Helical piles are commonly referred to as helical anchors, helical piers or screw piles. Helical piles are a form of a deep foundation system that has been in use since the early 1900’s in waterfront foundations. They work by bypassing weaker soil layers and transferring the loads of a structure to competent load bearing soils. Helical piles provide a cost-effective solution for supporting structures in poor soil conditions and increasing the capacity of existing structures. Helical piles are ideal for projects where noise, vibration, soil disturbance or site access, are of concern.
Helical Pile Installation
Helical Piles are installed by applying torque in order to rotate the helical pile into the ground, similar to the installation of a self-tapping wood screw.
Parts of a Helical Pile
The lead section of a helical pile refers to the first helical pile section to be installed. The lead section is responsible for penetrating the soil and transferring the load from the central steel shaft to the soil through helical bearing plates (helices), which are welded to the central steel shaft. The helices are formed with a carefully controlled pitch, which allows the pile to be rotated into the soil
Extensions of a helical pile consist of a central steel shaft with a coupler on each end (one male, one female). The first extension is bolted to the lead section and additional extensions are bolted on until the helical pile reaches the desired torque and/or depth.
Terminations connect the helical pile or helical anchor to the structure that they are supporting or tying down. There are a multitude of terminations depending on the application.
Advantages of Helical Piles
- Rapid installation
- Applicable to a wide variety of soil conditions
- Installed with a wide variety of readily available equipment
- Resists tensile, compressive, and shear (lateral) loads
- Generates no spoils to dispose of
- Eliminates need for concrete
- Eliminated need for dewatering
- Ready for immediate loading
- Can be easily load tested
- Can be removed and relocated
- No vibrations
- Low headroom installations
- Limited access installations
- Installation torque can help to verify capacity
- Year-round installation in any weather
- Helical foundations can be removed and re-used for temporary applications
- Can be installed in confined spaces with minimal damage and disruption making them ideal for remedial work