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
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 objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ea ...
, 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 dis ...
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
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
,
water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
,
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
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 Physical object, 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 Pr ...
, trenches are dug for foundations of buildings, retaining walls and dams, and for
cut-and-cover
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 ...
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 landsca ...
, 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 of sedimented material. In
geotechnical engineering, 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 military trenches, in which troops are well-protected from the enemy's small arms fire and are substantially sheltered from artillery. Trench warfare became ar ...
, soldiers occupy trenches to protect them against weapons fire.
Trenches are dug by use of manual tools such as
shovel
A shovel is a tool used for digging, lifting, and moving bulk materials, such as soil, coal, gravel, snow, sand, or ore.
Most shovels are hand tools consisting of a broad blade fixed to a medium-length handle. Shovel blades are usually made o ...
s and
pickaxe
A pickaxe, pick-axe, or pick is a generally T-shaped hand tool used for prying. Its head is typically metal, attached perpendicularly to a longer handle, traditionally made of wood, occasionally metal, and increasingly fiberglass.
A stand ...
s, or by heavy equipment such as
backhoes,
trenchers and
excavators.
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 flo ...
s and sunken roadways.
Geology
![Atlantic-trench](https://upload.wikimedia.org/wikipedia/commons/e/e2/Atlantic-trench.JPG)
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 dis ...
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 as ...
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
![Trench digger, Baku (P1090226)](https://upload.wikimedia.org/wikipedia/commons/4/41/Trench_digger%2C_Baku_%28P1090226%29.jpg)
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 main
Pipeline transport is the long-distance transportation of a liquid or gas through a system of pipes—a pipeline—typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than of pipeline in 120 countr ...
s,
water main
A water distribution system is a part of water supply network with components that carry potable water from a centralized treatment plant or wells to consumers to satisfy residential, commercial, industrial and fire fighting requirements.
Definit ...
s,
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
Trench shoring is the process of bracing the walls of a trench to prevent collapse and cave-ins. The phrase can also be used as a noun to refer to the materials used in the process.
Several methods can be used to shore up a trench. Hydrauli ...
is often used in trenchworks to protect workers and stabilise the steep walls.
An alternative to digging trenches is to create a
utility tunnel
A utility tunnel, utility corridor, or utilidor is a passage built underground or above ground to carry utility lines such as electricity, steam, water supply pipes, and sewer pipes. Communications utilities like fiber optics, cable television ...
. Such a tunnel may be dug by
boring or by using a trench for
cut-and-cover
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 ...
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 i ...
s, open
railway cuttings, 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 flo ...
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 la ...
boundaries between neighborhoods or other spaces.
Military engineering
Trenches have often been dug for military purposes. In the pre-
firearm era, they were mainly a type of hindrance to an attacker of a fortified location, such as the
moat around a
castle (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, 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 wh ...
, one of the early
battles
A battle is an occurrence of combat in warfare between opposing military units of any number or size. A war usually consists of multiple battles. In general, a battle is a military engagement that is well defined in duration, area, and force ...
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 mo ...
.
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 other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states ...
and
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
, 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
The Battle of Tuyutí (Tuiuti in Portuguese) was a Paraguayan offensive in the Paraguayan War targeting the Triple Alliance encampment of Tuyutí. It is considered to be the bloodiest battle ever in South America. The result of the battle was ...
.
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
The Battle of MagersfonteinSpelt incorrectly in various English texts as "Majersfontein", "Maaghersfontein" and "Maagersfontein". ( ) was fought on 11 December 1899, at Magersfontein, near Kimberley, South Africa, on the borders of the Cape Co ...
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 South ...
.
File:Snow at the front (4687960129).jpg, Soldiers in a trench on the Western Front in World War I in winter.
Archaeology
![Archaeological dig, Rectory Farm, Brampton, Cambs - geograph](https://upload.wikimedia.org/wikipedia/commons/2/20/Archaeological_dig%2C_Rectory_Farm%2C_Brampton%2C_Cambs_-_geograph.org.uk_-_1304628.jpg)
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 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
A cave-in is a collapse of a geologic formation, mine or structure which may occur during mining, tunneling, or steep-walled excavation such as trenching. Geologic structures prone to spontaneous cave-ins include alvar, tsingy and other limes ...
(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 ca ...
.
* 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
Trench shoring is the process of bracing the walls of a trench to prevent collapse and cave-ins. The phrase can also be used as a noun to refer to the materials used in the process.
Several methods can be used to shore up a trench. Hydrauli ...
stabilizes the walls, and
trench shielding 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 ca ...
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 carbo ...
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 carbo ...
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
*
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 gabardine, ...
*
Trench fever
Trench fever (also known as "five-day fever", "quintan fever" ( la, febris quintana), and "urban trench fever") is a moderately serious disease transmitted by body lice. It infected armies in Flanders, France, Poland, Galicia, Italy, Salonika, Ma ...
*
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
*
Trench warfare
Trench warfare is a type of land warfare using occupied lines largely comprising military trenches, in which troops are well-protected from the enemy's small arms fire and are substantially sheltered from artillery. Trench warfare became ar ...
*
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
Tunnel warfare involves war being conducted in tunnel and other underground cavities. It often includes the construction of underground facilities (mining or undermining) in order to attack or defend, and the use of existing natural caves and ...
*
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
A utility tunnel, utility corridor, or utilidor is a passage built underground or above ground to carry utility lines such as electricity, steam, water supply pipes, and sewer pipes. Communications utilities like fiber optics, cable television ...
References
External links
Trenching and Excavation(a
NIOSH 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, Georgi ...
)
Trench Safety Awareness(a
NIOSH 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, Georgi ...
)
{{Authority control
*