Designing Concrete Retaining Walls Designing Concrete Retaining Walls

Concrete retaining walls are constructed to help hold back soil to prevent it from falling down a slope. These walls are commonly built on mountainous areas or in terrains that are prone to landslides. The retaining walls can be designed for maximum holding strength while blending with the surroundings aesthetically.

Structural Design

Concrete retaining walls should be designed to retain the lateral pressure from the soil efficiently. To do so, it is important to take note of local building codes because these codes contain valuable information regarding building standards and limitations. For example, many states require that the walls be at least 1 foot high and structurally designed by a professional engineer.

To determine the lateral pressure exerted by the soil behind the wall, it is important to get information on soil properties. There are online databases that provide this information. This is helpful in getting the approximate weight of the wall and the pressure it exerts laterally towards the wall. With this information, the wall can be designed effectively to resist any of these pressures.

Some experts agree that keeping the wall below 3 feet high can structurally make it stronger. In addition, the wall should lean back a bit to ensure it does not easily tip over. A 90 degree vertical retaining wall can easily tip over if the soil and water exert too much pressure on it.

Drainage

The lateral pressure coming from the soil itself is only a small portion of the pressure held by the wall. The topmost soil on the wall exerts the least pressure while the lowermost portion exerts the greatest pressure. However, it is the water that seeps through the soil that causes the heaviest pressure that can overturn or crack the wall if the drainage system is not designed properly.

If the groundwater behind the wall does not have a way to dissipate through a drainage system, it adds to the horizontal hydrostatic pressure and can cause the wall to tip over. Designing an efficient drainage system at the back of the wall can improve its stability.

Wall Materials

The walls can be constructed using various materials such as concrete blocks, poured concrete or even wood. While wood can provide a nice looking wooden wall, it is not recommended in areas that are frequently wet. A wooden wall can be used in home gardens and landscape designs but not in very critical areas. Concrete blocks or poured concrete are best to use because they provide better stability and strength. If the walls need to be higher than 4 feet, they have to be built with an engineered solution, such as the addition of steel bars in the construction.

The Foundation

Concrete retaining walls should be built on top of firm foundations; however, not on the top soil. The wall should be buried at least 12 inches below the ground to provide added strength and durability. If the foundation is not strong enough to hold the soil efficiently, find a certain location that has a firm foundation. Take note of this when preparing the design.

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