Editing Foundation (engineering)

{{short description|Lowest and supporting layer of a structure}}
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[[File:Mock foundations for House and Apartment.png|thumb|[[Shallow foundation]]s of a house versus the [[deep foundation]]s of a [[skyscraper]].]]
[[File:Foundation 2.jpg|thumb|Foundation with pipe fixtures coming through the [[Sleeve (construction)|sleeves]]]]

In engineering, a '''foundation''' is the element of a [[structural engineering|structure]] which connects it to the ground or more rarely, water (as with [[Floating building|floating structures]]), transferring [[force|loads]] from the structure to the ground. Foundations are generally considered either [[Shallow foundation|shallow]] or [[Deep foundation|deep]].<ref>{{citation |last1=Terzaghi |first1=Karl |author1-link=Karl von Terzaghi |last2=Peck |first2=Ralph Brazelton |author2-link=Ralph Brazelton Peck |last3=Mesri |first3=Gholamreza |edition=3rd |title=Soil mechanics in engineering practice |date=1996 |publisher=John Wiley & Sons |location=New York |isbn=0-471-08658-4 |page=386 |url=https://books.google.com/books?id=bAwVvO71FXoC}}</ref>  Foundation engineering is the application of [[soil mechanics]] and [[rock mechanics]] ([[geotechnical engineering]]) in the design of foundation elements of structures.

==Purpose==
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Foundations provide the structure's stability from the ground:
* To distribute the weight of the structure over a large area in order to avoid overloading the underlying soil (possibly causing unequal settlement). 
* To anchor the structure against natural forces including [[earthquakes]], [[floods]], [[droughts]], frost heaves, tornadoes and wind.
* To provide a level surface for construction.
* To anchor the structure deeply into the ground, increasing its stability and preventing overloading.
* To prevent lateral movements of the supported structure (in some cases).

==Requirements of a good foundation==
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[[File:Lincoln Park Affordable Housing Phase 2 (53566542487).jpg|thumb|right|Pouring a concrete foundation]]
The design and the construction of a well-performing foundation must possess some basic requirements:<ref>{{Cite book |last=Ventura |first=Pierfranco |title=Fondazioni |publisher=Hoepli |year=2019 |isbn=9788820386443 |location=Milano |language=it}}</ref>
* The design and the construction of the foundation is done such that it can sustain as well as transmit the dead and the imposed loads to the soil. This transfer has to be carried out without resulting in any form of settlement that can cause stability issues for the structure.
*Differential settlements can be avoided by having a rigid base for the foundation. These issues are more pronounced in areas where the superimposed loads are not uniform in nature.
*Based on the soil and area it is recommended to have a deeper foundation so that it can guard any form of damage or distress. These are mainly caused due to the problem of shrinkage and swelling because of temperature changes.
*The location of the foundation chosen must be an area that is not affected or influenced by future works or factors.

==Historic types==
[[File:Lotyšské etnografické muzeum v přírodě (91).jpg|thumb|The simplest foundation, a padstone. [[The Ethnographic Open-Air Museum of Latvia]]]]

===Earthfast or post in ground construction===
Buildings and structures have a long history of being built with wood in contact with the ground.<ref>Crabtree, Pam J.. Medieval archaeology: an encyclopedia. New York: Garland Pub., 2001. 113.</ref><ref>Edwards, Jay Dearborn, and Nicolas Verton. A Creole lexicon architecture, landscape, people. Baton Rouge: Louisiana State University Press, 2004. 92.</ref> [[Post in ground]] construction may technically have no foundation. [[Timber pilings]] were used on soft or wet ground even below stone or masonry walls.<ref>Nicholson, Peter. Practical Masonry, Bricklaying and Plastering, Both Plain and Ornamental. Thomas Kelly: London. 1838. 30–31.</ref> In marine construction and bridge building a crisscross of timbers or steel beams in concrete is called grillage.<ref>Beohar, Rakesh Ranjan. Basic Civil Engineering. 2005. 90. {{ISBN|8170087937}}</ref>

===Padstones===
Perhaps the simplest foundation is the padstone, a single stone which both spreads the weight on the ground and raises the timber off the ground.<ref>Darvill, Timothy. The concise Oxford dictionary of archaeology. 6th ed. [i.e. 2nd ed. Oxford, U.K.: Oxford University Press, 2008. Padstone. {{ISBN|0199534047}}</ref> [[Staddle stones]] are a specific type of padstone.

