Every bridge, highway overpass and tall building starts below ground. Foundation drilling is how crews build that starting point. A foundation drill rig bores a deep hole, the crew reinforces it and fills it with concrete, and the finished pile keeps the structure above from sinking or shifting.
What Is Foundation Drilling?
Foundation drilling creates deep foundation elements called cast-in-drilled-hole (CIDH) piles. The rig drills a hole, the crew places reinforcement inside it, and the hole is filled with concrete.
Done right, these piles carry the weight of the structure down to the ground below. That keeps the foundation stable for the life of the building or bridge.
Why Do Tall Buildings and Bridges Need Deep Foundations?
Heavy structures need support that reaches well below the surface. A house usually sits on a shallow foundation built near the surface, which works because a home is relatively light.
A five-story building, a skyscraper or an interstate bridge is a different story. Foundation drill rigs install the roots of these foundations, reaching the deepest layer of soil or rock the rig can drill. Without drilled piles, these structures would be unstable and unsafe.
What Are the Main Foundation Drilling Methods?
There are four core foundation drilling methods: Kelly drilling, continuous flight auger (CFA) drilling, grab drilling and down-the-hole (DTH) drilling. Each one suits different ground conditions and pile types.
Kelly Drilling
Kelly drilling builds large-diameter bored piles with a telescoping Kelly bar. As the bar drills down, a hollow temporary casing is advanced into the hole to protect it. Once the drilling tool is pulled to the surface, a reinforcement cage is lowered in, the hole is filled with concrete, and the temporary casing is removed.
Common uses: rotary pile drilling and diaphragm wall construction.
Continuous Flight Auger (CFA) Drilling
CFA drilling happens in one continuous operation. As the auger turns its way down, the auger flights carry the drill cuttings up and out of the hole.
Common uses: short piles, such as those supporting soundwalls and standard retaining walls, and pre-drilling for driven piles.
Grab Drilling
Grab drilling uses a crane-operated grab that works inside a pre-placed casing. The grab closes on the soil or rock, is lifted to the surface to empty, and repeats the cycle until the hole reaches the target depth.
Common uses: well drilling and cast-in-place piles.
Down-the-Hole (DTH) Drilling
DTH drilling mounts a hammer at the drill bit on the end of the rod. Compressed air pumped through the hammer helps break up rock as the bit rotates. The same air pushes the cuttings up and out of the hole.
Common uses: jobs with rock or boulders that need to be broken up.
What Tools Do You Need for Foundation Drilling?
The right tooling is the difference between getting the job done right and putting your crew at risk. Gear to have on hand for your next foundation drilling job includes:
- Adapters
- Augers
- Drilling buckets
- Cleanout buckets
- Core barrels
- Casing spinners
Beyond tooling, you can upgrade your drill rig’s core components to improve performance or set it up for tougher terrain.
Drilling in hard soil or rock? Swap standard drilling teeth for heavy-duty carbide auger teeth to power through. Shop drill teeth and parts online.
What Causes a Foundation to Fail?
A foundation sinks when the ground beneath it shifts. Earthquakes, droughts, hurricanes and floods are common causes.
The damage shows up over time. Cracked walls, crumbling brick and chipped molding all point to a weakening foundation, and for a building owner, they usually mean bigger problems ahead. A properly drilled deep foundation is the best defense.
HPM Foundation Drill Rigs, Sold & Serviced by Blaze Equipment
Blaze Equipment, an Owen Company, has been an HPM dealer since 2016. We sell and service HPM foundation drill rigs nationwide from Fairfield, California; Dallas–Fort Worth, Texas; and Jessup, Maryland. Our factory-trained technicians know these rigs inside and out.
Whether you’re drilling short CFA piles or breaking through rock, our team will help you match the right HPM rig and tooling to the job. That way, you avoid costly foundation drilling mistakes down the road.
Frequently Asked Questions
What is foundation drilling?
Foundation drilling is the process of boring deep holes that are reinforced and filled with concrete to form cast-in-drilled-hole piles. These piles transfer the weight of a building or bridge to the ground below.
What are the four main foundation drilling methods?
Kelly drilling, continuous flight auger (CFA) drilling, grab drilling and down-the-hole (DTH) drilling. The right method depends on pile size, ground conditions and the type of structure.
Which foundation drilling method works best in rock?
Down-the-hole drilling is commonly used for jobs with rock or boulders. A hammer at the bit, powered by compressed air, breaks up the rock while the cuttings are pushed out of the hole.
Why don’t houses need deep foundations?
Houses are relatively light, so a shallow foundation built near the surface usually supports them. Tall buildings, skyscrapers and bridges carry much more weight and need deep, drilled foundations.
What are the signs of a weakening foundation?
Cracks in the walls, crumbling brick and chipped molding are common signs. They often appear after the ground shifts from earthquakes, droughts, hurricanes or floods.
Planning your next foundation drilling job?
Talk to Blaze Equipment about HPM foundation drill rigs or shop drill teeth and parts online.
Questions? Call 800.992.3656