G3铜陵长江公铁大桥桥塔基础设计

Design of Pylon Foundation of Tongling Changjiang River Rail-cum-Road Bridge Carrying a Section of G3 Expressway

G3铜陵长江公铁大桥主桥为主跨988 m的斜拉-悬索协作体系桥,桥塔采用钢筋混凝土门形结构。3号桥塔基础比选了钻孔桩基础与沉井基础方案,4号桥塔基础比选了钻孔桩基础与地下连续墙基础方案,综合考虑基础受力性能、经济性、施工风险等,均推荐采用钻孔桩基础方案。3号、4号桥塔塔座高4.5 m,承台分别为厚7 m的圆形-哑铃形和矩形-哑铃形结构,基础分别采用68根和64根∅3.0 m钻孔桩,桩长分别为95 m和79 m,按摩擦桩设计。承台系梁采用ANSYS软件进行实体有限元分析,系梁横向受力主筋、竖向抗剪箍筋采用优化分区配置,满足受力要求。

Carrying a section of the G3 expressway,the Tongling Changjiang River Rail-cum-Road Bridge is a hybrid cable-stayed suspension bridge with a main span of 988 m.The towers are portal-frame structures,for the tower No.3,the options of bored piles and caisson foundation were considered,while for the tower No.4,the options of bored piles and diaphragm wall foundation were compared,and the bored pile foundation was finally selected for both towers out of the comprehensive consideration of the mechanical property,economy and construction hazards.The footings of the towers No.3 and No.4 are 4.5 m high,resting on 7 m-deep dumbbell shaped pile cap with circular heads and dumbbell shaped pile cap with rectangular heads,respectively.The bored piles are friction piles of 3.0 m diameter,68 piles of 95 m long for tower No.3 and 64 piles of 79 m long for tower No.4.The tie beams(handles)of the heads of the dumbbell shaped pile caps were numerically simulated in ANSYS,the reinforced bars accommodating transverse tension and the vertical shear-resistant stirrups are placed zone by zone to achieve optimal load bearing performance.