Secant Pile Walls

Aarsleff Ground Engineering are a choice Secant Pile Wall contractor, designing and delivering operational excellence to create value-engineered solutions bespoke to your site.

Secant Pile Walls are formed by constructing intersecting reinforced concrete piles. The secant piles are reinforced with either steel rebar or with steel beams and are constructed by augering. Primary piles are installed first with secondary piles constructed in between primary piles once the latter gain sufficient strength. Pile overlap is typically in the order of 8 cm.  They are constructed when resistance to groundwater is required using the CFA technique or the cased CFA technology.

Secant Pile Walls are usually installed as retaining structures and support systems for deep foundations, retaining elements and at the same time load-bearing walls and deep foundations for engineering constructions (e.g. walls and foundations of underground storeys, stand-alone and framed bridgeheads, etc.).

Secant Pile Walls can be constructed using the CFA or the Cased CFA technology, consisting of reinforced piles with the gaps between them filled with

• columns made of low-strength material of 1-3 MPa (concrete or mortar, usually with bentonite), spaced approx. 620-670mm for drilling diameter of 470-500mm. This solution ensures resistance to groundwater (temporary support), but does not guarantee permanent water resistance. In order to ensure permanent water resistance, additional liners or sealing agents are required
•  Full-strength concrete piles with prolonged binding time, spaced approx. 400mm for a drilling diameter of 500mm. This solution also ensures long-term water resistance and is widely used as a support system for deep excavations with a pile wall constructed on circular plane, since waling beams and/or struts are not required.

Cantilever pile walls can be used for protecting land faults up to 5m high or, if using anchors or struts, up to 20m high. Secant pile walls allow for protecting land faults up to 5-6m or, if using anchors or struts, up to 25m high. Standard rake of installed pile wall does not exceed 1:75, however, under special monitoring the rake can be reduced to 1:125, and in some cases, even to 1:200 (for secant pile walls made of hard piles and installed using the CCFA technology).

• Increased wall stiffness compared to sheet piles
• Can be installed in difficult ground (cobbles/boulders)
• Less noisy construction
• Greater retained heights
• Axial loading