浅析斜拉桥超长无索梁段不平衡施工

Brief Analysis on Unbalanced Construction of Long-span Non-cable Girder in Cable-stayed Bridge

丰都长江二桥主桥为全长1 282 m的双塔双索面五跨连续钢箱梁斜拉桥,采用半漂浮结构体系,跨径布置为(70.5+215.5+680+245.5+70.5)m;其塔区无索梁段长度约为73 m,为克服三峡库区大型浮吊无法进入以及采用传统支架法施工困难的问题,拟采用托架配合桥面吊机法进行无索梁段不平衡施工。文章通过实例,对无索梁段不平衡施工工艺流程及采取的相关技术措施、塔梁临时固结形式及施工方法进行了详细介绍,分析了采用托架法施工的特点、难点;对各工况下托架及钢箱梁受力进行分析,并采用有限元软件进行验算,以确保结构安全。最后与传统大型落地支架施工方法进行对比,分析此方法与传统施工方法的优劣,为超长无索梁段施工提供了一种新的施工方法,大大节约了材料的用量。

The main bridge of Fengdu Second Yangtze River Bridge is a five-span continuous steel box girder cable-stayed bridge with a span of 1 282 m and double pylons and double cable-planes,the semi-floating structure is adopted,and the span is arranged as( 70. 5 + 215. 5 + 680 + 245. 5 + 70. 5) m. The cable free section length in the pylon area is about 73 m. In order to overcome the difficult problem of large floating crane cannot enter into Three Gorges reservoir area and the traditional scaffold construction,the bracket with bridge deck crane method is proposed for imbalanced construction at non-cable beam section. Through the example,the construction technological process and related technical measures,pylon beam temporary consolidation and construction method are introduced in detail,the characteristics and difficulties of bracket method construction are analyzed. The stresses of bracket and steel box girder under all working conditions are analyzed,and the finite element software is used to check calculation to ensure the safety of the structure.Finally,compared with the traditional large landing stand construction method,the pros and cons of the proposed method and the traditional construction method are analysed. It can greatly save the amount of material,which provided a new method for grand non-cable beam section construction.