Earth anchor

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Single helix earth anchors
Guyed mast anchor

An earth anchor is a device designed to support structures, most commonly used in geotechnical and construction applications. Also known as a ground anchor, percussion driven earth anchor or mechanical anchor, it may be impact driven into the ground or run in spirally, depending on its design and intended force-resistance characteristics.

Earth anchors are used in both temporary or permanent applications, including supporting retaining walls, guyed masts, and circus tents.


An earth anchor for guy wires on a guyed mast near Thabazimbi, South Africa

Earth anchors are typically used in civil engineering and construction projects, and have a variety of applications, including:


Once installed and load-locked, an earth anchor exerts effort to the soil above it, with the soil in turn providing resistance.[5] Upward soil compression created by the anchor is typically exerted in a frustum shaped cone,[6] reflecting:

  • The shear angle of the soil
  • The depth at which the anchor has been installed
  • The load applied to the anchor
  • The size of the anchor and size and angle of its lateral surfaces

When angled these lateral surfaces generate greater cone-shaped soil resistance than a simple cylinder created by purely perpendicular design.[7]


Site analysis determining soil load resistance is often required before earth anchor installation.[8] Included are depth that the anchor is to be driven, and soil strength, moisture content, and corrosivity.[9] When appropriate, test installations are done to determine optimal anchor design or conformance with project specifications.

Installation methods differ depending on soil composition and moisture.[8] Earth anchors are commonly driven into the ground using a drive rod and impact hammer. Pilot holes are required in denser soils. After an impact driven anchor has been installed, the drive rod is removed and the anchor load-locked, typically by rotating it ninety degrees. For lighter anchors a hand tool is often sufficient.


  1. ^ [1] Platipus Anchors, retrieved 2012-07-09
  2. ^ [2] Geotechnical Engineering Circular No. retrieved 2012-07-09
  3. ^ [3] Platipis Anchors, retrieved 2012-07-09
  4. ^ [4]
  5. ^ [5]
  6. ^ [6]
  7. ^ [7]
  8. ^ a b [8]
  9. ^ [9]