Secant Pile Shaft
As a design-build firm operating across the nation, Schnabel excels at crafting reliable, hard-wearing secant pile walls, offering efficient excavation support and effectively acting as groundwater barriers during excavations.
Secant pile wall construction involves the use of exceptionally rigid, overlapping shafts that come together to form a solid concrete wall. The secant pile shafts are drilled with specialized equipment that maintains the crucial alignment, pivotal for the efficacy of these walls. The diameters of these shafts typically vary from 2 to 4 feet. While secant piles overlap, tangent piles differ as their shafts merely touch, without any overlap.
Leveraging its decades-long expertise in delivering bespoke earth and water retention solutions, Schnabel is perfectly poised to deliver secant walls, even in the face of your toughest construction challenges. This expertise carries through to the design and construction of secant pile shafts, providing a solid foundation for a variety of builds.
Secant Pile Shaft Solutions
Secant piles, comprising a solid and robust system, amalgamate earth retention with groundwater barrier walls. Secant pile walls are constructed using a method that involves drilling a series of alternating primary (drilled first) and secondary (drilled second) overlapping shafts. This drilling sequence forms a continuous wall of secant pile shafts. The content of concrete in these shafts can range from being completely low-strength or high-strength or can be an effective combination of the two, with low-strength primary and high-strength secondary shafts. Reinforcing steel or steel piles are normally installed in the secondary shafts. Alternatively, high-strength unreinforced shafts can also be built in a self-sustaining circular structure, akin to those often utilized for access shafts leading to tunnels.
Secant pile walls exhibit considerable impermeability, proving their efficacy in controlling the ingress of groundwater into an excavation and restricting drawdown outside of the excavation. Owing to their stiffness, secant walls are commonly used when there exist structures sensitive to movement behind the wall.
A notable upside of opting for secant piles in cutoff wall construction lies in their compatibility with Schnabel’s high-torque drill rigs. These drills have the capability to penetrate tough drilling conditions, casing the drill hole simultaneously. They are equipped to drive a cased hole through natural and man-made obstructions encompassing cobbles, boulders, and reinforced concrete, providing exemplary secant pile shafts.
When the drilling conditions anticipated are challenging, secant piles emerge as a cost-effective solution for building cutoff walls. Additionally, we offer the advantage of relatively lower mobilization costs when compared to other types of cutoff walls like slurry and soil mix walls. For more nuanced advice on whether a secant wall would fit your specific project needs best, consider getting in touch with one of our eight regional offices. Our team of seasoned experts is available to guide you toward the most suitable construction solution, including the deployment of efficient secant pile shafts.
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.
