Helical or Screw Piles
Helical Piles generally consist of solid square or circular hollow section steel shafts to which individual helical plates are attached. Piles are installed by applying torsion to the head of the pile and due to the arrangement of helices, once installed, produce tension capacity as well as compression resistance, without the need for concrete. Helical Piles can be used in place of traditional piling methods for new build projects and are also particularly suited to;
- Underpinning – residential and commercial
- Guy anchors & foundations for towers
- Highways and rail structures and gantries
- Tiebacks for excavation bracing
- Soil nails for earth retention
- Temporary structures – (non-grouted piles can be easily removed)
Using a portable, hand held torque motor, ultimate pile capacities of 225kN can be achieved. Constructed as a 'Pulldown Micropile', with the addition of a grout column formed around the steel shaft during installation, capacities of 450kN are possible.
If plant mounted installation equipment is used, ultimate pile capacities in excess of 1000kN are achievable. If installed with a grout column, ultimate capacities in the order 2000kN can be realised.
Helical Piles can be installed with small plant, which means that the installation of a piling mat is generally not required. In addition the following benefits can make the use of helical piles advantageous;
- Quick, easy installation
- No vibration
- Low noise
- No spoil to remove
- Small installation equipment
- Immediate loading
- Installation can take place in any weather
- Restricted access sites
- Environmentally friendly
- No concrete