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Want to know about the different types of retaining walls there are? Your search ends here! We’re going to take a thorough look at what retaining walls are, their several types, and their features. Depending on the type of walls being built, it’ll become easier for you to understand which retaining wall is the best option in a situation after you’ve read through the article. Without wasting any more time, let’s straight jump to our matter of today, shall we?
What is a Retaining Wall?
Retaining walls are exactly what their name suggests them to be: they retain. Retain what, you ask? Depending on the situation, it can be used to retain soil or water, or both. How? It’s built and created in a way that withstands the pressure on the two sides, retaining the soil or water levels on both sides.
These are walls used to keep the soil at an incline that it otherwise wouldn’t remain in. When constructing specific structures such as an overpass or a farm. In these situations, the land should be designed in a specific way for the structure to work, and retaining walls keep the soil stable in that particular configuration.
13 Types of Retaining Walls
Let’s come to our primary topic for today and look at the different types of retaining walls and their features. We’ll also briefly look at their advantages and disadvantages and how they work toward retaining the soil.
1. Anchored Retaining Walls
These are the types of retaining walls that can be created using different styles such as gravity walls or gabion walls (which we’ll look into, in just a moment). But what separates these walls from the other types is the additional anchors that are used to provide extra support to the wall.
These anchors can be cable rods or wires that are inserted deep into the earth for maximum strength. Why the need for these anchors, you may ask? Well, sometimes the space allowed for retaining walls isn’t optimal, in which case some extra support should be provided to make up for the lack of weight and space that the retaining wall might have.
2. Cantilever Retaining Walls
These are walls with a foundation shaped like an L or a T to handle all the lateral pressure of the wall. The foundation or stem of the wall is made of concrete reinforced with steel for a larger tensile strength. These are the most common type of retaining walls, mostly for their ability to handle larger amounts of pressure, and because they’re ideal for heights up to 10m.
While an L-shaped foundation provides sufficient resistance to any stress, having it T-shaped provides further stability and prevents toppling altogether. One of the biggest advantages of these walls is that they take up minimal space after they’re complete.
3. Gravity-Retaining Walls
These are the simplest types of retaining walls out there, as they don’t employ any complex structures or methodologies to handle the lateral pressure of soil. These walls use their self-mass to withstand the pressure exerted by the earth. Naturally, they have to be built using heavy materials like stone or concrete, and they often require to be large.
These are all to ensure the walls have sufficient weight to handle the pressure. Up to small heights of 3m, these walls can be opted for. Generally, they have a trapezoid shape, with a thicker base to handle the higher pressure in the lower ranges, and a surface that is sloping in nature for better support.
4. Gabion Retaining Walls
These are a type of gravity retaining walls that use wire mesh boxes filled with rocks or other heavy materials to retain the surfaces on both sides. These are used for heights up to 3 to 4m and the wire boxes filled with stones are stacked on top of and adjacent to each other.
These walls are employed in situations where water is allowed to pass by, while retaining the soil level, thus effectively preventing erosion.
5. Crib Retaining Walls
Another type of gravity retaining walls, crib walls use interlocked boxes or cage-like structures to support areas with plantations. These interlocked boxes are made using concrete or timber while they’re filled with fine materials like crushed stone.
This material serves to create a draining layer that allows the water to pass through while retaining the soil on the other side. This, then, makes it ideal for farms built at lower heights.
6. Concrete Cantilever Retaining Walls
A type of cantilevered walls, these types of retaining walls use concrete to create a stable retaining wall that can hold back a large quantity of soil. Because of the pressure that’s generally exerted on them, they must be well-engineered when it comes to the angles and slopes of the foundation and the wall.
The slab foundation, on which the cantilevered wall is built, is often supported by a backfill that supports the weight of the wall and the lateral pressure exerted by the soil. The additional support also prevents any sliding or toppling.
7. Mechanically Stabilized Earth (MSE) Retaining Walls
Also called reinforced soil retaining walls, this type can withstand some amount of differential movement. These types of retaining walls are easy to construct as they don’t require any molding during construction. This also makes them economical and one of the most commonly used walls for retention.
Using plastic meshes or metallic strips as pillars to hold together the infillings of granular soil, these walls increase their holding capacity and exert a higher resistance to any movement. This is because of the interlocked grids that together achieve higher tensile strength.
8. Sheet Piled Retaining Walls
Literally speaking, piling means driving something through the ground to a certain depth. And that’s what these walls do too: they are driven down a certain depth that is enough to handle the lateral pressure applied from one or both sides. Since these involve using steel sheets that are driven down the ground, these are termed sheet-piled retaining walls.
They are often used in slopy terrains or excavation sites where a retaining wall of up to 6 meters in length is required. However, they don’t have high-pressure handling capabilities, which is why their variations are often used. Let’s talk about those variations now.
9. Secant and Tangent Piled Retaining Walls
These pile retaining walls offer more resistance to lateral soil pressure than sheet-piled retaining walls. The tangent walls have piles that do not intersect with each other, and only each other’s surfaces. Since there’s no overlap, they are sometimes tied down and/or reinforced with steel shafts or cages.
The secant walls, on the other hand, use reinforced concrete piles that intersect with each other. Here, a secondary layer of piles is built between the primary piles to provide a better holding capacity.
10. Embedded Retaining Walls
These retaining walls are handy when building underground structures, say, a parking lot or a basement. These walls use the resistance force offered by the ground to their advantage in differing amounts.
But how do they achieve that? Simply put, they extend deeper than the excavation site via a cantilever mechanism and use the earth’s pressure to balance out the pressure from the soil layers overhead. Sometimes, further anchoring is used to add internal support to the wall.
11. Counter-fort or Buttressed Retaining Walls
This type is required for walls of longer heights. As the height of the wall increases, so does the pressure that is being applied by the soil or water around it. To tackle all that, certain structures called counterforts are added. These counterforts, while taking up space, add more tensile strength-bearing capabilities to the wall, allowing it to withstand higher pressure.
These counterforts are triangular-shaped beams that are built alongside the wall and spaced at a length equal to half the height of the wall. Therefore, these beams prevent any bending or toppling of the walls and keep them stable.
12. Soil Nailed Retaining Walls
To hold unsupported soil up to 1 to 2m in height, nailing is performed quite often. It’s done by installing steel bars or nails to provide direct support to the soil slopes. This is a form of passive reinforcement wherein less space and construction material are required which provides a cost-effective solution.
These walls take less time as well, fulfilling both temporary and relatively more permanent requirements. However, these types of retaining walls are not suited in situations where water is in proximity or in regular contact with the wall, as there are high chances of corrosion.
13. Hybrid Systems
These types of walls are called hybrid systems because they take two mechanisms for stability, i.e. gravity and reinforcing, and combine them in one. Here, the lower part is comprised of soil-nailed retaining walls whereas the upper part has a mechanically stabilized wall.
The flexible design allows for quick installation and is a more cost-effective option. It can also be used for several earth configurations.
Retaining walls are often used to prevent erosion, retain soil levels on either or both sides, and several other functions. Keep in mind that the allowed height and space, surface type, and other factors are crucial in determining the types of retaining walls you’ll choose.