Secant Pile Walls Construction Methodology

Secant pile walls are an extremely effective type of embedded or in-ground retaining wall. They are formed with intersecting piles of concrete forming a continuous structure. Secant walls hold soil and rock back, even in unstable soil conditions, while preventing water flow into the excavation area. They provide a high lateral strength for embedded foundations with the added advantage of a top down construction method. This causes much less noise and vibration than other retaining wall options. All this translates into contractors being able to build walls and foundations very close to property lines, also in some cases work without additional construction in front of the excavated face.

  • Basement Construction

  • Underground Parking Garages

  • Waterfront Structures

  • Tunnel Approaches

  • Dam Construction

  • Developments that need to maximise space right up to property boundaries

  • Projects where excessive vibration will create dangerous soil disturbance

  • Urban sites that can’t accommodate large construction areas

  • Sites or soil conditions that cannot accommodate heavy specialized equipment

  • Hard and Rocky soil conditions

  • Wet soil conditions

Overlapping piles

The secant wall uses interlocking piles to create the continuous structure. The piles are installed in two stages – first the primary pile then the secondary pile. (These can also be referred to as the female and male piles.) The piles interlock or overlap to tolerances designed to achieve an effective interlock between the two.

*Concrete and reinforcing options


The combination of primary and secondary piles can be hard/hard, hard/firm or hard/soft with different concrete types and reinforcing methods. The choice depends on soil conditions, water retention required and other individual site factors. Soft sections may be made from a weaker reinforced concrete. Hard sections can be reinforced with steel beams or steel rebar.

Creating ‘cast in place’ formers

Installing the piles requires accurate forms to create the guide wall. Using EPS (expanded polystyrene) from Universal Foam Products is a popular choice for a number of technical and practical reasons:

  • EPS forms are produced to tight tolerances to achieve the important overlap required.

  • EPS secant forms are created in advance and offsite then shipped ready to use. Less space and time required onsite.

  • EPS forms are lightweight to move and set in place compared to options such as steel forms.

Choosing secant walls with EPS forms

Secant walls produce strong embedded walls in many applications. Areas that would otherwise cause construction problems: busy urban areas with space restrictions, soil conditions sensitive to vibrations and areas with wet soil. EPS secant forms from Universal Foam Products are the perfect compatible material for both technical accuracy and easy onsite handling.

Our team from Universal Foam Products take designers and contractors through the whole process from design to shipment. Contact the experts on EPS secant wall forms to learn more about how to achieve your wall construction goals. Call now on 410-498-0000.

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