深中通道伶仃洋大桥筑岛围堰施工关键技术

深中通道伶仃洋大桥为(580+1 666+580)m三跨钢箱梁悬索桥,东、西锚碇均为大型海中重力式锚碇,由于海上施工难度大,安全风险高,2座锚碇均采用筑岛围堰施工。东锚碇筑岛围堰采用锁扣钢管桩+工字形板桩组合方案;钢管桩按先上、下游侧,后两侧的顺序,采用YZ-300振动锤施沉;工字形板桩采用起重船起吊并插入相邻锁扣钢管桩,利用DZJ-240振动锤分区、分段施沉;围堰内侧吹填砂,外侧抛填袋装砂护坡。西锚碇筑岛围堰采用水上地基处理(DCM桩)+抗浪砂袋围堰+吹砂填筑+陆上地基处理(挤密桩)的施工方案;砂垫层抛完后由整平驳船进行水下整平;抗浪砂袋分4层施工,采用水下填充和水上填充2种方法。该桥锚碇采用2种筑岛围堰施工技术,施工期间结构安全,减小了海上施工风险,提高了施工工效。

Key Construction Techniques for Artificial Island Cofferdam of Lingdingyang Bridge on Shenzhen-Zhongshan Link

The Lingdingyang Bridge on Shenzhen-Zhongshan Link is a steel box girder suspension bridge with three spans of 580,1666 and 580 m.The east and west anchor blocks are all large-scale gravity-type anchors in sea.Given that the construction of the anchor blocks faces great challenges and safety risks in the marine environment,the utilization of cofferdam to form artificial island is proposed.The cofferdam for the east anchor is formed of interlocked steel tubular piles and I sheet piles.The steel tubular piles were driven to sink by the YZ-300 vibration hammer,the piles on the upper and lower stream sides first,and then the piles elsewhere.The I sheet piles were hoisted by floating cranes and inserted into adjacent interlocked steel tubular piles,and then driven to sink by DZJ-240 vibration hammer,following the sequence of divided zones and sections.The cofferdam for the west anchor was constructed following the sequence of underwater ground strengthening(DCM piles),anti-wave sand bags,sand filling and land ground improvement(compaction piles).After the formation of sand bed,the leveling barges were deployed to flatten the ground,the anti-wave sand bags were piled up in five layers,by the way of underwater filling and over water filling.By using the two construction techniques for the artifical island cofferdams,the structural safety was ensured,the construction risk in marine environment was reduced and construction efficiency was improved.