cofferdam

n. 围堰, 隔离舱, 潜水箱

cof.fer.dam

n.（名词）
A temporary watertight enclosure that is pumped dry to expose the bottom of a body of water so that construction, as of piers, may be undertaken.
围堰：一种临时性的水密围绕物，抽干后露出水体的底部，以便对建筑物（如桥墩）施工
A watertight chamber attached to the side of a ship to facilitate repairs below the water line.
潜箱：一种不漏水的容器，附着在船旁边以便在吃水线以下进行修理