Ground Anchors

A ground anchor is a load transfer system designed to transfer the forces applied to it to a competent stratum. An anchor is said to be temporary if it has a lifespan of under two years and permanent if the lifespan is over two years.

An anchor comprises three parts:

  • The head, transmitting the anchor force to the structure via the bearing plate.
  • The free length of tendon, from the head to the near end of the anchorage.
  • The grouted anchorage, which is the length of tendon by which the tensile force is transmitted to the surrounding ground through the grout.

ground-anchors-diagram

There are “active” and “passive” soil anchors:

  • A passive anchor is only tensioned by the structure itself applying load to it. It does not usually have a free length of tendon. Generally speaking, the tendon is made of steel or an alloy. An anchor is said to be temporary if it has a lifespan of under two years and permanent if the lifespan is over two years
  • An active anchor is pre-tensioned before it takes up the load, which prevents distortion of the structure. The tendon is usually made of pre-tensioned steel cables.