塹壕

WordNet

set, plant, or bury in a trench; "trench the fallen soldiers"; "trench the vegetables"
a ditch dug as a fortification having a parapet of the excavated earth
any long ditch cut in the ground
a long steep-sided depression in the ocean floor (同)deep, oceanic abyss
cut a trench in, as for drainage; "ditch the land to drain it"; "trench the fields" (同)ditch
cut or carve deeply into; "letters trenched into the stone"
dig a trench or trenches; "The National Guardsmen were sent out to trench"
fortify by surrounding with trenches; "He trenched his military camp"
established firmly and securely; "the entrenched power of the nobility"
dug in
an entrenched fortification; a position protected by trenches (同)intrenchment
a hand shovel carried by infantrymen for digging trenches (同)trenching spade
a military style raincoat; belted with deep pockets

PrepTutorEJDIC

みぞ,(細長い)堀 / ざんごう / 〈土地〉‘に'みぞを掘る / …をざんごうで固める
(権利・信念などが)確固とした / ざんごうで防備された
ざんごう掘り;〈C〉ざんごう

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/01/31 03:16:11」(JST)

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A gas main being laid in a trench

A trench is a type of excavation or depression in the ground that is generally deeper than it is wide (as opposed to a wider gully or ditch), and narrow compared to its length (as opposed to a simple hole).^[1]

In geology, trenches are created as a result of erosion by rivers or by geological movement of tectonic plates. In the civil engineering field of construction or maintenance of infrastructure, trenches are created to install underground infrastructure or utilities (such as gas mains, water mains or telephone lines), or later to search for these installations. Trenches have often been dug for military defensive purposes. In archaeology, the "trench method" is used for searching and excavating ancient ruins or to dig into strata of sedimented material.

Types and uses

Geology

Some trenches are created as a result of erosion by running water or by glaciers (which may have long since disappeared). Others, such as rift valleys or more commonly oceanic trenches, are created by geological movement of tectonic plates. Some oceanic trenches include the Mariana Trench and the Aleutian Trench. The former geoform is relatively deep (approximately 10 kilometres (6.2 mi)), linear and narrow, and is formed by plate subduction when plates converge.^[2]

Civil engineering

In the civil engineering field of construction or maintenance of infrastructure, trenches play a major role. They are used to place underground easily damaged and obstructive infrastructure or utilities (such as gas mains, water mains or telephone lines). A similar use for higher bulk would be in pipeline transport. They may also be created later to search for pipes and other infrastructure that is known to be underground in the general area, but whose exact location has been lost ('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 embankments.

An alternative to digging trenches is to create a utility tunnel. The advantages of utility tunnels are the reduction of maintenance manholes, one-time relocation, and less excavation and repair, compared to 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. One of the greatest advantages 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. For a comparison of utility tunnels vs. direct burial, see the article referred to above.

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 motorways, open railway cuttings, or canals.

Military engineering

Soldiers in a trench during the Gallipoli Campaign of World War I

The Boer trench at the Battle of Magersfontein contributed to the surprise defeat of the Highland Brigade on 11 December 1899 during the Second Boer War.

Trenches have often been dug for defensive purposes. In the pre-firearm eras, 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). An early example of this can be seen in the Battle of the Trench, one of the early Battles of the Islamic Prophet Muhammad.^[3]

With the advent of accurate firearms, trenches were used to shelter troops. Trench warfare and tactics evolved further in the Crimean War, the American Civil War and World War I, 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.

Archaeology

Archaeological trench on an English farm site

This is used for searching and excavating ancient ruins 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.^[4]

References

^ Code of Federal Regulations, Title 29, Volume 8, Page 374 (Code revised as of July 1, 2003, via Compliance Magazine's website) Archived June 2, 2007 at the Wayback Machine
^ Ocean trench (glossary from Student Resource Center website, Houghton Mifflin college division)
^ Sa'd, Ibn (1967). Kitab al-tabaqat al-kabir 2. Pakistan Historical Society. pp. 82–84. ASIN B0007JAWMK.
^ Archaeology – People! Magazine, Winter 1998

External links

Trenching and Excavation (a NIOSH Safety and Health Topic, Centers for Disease Control and Prevention)
Trench Safety Awareness (a NIOSH Publication, Centers for Disease Control and Prevention)

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English Journal

On mobility of electrons in a shallow Fermi sea over a rough seafloor.

