Due to the shape of the tree anchor and the
offset attachment point of the wire tendon, when a load is applied, the anchor will rotate in the ground by up to 90° and loadlock.

As the load exerted on the soil by the tree anchor system increases, a body of soil above the anchor is compressed and provides resistance to any further anchor movement. The size and spread of this body of soil can be visualised as being a truncated cone or frustum. We refer to this soil as the Frustum Cone.

The size and spread of a Frustum Cone will depend upon:

• The shear angle of the soil
• The size of the tree anchor
• The depth of installation (overburden height)
• The load applied