Dépouillements

The influence of intense fissuring on the mechanical behaviour of clays / C. Vitone in Géotechnique, Vol. 61 N° 12 (Décembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1003–1018 Titre : The influence of intense fissuring on the mechanical behaviour of clays Type de document : texte imprimé Auteurs : C. Vitone, Auteur ; F. Cotecchia, Auteur Année de publication : 2012 Article en page(s) : pp. 1003–1018 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Laboratory  tests  Fabric/structure  of  soils  Constitutive  relation  Compressibility  Soil  classification  Clays  Shear  strength Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The paper discusses the geological history, intrinsic properties, structural features and mechanical behaviour of three differently fissured clays outcropping within the Apennine chain in southern Italy. Based on a large experimental database, the mechanical behaviour of the clays is investigated in the light of their different fissuring features, which have been distinguished and characterised by means of a new chart. The study assumed the soil to be a continuum, despite the different fissuring features of the clay fabric. Therefore laboratory tests were carried out on both natural and reconstituted clay samples, and the results were compared with those recognised in the literature to be typical of unfissured sensitive clays. Based on these comparisons, a behavioural framework is proposed for clays possessing certain fissure structures. The results of the analysis show that the mini- to mesostructure of clays of fissuring intensity I5–I6 can be modelled as part of the structure variable controlling the clay behaviour. Where the structure variable refers solely to the micro scale for unfissured homogeneous clays, for fissured clays I5–I6 it spans from the micro to the meso scale. As for the microstructure of unfissured clays, this micro- to mesostructure influences the soil response as an internal state variable in addition to specific volume in controlling the mechanical response. In particular, it appears that for clays of fissuring intensity I5–I6, structure is detrimental to strength, so that the material is even weaker than the reconstituted clay. DEWEY : 624 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.005 [article] The influence of intense fissuring on the mechanical behaviour of clays [texte imprimé] / C. Vitone, Auteur ; F. Cotecchia, Auteur . - 2012 . - pp. 1003–1018. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1003–1018 Mots-clés : Laboratory  tests  Fabric/structure  of  soils  Constitutive  relation  Compressibility  Soil  classification  Clays  Shear  strength Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The paper discusses the geological history, intrinsic properties, structural features and mechanical behaviour of three differently fissured clays outcropping within the Apennine chain in southern Italy. Based on a large experimental database, the mechanical behaviour of the clays is investigated in the light of their different fissuring features, which have been distinguished and characterised by means of a new chart. The study assumed the soil to be a continuum, despite the different fissuring features of the clay fabric. Therefore laboratory tests were carried out on both natural and reconstituted clay samples, and the results were compared with those recognised in the literature to be typical of unfissured sensitive clays. Based on these comparisons, a behavioural framework is proposed for clays possessing certain fissure structures. The results of the analysis show that the mini- to mesostructure of clays of fissuring intensity I5–I6 can be modelled as part of the structure variable controlling the clay behaviour. Where the structure variable refers solely to the micro scale for unfissured homogeneous clays, for fissured clays I5–I6 it spans from the micro to the meso scale. As for the microstructure of unfissured clays, this micro- to mesostructure influences the soil response as an internal state variable in addition to specific volume in controlling the mechanical response. In particular, it appears that for clays of fissuring intensity I5–I6, structure is detrimental to strength, so that the material is even weaker than the reconstituted clay. DEWEY : 624 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.005

