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Sandbag
A sandbag or dirtbag is a bag or sack made of Hessian (cloth), hessian (burlap), polypropylene or other sturdy materials that is filled with sand or soil and used for such purposes as flood control, military fortification in trenches and bunkers, shielding glass windows in war zones, buoyancy compensator (aviation), ballast, counterweight, and in other applications requiring mobile fortification, such as adding improvised additional protection to armored vehicles or tanks. The advantages are that the bags and sand are inexpensive. When empty, the bags are compact and lightweight for easy storage and transportation. They can be brought to a site empty and filled with local sand or soil. Disadvantages are that filling bags is labor-intensive. Without proper training, sandbag walls can be constructed improperly causing them to fail at a lower height than expected, when used in flood-control purposes. They can degrade prematurely in the sun and elements once deployed. They can also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hessian (cloth)
Hessian (, ), burlap in North America, or crocus in Jamaica and the wider Caribbean, is a woven fabric made of vegetable fibres, usually the skin of the jute plant or sisal leaves. It is generally used (in the crude tow form known as gunny) for duties of rough handling, such as making sacks employed to ship farm products and to act as covers for sandbags (although woven plastics now often serve these purposes), and for wrapping tree- root balls. However, this dense woven fabric, historically coarse, more recently is being produced in a refined state, known simply as ''jute'', as an eco-friendly material for bags, rugs, and other products. The name "hessian" is attributed to the historic use of the fabric as part of the uniform of soldiers from the former Landgraviate of Hesse (1264–1567) and its successors, who were called '' Hessians''. Hessian cloth comes in different types of construction, form, size and color. The origin of the word ''burlap'' is uncertain, though ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flood Control
Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and runoff. Flood management methods can be either of the ''structural'' type (i.e. flood control) and of the ''non-structural'' type. Structural methods hold back floodwaters physically, while non-structural methods do not. Building hard infrastructure to prevent flooding, such as flood walls, is effective at managing flooding. However, it is best practice within landscape engineering to rely more on soft infrastructure and Nature-based solutions, natural systems, such as marshes and Floodplain, flood plains, for handling the increase in water. Flood management can include ''flood risk management,'' which focuses on measures to reduce risk, vulnerability and exposure to flood disasters and providing risk analysis through, for example, flood ris ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siege Of Ninety-Six
The siege of Ninety Six was a siege in western South Carolina late in the American Revolutionary War. From May 22 to June 18, 1781, Continental Army Major General Nathanael Greene led 1,000 troops in a siege against the 550 Loyalists in the fortified village of Ninety Six, South Carolina. The 28-day siege centered on an earthen fortification known as Star Fort. Despite having more troops, Greene was unsuccessful in taking the town, and was forced to lift the siege when Lord Rawdon approached from Charleston with British troops. The area is now protected as Ninety Six National Historic Site and was designated a National Historic Landmark. Many of the surviving Loyalists were later relocated by the Crown and granted land in Nova Scotia, where they named their township Rawdon to commemorate their rescuer. Background The British Army's "southern strategy" for winning the American Revolutionary War, which had been successful in taking Charleston and winning submission of much of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand Boil
Sand boils, sand volcanoes, or sand blows occur when water under pressure wells up through a bed of sand. The water looks like it is boiling up from the bed of sand, hence the name. Sand volcano A sand volcano or sand blow is a cone of sand formed by the ejection of sand onto a surface from a central point. The sand builds up as a cone with slopes at the sand's angle of repose. A crater is commonly seen at the summit. The cone looks like a small volcanic cone and can range in size from millimetres to metres in diameter. The process is often associated with soil liquefaction and the ejection of fluidized sand that can occur in water-saturated sediments during an earthquake. The New Madrid seismic zone exhibited many such features during the 1811–1812 New Madrid earthquakes. Adjacent sand blows aligned in a row along a linear fracture within fine-grained surface sediments are just as common, and can still be seen in the New Madrid area. These earthquakes also caused the la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fortification
A fortification (also called a fort, fortress, fastness, or stronghold) is a military construction designed for the defense of territories in warfare, and is used to establish rule in a region during peacetime. The term is derived from Latin ("strong") and ("to make"). From very early history to modern times, defensive walls have often been necessary for cities to survive in an ever-changing world of invasion and conquest. Some settlements in the Indus Valley Civilization were the first small cities to be fortified. In ancient Greece, large cyclopean stone walls fitted without mortar had been built in Mycenaean Greece, such as the ancient site of Mycenae. A Greek ''Towns of ancient Greece#Military settlements, phrourion'' was a fortified collection of buildings used as a military garrison, and is the equivalent of the ancient Roman, Roman castellum or fortress. These constructions mainly served the purpose of a watch tower, to guard certain roads, passes, and borders. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Revetment
