Bunker: Difference between revisions

{{shortShort description|Defensive military storage fortification}}

{{Use dmy dates|date=MarchDecember 20202022}}

In the [[First World War]] the [[belligerents]] built underground shelters, called [[Dugout (military)|dugouts]] in [[English language|English]], while the Germans used the term ''Bunker''.<ref>Harry Horstmann, ''Der Soldat: In Sprache und Tradition'' (2010), p. 153.</ref><ref>{{cite web |url=https://www.dwds.de/wb/Bunker |title=ArchivedDWDS copy– Bunker |access-date=2016-11-16 |url-status=live |archive-url=https://web.archive.org/web/20161116103616/https://www.dwds.de/wb/Bunker |archive-date=16 November 2016}} Das Wortauskunftssystem zur deutschen Sprache in Geschichte und Gegenwart</ref> By the [[Second World War]] the term came to be used by the Germans to describe permanent structures both large: ([[blockhouse]]s), and small: ([[Pillbox (military)|pillboxpillboxe]]s), and to bombproof shelters both above ground (as in ''[[Hochbunker]]'') and below ground (such as the ''[[Führerbunker]]'').<ref>"The German term Bunker was used to denote a type of shelter which was of permanent construction. It can be distinguished from the improvised type built in cellars or by reinforcing ordinary buildings. Bunkers were of two types: underground and tower" ({{cite book|author=Morale Division|year=1945|title=The effect of bombing on health and medical care in Germany| volume=65 |series=Reports: European war, United States Strategic Bombing Survey |edition=2 |publisher=United States War Department|page=189 (footnote "*")}})</ref>

The military sense of the word was imported into English during World War II, at first in reference to specifically German dug-outs; according to the [[Oxford English Dictionary]], the sense of "military dug-out; a reinforced concrete shelter" is first recorded on 13 October 1939, in "A Nazi field gun hidden in a cemented 'bunker' on the Western front".<ref name="OED">''War Pictorial'', cited after {{cite book|chapter=bunker, n.1.c|title=Oxford English Dictionary|publisher=Oxford University Press|edition=Second |orig-year=1989|date=December 2011|url=http://www.oed.com/view/Entry/24799}} {{subscription required}}</ref> All the early references to its usage in the Oxford English Dictionary are to German fortifications. However, in the [[South-East Asian theatre of World War II|Far East]] the term was also applied to the earth and log positions built by the Japanese, the term appearing in a 1943 instruction manual issued by the [[British Indian Army]] and quickly gaining wide currency.<ref>{{cite book|author=Tim Moreman|title=The Jungle, Japanese and the British Commonwealth Armies at War, 1941-45: Fighting Methods, Doctrine and Training for Jungle Warfare|url=https://books.google.com/books?id=QcKWCEHQ1jYC&pg=PA98|year=2013|publisher=Routledge|isbn=978-1-135-76455-5|page=98}}</ref>

By 1947 the word was familiar enough in English that [[Hugh Trevor-Roper]] in ''The Last Days of Hitler'' was describing [[Führerbunker|Hitler's underground complex]] near the [[New Reich Chancellery|Reich Chancellery]] as "Hitler's own bunker" without quotes around the word bunker.<ref name=OED/>

Typical industrial bunkers include mining sites, food storage areas, dumps for materials, data storage, and sometimes living quarters. They were built mainly by nations like Germany during World War II to protect important industries from [[bombingBombardment|aerial bombardment]]. Industrial bunkers are also built for control rooms of dangerous activities, such as tests of rocket engines or explosive experiments. They are also built in order to perform dangerous experiments in them or to store radioactive or explosive goods. Such bunkers also exist on non-military facilities.

When a house is purpose-built with a bunker, the normal location is a reinforced below-ground bathroom with large cabinets.{{Citation needed|date=March 2011}} One common design approach uses [[fibre-reinforced plastic]] shells. Compressive protection may be provided by inexpensive earth arching.{{Citation needed|date=March 2011}} The overburden is designed to shield from radiation.{{Citation needed|date=March 2011}} To prevent the shelter from floating to the surface in high groundwater, some designs have a skirt held- down with the overburden.<ref name=Kearny>{{cite book |last=Kearny |first=Cresson H |url=http://www.oism.org/nwss/ |access-date=2008-06-19 |title=Nuclear War Survival Skills |year=1987 |isbn=0-942487-01-X |publisher=Oak Ridge National Laboratory }} '''NOTE''': Kearny recommends stockpiling materials for a blast or [[fallout shelter]] and constructing it only if war appears very likely.</ref> It may also serve the purpose of a [[safe room]].{{Citation needed|date=March 2011}}

Munitions storage bunkers are designed to securely store [[explosive]] [[Shell (projectile)|ordnance]], and contain any internal explosions. The most common configuration for [[high explosives]] storage is the [[igloo]] shaped bunker.{{Citation needed|date=February 2019}} They are often built into a hillside in order to provide additional containment mass.

A specialized version of the munitions bunker called a [[Gravel Gertie]] is designed to contain [[radioactive]] debris from an explosive accident while assembling or disassembling [[nuclear warhead]]s. They are installed at all facilities in the United States and United Kingdom which do warhead assembly and disassembly, the largest being the [[Pantex]] plant in [[Amarillo, Texas]], which has 12 Gravel Gerties.<ref>{{CitationCite web needed|date=February5 2019March 2022|title=Bunker: What is it, types and all you need to know |url=http://www.news9live.com/knowledge/bunker-what-is-it-types-and-all-you-need-to-know-157289 |access-date=4 September 2023|website=News9live |language=en-US}}</ref>

<gallery mode="packed">

File:Objekt 17 5001 toegangsdeur 02.JPG|Object 17/5001 Prenden, Germany

File:Possum_Park_Bunker_8a.jpeg|Munitions bunker at [[Possum Park]], Queensland, Australia.

File:Bunker 2.jpg|[[Austria-Hungary|Austrian]] bunker from World War I in [[West Ukraine]]

Bunkers deflect the blast wave from nearby [[explosion]]s to prevent ear and internal injuries to people sheltering in the bunker. While frame buildings collapse from as little as {{cvt|3 [[Pound-force per square inch|psi]]|kPa (0.2psi [[Bar (unit)bar|bar]])lk=on|order=out}} of [[overpressure]], bunkers are regularly constructed to survive severalover hundred{{cvt|10|bar|kPa psi (over 10 bar)|order=out}}. This substantially decreases the likelihood that a [[bomb]] (other than a [[bunker buster]]) can harm the structure.

The basic plan is to provide a structure that is very strong in [[compression (physical)|physical compression]]. The most common purpose-built structure is a buried, steel [[reinforced concrete]] [[Vault (architecture)|vault]] or [[arch]]. Most expedient blast shelters are civil engineering structures that contain large, buried tubes or pipes such as sewage or rapid transit tunnels. Improvised purpose-built blast shelters normally use earthen arches or vaults. To form these, a narrow, {{convert|1|-|2 meter|m|ft|round=0.5|adj=on}}, flexible tent of thin wood is placed in a deep trench, and then covered with cloth or plastic, and then covered with 1–2 meters{{convert|1|-|2|m|ft|round=0.5|abbr=in}} of tamped earth.

Nuclear bunkers must also cope with the underpressure that lasts for several seconds after the [[shock wave]] passes, and block [[radiation]]. Usually, these features are easy to provide. The overburden ([[soil]]) and structure provide substantial radiation shielding, and the negative pressure is usually only {{frac|1/|3}} of the overpressure.<ref>The Survival Option: Guide to Living Through Nuclear War, Ivan Tyrrell. Publisher: Jonathan Cape Ltd; 1st Edition (1982), Language: English, Hardcover: 256 pages, {{ISBN|0224020595}}</ref>

The doors must be at least as strong as the walls. The usual design is now starting to incorporate [[Vault door|vault doors]]. To reduce the weight, the door is normally constructed of steel, with a fitted steel lintel and frame. Very thick wood also serves, and is more resistant to heat because it chars rather than melts.{{Citation needed|date=December 2008}} If the door is on the surface and will be exposed to the blast wave, the edge of the door is normally counter-sunk in the frame so that the blast wave or a reflection cannot lift the edge. A bunker should have two doors. Door shafts may double as ventilation shafts to reduce digging.

