In some cases, it is necessary to reinforce a steep slope with a ground retaining structure. When is reinforcement of a slope necessary? And what options are available?
What is the function of a slope?
First we look at what is actually the function of a slope in a structure. A sloping surface, also called an embankment, is found for example along a road, railroad, dike or waterway. Also at the transition to a bridge or tunnel you often see a slope. So it is constructed for various construction applications.
A slope lifts level differences between two adjacent plots, near a bank or between a building and ground level. The slope therefore has a ground retaining or water retaining function and protects the adjacent property or structure from the environment.
When should you reinforce a slope?
Every type of soil has a natural slope angle at which the soil will not shift. The size of this angle depends on the type of soil and the application.
Sometimes there is not enough space to create a large sloping surface with a smaller slope angle, for example in infrastructural applications within built-up areas. It may also be that there is less building space to save costs. In these cases, a steeper slope is used.
A steep slope often needs to be reinforced with a soil retaining structure, otherwise there is a risk that the soil will shift. Also, a steeper slope puts more pressure on the ground, because the weight of the slope rests on a smaller area. This is particularly a risk in areas with sandy soils and where rainfall is frequent, which can make the soil more unstable.
Additional reinforcement prevents shifting or washing away of the soil. It also prevents subsidence of the ground because the pressure of the slope is distributed over a larger area. In addition, ground slopes can become unstable when, for example, road works are taking place. Even then, additional reinforcement may be needed.
What options are there for reinforcing a slope?
You can strengthen a slope in several ways. One common measure is to install planting or ground covers. Plants that are firmly rooted in the ground prevent soil leaching (soil erosion). It also immediately gives a nice green look.
But there are also disadvantages to this. The limited accessibility on a slope makes maintenance difficult. Also, for steeper slopes greater than 45°, planting does not provide enough reinforcement.
Another solution to improve the stability of a sloped slope are nets or mats. These ground covers prevent erosion on slopes and protect, for example, banks from soil leaching. Anti-erosion mats are mainly suitable for granular soil types on which plants find it difficult to take root, and for slopes with a smaller gradient.
In addition, a wooden sheet pile wall can be used as an earth retaining structure for a steeper slope. This solution takes up little space. However, it is only suitable for lower slopes, because the soil pressure against the sheet piling would otherwise be too great.
Finally, for steep and high slopes, retaining walls made of concrete are the most ideal solution. The material has a long life and is easy to install. The higher the height difference becomes, the more pressure the underlying soil exerts on the wall. This must be taken into account in the construction strength.