Helical Piers Systems
The helical pier is a deep foundation system used to support or resist any load or application. Helical Pier installation is managed by mobile equipment ranging in size from lightweight units to more massive units depending on the load requirements, and it can be loaded immediately. The helical pier’s simplicity is its greatest asset. Its mechanical design and manufacture balance the capacities of its three essential parts and maximize the efficient use of their material.
Chance Civil Construction is the international leader in earth anchoring and piering. CHANCE Helical Piers are used worldwide to secure residential and commercial buildings, tower foundations, heavy equipment foundations, and many other deep foundation applications of multiple depths and capacities.
Components of a Helical Pier System
1. At least one bearing plate (helix)
Dies form each steel bearing plate into a true helix. The plates are formed in an actual helical shape to minimize soil disturbance during installation (as opposed to the inclined plane of an auger, which mixes soil as it excavates). Properly formed helical plates do not measurably disturb the soil. The helical bearing plates transfer the load to the soil bearing stratum deep below the ground surface. “Deep” is considered five-helix diameters vertically below the surface, where the helical plate can develop the full capacity of the plate-to-soil interaction.
2. A central shaft
During installation, the central steel shaft transmits torque to the helical plate(s). The shaft transfers the axial load to the helical plate(s) and on to the soil bearing stratum. In addition to having the torsional strength to resist the torque required to install the helical plates into load-bearing soils, the shaft must have the structural capacity to exceed the applied stresses from the building or structure that it will be supporting.
3. A termination
The termination connects the structure to the top of the helical pile/anchor transferring the load down the shaft to the helical plate(s) to the bearing soil. To evenly distribute the structure load to the helical piles/anchors, the termination may be a manufactured bracket or an attachment produced on site as designed by the structural engineer. Intech Anchoring and A.B. Chance design and create specialized termination brackets for a wide variety of loading conditions and applications including compression, tension, seismic, and lateral types of loading, among others.
Helical Pier Applications
In its simplest form, the helical pier is a deep foundation element, i.e., it transfers a structure’s dead and live loads to competent soil strata deep below grade. This is the same for any deep foundation elements such as driven piles, drilled shafts, grouted tendons, auger-cast piles, and belled piers.
Therefore, helical piers can be used as an alternative method to drilled shafts and driven piles. Practical constraints—primarily related to installation—currently limit the maximum design load per helical pier to 100 kips in tension and 200 kips in compression, which means helical piers can resist relatively light to medium loads on a per pier basis and much heavier loading when used in pile groups. But as is the case with virtually all engineering challenges, more than one solution exists. It is the responsibility of the engineer to evaluate all possible alternatives and to select the most cost-effective solution. This decision will take into consideration factors such as load capacity, the existing structure load, and soil conditions.
Today, helical piers are commonly used for residential and light commercial and heavy commercial construction, machinery/equipment foundations, telecommunication and transmission towers, tie-downs for wind and/or seismic forces, and virtually any application where site access is limited or remote. They have become the deep foundation of choice for walkways and boardwalks in environmentally sensitive areas, such as wetlands and protected forestland. In expansive soil areas, helical piles can save money and time when compared to expensive over-excavation and fill options.
Helical piles/anchors do have several advantages that make them the foundation of choice for many applications, including these general categories:
Wind and seismic loading
Replacement for drilled/driven piles
Helical Pier Advantages
No need for concrete to cure
Quick, easy turnkey installation
Small installation equipment
Easily field modified
Torque-to-capacity relationship for production control
Install in any weather
No spoils to remove
Restricted access sites
High water table
Weak surface soils
You Can Rely on the Expertise of Intech Anchoring
With Intech Anchoring, you can be sure that the equipment and products we recommend are not only high quality but also geared toward the specific goals of your project. Our team offers same-day response and two locations of inventory to pull from. Our experts can be at your side to coordinate your equipment and ensure it is installed according to the appropriate engineering specifications.
To learn more about Helical Piers and our support services, contact Intech Anchoring today.