Effects of soil density and earthquake intensity on flow deformation of the upper San Fernando dam / H. Y. Ming in Géotechnique, Vol. 61 N° 12 (Décembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1019–1034 Titre : Effects of soil density and earthquake intensity on flow deformation of the upper San Fernando dam Type de document : texte imprimé Auteurs : H. Y. Ming, Auteur ; X.S. Li, Auteur ; T. Y. Zheng, Auteur Année de publication : 2012 Article en page(s) : pp. 1019–1034 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Numerical  modelling  Earthquakes  Dynamics  Embankments  Liquefaction  Deformation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The seismic performance of the upper San Fernando dam is systematically studied by using a fully coupled finite-element procedure in conjunction with a unified state-dependent dilatancy sand model. With detailed information produced by this procedure, the effects of soil density and earthquake intensity on flow deformation of the embankment are examined. This paper provides convincing numerical evidence to prove that even though stronger earthquakes always produce larger deformation in the Upper San Fernando dam, an earthquake serves mainly as a trigger to initiate flow liquefaction. Once flow liquefaction is triggered by a sufficiently strong earthquake, the earthquake-induced flow deformation is controlled dominantly by the difference between the shear stress required for equilibrium and the shear strength of the liquefied soil, which is determined by its density under undrained earthquake loading conditions. The influence of the intensity of the earthquake itself on flow deformation of the embankment becomes secondary. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.004.3682 [article] Effects of soil density and earthquake intensity on flow deformation of the upper San Fernando dam [texte imprimé] / H. Y. Ming, Auteur ; X.S. Li, Auteur ; T. Y. Zheng, Auteur . - 2012 . - pp. 1019–1034. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1019–1034 Mots-clés : Numerical  modelling  Earthquakes  Dynamics  Embankments  Liquefaction  Deformation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The seismic performance of the upper San Fernando dam is systematically studied by using a fully coupled finite-element procedure in conjunction with a unified state-dependent dilatancy sand model. With detailed information produced by this procedure, the effects of soil density and earthquake intensity on flow deformation of the embankment are examined. This paper provides convincing numerical evidence to prove that even though stronger earthquakes always produce larger deformation in the Upper San Fernando dam, an earthquake serves mainly as a trigger to initiate flow liquefaction. Once flow liquefaction is triggered by a sufficiently strong earthquake, the earthquake-induced flow deformation is controlled dominantly by the difference between the shear stress required for equilibrium and the shear strength of the liquefied soil, which is determined by its density under undrained earthquake loading conditions. The influence of the intensity of the earthquake itself on flow deformation of the embankment becomes secondary. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.004.3682

The mechanism of steady friction between seabed pipelines and clay soils / D. J. White in Géotechnique, Vol. 61 N° 12 (Décembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1035–1041 Titre : The mechanism of steady friction between seabed pipelines and clay soils Type de document : texte imprimé Auteurs : D. J. White, Auteur ; H. R. C. Dingle, Auteur Année de publication : 2012 Article en page(s) : pp. 1035–1041 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Failure  Theoretical  analysis  Offshore  engineering  Pipelines  Clays  Centrifuge  modelling Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The large-amplitude lateral soil resistance between an on-bottom pipeline and the seabed is an important design parameter in assessing pipeline behaviour during lateral thermal buckling or under the impact of a submarine slide. This paper describes a series of centrifuge model tests that shed light on the underlying behaviour during large-amplitude lateral pipe movement. It is shown that at large displacements the lateral response is governed predominantly by the passive resistance of the growing berm of soil ahead of the pipe. Using a new analysis of this growing soil berm, based on conservation of volume, the ‘local' embedment of the pipe relative to the top of the idealised soil berm is defined. In this way, the normalised lateral pipe–soil resistance, H/s u D, from tests encompassing a range of pipe weights and initial embedments follows a single trend line. This idealisation of the response is more consistent than the usual terminology of a pipe–soil friction factor. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.t.036 [article] The mechanism of steady friction between seabed pipelines and clay soils [texte imprimé] / D. J. White, Auteur ; H. R. C. Dingle, Auteur . - 2012 . - pp. 1035–1041. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1035–1041 Mots-clés : Failure  Theoretical  analysis  Offshore  engineering  Pipelines  Clays  Centrifuge  modelling Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The large-amplitude lateral soil resistance between an on-bottom pipeline and the seabed is an important design parameter in assessing pipeline behaviour during lateral thermal buckling or under the impact of a submarine slide. This paper describes a series of centrifuge model tests that shed light on the underlying behaviour during large-amplitude lateral pipe movement. It is shown that at large displacements the lateral response is governed predominantly by the passive resistance of the growing berm of soil ahead of the pipe. Using a new analysis of this growing soil berm, based on conservation of volume, the ‘local' embedment of the pipe relative to the top of the idealised soil berm is defined. In this way, the normalised lateral pipe–soil resistance, H/s u D, from tests encompassing a range of pipe weights and initial embedments follows a single trend line. This idealisation of the response is more consistent than the usual terminology of a pipe–soil friction factor. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.t.036

Investigation of the potential of bottom water jetting to ease spudcan extraction in soft clay / C. Gaudin in Géotechnique, Vol. 61 N° 12 (Décembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1043–1054 Titre : Investigation of the potential of bottom water jetting to ease spudcan extraction in soft clay Type de document : texte imprimé Auteurs : C. Gaudin, Auteur ; B. Bienen, Auteur ; M. J. Cassidy, Auteur Année de publication : 2012 Article en page(s) : pp. 1043–1054 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Centrifuge  modelling  Suction  Clays  Water  flow  Offshore  engineering  Consolidation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Retrieval of jack-up rigs at the end of their operations is common practice in the offshore industry, notably to move the rigs to another drilling location. In some cases the process is difficult, time consuming and costly, because the high extraction resistance on the jack-up's spudcan footings can exceed the capacity of the rig to pull. This is particularly the case in soft clay, where significant suction is developed at the spudcan invert. The main option available to operators to ease the spudcan extraction resistance is to use a jetting system at the spudcan invert to attempt to break the suction generated. However, there is a general consensus within the offshore industry that jetting systems, under their current configurations, have a limited efficiency. Centrifuge experiments have been performed at the University of Western Australia in order to understand the mechanisms taking place during jetting extraction, and to provide recommendations to optimise the jetting performance. A reduced-scale spudcan model simulating a 17·11 m diameter prototype spudcan with jets has been tested at 200 times the acceleration of Earth's gravity (known as 200g). It was extracted from penetrations of up to 1·5 diameters in normally consolidated clay at variable extraction rates and variable jetting flow rates. Measurements of the generated suction and the total extraction resistance after a preloading period have provided insight into the extraction mechanisms with jetting. The study has demonstrated that jetting can lead to significant reduction in extraction resistance, provided that the extraction rate is fast enough to ensure undrained extraction, and that a sufficiently high flow rate is applied with respect to the extraction rate. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.152 [article] Investigation of the potential of bottom water jetting to ease spudcan extraction in soft clay [texte imprimé] / C. Gaudin, Auteur ; B. Bienen, Auteur ; M. J. Cassidy, Auteur . - 2012 . - pp. 1043–1054. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1043–1054 Mots-clés : Centrifuge  modelling  Suction  Clays  Water  flow  Offshore  engineering  Consolidation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Retrieval of jack-up rigs at the end of their operations is common practice in the offshore industry, notably to move the rigs to another drilling location. In some cases the process is difficult, time consuming and costly, because the high extraction resistance on the jack-up's spudcan footings can exceed the capacity of the rig to pull. This is particularly the case in soft clay, where significant suction is developed at the spudcan invert. The main option available to operators to ease the spudcan extraction resistance is to use a jetting system at the spudcan invert to attempt to break the suction generated. However, there is a general consensus within the offshore industry that jetting systems, under their current configurations, have a limited efficiency. Centrifuge experiments have been performed at the University of Western Australia in order to understand the mechanisms taking place during jetting extraction, and to provide recommendations to optimise the jetting performance. A reduced-scale spudcan model simulating a 17·11 m diameter prototype spudcan with jets has been tested at 200 times the acceleration of Earth's gravity (known as 200g). It was extracted from penetrations of up to 1·5 diameters in normally consolidated clay at variable extraction rates and variable jetting flow rates. Measurements of the generated suction and the total extraction resistance after a preloading period have provided insight into the extraction mechanisms with jetting. The study has demonstrated that jetting can lead to significant reduction in extraction resistance, provided that the extraction rate is fast enough to ensure undrained extraction, and that a sufficiently high flow rate is applied with respect to the extraction rate. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.152

