It is available in various cross-sections and shapes. They can be hot-rolled sheet piles, cold-rolled, or cold-formed sheet piles. Steel sheet piles durability is enhanced with the aid of corrosion protection measures such as coating and cathodic protection. Steel is the most common form of sheet piles as it has good resistance to high driving stresses,excellent water-tightness, and can be increased in length either by welding or bolting. They are connected by interlocking. There are four basic forms of steel sheet piles, Normal sections, Straight web sections, Box sections and Composite sections.
Sheet piles are commonly used for retaining walls, land reclamation, underground structures such as car parks and basements, in marine locations for riverbank protection, seawalls, cofferdams, and so on. Permanent steel sheet piles are designed to provide a long service life. Vibratory hammers are typically used to install sheet piles. If soils are too hard or dense, an impact hammer can be used to complete the installation. For the development of sheet piles, there are two main techniques: hot-rolled and cold-formed. At high temperatures, hot rolled piles are produced and the interlocks appear to be stronger and more resilient.
Steel sheet piling is manufactured in three basic configurations: “Z”, “U” and “straight” (flat). Historically, such shapes have been hot-rolled products produced at structural mills. Like other shapes such as beams or channels, the steel is heated in a furnace and then passes through a series of rolls to form the final shape and the interlock, which allows the sheet piles to be threaded together. Some use a cold-forming process in which steel coil is rolled at room temperature into the final sheet pile shape. Cold formed sheet piles have hook and grip interlocks.
The Z type configuration is generally considered the strongest and most efficient. These shapes resemble wide-flange beams, having a web and two flanges. The interlocks are located out on the flanges at maximum distance from the neutral axis, and this provides a high section modulus for resisting bending moments. Because of this, Z-shapes have traditionally been used for heavier construction projects. However, they are now complemented by the arch or U shapes for lighter work, and lightweight Z-shapes have been also introduced into the marketplace. Because of their inherent strength, Z-piles can be handled and shipped with less exposure to possible damage than some other style sheets. Z-piles are generally used in constructing straight wall structures – cofferdams, bulkheads and retaining walls.
U-type sheet piles are not generally used in some area as they are not as efficient or economical as Z-type sheet piles. Interlocks on u-type piles are located on the neutral axis of the pile, so the sheet piles must be crimped in order to achieve their full capacity. These types of sheet piles are still available in the international market.
Flat sheet piles are used for circular cell applications where the cells form a gravity structure. The sheet piles are interlocked together to form individual cells, or a series of cells, and are then filled with soil. Whereas z-type sheet piles require resistance in bending, the strength of the flat sheets come from their interlocks. Flat sheet interlocks are larger than those on z-type sheet piles and are designed to resist significant tensile forces.
Flat sheet piles have limited bending capacity.
