至喜长江大桥猫道设计与施工

Design and Construction of Catwalk of Zhixi Changjiang River Bridge

至喜长江大桥大江桥为主跨838m的结合梁悬索桥,主缆索股采用预制平行钢丝束股法制作。主缆施工采用3跨连续式猫道,猫道在两边跨呈八字形。猫道面宽4.0m,每条设6根48mm钢丝绳。锚碇前端设置转向架,改变猫道索锚固位置,使上、下部结构可同时施工。采用有限元法对猫道进行计算,确保猫道结构满足要求。施工过程中,采用拖轮水下过渡法使先导索过江,先导索过江后,塔顶横移先导索,将门架支承索过江,并安装承重索、猫道面网、侧网等。在猫道面架设完成后,通过锚碇处的千斤顶和塔顶转向鞍座处的导链,对猫道线形进行整体调整,使猫道线形满足施工要求。

The Dajiang Bridge of Zhixi Changjiang River Bridge is a composite girder suspension bridge with a main span of 838 mand the main cables are composed of prefabricated parallel steel wire strands.During the construction of the main cables,three-span continuous catwalk,which flared wide at the two side spans,was used.The deck of the catwalk was 4.0mwide.Each cat walk cable consisted of 6,48mm steel ropes.Steering frames were installed in front of the anchor blocks,so as to change the anchoring position of the catwalk cables and allow the superstructure and substructure to be simultaneously constructed.The finite element method was applied to do calculation for the catwalk,to ensure that the structure of the catwalk can meet the requirements.During the construction,the pilot ropes were dragged across the river with the assistance of the tow boats pulling.After crossing the river,the pilot ropes were transversely moved at the tower tops,using the portal frames to support the ropes to cross the river,and then,the load bearing cables,catwalk meshes and lateral meshes were installed.After the completion of the installation of catwalk deck,the overall geometry of the catwalk was adjusted using the jacks at the anchor blocks and the guiding chain at the deviation saddle on the tower tops,so as to make the geometry of the catwalk meet the construction requirements.