![]() ![]() time, cost and excavation method) and the retained depth required.įor 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). 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.Įmbedded retaining walls can be built using a number of different methods, depending on ground conditions, how watertight the excavation has to be, constructability (i.e. This type of retaining wall is used to form near-surface underground structures, such as basements, car parks and metro stations. Additional support is provided to these retaining structures by internal propping – usually from the base slab, ground slab and any intermediate floor slabs – or by ground anchors installed through the wall. Embedded retaining wallsĮmbedded retaining walls extend 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. However, construction does require space behind the wall, so these retaining walls are not particularly suited to supporting existing slopes, unless temporary support is provided during construction. Foundations sometimes include a ‘key’ in their base, which sticks into the ground to prevent sliding failure.Ī 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. Source: AsmithNJIT at English WikipediaĪdditionally, a T-shaped foundation benefits from the weight of soil (and therefore vertical stress) in front of the wall, providing further stability to the retaining structure. The vertical stress behind the wall is transferred onto the base, preventing toppling due to lateral earth pressure from the same soil mass, allowing cantilever walls to stand unobstructed. This kind of retaining wall wall consists of a stem and a base slab (or footing) which sits under the backfill. Cantilever retaining wallsĬantilever walls are built using reinforced concrete, with an L-shaped, or inverted T-shaped, foundation. Ultimately, this can result in the wall failing to retain soil. As such, this type of retaining wall is easy to build and suitable for retained heights of up to about 3m any higher, however, and these retaining structures tend to take up too much space and can end up being too heavy for the ground below, leading to bearing capacity failure. Gravity retaining walls are typically wider at their base, with sloped faces, enabling them to resist the higher lateral earth pressures at depth. 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. ![]() Ground Coffee Ask Andrew Episode 2: Andrew Lees explores the different types of retaining wall available to engineers. Use the links above to jump to the retaining wall types you’re most interested in learning about. The four main types of retaining wall are: This time around, we’re going to give a detailed overview of the main types of retaining walls available and give an insight to how they work, as well as their benefits and limitations. In our in-depth introduction to retaining walls, we also took a look at what purposes retaining structures achieve, how they work and how they are designed. In our last blog we looked at the basics of retaining walls, and established that they are vertical, or near-vertical structures designed specifically to retain soil, and create level areas for maximising development space and reducing sloping on sites. 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. ![]()
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