杭州市九堡大桥主桥拱肋制造及安装技术

Fabrication and Installation Technique for Arch Ribs of Main Bridge of Jiubao Bridge in Hangzhou

杭州九堡大桥主桥为3×210m结合梁-钢拱组合体系拱桥。拱肋系统由主拱肋,副拱肋,主、副拱肋之间的横向连杆以及拱顶横撑等构件组成。拱肋采用分节段工厂内制造、现场拼装成整体后顶推施工。为保证拱肋制造精度符合要求,每跨主拱、副拱分别划分为14、13个吊装节段,采用"以直代曲"的方法近似拟合拱肋曲线,并定制相应的胎架进行制造。拱肋节段制造完后利用平板车运至主拼装场,用120t龙门吊提升至拼装平台,松开龙门吊吊钩后利用三向调位千斤顶进行高程、里程(纵向)及横向精确调位,然后进行拱肋的焊接。九堡大桥拱肋按照该方法施工最终保证了拱肋线形连续性,提高了拱肋安装定位的精度和速度,确保了施工质量。

The main bridge of the Jiubao Bridge in Hangzhou is a （3 × 210） m arch bridge with steel-concrete composite girder. The arch rib system is composed of main arch ribs, subsid- iary arch ribs, the cross ties between the main arch ribs and the subsidiary arch ribs and the later- al bracings on the top of the arch crown. The arch ribs were fabricated in segments in the shop, and the arch rib segments were assembled into an integrated whole on site and then incrementally launched. To ensure that the fabrication accuracy of the arch ribs could meet the related require ments, the main arch ribs and subsidiary arch ribs in each span were divided respectively into 14 and 13 lifting segments, the curvature of the arch ribs was approximately fit following the princi- ple of ＂using straight line to replace curve line＂, and the specific moulding board was tailored for the fabrication. After the completion of fabrication, the arch rib segments were transported by the flat car to the main assembling yard and lifted to the assembling platform using the 120 t gan- try crane. When the hanging hooks of the gantry crane were loosened, the three-directional level- ing jack was applied to accurately adapt the elevation, longitudinal position and the transverse po- sition, and then the welding of the arch ribs began. By using these methods, the construction of arch ribs of the Jiubao Bridge was carried through and the continuity of the geometrical shape of the arch ribs was ensured. Additionally, the accuracy and speed of the installation and positioning of the arch ribs were improved and the construction quality was also ensured.