===Stone foundations===
[[Dry stone]] and stones laid in [[Mortar (masonry)|mortar]] to build foundations are common in many parts of the world. Dry laid stone foundations may have been painted with mortar after construction. Sometimes the top, visible course of stone is hewn, quarried stones.<ref>Garvin, James L.. ''A building history of northern New England''. Hanover: University Press of New England, 2001. 10. Print.</ref> Besides using mortar, stones can also be put in a [[gabion]].<ref>Stones in gabion for foundation, done in Diez Casas Para Diez Familias (10x10)'s Casa Rosenda; see Design Like You Give a Damn 2 book by Kate Stohr</ref> One disadvantage is that if using regular steel [[rebar]]s, the gabion would last much less long than when using mortar (due to rusting). Using [[weathering steel]] rebars could reduce this disadvantage somewhat.

===Rubble-trench foundations===
{{main|Rubble trench foundation}}
Rubble trench foundations are a shallow trench filled with rubble or stones. These foundations extend below the [[frost line]] and may have a drain pipe which helps groundwater drain away. They are suitable for soils with a capacity of more than 10 tonnes/m<sup>2</sup> (2,000 pounds per square foot).

==Gallery of shallow foundation types==
<gallery>
File:Drawing of Poteaux-en-Terre in the Beauvais House in Ste Genevieve MO.png|Drawing of Poteaux-en-Terre [[post in ground]] type of wall construction (this example technically called [[pallisade]] construction) in the Beauvais House in Ste Genevieve, Missouri
File:PSM V24 D321 A primitive lake dwelling in switzerland.jpg|PSM V24 D321 A primitive [[stilt house]] in Switzerland on [[wood piling]]s.
File:Hórreo tipo asturiano, O Piornedo, Cervantes.jpg|A granary on [[staddle stones]], a type of padstone
File:Black Eagle Dam - cross-section of construction plans for 1892 structure.jpg|Black Eagle Dam – cross-section of construction plans for 1892 structure
File:Davis House stone foundation ruin, Gardiner, NY.jpg|Davis House dry-laid stone foundation ruin, Gardiner, NY
File:Random rubble masonry1.jpg|A basic type of rubble trench foundation
File:Concrete cellar 10007.JPG|Typical residential poured concrete foundation, except for the lack of [[anchor bolt]]s. The concrete walls are supported on continuous footings. There is also a [[concrete slab]] floor. Note the standing water in the perimeter [[French drain]] trenches.
File:Modular home.jpg|[[Modular building]] to be placed on the foundation
</gallery>

==Modern types==
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===Shallow foundations===
{{Main|Shallow foundation}}
[[File:Construcción de una cimentación por zapata aislada.ogv|thumb|Shallow foundation construction example]]
Often called ''footings'', are usually embedded about a meter or so into [[soil]]. One common type is the spread footing which consists of strips or pads of concrete (or other materials) which extend below the [[frost line]] and transfer the weight from walls and columns to the soil or [[bedrock]].

Another common type of shallow foundation is the slab-on-grade foundation where the weight of the structure is transferred to the soil through a [[concrete]] slab placed at the surface. Slab-on-grade foundations can be reinforced mat slabs, which range from 25&nbsp;cm to several meters thick, depending on the size of the building, or post-tensioned slabs, which are typically at least 20&nbsp;cm for houses, and thicker for heavier structures.

Another way to install ready-to-build foundations that is more environmentally friendly is to use [[screw piles]]. Screw pile installations have also extended to residential applications, with many homeowners choosing a screw pile foundation over other options. Some common applications for helical pile foundations include wooden decks, fences, garden houses, pergolas, and carports.

===Deep foundations===
{{Main|Deep foundation}}	 
Used to transfer the load of a structure down through the upper weak layer of [[topsoil]] to the stronger layer of [[subsoil]] below. There are different types of deep footings including impact driven piles, drilled shafts, [[Caisson (engineering)|caissons]], [[screw piles]], geo-piers{{clarify|these are nowhere described or sourced|date=September 2020}} and earth-stabilized columns{{clarify|these are nowhere described or sourced|date=September 2020}}. The naming conventions for different types of footings vary between different engineers. Historically, piles were [[wood]], later [[steel]], [[reinforced concrete]], and [[prestressed concrete|pre-tensioned concrete]].

====Monopile foundation====
{{Main|Monopile foundation}}
A type of [[deep foundation]] which uses a single, generally large-diameter, structural element embedded into the earth to support all the loads (weight, wind, etc.) of a large above-surface structure.

Many monopile foundations<ref name=own20090909>[http://offshorewind.net/Other_Pages/Turbine-Foundations.html Offshore Wind Turbine Foundations] {{Webarchive|url=https://web.archive.org/web/20100228021556/http://offshorewind.net/Other_Pages/Turbine-Foundations.html |date=2010-02-28 }}, 2009-09-09, accessed 2010-04-12.</ref> have been used in recent years for economically constructing [[Windfarm#Fixed-bottom.2C foundation-based tower technologies|fixed-bottom]] [[List of offshore wind farms|offshore wind farm]]s in shallow-water [[subsea]] locations.<ref name=hre>
[http://www.hornsrev.dk/Engelsk/Opstillingen/uk-fundament.htm Constructing a turbine foundation] {{webarchive|url=https://web.archive.org/web/20110521095525/http://www.hornsrev.dk/Engelsk/Opstillingen/uk-fundament.htm |date=2011-05-21 }} Horns Rev project, Elsam monopile foundation construction process, accessed 2010-04-12</ref>  
For example, a single [[wind farm]] [[Lynn and Inner Dowsing Wind Farm#Construction|off the coast of England]] went online in 2008 with over 100 turbines, each mounted on a 4.74-meter-diameter monopile footing in ocean depths up to 16 meters of water.<ref>{{cite web|url=http://mth.com/Projects/Offshore/LynnInnerDowsing.aspx|title=Lynn & Inner Dowsing Offshore Wind Farms|publisher=MT Højgaard|access-date=15 September 2016|archive-url=https://web.archive.org/web/20161220065901/http://mth.com/Projects/Offshore/LynnInnerDowsing.aspx|archive-date=20 December 2016|url-status=dead}}</ref>

===Floating\barge===
A floating foundation is one that sits on a body of water, rather than dry land. This type of foundation is used for some [[bridge]]s and floating buildings.

==Design==
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[[File:Stompwijkseweg 68-70, Stompwijk, Netherlands.JPG|thumb|right|250px|Inadequate foundations in muddy soils below sea level caused these houses in the Netherlands to [[Subsidence|subside]].]]
Foundations are designed to have an adequate load capacity depending on the type of subsoil/rock supporting the foundation by a [[geotechnical engineer]], and the footing itself may be designed structurally by a [[structural engineer]]. The primary design concerns are [[consolidation (soil)|settlement]] and [[bearing capacity]]. When considering settlement, total settlement and differential settlement is normally considered. Differential settlement is when one part of a foundation settles more than another part. This can cause problems to the structure which the foundation is supporting. [[Expansive clay]] soils can also cause problems.

==See also==
*[[Underpinning]]
*[[Structural settlement]]
*[[Interference of the footings]]

==References==
{{reflist}}

== External links ==
{{Commons category|Foundations (architecture)}}
* [https://newspeak.today/articles/13 Common examples of possible deformations of foundations arising from improper construction.]

{{Geotechnical engineering}}
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