Ground anchors, otherwise known as an earth, percussion driven or mechanical anchors, are versatile devices used to hold, restrain and support building, civil engineering and other structures, either permanently or temporarily.
They come in a wide range of sizes and capacities, up to 70 m in length, with a capacity of more than 3,000 kN. They are lightweight, corrosion-resistant anchors that can be installed from ground level, either by hand or using portable equipment, depending on size and ground conditions. When loaded, they exert pressure on a cone of the ground that surrounds their length, providing very good resistance to movement.
The life expectancy of an anchor is dependent upon the corrosivity of the soil in which it is placed and the materials used (for example Steel Bar/ GRP/ Alumimium Alloy etc). Care must be taken to ensure that no services or other obstructions in the ground are damaged during installation.
The ultimate performance of the anchor is dependent upon:
- The shear angle of the soil.
- The size of the anchor.
- The depth of the installation.
- The load applied to the anchor.
Anchors can perform very well in granular soils as well as stiff, cohesive soils. Soft alluvial clays which are weaker may require a larger anchor size and a deeper driven depth. The pullout capability of anchors can be tested in similar ground conditions before installation.
There are several benefits to using ground anchors. These include:
- They are lightweight and corrosion-resistant which makes them suitable for a range of design life requirements and soil conditions.
- They are quick and easy to install.
- Installation allows for minimal disturbance, making them suited to complex and sensitive sites.
- They can be installed with minimum disruption to surface finishes.
- They can achieve a holding capacity of up to 3,000 kN.
- They have low environmental impact.