A sheet pile wall is a retaining structure built from interlocking steel profiles driven or pressed into the ground to form a continuous, relatively water-tight barrier. It resists lateral earth and water pressure and is used both as temporary excavation support and as permanent structural element in waterfront and flood-protection works.
Profile Types and Cross-Sections
Three basic cross-section families are used: U-profiles (trough-shaped), Z-profiles, and flat (straight-web) sections. In U-profiles the interlocks sit on the neutral axis of the pair, which reduces the effective moment of inertia when the interlocks slip under load. Z-profiles place the interlocks at the outer flanges, so the full cross-section acts more effectively in bending; for comparable steel consumption, Z-profiles achieve a higher section modulus per metre of wall than U-profiles. Manufacturer ranges span roughly 500 to 12,000 cm³/m for Z-sections and roughly 500 to 4,500 cm³/m for U-sections, depending on depth and web thickness. Flat sheet piles have no significant bending stiffness of their own and are mainly used for circular cellular cofferdams, where the wall works predominantly in hoop tension.
Steel Grades and Mechanical Properties
Hot-rolled sheet piling steel is supplied in grades such as S240GP, S270GP, S320GP, S355GP, S390GP and S430GP, with minimum yield strengths ranging from 240 N/mm² to 430 N/mm². Pile lengths of up to about 30 m are available from rolling mills; longer elements are produced by welding. Interlocks are rated for a defined tensile resistance, typically in the range of a few thousand kN per metre of wall, which governs arching and water-tightness in deep excavations and cellular structures.
Installation Methods
Sheet piles are installed by vibratory driving, impact driving, or hydraulic press-in (jacking). Vibratory hammers are fast and economical in granular, non-cohesive soils. Impact driving is used where higher soil resistance must be overcome, for example in dense gravel or when toe penetration into rock-like strata is required. Press-in (silent piling) methods generate minimal noise and vibration and are preferred near existing structures, in urban sites, or where vibration-sensitive utilities are present.
Applications
Typical uses include temporary shoring of excavation pits and trenches, permanent quay and harbour walls, riverbank and canal reinforcement, cofferdams for work below the water table, and flood defence embankments. Temporary walls are extracted after completion of the works and can be reused on subsequent projects; permanent walls remain in place and are designed with a corrosion allowance.
Corrosion Protection
Unprotected steel sheet piling corrodes at rates that depend strongly on exposure zone (atmospheric, splash, submerged, or embedded in soil). Design approaches account for this either by specifying a sacrificial thickness added to the structurally required section, by applying coatings, or by cathodic protection in permanently submerged conditions.
Design Standards
Structural design of steel sheet pile walls is covered by EN 1993-5 (Eurocode 3, Part 5: Piling), while geotechnical verification of earth and water pressure, embedment depth, and overall stability follows EN 1997 (Eurocode 7).