Shoring Walls, Cofferdams, and Cutoff Walls
CDI provides comprehensive solutions for earth retention and excavation support through the installation of shoring walls, cofferdams, and cutoff walls. We offer various types, including secant pile walls, soldier pile walls, sheet pile walls, O-pile walls, and passive walls. These systems are essential for stabilizing excavation sites, preventing soil movement, and ensuring the safety of surrounding structures. Our expertise in these methods ensures that your project remains secure and stable throughout its duration.
Secant Pile Walls & Cofferdams
Secant piles are concrete cast-in-place drilled shafts installed so that they overlap to form a continuous wall. The installation sequence starts with drilling and pouring every other shaft: these are called the “primary shafts.” Once the concrete is set in the primary shafts, the drill returns to drill and pour the “secondary shafts.” An interlock is created between the primary and secondary shafts as the secondary shafts are drilled and poured, creating an impervious wall.
Secant pile walls make it possible to advance through man-made and natural obstructions (such as reinforced concrete, bedrock, cobbles, boulders, and dense soil), while avoiding any risk to settlement that could damage adjacent structures.
Secant pile walls and coffer dams can be poured with soft or hard concrete. They can be permanent and incorporated into the permanent
structure as walls and foundations, e.g. the foundations, shear walls and underground parking of large buildings.
Soldier Pile Walls
Soldier pile walls are mostly used for temporary excavations. The walls are built by installing vertical steel piles (usually H piles) at regular intervals (6’ to 8’ centers) along the retention wall line. The piles are installed from the original grade before excavation. Excavation is usually dug in 4’ lifts from the top down. As the excavation is advanced, lagging is inserted behind the front pile flanges. Lagging can be wood beams, steel or pre-cast panels or shotcrete. The lagging resists the load of the retained soil and transfers that load to the soldier piles.
Sheet Pile Walls, Cofferdams, and O-Pile Walls
Sheet pile walls are used as an earth retention system in soils that allow driving from the surface to a termination depth. They do not work well in soil conditions with boulders or large obstructions. Sheet piles are pre-fabricated steel sheet sections with interlocking edges. As the sheets are installed, they form a continuous barrier in the ground. The sheets are typically driven with vibratory hammers or drop hammers.
Sheet piles can be arranged into geometric shapes to form cofferdams, allowing permanent in-ground construction to take place, such as a pier foundation in the middle of a river. Sheet pile retaining walls and cofferdams are usually restrained with steel bracing, soldier piles, anchors and deadmen.
Interlocking O-pile walls are a relatively new retention system. They are made up of interlocking steel pipes with welded interlocking connections that thread into one another. They can be drilled in any ground condition utilizing a down-hole hammer. Their application is the same as for sheet piles but with the added benefit of being able to advance through challenging geotechnical formations (e.g. soil with boulders or other obstructions), and the ability to be founded into bedrock.
Passive Walls
Our experience with passive walls has involved the replacement of permeable reaction treatment walls installed across the flow path of contaminated materials sites. These walls allow for the water portion of the contaminants to passively move through the wall while preventing the movement of contaminants.