Retaining walls are built after excavation or filling an embankment in order to prevent soil from slowly eroding or collapsing. If the soil were to collapse due to lack of a retaining wall it may put the building at risk. Hence, it is vital to properly construct and maintain retaining walls where necessary.
Types of Retaining Walls
There are many different types of retaining walls and it can depend on the location and soil type as to which one suits the job best. Each type of retaining wall uses different reaction forces to keep the soil retained and it’s important to understand how they work to decide which is the best fit for the project. Some of these include;
A retaining wall that has a thick base and as you may have guessed relies ultimately on gravitational forces from its own weight to keep the soil behind it in place. This type of wall requires a ‘set back’ meaning that it is not perfectly straight but rather has a small incline from bottom to top. The larger the set back the lower the pressure on the retaining wall is and the safer it is considered.
For temporary retaining walls, piling is generally used. A pile is embedded deeply into the soil, using only soil reaction forces to hold it in place and counteract the force pushing it outward from the soil. This allows for work to be completed with minimal soil disturbance to surrounding structures or properties. There are a large variety of different piling types when it comes to retaining walls and each one has their own various uses and it’s important to understand what type is most suitable for the job at hand.
An anchored wall is generally used for high retaining walls. It is constructed by using deep cable rods or wires that are driven sidewards into the soil and filling the ends with concrete to provide the ‘anchor’. These anchors are then attached to the retaining wall and use the forces of the soil against the anchor to remain in place. These types of walls are often used along roadways to keep rocks from falling onto the roads.
The cantilever wall is somewhat similar to the gravity wall, however, for extra safety, it includes a cantilever along the bottom of the wall that is embedded just below the soil that it is holding back. This allows the wall to hold even greater amounts of soil, as it uses the soil itself for an added gravitational force.
Each wall type has their own very specific uses and knowing when to use each one is incredibly important for structural jobs. Along with the type of retaining wall, it is also important to know what type of material to use. If you are planning any landscaping at home or as part of a project, it is strongly suggested to get a professional opinion before attempting to construct one on your own property. Most councils also require an engineering report on retaining walls before they can be legally constructed.