"Pile walls for use in positive cut-off construction consist of a series of overlapping/secant bored piles. The (great) advantage of this construction method is that the installation of the piles can be accomplished in almost any type of ground, especially in rock, such as karstic limestone. Thus it can be assured that the bottom of the wall is socketed into a firm base without leaving a gap between wall and the pervious ground."
Secant pile walls are formed by constructing intersecting concrete piles. Alternate primary piles (initial) are installed first with secondary piles (closure) constructed in between primary piles once the latter gain sufficient strength. Pile overlap is typically chosen to form a continuous wall with the specified minimum thickness.
Piles can be filled with either structural or lean concrete.
The main advantages of secant pile walls are:
- Increased construction alignment flexibility
- Simplified site setup
- Relatively smaller working platform required
- Can be installed in challenging ground (cobbles/boulders)
Care has to be taken
- to achieve specified verticality tolerances for deep piles
- to properly form the larger number of joints
- to consider the limited depth of the technique during design stage already
Bored cast-in-place concrete piles brochure