Bridge

The Xiangxi Changjiang River Highway Bridge in Hubei Province is a full-thrust half-through steel truss arch bridge without hinges.The main span is 519 min length(the calculated span length).The arch ring was erected by the cantilever assembly method using cable cranes and the tie-back system.The arch ring was divided into blocks to be fabricated in the factory,then pre-assembled and shipped to the bridge site.The arch ring blocks were hoisted and installed by cable cranes.For the arch spring section,the pre-buried components were positioned by scaffoldings and then hoisted to the design positon.Then,the integral arch ring blocks were hoisted and installed.Once the first four blocks were installed into position and the hinges were sealed,the first-time systematic transformation was carried out,and the installation of the remaining blocks was followed.Before closure,the last block(NS11)on the north bank was guided to pass the fissure by the way of"planting the onion in an inverse way"to realize the precise closure.The closure section was carefully put into place by doing scalable matching and cutting and with the aid of variation of temperatures.After the closure of the arch,the fastening anchor cables were dismantled to complete the second-time systematic transformation.