Foundation Ground Helical Anchors

Foundation ground helical anchors

Product description

      This Guide should be used for preliminary calculations only and applies only to the deep installation of Screw-Piles and Helical Anchors in uniform soils. It is only applicable for design when the depth (D) to the top helical plate is greater than 10 times the diameter (B) of the helical plate and the minimum depth of embedment of the helical plate is 5 ft. The methods described in this Guide provide an estimate of the ULTIMATE capacity; the Engineer must apply an appropriate Factor of Safety to obtain the ALLOWABLE capacity.

Contribution of Shaft to Capacity
     Many Foundation ground helical anchors are manufactured with square central shafts. For these Foundation ground helical anchors, the contribution of the shaft to the ultimate capacity is usually ignored and the total capacity is only calculated from the bearing capacity of the helical plate(s). For Foundation ground helical anchors with round steel central shafts the shaft section between plates for multi-helix elements is ignored, but the shaft above the top plate may be included in design, at least for that section of the shaft in full contact with the soil as discussed in Section 3.

   Foundation ground helical anchors are wound into the ground much like a screw into wood. Foundation ground helical anchors are installed using various earthmoving equipment fitted with rotary hydraulic attachments. Machinery varies from skid-steer loaders to 5 tonne through 80 tonne excavators. Rotary hydraulic powerheads with torque capacities ranging from 5,000 Nm to 500,000 Nm are custom fitted using various boom configurations.