What Does Secant Piling Method Mean?
A secant pile wall is a type of bored
pile retaining wall consisting of a system of interlocking reinforced concrete piles.
Secant-piled walls can be constructed using either Continuous Flight Auger
(CFA) or Bored Cast-in-Place (CIP) methods.
The interlocking piles typically overlap
each other by about three to five-inches and are reinforced with either reinforcement
bar cages or steel W, H or I beam sections.
Trenchlesspedia Explains Secant Piling Method
Secant pile walls are constructed by first casting a shallow concrete guide wall shaped to ensure the piles are located at the correct locations and the pile overlap is in accordance with the wall design. The primary (female) piles are first installed using a slow-gain (soft) concrete mix. After sufficient curing, the secondary (male) piles are drilled between the primary piles, removing segments of the primary pile in the process to create an interlock.
These type of retaining walls are often used to support temporary or permanent excavations and are best suited where:
- The retaining wall is required to be watertight.
- Excavation space is limited due to the presence of existing buildings and infrastructure.
- The retaining wall is meant to form part of a structural system.
This makes secant pile walls an ideal solution for basements, underground structures, motorway cuttings and bridge abutments.