Steel sheet pile cofferdams are widely used in bridge foundation construction. Dry construction conditions are achieved by inserting steel sheet piles into the riverbed to form a retaining structure. Steel sheet pile cofferdams can have a variety of shapes, including rectangular, square, circular, and flat.

Design requirements for steel sheet pile cofferdams

1. Selection of steel sheet piles

In China, SP-IV or SP-V steel sheet piles are the two typical lengths of steel sheet piles. The specific length of these steel sheet piles is determined by the geological and water depth conditions of the construction area. The standard steel sheet pile base elevation is 6 to 10 meters above or below the bed elevation. The high water level is 0.5 to 1 meter higher than the high water level during construction.

2. Planar Dimension Design of Steel Sheet Pile Cofferdams

The planar dimensions of the steel sheet pile raft are determined by the size of the bridge abutments and are generally 1.5 to 2.0 meters larger than the circumference.

3. Internal Support Design After the Steel Sheet Cofferdam is Completed

After the steel sheet piles form the cofferdam's retaining structure, the cofferdam must be drained and some soil removed. Due to the pumping, the water levels inside and outside the cofferdam differ, exerting significant pressure on the steel sheet piles. In this situation, supporting the steel sheet piles to resist the lateral pressure of the water is the next step.