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 and earth retaining construction market. Recent developments and research have granted 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 a helical shaped circular steel plates welded to a 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.