We're asked two questions pretty frequently: "What are screw piles?" and "Why should I use them on my project?"
So! These next few paragraphs are my attempt at quickly and succinctly answering both of those questions.
What are Screw Piles?
This one is pretty simple to answer: On the most basic level, a screw pile (or helical pier) is a steel tube--sporting permanently attached helical blades--that is twisted into the ground like a giant screw. These piles then act as foundations for any structure built on top of them.
Why Should I Use Screw Piles?
This gets a little more in-depth. There's three main advantages to using screw piles, over other foundation solutions.
1). They Install Rapidly
Screw Piles have a distinct edge over traditional foundation piles when it comes to installation speed. While a typical driven piling rig can install anywhere from ten-to-thirty piles per day depending on soil conditions, a screw-piling rig can install as many as one-hundred-and-ten piles in the course of a day, with a well trained crew.
This lets projects with large foundation components can drastically shorten their time-lines.
2). They Allow for More Flexible Work
This is where screw piles really shine. Because of the way screw piles are installed, they give general contractors a a lot of power over how their final foundation system is laid out. They're easily adjusted and moved, they allow for the simple design and construction of complicated foundation systems, and they can be installed in tight, hard-to-reach areas. Here's why:
Screw piling rigs use reversible articulating hydraulic drills to drive piles into the earth. By being able to reverse the motion of a drill, a piling crew can easily make fine adjustments to the final height of a pile, or can entirely remove a pile to install it in a different location.
Additionally, the drill's ability to articulate lets our crews install piles at a range of angles, making more complex battered foundation systems nearly as easy to install as normal ones.
Finally, even large screw piles are able to be installed by small three-tonne excavators. These little guys have no problem getting into tight areas that most traditional piling rigs couldn't dream of reaching.
This all adds up to a foundation solution that gives a contractor a significant amount of control over their foundation system. In as little as ten minutes per pile a complicated foundation layout can be completely removed, rotated, or shifted to an entirely new position.
3). They're Tough
Anyone who's done any deck removals or demolition work knows that removing old, stripped screws is infinitely more difficult that removing nails. If you don't have the option to turn screws out, removing them takes the application of a serious amount of force.
That's the theory behind Screw Piles: Once installed they are incredibly difficult to shift or move for anything other than a screw-piling drill. In fact, we once tried to remove one of our smallest deck piles with a 230 Excavator, and ended up having to cut the shaft off and bury the twisted remains in the earth. They are strong.
Here in the north the two most powerful forces we have to overcome are frost heave and snow/wind load. If the 25,000lbs plus of the excavator can't budge a pile then snow, wind or frost would have a similarly difficult time moving it around. And that's important up here in Canada, where frost heave causes tens of thousands of dollars worth of damage to structures every year.
Wrapping it All Up
I hope that's given you some insight onto what screw piles are, and how they can be used in construction projects. They are becoming a major part of the construction industry, and when used properly, they can have massive cost-controlling and timeline-accelerating effects on any major project.
Whether you're considering using screw piles in an upcoming project or just want to learn more about them, feel free to leave any thoughts or questions down below. I'd love to hear from you, and I'd love to talk about how we in the construction business can work together to improve the way we do foundations.
- Driven Pile installation rate: https://www.mkpiling.co.uk/piling_faq's_-_piling_specialists-_piling_contractors/3 || http://www.piledrivers.org/files/222878A6-57C7-493C-8E27-6DAD34F0CEBD--3E6630CF-2786-47C9-9AC7-D9A84D93E0E9/driven-v-bored-piles.pdf || https://www.methvin.org/construction-production-rates/foundation