When it comes to installing a poured concrete retaining wall, choosing the correct anchoring system is one of the most important choices you can make. While concrete is an enormous strong and durable material, the weight of so much piled earth pressing on the wall can be immense, and a suitable anchoring system can make the difference between decades of safety and strength and a collapsing disaster zone. Take care to note the advantages and disadvantages of each anchoring method before work begins to make sure you get the best results possible.
Gravity anchored wall
This is the simplest anchoring system, and simply relies on the weight and mass of the concrete itself to keep the wall and the soil it holds in place.The outward facing side of the wall is generally sloped to aid in this, with taller walls requiring a sharper angle.
The simplicity of this system means that gravity anchored walls can be much quicker and easier to install than walls with more complicated anchors. Unfortunately, they tend to have a very limited maximum height without posing a toppling risk, and the sloped construction means that a relatively large amount of concrete is used, potentially adding to costs and taking up more ground space.
Cantilever anchored walls
These walls resemble those with gravity anchoring, but have an integrated concrete 'lip' that extends several feet behind the wall, underneath the piled soil.
This added reinforcement gives cantilevered walls extra strength and a taller maximum height, while keeping the anchoring system well out of view. They are particularly useful for retaining rich, heavy soils and clays, as the added weight of the soil places more pressure on the cantilever to keep the wall in place. However, cantilevered walls use even more concrete than gravity anchored walls, and must be poured on-site by professional retaining wall installers.
Piling anchored walls
These walls are very simple. straight structures that use a surprisingly small amount of concrete. To add strength, these walls are generally much longer than walls with other anchoring systems, and are entrenched deeply into the ground to provide a firm foundation.
When combined with the enormous strength of poured concrete these anchoring systems can be very effective, and their slimline construction means that a minimum of floor space is wasted. However, they tend to have a limited maximum height. You should also check that the soils on both sides of a piling anchored wall are roughly similar in weight and density, or your wall may begin to lean in the direction of the denser soil.
Chain and cable-anchored walls
These anchors bear the closest resemblance in form and function to a ship's anchor, and they comprise expanding weights attached to the back of the wall via cables or chains. The anchors are then buried so they can lodge themselves in the soil, providing a significant increase in load-bearing strength with a minimum amount of extra space and material required.
The great advantage of these anchors is that they can be combined with other anchoring systems to provide added security to walls. Their relatively small size and simple construction also makes them cheap and relatively easy to install. Unfortunately, you will almost certainly have to pay for professional assistance if you choose this option, as placing the anchors in the most effective positions can be very difficult without an intimate knowledge of retaining wall construction.