Screw piles are a popular choice for foundations. Quick and easy to install, they are not weather reliant and are ready to use immediately. But that doesn’t mean that you don’t need to do your research before using them. And ground investigations are a key part of that. Here’s why.
How Your Ground Investigations Will Influence Your Screw Pile Installation
The length and diameter of the screw piles you need
Screw piles can come in a whole range of lengths and diameters. There are piles available ranging from 1m, with typical sections ranging from 2-6m in length, with most screw-piling happening at a depth of less than 20 meters. There are various screw pile diameters available, typically between 60.3–140.3 mm. However, diameters can reach 175.mm and even wider in special cases. The length and width of the piles you require is influenced by the projected load of the project, the use of the structure, the required torque, and the soil type. The more friable the soil, the deeper the pile will need to go and the broader the pile will need to be. So, as a general rule, if you’re working in loose sand, you’ll need longer, wider screw piles than if you’re working in stiff heavy clay. Your ground investigations will provide valuable guidance with this.
The placement of the screw piles
In most cases, screw piles should be configured to leave a minimum space of 3x the helix width between each pile with spans reaching 2m or much more depending on the supporting structure that will be fixed to the pile. Where there is a weak soil structure, heavy loads or high ground water, you may need to place your piles a little more closely together. Your ground survey should also be able to tell you whether there are likely to be any obstructions in your building site for example if there is flint or sandstone in the ground, which could prove a challenge to screw-piling.
Whether screw piles are appropriate
For some sites, screw piles simply aren’t an appropriate choice. If, for example, there is bedrock at a shallower depth than the project requires the screw piles to reach, an alternative foundation may be called for.
Understanding the ground conditions you’re working with is integral for any construction project. Soil tests and geotechnical reports provide you with the factual data you need to understand everything from groundwater levels and soil type to the overall geology of the site. All of which can help you to make more informed decisions regarding various features of the build. Including foundation choice. When you’re working with screw piles, ground investigations can help to ensure that you are making the right choices to ensure maximum stability and durability for your build.
Get in touch with UK Helix for all your screw pile design, supply, and installation needs.