Bunkers can be destroyed with powerful explosives and bunkerbusting warheads. The crew of a [[pillbox (fortification)|pillbox]] can be killed with [[flamethrower]]s.<ref>[{{Cite web|url=http://www.olive-drab.com/od_infweapons_flame.php Flame Thrower] {{webarchive|urlarchiveurl=https://web.archive.org/web/20170917153400/http://olive-drab.com/od_infweapons_flame.php|url-status=dead|title=Flame Thrower|archive-date=17 September 2017|access-date=19 December 2022}}</ref> Complex, well-built and well-protected fortifications are often vulnerable to attacks on access points. If the exits to the surface can be closed off, those manning the facility can be trapped. The fortification can then be bypassed.

Famous bunkers include the post-World War I [[Maginot Line]] on the French eastern border and [[Czechoslovak border fortifications]] mainly on the northern Czech border facing Germany (but to lesser extent all around), [[Fort Eben-Emael]] in Belgium, [[Alpine Wall]] on the north of Italy, World War II [[Führerbunker]] and in Italy, industrial [[Marnate's Bunker]], the V-weapon installations in Germany ([[Mittelwerk]]) & France ([[La Coupole]], and the [[Blockhaus d'Éperlecques]]) and the Cold War installations in the [[United States]] ([[Cheyenne Mountain Complex]], [[Site R]], and [[The Greenbrier]]), United Kingdom ([[Burlington (UK)|Burlington]]), Sweden ([[Boden Fortress]]) and Canada ([[Diefenbunker]]). In Switzerland, there is an unusually large number of bunkers because of a law requiring protective shelters to be constructed for all new buildings since 1963, as well as a number of bunkers built as part of its [[National Redoubt (Switzerland)|National Redoubt]] military defense plan.<ref>[http://www.forti.ch/files/2014/10/Foppa-Grande-Fortificazione-del-San-Gottardo-VBS-armasuisse-Bauten-2004.pdf Foppa Grande]</ref> Some of Switzerland's bunkers have since become tourist attractions housing hotels and museums such as Sasso San Gottardo Museum.<ref>{{cite magazine|last1=Nalewicki|first1=Jennifer|title=Switzerland's Historic Bunkers Get a New Lease on Life |url=http://www.smithsonianmag.com/travel/switzerlands-bunkers-get-new-lease-life-180958233/|access-date=4 April 2016|magazine=The Smithsonian|date=23 March 2016}}</ref>

* [[Air- raid shelter]]

* {{Citation|author=BACM Research|year=2009 |title=Vietnam War After Action Reports |publisher=BACM Research |page=[https://books.google.com/books?id=Dch3m7u2K5YC&lpg=PA263&pg=RA1-PA263#v=onepage&q&f=false 263]}}

* {{Citation|last=Davis |first=Tracy C. |year=2007 |title=Stages of emergency: Cold War nuclear civil defense |edition=illustrated |publisher=Duke University Press |isbn=978-0-8223-3970-0 |page=[https://books.google.com/books?id=WcdAe825xawC&lpg=PP1&pg=PA290#v=onepage&q&f=false 290]}}

|volume=3 |series=RTPI library series |edition=illustrated |publisher=Routledge |isbn=978-0-415-24136-6 |page=[https://books.google.com/books?id=D67xQE95qT4C&lpg=PA87&pg=PA87#v=onepage&q&f=false 87]}}

{{commons|Bunker}}