A retaining wall is a structure used for binding soil between two different heights and is therefore susceptible to lateral pressure from the held soil and other surcharges.  A variety of materials can be used in the construction of a retaining wall. The most popular materials however are poured concrete, treated timbers, concrete blocks and rocks.

The Planning Process

There are three main considerations that must be made when selecting a material for use in retaining wall structure. These are:

• The type of soil in the construction location
• The proposed height of the wall
• The structures that will be on top of the wall.

Retaining walls face pressure from the retained backfill and the top mass. Retaining wall calculation examples therefore put into consideration factors such as the seismic zones where the wall is built, the wind load for retaining walls with stems extending above the backfill and also surcharges such as different strip loads.

If you are building a retaining wall, that’s more than 3 to 4 feet, it is necessary to use a synthetic mesh material such as geogrid to enhance the strength of the wall and ensure stability. Geogrids also come in different types and sizes and your choice should, therefore, depend on your particular circumstance.

Ensuring Stability of a Retaining Wall

Typically, you should perform sliding, base bearing pressure and overturning checks to certain the stability of your retaining walls. In most Retaining wall calculation examples, the overturning and sliding stability checks are the ones popularly examined. In these examples, it’s always assumed that there is a friction coefficient between the concrete and soil and the no-surcharge load or water table is considered in the calculation. However, this is mostly just to make the calculation easy, and so should be an actual factor for consideration in the main project.

The weight of the retaining wall structure is mostly not also considered in retaining wall calculation examples although this should be ordinarily factored in if all the potential pressures are to be evaluated.

Checking For Sliding Failure

In addition to the trapezoidal seismic pressure, there is also a bearing pressure expected to act from underneath the wall, a horizontal pressure that may push the wall outwards and passive reassure that will act on the wall from the front.

During construction, the natural soil is bound to be disturbed. Because of this, a common practice during the calculation of the sliding factor is ignoring the top portion. If the passive forces are determined to be extremely high is a manner likely to counteract the pushing force, it is recommended to build a sheer key beneath the wall footing.

This is the most efficient way of increasing the sliding resistance when erecting a retaining wall. Although the position of the key on the footing is not a critical matter for consideration, a lot of engineers prefer building it under the stem and afterward building wall rebars down it.

It’s important to always design and plan the layout of the retaining wall before starting out on the project. Do the math regarding the length and height of the wall, the quality and quantity of materials to be used, and also consider the other nearby factors that may disturb the stability of the wall.