Retaining walls are basically rigid structures which are used to support soil. They can be vertical or with a certain slope. They are shaping the landscape in order to achieve certain engineering purposes. When you drive in a mountainous terrain or even on the highway for sure you will spot some kind of retaining wall on the side of the road. Find out more on this page https://www.constrofacilitator.com/retaining-wall-design-and-its-types-used-on-construction/.
What kind of retaining walls we can encounter?
Generally, there are four types of retaining walls: gravity, piling, cantilever and anchored wall. The sole purpose of a gravity wall is to resist the pressure of the soil with its mass. That’s why they are usually made of stone, concrete and other types of heavy materials. Cantilevered walls are usually like inverted T section and are generally made from reinforced concrete. They have big structural footing in order to convert the horizontal soil pressure in vertical pressure that will be transferred to the ground.
Diaphragm walls are generally rigid and watertight and can be divided into sheet piling and bored piles. Sheet piling can be with different materials such as aluminum, wood and steel. They are generally used for soft soils and are driven approximately one third above ground and two thirds below.
Bored piles are often used for bridges and structures that require deep foundations since they support heavy vertical loads. The use of rods and wires which are driven deep inside the soil is the main principle for anchored retaining walls. Alternative retaining techniques used, are soil nailing, soil-strengthening and mechanical stabilization as a way of artificial reinforcing with geosynthetics. For more information click here.
Steel retaining walls
The most widely used retaining walls are steel sheets. They are mainly used in engineering structures that should be founded in shallow open waters or for construction pits with high groundwater level.
Due to their geometric shape, they can easily penetrate large depths even greater than 10m, and they are well penetrated through both coherent and incoherent soils. There are a number of types of steel sheets that can be divided into two basic groups: the ones who bear in tension or in bending. The first group includes the types: ROMBAS and LACAWANA and the second LARSSEN, HOESCH, KRUPP. You can check out different types of steel retaining walls if you simply do some research online.
Sheet piles can be used for temporary or permanent retaining walls. The biggest advantage is that they are installed in relatively short period. They should be designed generally for bending, since they are putting the weight of the soil “on their shoulders”. Stresses and deflections should always be checked and verified.
Sometimes if the pressure from the soil is too high or the soil is incoherent the steel sheets can be anchored with rods or anchors. If the soil is generally hard, beams and lagging walls can be used. Another good solution for interrupting the failure plane is the use of soil nails walls.
Other types of retaining walls
Wood as a building material can be successfully used for retaining walls. However, its use is limited and depends on the geomechanical composition of the environment in which the foundation is made, the depth, the presence of groundwater and oscillations at its level. If coarse-grained materials are found in the soil, then the penetration of the wooden elements is difficult or impossible.
In the last thirty years with the development of equipment for excavation of soil below the groundwater level, and for the needs of support and protection of construction pits, especially in settlements, cast diaphragms are used.
It is often required to build structures on terrains whose surface layers are composed of soil materials with weak or insufficiently high load-bearing characteristics. In those cases, the foundation of the structure should be done in deeper layers with better load bearing capacity and deformability characteristics.
The foundation in which the loads are transferred to the deeper layers of the soil environment is called deep foundation. This can be done with the help of piles, wells and caissons/cofferdams.
Which way will be applied depends on the geomechanical composition of the terrain, the size and type of the construction, the experience gained for performing deep foundation, and of course the technical and economic optimality for the construction. For the construction of bridges where the foundation should be done in an aqueous environment, steel retaining sheets are used for the cofferdams.