Screw Piles (Helical Piles)

Traditional concrete can be a difficult and expensive option on steep slopes, with sheet piling often required to enable construction and prevent slip circles. Screw piles offer a simple and efficient solution which can cater for slopes by adjusting the pile protrusion. If necessary, the piles are braced. The piles extend below the toe of the slope to mitigate slip circle failure.

Screw piles are ideally suited to the softer ground conditions of sands and clays with SPT N<50, some chalks and engineered fill, which makes them particularly useful on embankments, made-up ground or where the ground is soft to depth and traditional concrete or piling solutions are not feasible.

"If there is no other option other than to build the substation in a flood risk area then the most effective way of protecting critical plant and equipment is to elevate it above the level of the flood."
UK Power Networks – Engineering Design Standard EDS 07 0106 4.1 – Substation Flood Protection.

Screw piles can support low-cost flood mitigation solutions

With no concrete there is no need for excavation. Not only does this save money with no digging and no cart away, it also reduces the risk of hitting unforeseen features in the ground and avoids the problems associated with excavating contaminated ground.

FLI can design piles & grillages to span over buried services or infrastructure. For example, upgrading telecoms towers where the existing foundation is not suitable for the new loading. To reduce time out of service, piles are installed while the old infrastructure remains in service. The old tower is then removed and the new grillage and tower installed in a matter of hours. No time is lost to breaking out and remediating the old foundation and there is no cart away or casting of a new foundation, with associated delays due to curing time. Existing services do not have to be re-routed.

Screw piles only require a compact footprint, enabling a larger new tower or other asset to be installed without having to extend the site demise.

Not only do screw piles remove the need for excavation works, but the grillage and piles can be designed to component sizes and weights that enable access on hard-to-reach sites.
Previous solutions have included folding grillages and replacing large diameter piles with a larger number of small hand-carry piles.

Saves time and cost compared to traditional foundations.
Screw Piles are screwed into the ground in minutes, using a torque-motor, and once installed, provide immediate structural support without needing excavation or curing time.

Telecoms: Reduces outage time and cost for upgrade sites.
Rail: Reduces possession time, plant and labour costs.
Highways: Reduces time and cost for traffic management.

Screw piles offer major advantages over concrete.
They are fully and easily recyclable. At end of life, they are simply unscrewed and the ground is clear.

81% reduction in CO₂ footprint over mass concrete
This figure is taken from the foundation for our most commonly specified mobile phone tower, in a UK average windspeed area. In addition to that 81%, further reductions would be made as there is a saving on transport over concrete. An even greater reduction can be achieved by specifying ‘green’ steel from an electric arc furnace.

FLI Sustainability

FLI’s factory is on the same site as the design engineers and project managers, enabling a degree of teamwork across the whole design and production process, not possible when subcontracting out manufacturing or working purely as a fabricator.

This shortens the supply chain, reducing development, production and delivery times and enables fast and efficient responses to variations arising during programme delivery.

It is key to FLI’s reputation as a company that solves problems for their customers.

Screw Piles are ideal for supporting structures with significant overturning moments. They are dependable foundations even under demanding loads and conditions, delivering high resistance to axial compression forces, high capacity to counteract tension forces and reliable lateral stability.

Once geotechnical parameters are confirmed through the Client’s investigation, our design tool allows direct input of measured values to produce an optimised configuration tailored to the project’s structural and serviceability needs.

While screw piles can be galvanised to a standard that offers a 100 year life, the ability to unscrew them in minutes, as well as screw them in, means they offer an ideal solution for the temporary installation of structures, particularly those with a high overturning moment, like transmission pylons or large towers, that would otherwise demand a large and permanent concrete foundation.

For temporary foundations that do not pierce the ground at all, there are FLI’s kentledge solutions:
For small installations like relay poles, there are hand carry kentledge plates.

Hinged Poles

For full capacity 5G towers, there is FLI’s latest gravity grillage, with a clear platform and integral capacity for cabinets and fencing.

Temporary Towers