Secant (Caisson Walls)

Secant/Caisson Wall

Secant/Caisson Wall Secant or Caisson Walls, also known as drilled concrete pile walls, are created by first drilling primary piles at a specific spacing and backfilling with concrete. Secondary piles, sometimes called soldier piles, are then drilled in between the primary piles such that they overlap by a specified amount, drilling out part of the concrete from the primary piles on each side before backfilling with concrete. The result is a continuous wall of concrete piles known as a Secant Wall. Additional reinforcement may be provided by inserting steel section or rebar cage within the secondary piles. Tie-back anchors and walers can be installed to provide added stability.

Advantages

  • While secant walls can be more costly than other shoring solutions, they offer greater wall stiffness and minimal movement which can be critical for some projects.
  • Different installation methods can be used to achieve secant walls depending on site and ground conditions, enabling construction in difficult soils and limited overhead room.

West Harbour Go Station

Applications

In a recent condominium project in downtown Toronto, SBC used this technique to construct the foundation for an eight-story underground parking garage.

Check out some of our Secant/Caisson Walls projects: