A retaining wall is a structure designed and constructed to resist the lateral pressure of soil when there is a desired change in ground elevation that exceeds the angle of repose of the soil. A basement wall is thus one kind of retaining wall .
A retaining wall is a structure that holds or retains soil behind it. There are many types of materials that can be used to create retaining walls like concrete blocks, poured concrete, treated timbers, rocks or boulders. Some are easy to use, others have a shorter life span, but all can retain soil.
cantilever Retaining Walls :
Cantilever retaining walls are constructed of reinforced concrete. They consist of a relatively thin stem and a base slab. The base is also divided into two parts, the heel and toe. The heel is the part of the base under the backfill. The toe is the other part of the base.
Counterfort Retaining Walls :
Counterfort retaining walls are similar to cantilever walls except they have thin vertical concrete webs at regular intervals along the backside of the wall. These webs are known as counterforts .
The counterforts tie the slab and base together, and the purpose of them is to reduce the shear forces and bending moments imposed on the wall by the soil. A secondary effect is to increase the weight of the wall from the added concrete . Counterfort retaining walls are more economical than cantilever walls for heights above 25 ft .
Gravity Poured Concrete Retaining Walls :
Gravity retaining walls depend on their own weight and any soil resting on the concrete in resisting lateral earth forces.They are generally economical up to 10 feet in height for cast concrete structures.Usually are sufficiently massive to be unreinforced.Monolithic cast walls are generally formed on site .
Semi-Gravity Retaining Walls
A specialized form of gravity walls is a semi-gravity retaining wall. These have some tension reinforcing steel included so as to minimize the thickness of the wall without requiring extensive reinforcement. They are a blend of the gravity wall and the cantilever wall designs..