Helical piers or piles are one of the most commonly used mid-strength foundation solutions. These foundations are excellent in tension and adequate in compression, but are relatively quick to install.
Helical piers, like micropiles, are often chosen for jobs with limited access or headroom. They can be installed quickly with a variety of equipment, including skid steers, mini-excavators, forklifts, excavators, etc.
Helical piers can be installed inside buildings and in areas with limited headroom. They are used as deep foundations for new structures or to underpin existing structures. Since these foundations are most efficient in tension, helicals are extremely effective as tiebacks or when resisting uplift.
How it's done
Helicals consist of a lead with screw-like plate flights that allow for drilling into the soil, and extensions that are bolted together as the pier is drilled to the required depth or capacity. These members are customizable for use in various soil and load applications.
Helical piers are one of the most common foundations for a reason. They mitigate access issues and can be installed in most types of soil. There is no disruption or vibration when installing and no drilling spoils. Pile capacity is dependent on end bearing of the helical lead flights into competent soil. As a pile is installed, torque applied to the pile from the drill is monitored. Pile capacity can be calculated from this torque which often decreases project costs thanks to the elimination of load tests to prove capacity.
Chris-Hill has installed helicals for over 15 years. We have used them for foundation lifting, new construction, as tiebacks for telephone poles and cell towers, and in a number of other applications.