深中大桥海中桥塔下横梁施工关键控制技术

Key Technology for Lower Crossbeam Construction of Tower of Shenzhong Bridge in the Sea

深中大桥为580 m+1 666 m+580 m三跨全漂浮体系的悬索桥。索塔共设置有上中下三道横梁,其中下横梁为空间大尺寸变截面箱型结构,位于承台顶面与索塔和承台呈固结形式。整体结构处于伶仃洋海面潮汐变化区域。针对下横梁结构施工的特点及难点,采取塔梁异步施工方法,设计了钻孔灌注桩+锁扣钢管桩的结构形式作为下横梁的支撑及止水系统,采用了竖向分3层浇筑并预留1.5 m后浇带的施工方法,提出了大体积混凝土温控和预应力控制技术措施。

Shenzhong Bridge was a 580 m+1666 m+580 m full-floating suspension bridge,with upper,middle,and lower beams.The lower beam was a large-size box-shaped structure with variable cross-sections,which was located on the top surface of the cap and was in a consolidated form with the pylon and the cap.The structure was situated in the tidal change area of the Lingding Ocean.In view of the characteristics and difficulties in the construction of the lower beam structure,an asynchronous construction method was adopted,and the structure of drilled grouting piles with locking steel pipes was selected as the support and positive sealing system for the lower beam.To avoid temperature,shrinkage,and creep effects on the lower beam,a construction plan was proposed that adopted vertical pouring in 3 layers and reserved a 1.5m post-pouring belt.