SECANT PILE WALL SOLUTIONS
Secant piles are part of a rigid, robust system that combines earth retention and groundwater cut-off walls. Secant pile walls are constructed by drilling in a series of alternating primary (drilled first) and secondary (drilled second) overlapping shafts to form a continuous secant wall. The concrete in the shafts can be all low-strength, all high-strength, or a combination of low-strength primary and high-strength secondary shafts. Steel piles or reinforcing steel are typically placed in the secondary shafts. Unreinforced high-strength shafts can also be constructed in a self-supporting circular ring, such as those frequently used for access shafts to tunnels.
Secant pile walls are relatively impermeable and can be used to control the flow of groundwater into an excavation and limit draw down outside the excavation. Secant walls are also very stiff and are often used when there are sensitive structures behind the wall.
An advantage of using secant piles for cutoff wall construction is the ability of Schnabel’s high torque drill rigs to penetrate hard-drilling conditions while simultaneously casing the drill hole. These drills can advance a cased hole through man-made and natural obstructions including cobbles, boulders, and reinforced concrete.
When difficult drilling conditions are anticipated, secant piles can be a very economical method for cutoff wall construction. Another benefit is the relatively low cost of mobilization when compared to other cutoff wall types such as slurry walls and soil mix walls. To learn more about whether a secant wall is the right solution for your project, contact one of Schnabel’s eight regional offices today.
Always innovating new approaches to better solve old problems.
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.