Helical Screw Piles

A helical anchor/pile is an extendable deep foundation system with helical bearing plates welded to a central steel shaft. Load is transferred from the shaft to the soil through these bearing plates. Central steel shafts are available in either Type SS (Square Shaft) series or Type RS (Round Shaft) series. The Type SS series are available in 1-1/4″ to 2-1/4″ square sizes. The Type RS series are available in 2-7/8″ to 4-1/2″ diameter sizes. Type SS-RS combinations are also available for compression applications in soil conditions where dense/hard soils must be penetrated with softer/loose soils above the bearing strata. The Helical Pulldown® Micropile series is also used in applications similar to those requiring the use of the Type SS-RS combinations.

Segments or sections are joined with bolted couplings. Installation depth is limited only by soil density and practicality based on economics. A helical bearing plate or helix is one pitch of a screw thread. All helices, regardless of their diameter, have a standard 3″ pitch. Being a true helical shape, the helices do not auger into the soil but rather screw into it with minimal soil disturbance.

Product Description

Typical Construction Applications:

  • Building-site preparation
  • Roadways
  • Retaining walls
  • Levees
  • Dams
  • Revetments
  • Lighting Foundations
  • Transmission Foundations
  • Self Supported Towers
  • Monopole Towers

Features

  • Predictable results
  • Cost-effective method
  • Easy to store, reusable
  • Pre-engineered system
  • Labor-saving, keeps crew small
  • Screws into place (not predrilled)
  • Site-specific to conditions and loads
  • Terminations for various thread bars
  • Less equipment than grouted tendons
  • Bearing device, not friction dependent
  • Extendable with bolted joint connection

Benefits

  • Installs in inclement weather
  • Installs in limited access areas
  • No excavation or spoils to remove
  • Immediate proof testing and loading
  • Permanent or temporary (removable)
  • Labor saving – as few as four on a crew
  • Capacity proportional to installing torque
  • No concrete trucks or grout pumps needed
  • Install with equipment for grouted tendons

No delays because there is no grout

  • Typical production rate of 30 to 40 per day for installing and testing
  • No holes to drill
  • Cuts labor and equipment costs
  • Can save 30% while obtaining high anchor-load capacities

Solves construction problems

  • In cohesive soils, no belled and/or long sockets
  • In non-cohesive soils, no casings or grouted sockets
  • Bearing mode (not friction mode) anchors
  • No de-watering for below-water-table applications

Helical Capacity Design Software

HeliCAP® – Helical Capacity Design Software – helps design professionals quickly derive the proper helical tieback anchor for site and load specific data. Contact your local distributor or territory manager about how to get a copy today.

Site-Specific Basics of Screw Anchor Design

  • Two typical steps to anchorage design:
  • Select helix configuration based on accurate soil characteristics data and tension load.
  • Select shaft configuration based on tension load and anticipated installation torque.
  • Anchor load capacity equals the sum of all its individual helix bearing capacities. Bearing capacity of each helix equals the product of its projected area and bearing pressure
  • Pre-engineered CHANCE screw anchors optimize helix spacing at three times the next lower helix diameter. This assures more predictable torque-to-capacity relationship
  • Holding capacity is proportional to installation torque (recommended 10 lbs per ft-lb) Monitor torque while installing to ensure a minimum and not to exceed anchor rating
  

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