The advantages of steel sheet piling

Introduction

Steel sheet piling (SSP) is a hot-rolled structural shape with interlocks on the flange tips. The interlocks permit individual sections to be connected to form a continuous steel wall which is earth-tight and water resistant. Because it is readily available and transportable, SSP is in many cases a fast and economical solution to an owner’s need for a durable, long lasting wall system.

Applications are far-reaching, and include, for permanent construction, retaining walls, bulkheads, bridge abutments, graving docks, cut-off walls, mooring dolphins and pier protection cells. Common uses also include temporary structures, such as trenches, cofferdams for building excavations, bridge piers, and lock and dams on the inland river system. At the end of the project, the steel sheet piles can be extracted, and the steel reused.

Hot rolled steel sheet piling is an engineered product meeting one of several applicable ASTM specifications. These specifications, combined with the SSP producer’s quality control programme, provide a quality product which is ductile, durable and long-lived. In fact, construction in West London, UK, recently unearthed steel sheet piles over 80 years old.

When pulled from the native wet soil, the piles were so well preserved, the original mill marks could be seen. Steel pilings in continuously submerged conditions tend to have relatively low corrosion rates, because oxygen levels decrease with depth. Steel pilings are also a zero-waste product: after extraction, they can be reused or 100% recycled.

Considerations in choosing steel sheet pile

The most common SSP end use is for sections that resist bending moment. These applications include retaining walls, cofferdams and other structures where lateral loads impart bending stresses into the structure. This requirement for beam strength, or section modulus, is provided by Z-profiles and U-profiles. Although the installed cross-section of a SSP wall constructed of Z-profiles and that of U-profiles is similar, the individual pile shapes differ, as does the location of the interlocks, both of which may impact the structural characteristics of the resulting structure. Although SSP is more typically used to carry lateral loads from soil and water pressures, sheet piling can also be designed to carry both lateral and vertical loads. Straight or flat web, steel sheet piles are used to form circular cells that are filled with granular soil. The fill pushes- out against the sheeting and places the interlocks in tension. In this application, therefore, it is the interlock strength rather than the section modulus, which is the most important design parameter. These cells may function as single structures such as mooring cells or bridge pier protection cells. They are commonly connected together with arcs to form continuous walls to function as bulkheads, cofferdams, and similar structures.

Because the interlocks of hot-rolled sheet piling are waterresistant, products are available to seal the interlock and reduce or eliminate seepage through the interlocks. These products are commonly used in applications such as cut-off walls underhydraulic structures in locks & dams, and for cut-off walls at hazardous waste sites.

The chosen pile section also needs to be strong enough to be driven through the various soil strata to the required penetration depth. The drivability of a piling section is a function of its crosssectionalproperties, length, the steel grade used and, in some cases, the installation method used. The cross-sectional properties are available from the SSP producer, and vary with the section’s thickness, depth, width, and shape.

This article comes from PORT TECHNOLOGY edit released