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A trench is a type of
excavation Excavation may refer to: * Excavation (archaeology) * Excavation (medicine) * ''Excavation'' (The Haxan Cloak album), 2013 * ''Excavation'' (Ben Monder album), 2000 * ''Excavation'' (novel), a 2000 novel by James Rollins * '' Excavation: A Mem ...
or in the ground that is generally deeper than it is wide (as opposed to a wider
gully A gully is a landform created by running water, mass movement, or commonly a combination of both eroding sharply into soil or other relatively erodible material, typically on a hillside or in river floodplains or terraces. Gullies resemble lar ...
, or
ditch A ditch is a small to moderate divot created to channel water. A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for plant irrigation. Ditches ar ...
), and narrow compared with its length (as opposed to a simple hole or pit). In
geology Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...
, trenches result from
erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...
by rivers or by geological movement of
tectonic plates Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...
. In
civil engineering Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports, sewa ...
, trenches are often created to install underground
utilities A public utility company (usually just utility) is an organization that maintains the infrastructure for a public service (often also providing a service using that infrastructure). Public utilities are subject to forms of public control and ...
such as gas,
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
, power and
communication Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inqui ...
lines. In
construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and ...
, trenches are dug for foundations of buildings, retaining walls and dams, and for cut-and-cover construction of tunnels. In
archaeology Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landsc ...
, the "trench method" is used for searching and excavating ancient
ruin Ruins () are the remains of a civilization's architecture. The term refers to formerly intact structures that have fallen into a state of partial or total disrepair over time due to a variety of factors, such as lack of maintenance, deliberate ...
s or to dig into
strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as e ...
of sedimented material. In
geotechnical engineering Geotechnical engineering is the branch of civil engineering concerned with the engineering behavior of earth materials. It uses the principles of soil mechanics and rock mechanics for the solution of its respective engineering problems. It ...
, trenches serve for locating faults and investigating deep soil properties. In
trench warfare Trench warfare is a type of land warfare using occupied lines largely comprising Trench#Military engineering, military trenches, in which troops are well-protected from the enemy's small arms fire and are substantially sheltered from artille ...
, soldiers occupy trenches to protect them against weapons fire. Trenches are dug by use of manual tools such as shovels and pickaxes, or by heavy equipment such as
backhoe A backhoe—also called rear actor or back actor—is a type of excavating equipment, or digger, consisting of a digging bucket on the end of a two-part articulated arm. It is typically mounted on the back of a tractor or front loader, the latt ...
s, trenchers and
excavator Excavators are heavy construction equipment consisting of a boom, dipper (or stick), bucket and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels. They are a natural progression fr ...
s. For deep trenches, the instability of steep earthen walls requires engineering and safety techniques such as
shoring Shoring is the process of temporarily supporting a building, vessel, structure, or trench with shores (props) when in danger of collapse or during repairs or alterations. ''Shoring'' comes from ''shore'', a timber or metal prop. Shoring may be verti ...
. Trenches are usually considered temporary structures to be backfilled with soil after construction, or abandoned after use. Some trenches are stabilized using durable materials such as
concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
to create open passages such as
canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface f ...
s and sunken roadways.


Geology

Some trenches are created as a result of
erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...
by running water or by
glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such a ...
s (which may have long since disappeared). Others, such as
rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear d ...
s or
oceanic trench Oceanic trenches are prominent long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic tren ...
es, are created by geological movement of
tectonic plates Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...
. Some oceanic trenches include the
Mariana Trench The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maximum known ...
and the
Aleutian Trench The Aleutian Trench (or Aleutian Trough) is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for from a triple junction in the west with the Ulak ...
. The former geoform is relatively deep (approximately ), linear and narrow, and is formed by plate subduction when plates converge.


Civil engineering

In the
civil engineering Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports, sewa ...
fields of construction and maintenance of infrastructure, trenches play a major role. They are used for installation of underground infrastructure or utilities (such as gas mains, water mains,
communication Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inqui ...
lines and pipelines) that would be obstructive or easily damaged if placed above ground. Trenches are needed later for access to these installations for service. They may be created to search for pipes and other infrastructure whose exact location is no longer known ("search trench" or "search slit"). Finally, trenches may be created as the first step of creating a foundation wall. Trench shoring is often used in trenchworks to protect workers and stabilise the steep walls. An alternative to digging trenches is to create a utility tunnel. Such a tunnel may be dug by boring or by using a trench for cut-and-cover construction. The advantages of utility tunnels are the reduction of maintenance manholes, one-time relocation, and less excavation and repair, compared with separate cable ducts for each service. When they are well mapped, they also allow rapid access to all utilities without having to dig access trenches or resort to confused and often inaccurate utility maps. An important advantage to placing utilities underground is public safety. Underground power lines, whether in common or separate channels, prevent downed utility cables from blocking roads, thus speeding emergency access after natural disasters such as earthquakes, hurricanes, and tsunamis. In some cases, a large trench is dug and deliberately preserved (not filled in), often for transport purposes. This is typically done to install depressed
motorway A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms ...
s, open
railway cutting Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a prep ...
s, or
canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface f ...
s. However, these large, permanent trenches are significant barriers to other forms of travel, and often become
de facto ''De facto'' ( ; , "in fact") describes practices that exist in reality, whether or not they are officially recognized by laws or other formal norms. It is commonly used to refer to what happens in practice, in contrast with '' de jure'' ("by l ...
boundaries between neighborhoods or other spaces.


