Retaining Walls

There are generally four main common types of concrete retaining walls:

Gravity retaining walls
Gravity retaining walls are retaining walls that depend on their own weight and also any soil that is resting on the concrete in resisting lateral earth forces. Gravity retaining walls are generally economical up to 10 feet in height for cast concrete structures. Gravity retaining walls are usually sufficiently massive to be unreinforced. These monolithic concrete cast walls are generally formed on site.

Semigravity retaining walls
Ssemi-gravity retaining walls are a specialized form of gravity walls. They have some tension reinforcing steel included so as to therefore minimize the thickness of the wall without requiring extensive reinforcement. Semigravity retainging walls are a blend of the gravity wall and also the cantilever wall designs.

Cantilever retaining walls
Cantilever retaining walls are constructed of reinforced concrete. Cantilever retaining walls consist of a (relatively) thin stem and a base slab. This base is also divided into two parts - the heel and toe. The heel is the part of the base that is located under the backfill. The toe is therefore the other part of the base. Cantilever retaining walls use much less concrete than monolithic gravity walls, however they require more design and careful construction.Cantilever retaining walls are generally economical up to about 25 ft. in height, and they can be precast in a factory or formed on site.

Counterfort retaining walls
Counterfort retaining walls are very similar to cantilever walls exceptfor the fact that they have thin vertical concrete webs at regular intervals along the backside of the wall. These webs are also known as counterforts. In counterfort retaining walls,
the counterforts tie the slab and base together. The purpose of them is to reduce the shear forces and bending moments that are imposed on the wall by the soil. A secondary effect is the increasing of the weight of the wall from the added concrete.
Counterfort retaining walls can be precast or formed on site. Counterfort retaining walls are usually more economical than cantilever walls for heights above 25 ft.