Retaining walls may be defined as ground retaining system that serves the dual purpose of enhancing the looks of the landscape and retaining the soil and rocks behind the wall to prevent them from flowing down. Usually, reinforced concrete frames, wood, heavy blocks, cinder blocks, stones and various other such building materials are used for creating these retaining walls to counteract the pressure of the soil behind the wall.
Sometimes, these retaining walls are also anchored in to the ground with a steel beam. Retaining walls have been in use for thousands of years. Many different types are extensively used all over the world.
There are many different types of retaining walls and the choice of a particular type depends on the purpose of the retaining wall, soil in the area as well as availability of the building materials. Here is a small list of different types of retaining walls.
Types of Retaining Walls
One of the most common types is gravity walls. As the name suggests, mass of the wall is used for resisting the pressure of the soil behind it. Usually, these walls have a height of 3 to 4 feet. These are typically made from masonry units or mortar-less stones. These walls are made from a huge volume of material which is stacked together tightly. The force of friction created by the building material packed tightly is able to resist the pressure of the soil behind the wall.
In this type of retaining wall, the thickness at the base is more than the thickness at the top to keep it stable. The wall tilts backwards as the height increases. Battering is also done for enhancing the life of gravity walls. Since huge quantity of building materials is needed to build a higher gravity wall, these walls are typically used only for short heights as building taller walls gets more cumbersome.
When it comes to creating taller retaining walls, cantilever walls are generally preferred over other designs of retaining walls. As the name suggests, these walls have uniform thickness from top to bottom. These walls are usually tied to a footing for stability and strength. It is important that these walls are designed by a professional to ensure that these are able to hold back the required amount of soil.
One of the most common examples of such retaining walls is the basements in a house. These walls are designed in the form of an inverted T. This design allows the wall to transform the horizontal pressure from soil behind the wall into vertical pressure on the base of the wall.
It is important that the base is made wide enough to prevent it from tipping. Reinforced concreted is usually used in the footing as well as wall structure. These walls should be designed only by structural engineers to ensure that these are constructed in the right manner.
Some of the areas are not well-suited for making gravity or cantilever falls due to lose soils and tight spaces. In these areas, sheet piling retaining walls are typically preferred over other designs. Wood planks, steel or vinyl are typically used to make this type of retaining wall. Almost 2/3 of the wall lies below the ground and a cable is used for tying back the anchor to the wall.
The support rods are usually placed at a distance for better support. However, these walls are vulnerable to hydrostatic pressure. Therefore, proper drainage around the wall needs to be there while constructing the wall to ensure that these walls do not become unstable due to hydrostatic pressure.
Another type of retaining wall is the counterfort retaining wall. These are similar in design to the cantilever walls but with the additional benefit of strength provided by triangular support walls. The top of the wall is connected to the back of the footer with the help of these triangular walls. The additional triangular support walls, retaining wall as well as the footer is made using reinforced concrete.
The triangular support walls provide additional strength to the retaining walls and enhance their durability. These walls should also be designed only by structural engineers to ensure durability.
Another common type of retaining wall usually seen in gardens and various other outdoor landscapes is the concrete retaining walls. These walls are ideal for vertically slanting slopes. These walls are usually high and are built on deeper and heavier soil. The construction is not only strong but also looks much better. A greater base depth is required for these walls to remain stable. Also, these walls are not susceptible to the climate induced degradation that is often the case with some of the other types of walls.
Block retaining walls are usually used for enclosing a space in a garden. There are two types of block retaining walls namely modular and segmental walls. These concrete units come with interlocking feature which is used to resist the pressure created by the soil behind the wall. These work in a manner similar to the gravity walls as gravity is used for resisting the pressure created by the soil behind the wall. Due to use of concrete, these walls also resist hydrostatic pressure.
Rock retaining walls are typically used for leveling flower beds. However, it is important to use stones and rock that match the landscape. The spaces left between the rocks that are stacked together are usually filled with soil mix. These spaces can also be used to grow plants as these help in preventing soil erosion and provide additional strength.