A revetment in stream restoration, river engineering or coastal engineering is a facing of impact-resistant material (such as stone, concrete, sandbags, or wooden piles) applied to a bank or wall in order to absorb the energy of incoming water and protect it from erosion. River or coastal revetments are usually built to preserve the existing uses of the shoreline and to protect the slope. In architecture generally, it means a retaining wall. In military engineering it is a structure formed to secure an area from artillery, bombing, or stored explosives. 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 or concrete shapes, or more solid banks. Concrete revetments are the most common type of infrastructure used to control the Mississippi River. More than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Levee
A levee ( or ), dike (American English), dyke (British English; see American and British English spelling differences#Miscellaneous spelling differences, spelling differences), embankment, floodbank, or stop bank is an elevated ridge, natural or artificial, alongside the river banks, banks of a river, often intended to flood control, protect against flooding of the area adjoining the river. It is usually soil, earthen and often runs parallel (geometry), parallel to the course of a river in its floodplain or along low-lying coastlines. Naturally occurring levees form on river floodplains following flooding. Sediment and alluvium are deposition (geology), deposited on the banks and settle, forming a ridge that increases the river channel's capacity. Alternatively, levees can be artificially constructed from fill dirt, fill, designed to regulate water levels. In some circumstances, artificial levees can be environmental degradation, environmentally damaging. Ancient civilization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flood
A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant concern in agriculture, civil engineering and public health. Environmental issues, Human changes to the environment often increase the intensity and frequency of flooding. Examples for human changes are land use changes such as deforestation and Wetland conservation, removal of wetlands, changes in waterway course or flood controls such as with levees. Global environmental issues also influence causes of floods, namely climate change which causes an Effects of climate change on the water cycle, intensification of the water cycle and sea level rise. For example, climate change makes Extreme weather, extreme weather events more frequent and stronger. This leads to more intense floods and increased flood risk. Natural types of floods include riv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berm
A berm is a level space, shelf, or raised barrier (usually made of Soil compaction, compacted soil) separating areas in a vertical way, especially partway up a long slope. It can serve as a terrace road, track, path, a fortification line, a border wall, border/separation barrier for navigation, good drainage, industry, or other purposes. Etymology The word is from Middle Dutch and came into usage in English via French. Military use History In medieval military engineering, a berm (or berme) was a level space between a parapet or defensive wall and an adjacent steep-walled ditch (fortification), ditch or moat. It was intended to reduce soil pressure on the walls of the excavated part to prevent its collapse. It also meant that debris dislodged from fortifications would not fall into (and fill) a ditch or moat. In the trench warfare of World War I, the name was applied to a similar feature at the lip of a trench, which served mainly as an elbow-rest for riflemen. Modern u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy Compensator (aviation)
The static buoyancy of airships in flight is not constant. It is therefore necessary to control the altitude of an airship by controlling its buoyancy: buoyancy compensation. Changes which have an effect on buoyancy * Changes in air temperature (and thus the density of air) * Changes in lifting gas temperature (for example, the heating of the hull by the sun). * Accumulation of additional ballast (for example, precipitation or icing on the envelope) * Changes in ballast (for example, during a flight maneuver or the dropping of ballast) * Changes in weight of fuel on board, due to fuel consumption. This was a challenge especially in the large historic airships like the Zeppelins. For example, on a flight from Friedrichshafen to Lakehurst, the rigid airship USS Los Angeles (ZR-3), LZ 126, built in 1923-24, used 23,000 kg gasoline and 1300 kg of oil (an average consumption of 290 kg/100 km). During the landing the airship had to release approximately 24,000 cubi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barricade
Barricade (from the French ''barrique'' - 'barrel') is any object or structure that creates a barrier or obstacle to control, block passage or force the flow of traffic in the desired direction. Adopted as a military term, a barricade denotes any improvised field fortification, such as on city streets during urban warfare. Barricades also include temporary traffic barricades designed with the goal of dissuading passage into a protected or risk, hazardous area or large slabs of cement whose goal is to prevent forcible passage by a vehicle. Stripes on barricades and panel devices slope downward in the direction traffic must travel. There are also pedestrian barricades - sometimes called bike rack barricades for their resemblance to a now obsolete form of bicycle stand, or police barriers. They originated in France approximately 50 years ago and are now used around the world. They were first used in the U.S. 40 years ago by Friedrichs Mfg for New Orleans's Mardi Gras parades. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portland Cement
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar (masonry), mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin, and is usually made from limestone. It is a fine powder (substance), powder, produced by heating limestone and clay minerals in a kiln to form Clinker (cement), clinker, and then #Cement grinding, grinding the clinker with the addition of several percent (often around 5%) gypsum. Several types of portland cement are available. The most common, historically called ordinary portland cement (OPC), is grey, but white portland cement is also available. The cement was so named by Joseph Aspdin, who obtained a patent for it in 1824, because, once hardened, it resembled the fine, pale limestone known as Portland stone, quarried from the windswept cliffs of the Isle of Portland in Dorset. Portland stone was p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
