Secant Pile Method
Schnabel, a nationwide design-build firm, specializes in constructing firmly anchored and structurally robust secant pile walls using the secant pile method. These walls serve dual purposes, offering reliable support for excavations and acting as barriers against groundwater.
The secant pile method involves drilling very rigid, overlapping shafts to create a continuous concrete wall. These secant pile shafts are bored using specialized drills to maintain the essential alignment required for effective secant pile wall functionality. Typically, these shafts range from 2 to 4-foot in diameter. Tangent piles share similarities with secant piles, the only difference being that their shafts touch without overlapping.
Having practiced for decades in crafting customized solutions for earth and water retention, Schnabel possesses the expertise required to construct secant walls that aid in achieving your toughest construction objectives.
Secant Pile Method Solutions
Secant piles, forming part of a firm and sturdy system, merge the functionalities of earth retention and groundwater barrier walls. The construction of secant pile walls, executed using the secant pile method, involves drilling primary and secondary overlapping shafts alternately to form a continuous secant wall. The concrete filling in the shafts can be uniformly low-strength, high-strength, or a mixture of primary low-strength and secondary high-strength. Secondary shafts usually contain steel piles or reinforcing steel. Non-strengthened high-strength shafts can additionally be constructed in a freestanding circular ring, a common application for tunnel access shafts.
Secant pile walls are relatively impermeable, making them ideal for controlling groundwater inflow into an excavation and limiting external drainage. Their significant rigidity makes them a standard choice where sensitive structures exist behind the wall.
A noted advantage of employing the secant pile method for constructing cutoff walls comes from Schnabel’s capability to traverse tough drilling conditions while casing the drill hole at the same time with their high torque drill rigs. These drills have the ability to push a cased hole through various obstacles, both man-made and naturally occurring, including cobbles, boulders, and reinforced concrete. This makes secant pile walls a versatile and efficient solution for many construction projects.
When expecting challenging drilling situations, the secant pile method can prove to be a cost-efficient approach for building cutoff walls. Another advantage lies in the relatively lower mobilization charges compared to other types of cutoff walls, such as slurry walls and soil mix walls. To find out if the implementation of a secant wall is the proper solution 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.
