What are the different types of retaining wall?

by Andrew Lees, on 21-Jan-2021 05:13:02

Retaining walls come in all types, shapes and sizes – from simple gravity walls to bored pile walls for basements and reinforced soil walls using geogrids – to suit a wide range of project needs, and site conditions.

In my last blog I looked at the basics of retaining walls, what they do, how they work and how they are designed. This time around, I’m going to give a brief overview of the main types of retaining walls available and give an insight to how they work, as well as their benefits and limitations.

The four main types of retaining wall are:

Use the links above to jump to the retaining wall types you’re most interested in learning about.

Ground Coffee Ask Andrew Episode 2:  Andrew Lees explores the different types of retaining wall available to engineers.

Gravity retaining walls

Gravity retaining walls use the gravitational force of their own weight to resist the lateral earth pressure from the soil behind them, which prevents toppling and sliding.  They are the simplest and earliest recorded type of retaining wall, and are usually built of masonry, brick, concrete blocks or mass cast-in-situ concrete.


Types of retaining walls
AsmithNJIT at English Wikipedia

Gravity retaining walls are typically wider at their base, with sloped faces, enabling them to resist the higher lateral earth pressures at depth. This means that, while they are easy to build and suitable for retained heights of up to about 3m, any higher and they tend to take up too much space and can end up being too heavy for the ground below, leading to bearing capacity failure. This can result in the wall failing to retain soil.

Cantilever retaining walls

Cantilever walls are built using reinforced concrete, with an L-shaped, or inverted T-shaped, foundation. The vertical stress behind the wall is transferred onto the foundation, preventing toppling due to lateral earth pressure from the same soil mass.
Source: AsmithNJIT at English Wikipedia

cantilver wall

Additionally, a T-shaped foundation benefits from the weight of soil (and therefore vertical stress) in front of the wall, providing further stability. Foundations sometimes include a ‘key’ in their base, which sticks into the ground to prevent sliding failure.

A big advantage of cantilever walls compared to other retaining wall types is that they take up little space once built, and are suitable for retained heights of up to 5m. However, construction does require space behind the wall, so they are not particularly suited to retaining existing slopes, unless temporary support is provided during construction.

Embedded retaining walls

Embedded retaining walls are used to form near-surface underground structures, such as basements, car parks and metro stations. Walls can be huge – those for Westminster Underground Station on the Jubilee Line in London, next to the Houses of Parliament, are 40m deep, for example.

This type of retaining wall is built using a number of different methods, depending on ground conditions, how watertight the excavation has to be, constructability (i.e. time, cost and excavation method) and the retained depth required.

SpundwandExample of an embedded retaining wall 
Störfix at English Wikipedia

For deep excavations, methods include diaphragm walls and panels, as well as bored concrete piles, where piles are either interlocking (secant) or installed next to one another (contiguous). For shallow and temporary excavations, sheet piles and king post walls are commonly used, as shown in the image above.

Embedded retaining walls act like cantilever walls, extending deeper than the excavation to take advantage of passive earth pressure of the ground below to, at least partly, counteract the active earth pressure being exerted on the wall above. Additional support is provided by internal propping – usually from the base slab, ground slab and any intermediate floor slabs – or by ground anchors installed through the wall.

Reinforced soil, or mechanically stabilised earth, retaining walls

Last, but not least, there are reinforced soil walls, sometimes referred to as mechanically stabilised earth walls. This retaining wall type uses layers of geogrid to reinforce the soil, increasing its bearing capacity and increasing resistance to differential settlement. I’ve discussed these walls in more detail in our "what is a reinforced soil wall?" blog.

Main Image (1)

Tensar's wall and slope systems

TensarTech reinforced soil wall and slope systems include precast concrete, dry-laid modular block systems (with the option of adding architectural, masonry or brick finishes); precast concrete panels; gabion and crib walls; and robust units suitable for aggressive marine environments. Our reinforced soil slope solutions can create vegetated slopes with angles of up to 70˚.

Want to learn more about retaining walls?

Learn more in our introduction to retaining walls

Topics:Walls & Slopes