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{{short description|Scientific study of earth materials in engineering problems}} | |||
{{Use American English|date=July 2023}} | {{Use American English|date=July 2023}} | ||
[[Image:Boston CAT Project-construction view from air.jpeg|thumb|upright=1.15|[[Boston]]'s [[Big Dig]] presented geotechnical challenges in an urban environment.]] | |||
[[File:Precastconcreteretainingwall.tif|thumb|Precast concrete retaining wall]] | [[File:Precastconcreteretainingwall.tif|thumb|Precast concrete retaining wall]] | ||
[[File:slope 2d plain.svg|thumb|A typical cross-section of a slope used in two-dimensional analyzes.]] | [[File:slope 2d plain.svg|thumb|A typical cross-section of a slope used in two-dimensional analyzes.]] | ||
'''Geotechnical engineering''', also known as '''geotechnics''', is the branch of [[civil engineering]] concerned with the engineering behavior of [[earth materials]]. It uses the principles of [[soil mechanics]] and [[rock mechanics]] to solve its [[engineering]] problems. It also relies on knowledge of [[geology]], [[hydrology]], [[geophysics]], and other related sciences. | '''Geotechnical engineering''', also known as '''geotechnics''', is the branch of [[civil engineering]] concerned with the engineering behavior of [[earth materials]]. It uses the principles of [[soil mechanics]] and [[rock mechanics]] to solve its [[engineering]] problems. It also relies on knowledge of [[geology]], [[hydrology]], [[geophysics]], and other related sciences. | ||
Geotechnical engineering has applications in [[military engineering]], [[mining engineering]], [[petroleum engineering]], [[coastal engineering]], and [[offshore construction]]. The fields of geotechnical engineering and [[engineering geology]] have overlapping knowledge areas. However, while geotechnical engineering is a specialty of [[civil engineering]], engineering geology is a specialty of [[geology]]. | Geotechnical engineering has applications in [[military engineering]], [[mining engineering]], [[petroleum engineering]], [[coastal engineering]], and [[offshore construction]]. The fields of geotechnical engineering and [[engineering geology]] have overlapping knowledge areas. However, while geotechnical engineering is a specialty of [[civil engineering]], engineering geology is a specialty of [[geology]]. | ||
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The application of the principles of [[mechanics]] to soils was documented as early as 1773 when [[Charles-Augustin de Coulomb|Charles Coulomb]], a physicist and engineer, developed improved methods to determine the earth pressures against military ramparts. Coulomb observed that, at failure, a distinct slip plane would form behind a sliding retaining wall and suggested that the maximum shear stress on the slip plane, for design purposes, was the sum of the soil cohesion, <math>c</math>, and friction <math>\sigma\,\!</math> <math> \tan(\phi\,\!)</math>, where <math>\sigma\,\!</math> is the normal stress on the slip plane and <math>\phi\,\!</math> is the friction angle of the soil. By combining Coulomb's theory with [[Christian Otto Mohr]]'s [[Mohr's circle|2D stress state]], the theory became known as [[Mohr-Coulomb theory]]. Although it is now recognized that precise determination of cohesion is impossible because <math>c</math> is not a fundamental soil property, the Mohr-Coulomb theory is still used in practice today.<ref name="schofield">Disturbed soil properties and geotechnical design, Schofield, Andrew N., Thomas Telford, 2006. {{ISBN|0-7277-2982-9}}</ref> | The application of the principles of [[mechanics]] to soils was documented as early as 1773 when [[Charles-Augustin de Coulomb|Charles Coulomb]], a physicist and engineer, developed improved methods to determine the earth pressures against military ramparts. Coulomb observed that, at failure, a distinct slip plane would form behind a sliding retaining wall and suggested that the maximum shear stress on the slip plane, for design purposes, was the sum of the soil cohesion, <math>c</math>, and friction <math>\sigma\,\!</math> <math> \tan(\phi\,\!)</math>, where <math>\sigma\,\!</math> is the normal stress on the slip plane and <math>\phi\,\!</math> is the friction angle of the soil. By combining Coulomb's theory with [[Christian Otto Mohr]]'s [[Mohr's circle|2D stress state]], the theory became known as [[Mohr-Coulomb theory]]. Although it is now recognized that precise determination of cohesion is impossible because <math>c</math> is not a fundamental soil property, the Mohr-Coulomb theory is still used in practice today.<ref name="schofield">Disturbed soil properties and geotechnical design, Schofield, Andrew N., Thomas Telford, 2006. {{ISBN|0-7277-2982-9}}</ref> | ||
