The ECP Torque Anchor™ consists of a shaft fabricated from either solid square steel bar or tubular steel. Welded to the shaft are one or more helical plates. The plates can vary in diameter from 6″ to 16″ and have a thickness of 3/8″ or 1/2″ depending upon the soil and the application. Typically the plate diameters increase from the bottom of the shaft upward and are spaced a distance of three times the diameter of the plate directly below, unless specified otherwise by the engineer. The standard thickness for all helical plates diameters is 3/8 inch, except the 16″ diameter which is manufactured only in 1/2″ thickness. In high load applications plate thickness of 1/2″ may be specified for all plates. The pitch of the helical plate is three inches, which means that the anchor advances into the soil a distance of three inches during one revolution of the shaft. The available lead shaft lengths are 10″, 60″, 84″ and 120″, however, other lengths may be specially fabricated. Because Helical piers are considered deep foundation elements; they are usually installed into the soil to a depth greater than just the length of the typical lead section. Extensions of various lengths are available and are supplied with couplings and hardware for attachment to the lead or other extensions allowing the Helical piers assembly to reach the desired depth. Helical plates may also be installed on the extensions where the length of the lead is not sufficient to allow for the proper interval between plates. The number of the plates per Helical Torque Anchor™ is limited only by the capacity of the shaft to transmit the torque required to advance the Helical Torque Anchor™ into the soil.
Helical piers may terminate with a pier cap that will be embedded into a concrete foundation. In other applications such as tieback anchors, a transition is made from the anchor shaft to a continuously threaded rod. Various beams, wall plates, etc. can be attached to the threaded bar for wall support, and to restore or to simply stabilize walls or other structure from overturning forces. In foundation restoration repair and stabilization applications, foundation brackets are available that attach between the Helical Torque Anchor™ and the foundation beam or footing. Transferring the load from the soil below the footing to the Helical piers restores the structure.
ECP recommends that only a registered engineer design and oversee the application of helical anchors when used in foundation repair or new construction projects.