Helical Piles / Resistance Piles
Helical anchors have found increasingly widespread use in the geotechnical market. These foundation systems have the advantages of rapid installation, immediate loading capabilities and cost efficiency compared to concrete piers and driven piles. Over the years, helical anchors have evolved from the utility industry to the foundation support and earth retention sectors of the construction market. Recent developments and research has resulted in the rapid development of rational geotechnical engineering-based design and analysis procedures that can be used to provide helical anchor design solutions.
Modern helical anchors are constructed of helical shaped circular steel plates welded to a central square or round steel shaft. The plates are constructed as a helix with a carefully controlled pitch. The anchors can have more than one helix located at appropriate spacing on the shaft. The central shaft is used to transmit torque during installation and to transfer axial loads to the helical plates. The central shaft also provides a major component of the resistance to lateral loading.
These anchors are rotary advanced into the ground until the appropriate bearing stratum is reached or until the applied torque value is obtained. Extensions are added to the central steel shaft as needed. The applied loads may be tensile (uplift), compressive (bearing), shear (lateral), or some combination.
The helical steel piers are installed using rotary motors having forward and reverse capabilities. The piers are positioned and angled as specified in the approved construction/engineering plans. Helical steel piers attached to structures are installed either vertically plumb or at a slight inward slope projecting under the foundations. The helical steel piers must be installed in a continuous manner, with the rate of pier rotation in the range of 5 to 20 revolutions per minute. Extensions are selected based on the number and length, installation torque and site conditions as specified in the approved plans and are connected to the helical steel piers with the coupling bolts. Coupling bolts are tightened firmly with a wrench. The piers are installed to the minimum depth shown on the plans, but with the top helix not less than 5 feet (1525 mm) below the bottom of the foundation.
- Installation of helical piers by trained, certified installers.
- No cure time required. Immediate loading of pier upon installation.
- Future adjustments available if required.
- Minimal site impact. This allows very little disturbance to landscaping and interior finishes.
- Allows for limited access to building interior locations.
- Excellent application for installation of structures in wet conditions.
- Minimal environmental impact during installation.
THE MACLEAN DIXIE DIFFERENCE
The MacLean/Dixie Helical Foundation System is one of the leading manufacturers of helical anchoring products. MacLean/Dixie provides systems for the structural support of new and existing residential and commercial structures.
MacLean/Dixie Helical Foundation Systems are used to underpin foundations of existing structures, to form deep foundations for new structures, to retrofit or remediate deficient foundations of existing structures, and to provide bearing for new foundations. The systems consist of foundation attachments (brackets) and helical steel piers. The foundation attachments are used to connect the foundation of the structure to the installed helical steel pier.