In the 19th century, [[Henry Darcy]] developed what is now known as [[Darcy's | In the 19th century, [[Henry Darcy]] developed what is now known as [[Darcy's law]], describing the flow of fluids in a [[Porous medium|porous media]]. [[Joseph Boussinesq]], a mathematician and physicist, developed theories of stress distribution in elastic solids that proved useful for estimating stresses at depth in the ground. [[William Rankine]], an engineer and physicist, developed an alternative to Coulomb's earth pressure theory. [[Albert Atterberg]] developed the [[Atterberg limits|clay consistency]] indices that are still used today for soil classification.<ref name=das/><ref name=budhu/> In 1885, [[Osborne Reynolds]] recognized that shearing causes volumetric dilation of dense materials and contraction of loose [[granular material]]s. | ||
Modern geotechnical engineering is said to have begun in 1925 with the publication of ''Erdbaumechanik'' by [[Karl Terzaghi|Karl von Terzaghi]], a mechanical engineer and geologist. Considered by many to be the father of modern soil mechanics and geotechnical engineering, Terzaghi developed the principle of effective | Modern geotechnical engineering is said to have begun in 1925 with the publication of ''Erdbaumechanik'' by [[Karl Terzaghi|Karl von Terzaghi]], a mechanical engineer and geologist. Considered by many to be the father of modern soil mechanics and geotechnical engineering, Terzaghi developed the [[Terzaghi's principle|principle of effective stress]], and demonstrated that the [[Shear strength (soil)|shear strength]] of soil is controlled by effective stress.<ref>{{cite journal |last1=Guerriero V. |first1=Mazzoli S. |title=Theory of Effective Stress in Soil and Rock and Implications for Fracturing Processes: A Review |journal=Geosciences |date=2021 |volume=11 |issue=3 |page=119 |doi=10.3390/geosciences11030119|bibcode=2021Geosc..11..119G |doi-access=free }}</ref> Terzaghi also developed the framework for theories of bearing capacity of foundations, and the theory for prediction of the rate of settlement of clay layers due to [[consolidation (soil)|consolidation]].<ref name=das/><ref name=schofield/><ref name="Lambe and Whitman">Soil Mechanics, Lambe, T.William and Whitman, Robert V., Massachusetts Institute of Technology, John Wiley & Sons., 1969. {{ISBN|0-471-51192-7}}</ref> Afterwards, [[Maurice Biot]] fully developed the three-dimensional soil consolidation theory, extending the one-dimensional model previously developed by Terzaghi to more general hypotheses and introducing the set of basic equations of [[Poroelasticity]]. | ||
In his 1948 book, Donald Taylor recognized that the interlocking and dilation of densely packed particles contributed to the peak strength of the soil. Roscoe, Schofield, and Wroth, with the publication of ''On the Yielding of Soils'' in 1958, established the interrelationships between the volume change behavior (dilation, contraction, and consolidation) and shearing behavior with the theory of [[plasticity (physics)|plasticity]] using critical state soil mechanics. [[Critical state soil mechanics]] is the basis for many contemporary advanced [[constitutive model]]s describing the behavior of soil.<ref name="Wood">Soil Behavior and Critical State Soil Mechanics, Wood, David Muir, Cambridge University Press, 1990. {{ISBN|0-521-33782-8}}</ref> | In his 1948 book, Donald Taylor recognized that the interlocking and dilation of densely packed particles contributed to the peak strength of the soil. Roscoe, Schofield, and Wroth, with the publication of ''On the Yielding of Soils'' in 1958, established the interrelationships between the volume change behavior (dilation, contraction, and consolidation) and shearing behavior with the theory of [[plasticity (physics)|plasticity]] using critical state soil mechanics. [[Critical state soil mechanics]] is the basis for many contemporary advanced [[constitutive model]]s describing the behavior of soil.<ref name="Wood">Soil Behavior and Critical State Soil Mechanics, Wood, David Muir, Cambridge University Press, 1990. {{ISBN|0-521-33782-8}}</ref> | ||
