Secant Pile Walls
Schnabel, a prominent design-build firm operating across the nation, is known for its reliable and structurally secure secant pile walls. These structures are highly effective as both support for excavations and barriers against groundwater.
Secant pile walls employ rigid, overlapping shafts to create an unbroken concrete barrier. The process of drilling these shafts involves the use of specialty drills that ensure that the necessary alignment is maintained for maximum effectiveness. The shafts usually measure between 2 and 4 feet in diameter. They bear a similarity to tangent piles, the only difference being that while tangent piles’ shafts touch, they do not overlap.
Having spent several decades in the business, Schnabel is equipped with significant expertise in crafting custom solutions for earth and water retention. This experience enables them to provide you with secant walls tailored to overcome even the most challenging construction objectives.
SECANT PILE WALL SOLUTIONS
Secant piles are sturdy and inflexible systems that offer both groundwater barrier walls and earth retention solutions. In the construction of secant pile walls, a series of primary and secondary overlapping shafts are drilled in alternate fashion, forming a continuous wall. The concrete used in the shafts could be exclusively low-strength, high-strength, or a mix of primary low-strength and secondary high-strength shafts. Steel piles or reinforcing steel are commonly used in the secondary shafts. Moreover, unreinforced high-strength shafts can also be constructed in a self-standing circular frame, frequently used for tunnel access shafts.
Secant pile walls are considerably leak-proof therefore, they are effective in controlling the seepage of groundwater into an excavation site and minimizing drainage outside the excavation. Furthermore, secant walls are inherently rigid, making them an ideal choice when sensitive structures are located behind the wall.
A key benefit of using secant piles for cutoff wall construction is the capacity of Schnabel’s high-powered drilling rigs. These can confront hard-drilling conditions while casing the drill hole at the same time, allowing for the advancement of cased holes through man-made and natural obstacles such as cobbles, boulders, and reinforced concrete.
Secant piles offer an affordable solution for constructing cutoff walls, particularly when challenging drilling conditions are expected. Furthermore, they have a comparative advantage in mobilization costs against other forms of cutoff walls like slurry walls and soil mix walls. If you wonder whether a secant wall is the right approach for your project, please reach out to one of Schnabel’s eight regional offices today for more information.
Always innovating new approaches to better solve old problems.
Rondout West Branch Bypass Tunnel Shaft
Schnabel installed secant piles in a self-supporting circular ring to support the construction of a new bypass tunnel to allow water to flow under the Hudson River to New York City after an older tunnel started to leak.
Barnes-Jewish Hospital
Schnabel designed and constructed a secant pile wall for the Barnes-Jewish Hospital Parkview Tower on the Washington University Medical Campus in St. Louis, Missouri. The perimeter secant wall served as both the permanent structural basement wall and the temporary earth-retention system for the new hospital building.
In 31 years of building deep foundation projects for Schnabel, building a 90’ deep reinforced circular shaft was one that was very challenging and deeply rewarding. Looking forward to working on the next one with our client Schiavone.