Behnia K1.
Journal of physics. Condensed matter : an Institute of Physics journal.J Phys Condens Matter.2015 Sep 23;27(37):375501. doi: 10.1088/0953-8984/27/37/375501. Epub 2015 Sep 1.
Several doped semiconductors, in contrast to heavily-doped silicon and germanium, host extremely mobile carriers, which give rise to quantum oscillations detectable in relatively low magnetic fields. The small Fermi energy in these dilute metals quantifies the depth of the Fermi sea. When the carrie
PMID 26325595

Pathology and Laboratory Medicine Support for the American Expeditionary Forces by the US Army Medical Corps During World War I.

Wright JR Jr, Baskin LB1.
Archives of pathology & laboratory medicine.Arch Pathol Lab Med.2015 Sep;139(9):1161-72. doi: 10.5858/arpa.2014-0528-HP.
Context .- Historical research on pathology and laboratory medicine services in World War I has been limited. In the Spanish American War, these efforts were primarily focused on tropical diseases. World War I problems that could be addressed by pathology and laboratory medicine were strikingly diff
PMID 26317455

Pedicle-in-a-trench technique for lower extremity reconstruction.

Yoshimatsu H1, Yamamoto T2, Iwamoto T2, Haragi M2, Narushima M2, Iida T2, Koshima I2.
Journal of plastic, reconstructive & aesthetic surgery : JPRAS.J Plast Reconstr Aesthet Surg.2015 Sep;68(9):1318-9. doi: 10.1016/j.bjps.2015.05.002. Epub 2015 May 22.
PMID 26037221

The role of ridges in the formation and longevity of flat slabs.

Antonijevic SK1, Wagner LS2, Kumar A1, Beck SL3, Long MD4, Zandt G3, Tavera H5, Condori C5.
Nature.Nature.2015 Aug 13;524(7564):212-5. doi: 10.1038/nature14648.
Flat-slab subduction occurs when the descending plate becomes horizontal at some depth before resuming its descent into the mantle. It is often proposed as a mechanism for the uplifting of deep crustal rocks ('thick-skinned' deformation) far from plate boundaries, and for causing unusual patterns of
PMID 26268192

Japanese Journal

Agglomeration and diffusion in Cu thin films under supercritical CO

Nakamura Yoshiki,Watanabe Mitsuhiro,Kondoh Eiichi
Jpn. J. Appl. Phys. 54(5S), 05EA03, 2015-04-15
… Cu was deposited by using direct current magnetron sputtering on trench-patterned substrates. …
NAID 150000110604

1.8 mΩ·cm

Oka Tohru,Ina Tsutomu,Ueno Yukihisa,Nishii Junya
Appl. Phys. Express 8(5), 054101, 2015-04-14
… In this paper, we report on 1.2-kV-class vertical GaN-based trench metal–oxide–semiconductor field-effect transistors (MOSFETs) on a free-standing GaN substrate with a low specific on-resistance. … A redesigned epitaxial layer structure following our previous work with a regular hexagonal trench gate layout enables us to reduce the specific on-resistance to as low as 1.8 mΩ·cm<sup>2</sup>while obtaining a sufficient blocking voltage for 1.2-kV-class operation. …
NAID 150000110560

Side wall tilt-implanted trench termination for SiC power devices

Song Gil-Yong,Cho Doo-Hyung,Song Gwan-Hoon,Kim Kwang-Soo
Jpn. J. Appl. Phys. 54(4S), 04DP16, 2015-03-25
… The trench termination technique is the effective for obtaining a high breakdown voltage while simultaneously minimizing the termination area. … In this paper, a tilt-implanted trench termination (TITT) technique for SiC power devices is presented. … With this technique, the trench insulator retains all potential energy while maintaining its breakdown voltage. …
NAID 150000110415

Switching characteristics of a 4H-SiC insulated-gate bipolar transistor with interface defects up to the nonquasi-static regime

Pesic Iliya,Navarro Dondee,Fujinaga Masato,Furui Yoshiharu,Miura-Mattausch Mitiko
Jpn. J. Appl. Phys. 54(4S), 04DP11, 2015-03-02
… The switching characteristics of a trench-type 4H-SiC insulated-gate bipolar transistor (IGBT) device with interface defects are analyzed up to the nonquasi-static (NQS) switching regime using reported interface density measurements and device simulation. …
NAID 150000110305