In 1960, [[Alec Skempton]] carried out an extensive review of the available formulations and experimental data in the literature about the effective stress validity in soil, concrete, and rock in order to reject some of these expressions, as well as clarify what expressions were appropriate according to several working hypotheses, such as stress-strain or strength behavior, saturated or non-saturated media, and rock, concrete or soil behavior. | In 1960, [[Alec Skempton]] carried out an extensive review of the available formulations and experimental data in the literature about the effective stress validity in soil, concrete, and rock in order to reject some of these expressions, as well as clarify what expressions were appropriate according to several working hypotheses, such as stress-strain or strength behavior, saturated or non-saturated media, and rock, concrete or soil behavior. | ||
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Surface [[exploration]] can include on-foot surveys, [[geological map]]ping, [[Exploration geophysics|geophysical methods]], and [[photogrammetry]]. Geological mapping and interpretation of [[geomorphology]] are typically completed in consultation with a [[geologist]] or [[engineering geologist]]. Subsurface exploration usually involves in-situ testing (for example, the [[standard penetration test]] and [[cone penetration test]]). The digging of test pits and trenching (particularly for locating [[Fault (geology)|faults]] and [[landslide|slide planes]]) may also be used to learn about soil conditions at depth. Large-diameter borings are rarely used due to safety concerns and expense. Still, they are sometimes used to allow a geologist or engineer to be lowered into the borehole for direct visual and manual examination of the soil and rock [[stratigraphy]]. | Surface [[exploration]] can include on-foot surveys, [[geological map]]ping, [[Exploration geophysics|geophysical methods]], and [[photogrammetry]]. Geological mapping and interpretation of [[geomorphology]] are typically completed in consultation with a [[geologist]] or [[engineering geologist]]. Subsurface exploration usually involves in-situ testing (for example, the [[standard penetration test]] and [[cone penetration test]]). The digging of test pits and trenching (particularly for locating [[Fault (geology)|faults]] and [[landslide|slide planes]]) may also be used to learn about soil conditions at depth. Large-diameter borings are rarely used due to safety concerns and expense. Still, they are sometimes used to allow a geologist or engineer to be lowered into the borehole for direct visual and manual examination of the soil and rock [[stratigraphy]]. | ||
Various [[Geotechnical investigation#Soil sampling|soil samplers]] exist to meet the needs of different engineering projects. The [[standard penetration test]], which uses a thick-walled split spoon sampler, is the most common way to collect disturbed samples. Piston samplers, employing a thin-walled tube, are most commonly used to collect less disturbed samples. More advanced methods, such as the Sherbrooke block sampler, are superior but expensive. Coring frozen ground provides high-quality undisturbed samples from ground conditions, such as fill, sand, [[moraine]], and rock fracture zones.<ref name="Coring frozen ground">{{cite web | url=https://www.geofrost.no/en/ground-investigations/#Undisturbed%20samples | title=Geofrost Coring | publisher=GEOFROST | access-date=20 November 2020}}</ref> | Various [[Geotechnical investigation#Soil sampling|soil samplers]] exist to meet the needs of different engineering projects. The [[standard penetration test]], which uses a thick-walled split spoon sampler, is the most common way to collect disturbed samples. Piston samplers, employing a thin-walled tube, are most commonly used to collect less disturbed samples. More advanced methods, such as the Sherbrooke block sampler, are superior but expensive. Coring frozen ground provides high-quality undisturbed samples from ground conditions, such as fill, sand, [[moraine]], and rock fracture zones.<ref name="Coring frozen ground">{{cite web | url=https://www.geofrost.no/en/ground-investigations/#Undisturbed%20samples | title=Geofrost Coring | publisher=GEOFROST | access-date=20 November 2020}}</ref> | ||
[[Geotechnical centrifuge modeling]] is another method of testing physical-scale models of geotechnical problems. The use of a centrifuge enhances the similarity of the scale model tests involving soil because soil's strength and [[stiffness]] are susceptible to the confining [[pressure]]. The [[Centrifugal force|centrifugal acceleration]] allows a researcher to obtain large (prototype-scale) stresses in small physical models. | [[Geotechnical centrifuge modeling]] is another method of testing physical-scale models of geotechnical problems. The use of a centrifuge enhances the similarity of the scale model tests involving soil because soil's strength and [[stiffness]] are susceptible to the confining [[pressure]]. The [[Centrifugal force|centrifugal acceleration]] allows a researcher to obtain large (prototype-scale) stresses in small physical models. | ||
