安庆长江铁路大桥下部结构设计

Design of Substructure of Anqing Changjiang River Railway Bridge

安庆长江铁路大桥全长2 996.8 m,主桥为（101.5＋188.5＋580＋217.5＋159.5＋116）m的钢桁梁斜拉桥。铁路等级为两线客运专线,两线Ⅰ级干线。3号、4号桥塔墩采用梅花形布置的37根φ3.0 m钻孔桩基础,按摩擦桩设计,桩长分别为108 m、110 m;1号、2号墩位于陆地上,设计为矩形空心墩,采用行列式布置的14根φ1.5 m钻孔桩基础,按摩擦桩设计,桩长分别为28 m、39 m;5~7号墩处于河道内,由于有防船撞要求设计为矩形实心墩。主桥3号和4号墩基础采用双壁钢套箱围堰施工方案,围堰采用无导向船的前后定位船锚碇系统定位。

Anqing Changjiang River Railway Bridge totals 2 996.8 m in length,of which the main bridge is a steel truss girder cable-stayed bridge with span arrangement（101.5＋188.5＋580＋217.5＋159.5＋116） m.The grades of railway on the Bridge are of two tracks of passenger dedicated lines and two tracks of Grade I trunk lines.A foundation for pier No.3 or No.4 of the pylons is composed of 37 nos.of φ3.0 m bored piles arranged in quincunx.The piles are designed as the frictional ones,respectively having the length of 108 m and 110 m.The piers No.1 and No.2 are located on land and are designed as the rectangular hollow ones.A foundation for the piers is composed of 14 nos.of φ1.5 m bored piles arranged in arrays.The piles of the piers are also designed as the frictional ones,respectively having the length of 28 m and 39 m.The piers No.5~7 are located in the river channel and the piers are designed as the rectangular solid ones owing to the requirement of ship collision protection.The foundations for piers No.3 and No.4 are constructed by the double-wall steel boxed cofferdams that are positioned by the anchor systems from the front and rear positioning barges without utilization of guiding barges.