水下岩层中大直径轻型双壁钢围堰设计与施工

广深港铁路客运专线沙湾水道特大桥6号主墩双壁钢围堰设计嵌入水下岩层中7 m.6号墩双壁钢围堰采用圆形双薄壁钢壳和混凝土组合结构,结合6号墩双壁钢围堰的施工,介绍32.6 m大直径轻型双壁钢围堰结构设计、抗浮设计和水下岩层基坑开挖、双壁钢围堰制作、浮运、定位、下沉、封底、拆除等关键施工技术.该施工过程中采用的"先挖后沉"的施工工艺安全、可靠,大方量抓斗船开挖水下软质岩层快速、精确.

Design and Construction of Large Diameter and Lightweight Double-Wall Steel Cofferdam Socketed in Underwater Rock

The double-wall steel cofferdam for the main pier No.6 of Shawan Water Course Bridge on Guangzhou-Shenzhen-Hong Kong Passenger Dedicated Railway is designed to be socketed 7 m into the rock stratum under water. The cofferdam used for the pier is a structure composited with round double thin wall steel shells and concrete. With reference to the construction of the cofferdam, the structural design of the 32.6 m large diameter and lightweight double-wall steel cofferdam and the design of the anti-buoyancy of the cofferdam are presented, and the key construction techniques for excavating of the foundation pit for the cofferdam in the rock stratum under water, the manufacturing, floating, positioning, sinking, base sealing and dismantling of the cofferdam are described as well. In the construction of the cofferdam, the construction technology of "excavating first and sinking late" adopted for the cofferdam is safe and reliable and the excavating of the soft rock stratum under water by the large cubic grab barge is fast and accurate.