The width between the parallel piles is empirically set as h 2 1 5m.
Double wall sheet pile cofferdam.
This type of cofferdam can be used in depth of water up to 12 m.
Double wall sheet pile cofferdam higher than 7 5 feet should be strutted.
The gap between walls is filled with soil.
The width between the parallel piles is h 2 1 50 m.
This consists of two straight parallel vertical wall of sheet piling tied to each other and the space between them filled with soil.
They are cofferdams comprising two parallel rows of sheet piles driven into the ground and connected together by a system of tie rods at one or more levels.
Double walled sheet pile cofferdams.
The space between the walls is generally filled with granular material such as sand gravel or broken rock.
Its construction is essentially the same as that of a single walled cofferdam except that in place of one wall a pair of walls with a gap in between is used all along the boundary of the space to be enclosed.
This type of cofferdams if higher than 2 5 m should be strutted.
Double walled cofferdams are those in which two parallel rows of steel sheet piles are connected with means of a track or a plurality of steel enclosed purlin brackets.
A double wall sheet piling cofferdam comprises two straight parallel vertical walls of sheet piling tied to each other.
Double wall sheet piles this type of cofferdam is suitable when it is required to exclude water over 36 feet.
Double walled cofferdam is provided in such situations.