Secant Pile Wall Construction
Secant pile walls is constructed by inserting a reinforced concrete pile into the middle of two other concrete piles that forms a row. This method is by far more superior than the ordinary sheet pile layout, since the secant pile has less gaps compared to the ordinary pile, making it more watertight and stronger to resist against harsh environments. Secant pile wall can be found in harbors, sea walls, and riverbanks.
Secant pile wall is divided into two parts: the primary pile, which is a bore pile without reinforcement, and the secondary pile, which is a bore pile reinforced with rebar that is larger than the primary pile. In the process of working on the wall layout, the secondary pile will be drilled between the two primary piles. The primary pile is given a retarder additive that makes it soft, which can extend the setting time of the concrete. The condition of the soft pile has a big influence on the construction of the secant pile wall. This is because the part of the primary pile will be destroyed and replaced by the secondary pile. In the drilling process, the secant pile will be placed by overlapping the two primary piles. The overlap usually takes away 3 inch of the primary piles and it is aimed to produce an interlocking joint between one pile and another.
Secant pile has a few advantages such as the depth of the pile that can be varied and can be directly installed in any type of terrain or even rocky grounds, it also has no risk of ground level rise and increase in wall strength compared to other constructions that does use this type of foundation, it can decrease the amount of sway that occurs due to the clay buildup in the bottom of the pile, and it can also be installed to a great depth and a large diameter to anticipate the soft rocks or clay on the bottom of the foundation.
Railsystem. (2016). Secant Pile Wall Construction. Retrieved from: http://www.railsystem.net/secant-pile-walls/