Military engineering

Trenches have often been dug for military purposes. In the pre-
firearm A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions). The first firearms originated in 10th-century China, when bamboo tubes ...
era, they were mainly a type of hindrance to an attacker of a fortified location, such as the
moat A moat is a deep, broad ditch, either dry or filled with water, that is dug and surrounds a castle, fortification, building or town, historically to provide it with a preliminary line of defence. In some places moats evolved into more extensive ...
around a
castle A castle is a type of fortified structure built during the Middle Ages predominantly by the nobility or royalty and by military orders. Scholars debate the scope of the word ''castle'', but usually consider it to be the private fortified r ...
(this is technically called a
ditch A ditch is a small to moderate divot created to channel water. A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for plant irrigation. Ditches ar ...
). An early example of this can be seen in the
Battle of the Trench The Battle of the Trench ( ar, غزوة الخندق, Ghazwat al-Khandaq), also known as the Battle of Khandaq ( ar, معركة الخندق, Ma’rakah al-Khandaq) and the Battle of the Confederates ( ar, غزوة الاحزاب, Ghazwat al- ...
, a
religious war A religious war or a war of religion, sometimes also known as a holy war ( la, sanctum bellum), is a war which is primarily caused or justified by differences in religion. In the modern period, there are frequent debates over the extent to ...
, one of the early battles fought by
Muhammad Muhammad ( ar, مُحَمَّد;  570 – 8 June 632 CE) was an Arab religious, social, and political leader and the founder of Islam. According to Islamic doctrine, he was a prophet divinely inspired to preach and confirm the mon ...
. With the advent of accurate firearms, trenches were used to shelter troops. Trench warfare and tactics evolved further in the
Crimean War The Crimean War, , was fought from October 1853 to February 1856 between Russia and an ultimately victorious alliance of the Ottoman Empire, France, the United Kingdom and Piedmont-Sardinia. Geopolitical causes of the war included the ...
, the
American Civil War The American Civil War (April 12, 1861 – May 26, 1865; also known by Names of the American Civil War, other names) was a civil war in the United States. It was fought between the Union (American Civil War), Union ("the North") and t ...
and
World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...
, until systems of extensive main trenches, backup trenches (in case the first lines were overrun) and communication trenches often stretched dozens of kilometres along a front without interruption, and some kilometres further back from the front line. After WW1 had concluded, the trench became a symbol of WW1 and its horrors.


Gallery

File:Tuyuti1.jpg, Allied troops entrenched in the Battle of Tuyutí. File:Soldiers in trench.jpg, Soldiers in a trench during the Gallipoli Campaign of World War I. File:Boer Trench.jpg, The
Boer Boers ( ; af, Boere ()) are the descendants of the Dutch-speaking Free Burghers of the eastern Cape frontier in Southern Africa during the 17th, 18th, and 19th centuries. From 1652 to 1795, the Dutch East India Company controlled this are ...
trench at the Battle of Magersfontein contributed to the surprise defeat of the Highland Brigade on 11 December 1899 during the
Second Boer War The Second Boer War ( af, Tweede Vryheidsoorlog, , 11 October 189931 May 1902), also known as the Boer War, the Anglo–Boer War, or the South African War, was a conflict fought between the British Empire and the two Boer Republics (the So ...
. File:Snow at the front (4687960129).jpg, Soldiers in a trench on the Western Front in World War I in winter.


Archaeology

Trenches are used for searching and excavating ancient
ruin Ruins () are the remains of a civilization's architecture. The term refers to formerly intact structures that have fallen into a state of partial or total disrepair over time due to a variety of factors, such as lack of maintenance, deliberate ...
s or to dig into
strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as e ...
of sedimented material to get a sideways (layered) view of the deposits – with a hope of being able to place found objects or materials in a chronological order. The advantage of this method is that it destroys only a small part of the site (those areas where the trenches, often arranged in a grid pattern, are located). However, this method also has the disadvantage of only revealing small slices of the whole volume, and modern archeological digs usually employ combination methods.


