Foundation (engineering) 693334 225330513 2008-07-13T03:26:00Z Eh kia 7109427 Adding Persian Language link [[Image:Found-House-Apt.png|thumb|right|Shallow foundations of a [[house]] versus the deep foundations of a [[Skyscraper]].]] A '''foundation''' is a [[structure]] that transfers loads to the earth. Foundations are generally broken into two categories: [[shallow foundations]] and [[deep foundations]]. ==Shallow foundations== {{main|Shallow foundation}} Shallow foundations are usually embedded 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 is the '''slab-on-grade foundation''' where the weight of the building is transferred to the soil through a [[concrete]] slab placed at the surface. ==Deep foundations== {{main|Deep foundation}} Deep foundations are used to transfer a load from a structure through an upper weak layer of soil to a stronger deeper layer of soil. There are different types of deep foundations including piles, drilled shafts, caissons, piers, and earth stabilized columns. The naming conventions for different types of foundations vary between different engineers. Historically, piles were [[wood]], later [[steel]], [[reinforced concrete]], and [[prestressed concrete|pre-tensioned concrete]]. Sometimes these foundations penetrate [[bedrock]]. ==Design== Foundations are designed to have an adequate load capacity with limited settlement by a [[geotechnical engineer]], and the foundation itself is 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 the foundation is supporting. It is necessary that a foundation is not loaded beyond its bearing capacity or the foundation will "fail". Other design considerations include scour and [[frost heave]]. Scour is when flowing water removes supporting soil from around a foundation (like a pier supporting a bridge over a river). Frost heave occurs when water in the ground freezes to form ice lenses. Changes in soil moisture can cause [[expansive clay]] to swell and shrink. This swelling can vary across the footing due to seasonal changes or the effects of vegetation removing moisture. The variation in swell can cause the soil to distort, cracking the structure over it. This is a particular problem for house footings in semi-arid [[climate]]s such as [[South Australia]], [[Southwestern US]], [[Turkey]], [[Israel]], [[Iran]] and [[South Africa]] where wet winters are followed by hot dry summers. Raft slabs with inherent stiffness have been developed in Australia with capabilities to resist this movement. When structures are built in areas of [[permafrost]], special consideration must be given to the thermal effect the structure will have on the permafrost. Generally, the structure is designed in a way that tries to prevent the permafrost from melting. ==See also== *[[Construction]] *[[Geotechnical engineering]] *[[Shallow foundation]] *[[Deep foundation]] {{Geotechnical engineering}} [[Category:Archaeological features]] [[Category:Building engineering]] [[Category:Construction]] [[Category:Geotechnical engineering]] [[Category:Architectural elements]] [[ar:اساس (بناء)]] [[an:Alazet]] [[da:Bygningsfundament]] [[de:Gründung (Bauwesen)]] [[es:Cimentación]] [[fa:پی]] [[fr:Fondation (construction)]] [[gl:Cimento]] [[it:Fondazioni]] [[nl:Fundering]] [[ja:基礎]] [[pl:Fundament]] [[pt:Fundação (construção)]] [[ru:Фундамент]] [[fi:Perustus]] [[sv:Fundament]] [[ta:அடித்தளம் (கட்டுமானம்)]] [[uk:Фундамент]] [[zh:基础]]