Gabions (from Italian gabbione meaning "big cage"; from Italian gabbia and Latin cavea meaning "cage") are cages, cylinders, or boxes filled with soil or sand that are used in civil engineering, road building, and military application. For erosion control caged riprap is used. For dams or foundation construction, cylindrical metal structures are used. In a military context, earth or sand-filled gabions are used to protect artillery crews.
Civil engineering: The most common civil engineering use is to stabilize shore against erosion. Other uses include retaining walls, temporary floodwalls, to filter silt from runoff, for small or temporary/permanent dams, river training, channel lining. They may be used to direct the force of a flow of flood water around a vulnerable structure. Gabions are also used as fish barriers on small streams. Gabion baskets have some advantages over loose riprap because of their modularity and ability to be stacked in various shapes. They also have advantages over more rigid structures because they can conform to ground movement, dissipate energy from flowing water and drain freely. Their strength and effectiveness may increase with time in some cases, as silt and vegetation fill the interstitial voids and reinforce the structure. They are sometimes used to keep stones which may fall from a cutting or cliff from endangering traffic on a thoroughfare.
Gabions have also been used in building, as in the Dominus Winery in Napa Valley, California. The exterior is formed by modular wire mesh gabions containing locally quarried stone; this construction creates an environment of moderate temperatures within the building.
Military use: In the medieval era, gabions were round cages with open tops and bottoms, made from wickerwork and filled with earth for use as military fortifications. These early military gabions were used to protect field artillery gunners. The wickerwork cylinders were light and could be carried relatively conveniently in the ammunition train, particularly if they were made in several diameters to fit one in another. At the site of use in the field, they could be stood on end, staked in position, and filled with soil to form an effective wall around the gun. Today, gabions are often used to protect forward operating bases.