Safety

Trenches that are deeper than about 1.5 m present safety risks arising from their steep walls and confined space. These risks are similar those from pits or any steep-walled excavations. The risks include falling, injury from cave-in (wall collapse), inability to escape the trench, drowning and
asphyxiation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can ...
. * Falling into the trench. Mitigation methods include barriers such as railings or fencing. * Injury from cave-in, meaning collapse of a steep wall. Mitigation includes construction of sloped walls (''sloped trench'') or stepped walls (''benched trench''). For vertical walls, trench shoring stabilizes the walls, and
trench shielding A trench is a type of excavation or in the ground that is generally deeper than it is wide (as opposed to a wider gully, or ditch), and narrow compared with its length (as opposed to a simple hole or pit). In geology, trenches result from er ...
provides a barrier against collapsed material. The risk of cave-in increases from ''surcharge load'', which is any weight placed outside the trench near its edge. These loads include the ''spoil pile'' (soil excavated from the trench) or heavy equipment. These add extra stress to the walls of the trench. * Inability to escape the trench because of steep and unstable walls, which may be difficult to climb. Ladders, stairs, or ramps allow exit. Cranes may assist rescue. * Drowning in water or mud that has accumulated in the trench from rain, seepage, or leaking water pipes. * Asphyxiation, poisoning, fire and explosion from gasses that are denser than air that have settled in a trench. These may come from nearby industrial processing of these gasses, intentional use within the trench, or leakage from nearby plumbing. These present an
asphyxiation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can ...
hazard and may also be toxic. Burnable gasses such as
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon d ...
present a fire and explosion risk. Oxidizers such as pure oxygen increase the risk of fire from other fuels present in the trench. Gasses such as pure
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
and
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon d ...
have densities similar to pure air but are denser when cold, for example when they have evaporated from liquid form, and may creep along the ground and fill the trench. Ventilation fans and ducts reduce the risk. Oxygen sensors and other gas sensors detect the danger; alarms from the sensors can warn the occupants.


See also

*
Abyssal plain An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between and . Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface ...
*
Cut (earthmoving) In civil engineering, a cut or cutting is where soil or rock from a relative rise along a route is removed. The term is also used in river management to speed a waterway's flow by short-cutting a meander. Cuts are typically used in road, rail ...
*
Cut and fill In earthmoving, cut and fill is the process of constructing a railway, road or canal whereby the amount of material from cuts roughly matches the amount of fill needed to make nearby embankments to minimize the amount of construction labor. ...
*
Ditch A ditch is a small to moderate divot created to channel water. A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for plant irrigation. Ditches ar ...
*
Gully A gully is a landform created by running water, mass movement, or commonly a combination of both eroding sharply into soil or other relatively erodible material, typically on a hillside or in river floodplains or terraces. Gullies resemble lar ...
* Sunken lane#Erosion * ''Trench'' (album) *
Trench coat A trench coat or trenchcoat is a variety of coat made of waterproof heavy-duty fabric, originally developed for British Army officers before the First World War, and becoming popular while used in the trenches. Originally made from gabardin ...
* Trench fever *
Trench foot Trench foot is a type of foot damage due to moisture. Initial symptoms often include tingling or itching which can progress to numbness. The feet may become red or bluish in color. As the condition worsens the feet can start to swell and sm ...
*
Trench mouth A trench is a type of excavation or in the ground that is generally deeper than it is wide (as opposed to a wider gully, or ditch), and narrow compared with its length (as opposed to a simple hole or pit). In geology, trenches result from eros ...
*
Trench warfare Trench warfare is a type of land warfare using occupied lines largely comprising Trench#Military engineering, military trenches, in which troops are well-protected from the enemy's small arms fire and are substantially sheltered from artille ...
*
Tunnel A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...
* Tunnel warfare *
Underground city An underground city is a series of linked subterranean spaces that may provide a defensive refuge; a place for living, working or shopping; a transit system; mausolea; wine or storage cellars; cisterns or drainage channels; or several of th ...
*
Underground living Underground living refers to living below the ground's surface, whether in natural or manmade caves or structures. Underground dwellings are an alternative to above-ground dwellings for some home seekers, including those who are looking to mini ...
* Utility tunnel


References


External links


Trenching and Excavation
(a
NIOSH The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the ...
Safety and Health Topic,
Centers for Disease Control and Prevention The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georg ...
)
Trench Safety Awareness
(a
NIOSH The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the ...
Publication,
Centers for Disease Control and Prevention The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georg ...
) {{Authority control *