Secant piles form a steadfast, robust system that merges the dual functions of earth retention and groundwater cut-off walls. Using the secant pile wall construction method, walls are constructed by drilling a series of alternating primary and secondary overlapping shafts to produce a continuous secant wall. The concrete filled into these shafts could be totally low-strength, solely high-strength, or a mix of low-strength primary and high-strength secondary types. Typically, the secondary shafts embed steel piles or reinforcing steel. Additionally, unreinforced high-strength shafts can also be constructed as self-supporting circular rings, a structure often employed for tunnel access shafts.
Relatively impermeable, secant pile walls are used to control the inflow of groundwater into an excavation and limit external draw down. Due to their considerable rigidity, secant walls are commonly utilized when sensitive structures are located behind the wall.
One of the main advantages of applying the secant pile wall construction method for building cutoff walls lies in Schnabel’s capacity of their high torque drill rigs. These can pierce through tough drilling conditions while simultaneously casing the drill hole. These drills are also capable of driving a cased hole through both man-made and naturally occurring obstructions like cobbles, boulders, and reinforced concrete.