Sheet piles are used for both temporary and permanent retaining walls. Structures include basements, underground carparks and abutments for bridges including integral bridges.
The concept of sheet pile
U & Z & straight sheet pile
Types of Retaining Walls for Sheet pile
The Safety of Sheet pile
The concept of sheet pile
The concept of sheet pile is straightforward. Wherever a wall or siding needs to be held back, steel sheets are wedged into the earth at predetermined intervals. The sheets are driven into the soil with vibratory or impact hammers. In some cases they may be installed with hydraulic presses. The placed sheets interlock with each other, enabling variable designs that can be adapted for a specific retention job. If even more strength is needed, anchors are easy to add. The adaptability of the sheet pile means supports can be as temporary or permanent as needed. Sheet pile is used to protect or construct:
Seawalls and bulkheads
Below ground facilities
In the UK, three profiles designated as U, Z and straight web are available. They are predominantly manufactured as hot-rolled section, although cold formed sheet piles are also manufactured.
Cold formed U and Z profile sheet piles are also manufactured, however, they are primarily used for reinforcing dams and river or canal banks. They are also used for containment barriers in contaminated land and as noise barriers when sound absorbent facing is attached to the front of the pile.
Where the depth of excavation is small, cold formed trench sheet sections can be used as an alternative to U and Z sheet piles. Projects include sewerage and drainage works, and particularly sheeting for temporary works.
Z-profiles are used for intermediate to deep wall construction as they are considered to be the most efficient type of sheet pile available. They are commonly used for cantilever and tied-back retaining wall systems. U-profile sheet piles are used for similar applications as Z-profiles, however, because the interlock between adjacent sheet piles is at the neutral axis of the section, their bending resistances are lower than that of comparable Z-profiles.
Straight web sheet piles are designed to form cylindrical structures, generally closed, retaining a soil backfill. In general, they are used where the piles are liable to be subjected to tensile forces, hence interlocking strength is of prime importance. They include cellular cell structures (cofferdams) and diaphragm cell structures.
Different sites need different walls. With each technique specifically designed for the scenario, the following are the most common retention walls:
Cantilever – These walls provide support by the sheer strength of the sheets.
Braced and Anchored – These are necessary for high pressure situations, increasing retaining strength with lateral braces and anchors.
Soldier Piles – H-section pipes or piles are inserted into drilled holes.
Secant or Tangent Piles – Drilled out sections are filled will soil to stiffen the walls.
Structural Slurry Walls – Trenches are dug and filled with concrete as an alternative to steel.
Whatever site needs to be protected, there is likely a sheet pile solution appropriate for the situation. Investing the resources to have the sheet pile properly designed and driven can save the facility from higher costs down the road by getting the job done right the first time. STI group provides expert deep foundation and pile driving services and can assist clients in getting the sheet pile they need to thoroughly and completely protect their worksites.
When designed correctly, sheet pile can almost eliminate the risk of landslide, erosion, collapse or water breech. Construction sites are teeming with people and expensive equipment, so there really is no excuse for taking risks. With a simple survey, an optimal retention plan can be designed, minimizing construction costs just as much as safety risks. Properly designed and driven sheet pile can provide outstanding protection to construction sites and permanent retention walls.
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