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=== Foundation design === | === Foundation design === | ||
{{Main|Foundation (engineering)}} | {{Main|Foundation (engineering)}} | ||
The foundation of a structure's infrastructure transmits loads from the structure to the earth. Geotechnical [[engineer]]s design foundations based on the load characteristics of the structure and the properties of the soils and [[bedrock]] at the site. Generally, geotechnical engineers first estimate the magnitude and location of loads to be supported before developing an investigation plan to explore the subsurface and determine the necessary soil parameters through field and lab testing. Following this, they may begin the design of an engineering foundation. The primary considerations for a geotechnical engineer in foundation design are [[bearing capacity]], settlement, and ground movement beneath the foundations.<ref name="Han 2015">{{Cite book |last=Han |first=Jie |title=Principles and Practice of Ground Improvement |publisher=Wiley |year=2015 |isbn=9781118421307}}</ref> | The foundation of a structure's infrastructure transmits loads from the structure to the earth. Geotechnical [[engineer]]s design foundations based on the load characteristics of the structure and the properties of the soils and [[bedrock]] at the site. Generally, geotechnical engineers first estimate the magnitude and location of loads to be supported before developing an investigation plan to explore the subsurface and determine the necessary soil parameters through field and lab testing. Following this, they may begin the design of an engineering foundation. The primary considerations for a geotechnical engineer in foundation design are [[bearing capacity]], settlement, and ground movement beneath the foundations.<ref name="Han 2015">{{Cite book |last=Han |first=Jie |title=Principles and Practice of Ground Improvement |publisher=Wiley |year=2015 |isbn=9781118421307}}</ref> | ||
=== Earthworks === | === Earthworks === | ||
[[Image:Seabees compactor roller.jpg|thumb|A [[compactor]]/[[road roller|roller]] operated by U.S. Navy Seabees]] | [[Image:Seabees compactor roller.jpg|thumb|A [[compactor]]/[[road roller|roller]] operated by U.S. Navy Seabees]] | ||
{{See also|Earthworks (engineering)}}Geotechnical engineers are also involved in the planning and execution of [[Earthworks (engineering)|earthworks]], which include ground improvement,<ref name="Han 2015" /> slope stabilization, and slope stability analysis. | {{See also|Earthworks (engineering)}}Geotechnical engineers are also involved in the planning and execution of [[Earthworks (engineering)|earthworks]], which include ground improvement,<ref name="Han 2015" /> slope stabilization, and slope stability analysis. | ||
====Ground improvement==== | ====Ground improvement==== | ||
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====Slope stabilization==== | ====Slope stabilization==== | ||
{{Main|Slope stability}} | |||
[[Image:Slopslump2.jpg|thumb|upright=1.15|Simple slope slip section.]] | [[Image:Slopslump2.jpg|thumb|upright=1.15|Simple slope slip section.]] | ||
Geotechnical engineers can analyze and improve slope stability using engineering methods. Slope stability is determined by the balance of [[shear stress]] and [[shear strength (soil)|shear strength]]. A previously stable slope may be initially affected by various factors, making it unstable. Nonetheless, geotechnical engineers can design and implement engineered slopes to increase stability. | Geotechnical engineers can analyze and improve slope stability using engineering methods. Slope stability is determined by the balance of [[shear stress]] and [[shear strength (soil)|shear strength]]. A previously stable slope may be initially affected by various factors, making it unstable. Nonetheless, geotechnical engineers can design and implement engineered slopes to increase stability. | ||
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[[Image:Geocollage.JPG|thumb|upright=1.15|A collage of geosynthetic products.]] | [[Image:Geocollage.JPG|thumb|upright=1.15|A collage of geosynthetic products.]] | ||
