TYPES OF RETAINING WALLS

 Types of Retaining Structures

There are many types of retaining structures for soil and other materials, but listed below are the types of retaining walls used today. Most of these will be discussed in later chapters.

Cantilevered retaining walls

These are the most common type of retaining walls. Cantilevered walls are classified as "yielding" because they are free to rotate without any lateral restraint. Cantilevered retaining walls are generally of masonry or concrete, or both, but can also take other forms as will be described..

Types of cantilevered retaining walls include:

Masonry or concrete walls

Masonry stems are usually either 8" or 12" concrete block masonry units, partially or solid grouted, and reinforced. Higher walls require 12" blocks and are often stepped back to 8" thick as the retained height diminishes.

The stems of a concrete wall must be formed, and can be tapered for economy, usually with the taper on the inside (earth side) to present a vertical exposed face.

Hybrid walls, with both concrete and masonry, can also be constructed using formed concrete at the base, where higher strength is required, then changing to masonry higher up the wall.

A variation for masonry cantilever walls uses spaced vertical pilasters (usually of square masonry units) and with infilled walls of lesser thickness, usually 6" masonry. The pilasters cantilever up from the footing and are usually spaced from four to eight feet on center. These walls are usually used where lower walls are needed under about six feet high.

Counterfort retaining walls

Counterfort cantilevered retaining walls incorporates wing walls projecting from the heel into the stem. The stem between counterforts is thinner and spans horizontally between the counterfort (wing) walls. The counterforts act as cantilevered elements and are structurally efficient because the counterforts are tapered down to a wider (deeper) base where moments are higher. The high cost of forming the counterforts and infill stem walls make such walls usually not practical for walls less than about 16 feet high. See

Buttress retaining walls

These are similar to counterfort walls, but the wings project from the outside face of the wall. Such walls are generally used in those cases where property line limitations on the interior face provide limited space for the heel of a traditional cantilvered retaining wall.

Gravity retaining walls

This type of wall depends upon dead load mass of the wall for stability rather than

cantilevering from a foundation.tacked and mortar-bonded stone, rubble, or rock walls

These are usually relegated to landscaping features and retaining less than about four feet

high. Engineering for these walls is limited, or none at all, and rules-of-thumb prevail (such

as a retained height not more than two or three times the base width). Higher walls need

engineering to evaluate global stability, overturning, sliding, and to verify that little or no flexural tension exists within the wall because these are generally unreinforced