Secant piles, forming part of a firm and sturdy system, merge the functionalities of earth retention and groundwater barrier walls. The construction of secant pile walls, executed using the secant pile method, involves drilling primary and secondary overlapping shafts alternately to form a continuous secant wall. The concrete filling in the shafts can be uniformly low-strength, high-strength, or a mixture of primary low-strength and secondary high-strength. Secondary shafts usually contain steel piles or reinforcing steel. Non-strengthened high-strength shafts can additionally be constructed in a freestanding circular ring, a common application for tunnel access shafts.
Secant pile walls are relatively impermeable, making them ideal for controlling groundwater inflow into an excavation and limiting external drainage. Their significant rigidity makes them a standard choice where sensitive structures exist behind the wall.
A noted advantage of employing the secant pile method for constructing cutoff walls comes from Schnabel’s capability to traverse tough drilling conditions while casing the drill hole at the same time with their high torque drill rigs. These drills have the ability to push a cased hole through various obstacles, both man-made and naturally occurring, including cobbles, boulders, and reinforced concrete. This makes secant pile walls a versatile and efficient solution for many construction projects.