[[Geosynthetics]] are a type of plastic [[polymer]] products used in geotechnical engineering that improve engineering performance while reducing costs. This includes [[geotextiles]], [[geogrids]], [[geomembranes]], [[geocells]], and [[geocomposites]]. The synthetic nature of the products make them suitable for use in the ground where high levels of durability are required. Their main functions include [[drainage]], [[filtration]], reinforcement, separation, and containment. | [[Geosynthetics]] are a type of plastic [[polymer]] products used in geotechnical engineering that improve engineering performance while reducing costs. This includes [[geotextiles]], [[geogrids]], [[geomembranes]], [[geocells]], and [[geocomposites]]. The synthetic nature of the products make them suitable for use in the ground where high levels of durability are required. Their main functions include [[drainage]], [[filtration]], reinforcement, separation, and containment. | ||
Geosynthetics are available in a wide range of forms and materials, each to suit a slightly different end-use, although they are frequently used together. Some reinforcement geosynthetics, such as geogrids and more recently, [[cellular confinement]] systems, have shown to improve bearing capacity, modulus factors and soil stiffness and strength.<ref>Hegde, A.M. and Palsule P.S. (2020), Performance of Geosynthetics Reinforced Subgrade Subjected to Repeated Vehicle Loads: Experimental and Numerical Studies. Front. Built Environ. 6:15. https://www.frontiersin.org/articles/10.3389/fbuil.2020.00015/full.</ref> These products have a wide range of applications and are currently used in many civil and geotechnical engineering applications including roads, airfields, railroads, [[Embankment (earthworks)|embankments]], piled embankments, retaining structures, [[reservoir]]s, canals, dams, [[landfill]]s, bank protection and coastal engineering.<ref>{{Cite book |last=Koerner |first=Robert M. |title=Designing with Geosynthetics |publisher=Xlibris |year=2012 |isbn=9781462882892 |edition=6th Edition, Vol. 1}}</ref> | Geosynthetics are available in a wide range of forms and materials, each to suit a slightly different end-use, although they are frequently used together. Some reinforcement geosynthetics, such as geogrids and more recently, [[cellular confinement]] systems, have shown to improve bearing capacity, modulus factors and soil stiffness and strength.<ref>Hegde, A.M. and Palsule P.S. (2020), Performance of Geosynthetics Reinforced Subgrade Subjected to Repeated Vehicle Loads: Experimental and Numerical Studies. Front. Built Environ. 6:15. https://www.frontiersin.org/articles/10.3389/fbuil.2020.00015/full.</ref> These products have a wide range of applications and are currently used in many civil and geotechnical engineering applications including roads, airfields, railroads, [[Embankment (earthworks)|embankments]], piled embankments, retaining structures, [[reservoir]]s, canals, dams, [[landfill]]s, bank protection and coastal engineering.<ref>{{Cite book |last=Koerner |first=Robert M. |title=Designing with Geosynthetics |publisher=Xlibris |year=2012 |isbn=9781462882892 |edition=6th Edition, Vol. 1}}</ref> | ||
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== See also == | == See also == | ||
{{ | {{Engineering side bar}} | ||
{{Div col|small=yes}} | {{Div col|small=yes}} | ||
* [[Civil engineering]] | * [[Civil engineering]] | ||
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* [[Soil science]] | * [[Soil science]] | ||
{{Div col end}} | {{Div col end}} | ||
==Notes== | ==Notes== | ||
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* Bates and Jackson, 1980, Glossary of Geology: American Geological Institute. | * Bates and Jackson, 1980, Glossary of Geology: American Geological Institute. | ||
* Krynine and Judd, 1957, Principles of Engineering Geology and Geotechnics: McGraw-Hill, New York. | * Krynine and Judd, 1957, Principles of Engineering Geology and Geotechnics: McGraw-Hill, New York. | ||
* Pierfranco Ventura, Fondazioni, Modellazioni: Verifiche Statiche e Sismiche Strutture-Terreni, vol. I, Milano Hoepli, 2019, pp.770, ISBN 978-88203-8644-3 | * Pierfranco Ventura, Fondazioni, Modellazioni: Verifiche Statiche e Sismiche Strutture-Terreni, vol. I, Milano Hoepli, 2019, pp. 770, ISBN 978-88203-8644-3 | ||
* Pierfranco Ventura, Fondazioni, Applicazioni: Verifiche Statiche e Sismiche Strutture-Terreni, vol. II | * Pierfranco Ventura, Fondazioni, Applicazioni: Verifiche Statiche e Sismiche Strutture-Terreni, vol. II, Milano, Hoepli, 2019, pp. 749, ISBN 978-88-203-8645-0 https://www.hoeplieditore.it/hoepli-catalogo/articolo/fondazioni-modellazioni-pierfrancventura/9788820386443/1451 | ||
{{Col-begin}} | {{Col-begin}} | ||
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{{Construction overview}} | {{Construction overview}} | ||
{{Authority control}} | {{Authority control}} | ||
[[Category:Geotechnical engineering| ]] | [[Category:Geotechnical engineering| ]] | ||