704 - Steel Sheet Piling and Cofferdams
Steel sheet piling may permanent, temporary, or temporary left in place, meaning the sheeting was designed to support earth pressures during staged construction, and removal of the sheeting may be detrimental to permanent structures. Sheeting may also be part of a cofferdam, along with other structural components such as bracing, struts, walers, tie backs, and other related structural components act to create a water tight seal, as to construct substructure elements in the dry. Steel sheeting consists of new or used continuous interlock-type steel sections including connections and corner pieces. Steel sheet piling can resist loads via cantilever capacity, or in combination with bracing such as walers and struts.
Used steel sheet piling must be in good condition, and its use must be approved by the Engineer prior to driving. The most common steel sheet piling shapes are the PZ types. For example, for a PZ-27 section, the P stands for “pile” the Z is for the “type or shape”, and 27 represents the unit weight per ft2 of material. Figure 704-1 shows a typical PZ shape configuration: