哑铃形承台无辅助桩分区施工技术  

Zoned Construction of Dumb-Bell Shaped Pile Cap without Auxiliary Piles

作　　者：徐启利[1] XU Qi-li(China Railway Major Bridge Engineering Group Co.,Ltd.,Wuhan 430050,China)

机构地区：[1]中国中铁大桥局集团有限公司,湖北武汉430050

出　　处：《世界桥梁》2018年第5期36-40,共5页World Bridges

摘　　要：平潭海峡公铁两用大桥3座通航孔桥斜拉桥的6个桥塔墩均采用哑铃形承台,桩基直径大,桩间距大,系梁跨度最大达30m,且系梁区无钻孔桩,桥址处海洋环境恶劣、地质条件复杂。根据该桥承台结构特点,为解决恶劣海况及复杂地质条件下施工难题,哑铃形承台采用无辅助桩分区施工技术,取消系梁区封底混凝土和辅助钻孔桩,设置系梁桁架和单壁隔舱,将围堰(侧板利用主体防撞箱结构)分为2个单圆区和1个系梁区,进行围堰内分步抽水、承台分区施工。施工过程中,系梁桁架区系梁底板与围堰防撞箱间不焊接,通过涂抹遇水膨胀的密封胶止水,系梁底板与两侧封底混凝土间设置伸缩板止水;系梁区浮力通过系梁桁架传递至已浇筑承台;系梁桁架两侧吊挂于已浇筑承台,将系梁区承台混凝土荷载通过系梁桁架传递至已浇筑承台。The Pingtan Straits Rail-cum-Road Bridge consists of three navigational channel cable-stayed bridges.The six main pylon piers of the three bridges are topped with dumb-bell shaped pile caps.The pile caps rest on foundations formed of large-diameter piles spaced at big intervals.The tie beam spans a maximum length up to 30 m and no bored piles stand in the tie beam area.The bridge site is located where the ocean environment is harsh and the geological condition is complex.According to the structural characteristics,the dumb-bell shaped pile cap was divided into several zones for construction,and during the construction process,no auxiliary piles were used.Instead of base sealing concrete and auxiliary bored piles,the tie beam area was equipped with the tie beam truss and single-walled chambers.The cofferdam(the side walls of which adopt the anti-impacting box structure)was divided into two round zones and one tie beam zone,the water inside the cofferdam was pumped out and the pile cap was constructed zone by zone.During the construction process,the tie beam base plate in the tie beam truss zone was not welded to the anti-impacting boxes of the cofferdam,but to realize the water stopping purpose by brushing expansion sealant.And expansion plate was installed between the tie beam base plate and the base sealing concrete on the two sides.The buoyancy in the tie beam area was transmitted to the already-cast pile cap via the tie beam truss.The tie beam truss was hung to the already-cast pile cap from the two sides,to transmit the pile cap concrete loads in the tie beam area to the already-cast pile cap via tie beam truss.

关 键 词：斜拉桥 哑铃形承台 无辅助桩 系梁桁架 单壁隔舱 柔性止水 分区施工 

分 类 号：U443.25[建筑科学—桥梁与隧道工程] U445.4[交通运输工程—道路与铁道工程]