沌口长江公路大桥主桥为(100+275+760+275+100)m双塔双索面钢箱梁斜拉桥,钢箱梁含风嘴宽46 m,中跨合龙段长4.6 m、重122.4 t.该桥中跨采用单侧起吊、顶推辅助合龙方案,即北岸侧塔梁纵向临时约束兼顾作为纵向顶推装置顶推北主桥,由南岸桥面吊机单侧起吊合龙段进行喂梁.合龙施工时,结合合龙段起吊操作间隙、喂梁温度对合龙口宽度的影响等,纵向顶推装置的顶推量按20 cm、顶推力按6000 kN设计;针对顶推过程中结构响应,通过支撑型钢将合龙段重量平均分配至合龙口两侧梁段上、斜拉索张拉调整合龙口相对高差、对拉系统进行轴线调整、纵向牵引辅助进行缝宽调整和锁定等技术措施,完成合龙口姿态调整;合龙段匹配时,以边腹板对齐,中腹板处马板配合千斤顶进行匹配错台控制.全桥合龙后,合龙段轴线偏位5 mm,标高与目标值的误差为2 mm,合龙段与两侧标准段匹配良好.%The main bridge of Zhuankou Changjiang River Bridge is a two-pylon steel box gird-er cable-stayed bridge with spans of 100 m,275 m,760 m,275 m and 100 m.The stay cables are fanned out in double cable planes.The steel box girder together with the wind fairing is 46 m wide.The closure section in the central span is 4.6 m long and weighs 122.4 t.The central span was closed by the scheme of single-side lifting and pushing to aid closure,that is to use the pylon-girder temporary longitudinal constraints at the north bank side as the longitudinal pushing devices to push the north main bridge,and to lift the closure section from one side using the derrick crane at the south bank side to feed the girder.During the closure construction,the pushing amount of the longitudinal pushing devices was set to be 20 cm and the pushing force was designed to be 6 000 kN,taking into account of the influence of the gap for the lifting operation of the closure section and the temperature when the section was fed.In light of the structural response during the push-ing,the weight of the closure section was uniformly distributed to the sections at the two sides of the closure gap via the supporting section steel.The stay cables were tensioned to adjust the rele-vant height difference of the closure gap.And several technical measures were used to adjust the position of the closure gap,like using the pull-back system to adjust the axial line,longitudinal traction to adjust the gap width and closure gap locking.During the matching process,the closure section was aligned with the side webs,and the strongback plate at the central web was used to aid the jack to control the staggering in the matching process.After the closure of the full bridge,the axial line of the closure section was measured having a 5 mm deviation,just a 2 mm difference exis-ted betw een the elevation and the target value,and the closure section and the standard sections at the two sides of the gap matched well.
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