revetment

1. A facing, as of masonry, used to support an embankment.
2. A barricade against explosives.

A facing or veneer of stone, concrete, or other materials constructed on a sloping embankment, dike, or beach face to protect it against erosion caused by waves or currents. The revetment may be a rigid cast-in-place concrete structure; but more commonly it is a flexible structure constructed of stone riprap or interlocking concrete blocks. It is sometimes an articulated block structure where the armor blocks are set in a form known as a flexible carpet; that is, the blocks interlock for stability, but the interlocking makes them flexible enough to respond to settlement of the underlying soil. A flexible revetment provides protection from exterior hydraulic forces, and it also can tolerate some settlement or consolidation of the underlying soil.

A typical revetment might employ stone riprap as the armor material (see illustration). A revetment typically has three major components: (1) the armor layer, which resists the wave or current-induced hydraulic forces; (2) a filter layer under the armor layer to allow water seepage out of the underlying soil without the removal of fine soil particles; and (3) a mechanism to stabilize the structure toe. Toe stabilization is particularly important where waves break on the structure, but may not be necessary if the revetment extends to sufficient depths where hydraulic forces will not erode the toe of the slope. The design water level (see illus.) for the structure may be higher than the normal water level during nonstorm conditions. If the revetment is exposed to waves that will break and run up the face of the revetment, the upper extent of the revetment must be sufficiently high to counter the force exerted by the waves.

Cross-sectional profile of a typical stone revetment.

Although stone riprap is the most commonly used material for revetment armor layers, a wide variety of other materials have been used, including cast-in-place concrete and poured asphalt, wire bags filled with stone (gabions), interlocking concrete blocks, soil cement, cement-filled bags, interlocked tires, woven wooden mattresses, and vegetation (only used for surfaces exposed to very low waves or slow-moving currents). See also Retaining wall; River engineering.

riˈvetmǝnt n. 1. (especially in fortification) a retaining wall or facing of masonry or other material, supporting or protecting a rampart, wall, etc.

2. a barricade of earth or sandbags set up to provide protection from blast or to prevent planes from overrunning when landing.

See the Introduction, Abbreviations and Pronunciation for further details.

1. Any facing of stone, metal, or wood over a less attractive or less durable substance or construction.
2. A retaining wall or breast wall; a facing on an embankment to prevent erosion.

Rocky revetment at a restoration site along Keene Creek, Duluth, Minnesota. Spring 1994.

Revetments, or revêtements (the original French word, meaning something to re-cloth or re-cover), have a variety of meanings in architecture, engineering and art history. In stream restoration, river engineering or coastal defence, they are sloping structures placed on banks or cliffs in such a way as to absorb the energy of incoming water. In military engineering they are structures, again sloped, formed to secure an area from artillery, bombing, or stored explosives. In architecture they are a variety of structures, normally vertical, used to retain a wall, or sometimes just to decorate it. River or coastal revetments are usually built to preserve the existing uses of the shoreline and to protect the slope, as defense against erosion. For other meanings see below.

Contents 1 Freshwater Revetments 2 Fortifications 3 Architecture and art history 4 External links 4.1 Fortifications 4.2 River and Levee Management 5 References

Freshwater Revetments

Many revetments are used to line the banks of freshwater rivers, lakes, and man-made reservoirs, especially to prevent damage during periods of floods or heavy seasonal rains (see riprap). Many materials may be used: wooden piles, loose-piled boulders^[1] or concrete shapes,^[2] or more solid banks.

Fortifications

World War I: British diagram for the construction of reveted trenches - the revetment here is the part forward of the standing soldier.

World War II: Japanese aircraft sheltered in revetments on Rabaul, 1943

According to the U.S. National Park Service, and referring mostly to their employment in the American Civil War, a revetment is defined as a "retaining wall constructed to support the interior slope of a parapet. Made of logs, wood planks, fence rails, fascines, gabions, hurdles, sods, or stones, the revetment provided additional protection from enemy fire, and, most importantly, kept the interior slope nearly vertical. Stone revetments commonly survive. A few log revetments have been preserved due to high resin pine or cypress and porous sandy soils. After an entrenchment was abandoned, many log or rail revetments were scavenged for other uses, causing the interior slope to slump more quickly. An interior slope will appear more vertical if the parapet eroded with the revetment still in place."^[3]

Architecture and art history

Revetment can be used as a term for a retaining wall, or just for the covering of a wall. In particular the term is used for stone slabs or decorated ceramic plaques used as the outer facing layer of a wall, especially in Ancient Roman architecture. These may or may not have a structural function in the internal construction of the wall, and may be essentially decorative. Marble or terracotta was used, the latter often decorated in moulded reliefs.^[4] Revetment is also a term used for a riza or decorated metal cover for most, typically all but the face and perhaps hands, of an Eastern Orthodox icon.

External links

Fortifications

• Pisa Revetment
• Gabion Revetment

River and Levee Management

• EPA - River Bend Project
• Levee and Revetment Routine Maintenance

References

1. ^ Lake Ontario Riparian Alliance. "Stone Revetments...Frequently Asked Questions."] Accessed 2009-05-25.
2. ^ Concrete shaped revetments
3. ^ U.S. National Park Service. "Military Earthworks Terms". http://www.cr.nps.gov/HPS/hli/currents/earthworks/glossaryQ_Z.htm. Retrieved on 2009-05-25. 
4. ^ Marina De Franceschini. "Hadrian's villa." Accessed 2009-05-25.

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