What are the Different Types of Ground Anchor?
Ground anchors, also known as earth anchors, are vital parts of sheet piling construction projects and are used to stabilise ground conditions at a project where stability of the earth is key.
Ground-anchoring devices can hold, restrain and support structures in the built environment, which are either temporary or permanent in nature. They can also help maximise the working area available, for projects being carried out in tight spaces.
These ground anchoring mechanisms transmit the vertical loads of the structure being erected – tensile force – to deeper, stable areas within the ground. This helps keep ground stable and keeps any movement of the ground within a level that can be tolerated by the structure being installed.
By incorporating ground anchors into their sheet piling designs, a contractor can build on land that is unstable, or which has a low load-bearing capacity. When Installed within slopes, ground anchors can be a landslide prevention measure.
Ground anchors can be:
- temporary – removed as the work is completed, up to two years from installation date. These can be either single-rod anchors or strand anchors;
- permanent – in situ for more than two years and benefiting from the anti-corrosion treatments applied to permanent ground anchors. These can be strand anchors or single-rod pressure tube anchors.
The different types of ground anchor devices:
Although often generically known as ‘ground anchors’, there are different anchoring devices for use in different conditions, namely:
- Ground anchors
- Soil nails
- Rock bolts
- Port tie-rods
- Micropiles
Ground anchors
These are made using either bars or strands and are inserted into bore holes 30mm to 200mm in diameter. Grouting around the anchor can then occur. Ground anchors are typically pre-stressed.
Soil Nails
These are typically 20mm to 50mm diameter nails deployed in soft ground conditions and inserted into bore holes of between 70mm and 150mm diameter. They can be anything from 6 metres to 20 metres in length and bonded along their entire length by cement grouting.
Rock bolts
These are shorter than soil nails, usually having a length of 3 metres to 6 metres and are used in rocky ground. They can either have a similar cement grouting to soil nails or be anchored at the base of the hole though a mechanical means or by using resin.
Port Tie-Rods
These anchoring devices are used in marine environments and take up the forces that the ground applies to a quay wall. The load that is transmitted to the rod is then transferred to a structure to the rear, such as a steel sheet pile wall.
Micropiles
These are small-diameter steel piles that are drilled and grouted, again taking up the tensile forces transmitted to the ground by the structure being erected. They are often called mini-piles and are typically used in deep-foundation projects.
Which types of ground anchor system to choose really depends on the soil conditions, the type of structure being erected and the length of time supporting structures will be required. As a sheet pile specialist, Sheet Piling (UK) Ltd can assist with this at the project design stage, determining exactly how to best achieve the aims of the project.
Please call us on +44 (0)1772 79 41 41, to find out more.
- Ends -NOTES TO EDITORS
Sheet Piling (UK) Limited is one of the UK's leading piling contractors. Owning and operating a comprehensive range of specialist piling equipment Sheet Piling (UK) Ltd also carry extensive stocks of new and used piles enabling rapid reaction to any urgent requirements or emergency situations.