A retaining wall is a structure designed and built to hold back soil and define exterior sections of a property. It is designed in such a way that it would withstand the lateral pressure exerted either by soil, liquid pressure, or other granular materials that are held by the wall.
Retaining walls can be built to perform various functions in different properties. Therefore, there is a variety of wall systems that can be used to meet various goals. In this article, we will have a look at the major retaining wall structures used in the construction industry.
1. Cantilevered Wall
This is perhaps the most common system used by property owners. Cantilever walls are composed of stem and base slab. It can be constructed on-site or prefabricated elsewhere then transported to the site. The material used for this wall is concrete which can either be reinforced concrete, prestressed concrete, or precast concrete.
The loading on these walls is cantilevered to a structural footing, allowing it to convert the horizontal pressure from the materials lying behind the wall to vertical pressure that is transferred to the ground.
Compared to other types of retaining walls such as the gravity wall, cantilever walls require a relatively small amount of concrete. The part of the slab that is located beneath the back-fill material is called the heel while the other section is called the toe.
These types of walls are best for walls that are 10 meters and below, beyond which they become uneconomical.
2. Counterfort Wall
These are similar to cantilever walls, the difference being that they require support along their backside.
They have counterforts (concrete webs) that are constructed at an angle to make them more stable. These counterforts are located at regular intervals along the length of the wall, enabling it to sustain the pressures exerted on it by the soil. The concrete webs also increase the weight of the wall.
For taller walls, these walls are better than cantilever walls.
3. Gravity Wall
These walls depend on their mass to withstand the pressure exerted by the materials behind them. That explains why they are constructed using heavy materials such as stone and masonry units. In some cases, it may be constructed leaning toward the material it is meant to hold to improve its general stability.
In the construction of short retaining walls, these walls are often made of loose stones without any binding material since the weight of the stones suffices.
Gravity walls are often massive because they require significant gravity loading to withstand lateral pressure from the soil.
There are various types of gravity wall structures. Here are the most common ones:
Large Block Wall
This wall is constructed using large blocks of either stone, masonry units, or precast concrete blocks. These blocks are usually of relatively the same size. They offer superb resistance to the lateral pressures exerted by the soil due to their large mass.
Interlocking walls are another type of gravity wall. They are designed in such a way that the concrete blocks interlock successively with one another. Some are made with flanges that slip over the edge of the preceding course.
MagnumStone specializes in constructing interlocking retaining walls. We highly recommend that you visit their website to find out more information on these types of structures.
Crib Retaining Wall
This wall is constructed using interlocking boxes that are made from either precast concrete or timber. These are then filled with coarse granular materials to improve the drainage of the wall. These are highly recommended for use in retaining garden areas. Since they are hollow and relatively light, they may not work well for supporting soil in sloping land.
Gabion Mesh Wall
Cuboidal wire mesh boxes are filled with stone or other suitable materials and then stacked together to form a wall. The wire mesh boxes containing the stones are usually put to lie on the side of the soil. Gabion mesh walls are mainly used to control soil erosion and to retain soil on steeply sloping land.
4. Anchored Wall
As their name suggests, these wall systems are anchored by driving cable rods sideways deep into the ground. The ends of these rods are filled with concrete to further increase the strength of the anchor.
These types of hardscaping structures are used in situations where there is little space for the erection of a retaining wall or where a small wall is essentially required. Since they are anchored, retaining walls of considerable height can be constructed using this wall system. The anchor supports the wall from being overpowered by the lateral forces exerted by the soil.
5. Piled Wall
Piled walls come in two forms— either the concrete pile system or the sheet pile wall. Reinforced concrete pile retaining walls are constructed by setting reinforced concrete piles adjacent to one another. The concrete piles are driven to a depth sufficient for them to withstand the lateral earth pressure exerted by the soil behind them.
Concrete piles provide high resistance to lateral earth pressure and can therefore be used in large excavation depths. They can be used to construct both permanent walls and temporary retaining structures.
Sheet piling walls are employed in situations where there is limited space for the construction of the wall. It is usually a thin wall of wood, vinyl, or steel driven directly into the earth. To provide additional reinforcement, these sheets are sometimes vertically corrugated. These types of walls for retaining soil work best in softer soils and for relatively short walls. For higher walls, they must be anchored to withstand the lateral earth pressure.
6. Hybrid Wall
Some outdoor walls hold back the soil by employing two mechanisms— gravity and anchorage/ reinforcement. These are referred to as hybrid retaining walls. They provide better resistance against the weight of the soil behind them. They are suitable for steeply sloping land prone to soil erosion.
As you choose the best wall system for your project, do a comprehensive analysis of your site to know the type of soil, its drainage requirements, the nature of its slope, and even the prevalent weather condition around the subject property. Get to know the construction requirements for each system, and be informed about their pros and cons as well.
With all these pieces of information at hand, you are set to construct an outdoor wall that will maximize the aesthetic appeal, functionality, and value of your property.