商合杭铁路芜湖长江公铁大桥桥塔施工关键技术

商合杭铁路芜湖长江公铁大桥主桥为主跨588m的双塔双索面矮塔箱桁组合梁斜拉桥,2号和3号主墩均采用门形钢筋混凝土桥塔,塔高分别为155m和130.5m。桥塔设上、下2道横梁,下塔柱外倾,上塔柱内倾。该桥塔柱采用液压爬模分节施工,在两侧上、下塔柱间分别设置钢管横撑和临时对拉钢绞线;下横梁采用落地支架法施工,上横梁采用“牛腿+支架”法施工,上、下横梁混凝土与塔柱同步浇筑;索塔锚固区采用钢锚梁拉索锚固体系与预应力锚固体系相结合的方式锚固,塔柱预应力采用“#”形布置,利用定位支架精确定位钢锚梁。在施工期间,采用“零状态”测量+相对设站法定位等措施控制塔柱线形;并采用高性能混凝土抗裂技术防止大体积混凝土表面开裂。

Key Techniques for Construction of Pylons of Wuhu Changjiang River Rail-cum-Road Bridge on Shangqiu-Hefei-Hangzhou Railway

The main bridge of Wuhu Changjiang River Rail-cum-Road Bridge on the Shangqiu-Hefei-Hangzhou Railway is an extra dosed cable-stayed bridge which consists of a box-truss composite girder, two pylons, and two cable planes, and has a main span of 588 m. Portal-shaped reinforced concrete pylons are adopted in both No.2 and No.3 main piers, which have heights of 155 m and 130.5 m, respectively. Each pylon has an upper cross beam and a lower cross beam. The lower pylon column leans outwards and the upper pylon column leans inwards. The pylon column is constructed in segments by hydraulic climbing formwork. During the construction, steel-tube temporary cross braces are set between the upper pylon columns and temporary tensioned steel stranded wires are set between the lower pylon columns. The lower cross beam is constructed on the scaffolding supported on the ground and the upper cross beam is constructed by a "corbel+ scaffolding" method. The concrete of upper and lower beams is cast synchronously with the concrete of pylon columns. The combination of an anchorage system of steel anchor beam and an anchorage system of prestressing is adopted in the cable anchorage zone, and the #-shaped pattern is adopted for the prestressing of pylon columns. Positioning brackets are adopted to position the steel anchor beams accurately. During the construction, a"0-state measure+relative setting stations" method is applied to control the alignment of pylon columns. Meanwhile, the anti-crack technology of high performance concrete is used to prevent the surface of mass concrete from cracking.