A centrifuge study on the effect of embedment on the drained response of shallow foundations under combined loading / L. Govoni in Géotechnique, Vol. 61 N° 12 (Décembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1055–1068 Titre : A centrifuge study on the effect of embedment on the drained response of shallow foundations under combined loading Type de document : texte imprimé Auteurs : L. Govoni, Auteur ; S. Gourvenec, Auteur ; G. Gottardi, Auteur Année de publication : 2012 Article en page(s) : pp. 1055–1068 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Bearing  capacity  Footings/foundations  Centrifuge  modelling  Plasticity  Settlement Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Drum centrifuge tests with surface and buried circular footings on medium dense silica sand subjected to planar combined loading are reported. The experimental work specifically addresses the effect of the footing embedment within a work-hardening plasticity approach, which to date has been used predominantly for interpretation of the behaviour of small-scale models of surface foundations. Vertical loading and swipe tests were carried out, and results are compared with existing data from similar studies on small-scale 1g foundation models. The overall trend of the centrifuge results confirms the general framework, suggesting that a work-hardening plasticity approach in terms of force-resultant modelling for the soil–footing system (the so-called ‘macro-element') applies under properly scaled stress conditions. The data also indicate that the traditional assumption of a yield surface, isotropically expanding with increasing vertical penetration is not suitable for an embedded foundation. An enhancement of the existing yield surface formulation enables generalisation of the existing work-hardening models from surface to embedded footings. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00109 [article] A centrifuge study on the effect of embedment on the drained response of shallow foundations under combined loading [texte imprimé] / L. Govoni, Auteur ; S. Gourvenec, Auteur ; G. Gottardi, Auteur . - 2012 . - pp. 1055–1068. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1055–1068 Mots-clés : Bearing  capacity  Footings/foundations  Centrifuge  modelling  Plasticity  Settlement Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Drum centrifuge tests with surface and buried circular footings on medium dense silica sand subjected to planar combined loading are reported. The experimental work specifically addresses the effect of the footing embedment within a work-hardening plasticity approach, which to date has been used predominantly for interpretation of the behaviour of small-scale models of surface foundations. Vertical loading and swipe tests were carried out, and results are compared with existing data from similar studies on small-scale 1g foundation models. The overall trend of the centrifuge results confirms the general framework, suggesting that a work-hardening plasticity approach in terms of force-resultant modelling for the soil–footing system (the so-called ‘macro-element') applies under properly scaled stress conditions. The data also indicate that the traditional assumption of a yield surface, isotropically expanding with increasing vertical penetration is not suitable for an embedded foundation. An enhancement of the existing yield surface formulation enables generalisation of the existing work-hardening models from surface to embedded footings. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00109

Stability and strength analysis of leaning towers / M. Marchi in Géotechnique, Vol. 61 N° 12 (Décembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1069–1079 Titre : Stability and strength analysis of leaning towers Type de document : texte imprimé Auteurs : M. Marchi, Auteur ; R. Butterfield, Auteur ; G. Gottardi, Auteur Année de publication : 2012 Article en page(s) : pp. 1069–1079 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Plasticity  Failure  Stiffness  Soil/structure  interaction  Footings/foundations  Creep  Bearing  capacity Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Many ancient towers are afflicted by stability problems. Shallow foundations are typical components of such structures, and their behaviour strongly influences the overall safety of the tower. This paper is concerned with two major, geotechnically related, failure modes of tower foundations: (a) bearing capacity failure, due to lack of strength of the supporting soil; and (b) instability of equilibrium, due to lack of foundation stiffness. Both of these hazards are tackled in a unified way in the paper, using a strain-hardening plasticity model for shallow footings from which a non-linear rotational stiffness (moment–rotation curve) for the soil–foundation system can be derived. The stability of equilibrium analysis is augmented by the inclusion of rotational creep, which is new, and an important feature of the behaviour of real towers. The practical utility of the analysis resides in its simplicity, input parameters being derived from conventional geotechnical data. The analysis provides not only a complete framework within which both failure mechanisms can be assessed but also a prediction of which of them is eventually most likely to be critical. The methodology is demonstrated in relation to the Pisa Tower. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.054 [article] Stability and strength analysis of leaning towers [texte imprimé] / M. Marchi, Auteur ; R. Butterfield, Auteur ; G. Gottardi, Auteur . - 2012 . - pp. 1069–1079. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1069–1079 Mots-clés : Plasticity  Failure  Stiffness  Soil/structure  interaction  Footings/foundations  Creep  Bearing  capacity Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Many ancient towers are afflicted by stability problems. Shallow foundations are typical components of such structures, and their behaviour strongly influences the overall safety of the tower. This paper is concerned with two major, geotechnically related, failure modes of tower foundations: (a) bearing capacity failure, due to lack of strength of the supporting soil; and (b) instability of equilibrium, due to lack of foundation stiffness. Both of these hazards are tackled in a unified way in the paper, using a strain-hardening plasticity model for shallow footings from which a non-linear rotational stiffness (moment–rotation curve) for the soil–foundation system can be derived. The stability of equilibrium analysis is augmented by the inclusion of rotational creep, which is new, and an important feature of the behaviour of real towers. The practical utility of the analysis resides in its simplicity, input parameters being derived from conventional geotechnical data. The analysis provides not only a complete framework within which both failure mechanisms can be assessed but also a prediction of which of them is eventually most likely to be critical. The methodology is demonstrated in relation to the Pisa Tower. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.054

Influence of temperature on the permeability of rocks / A. Kozusnikova in Géotechnique, Vol. 61 N° 12 (Décembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1081–1085 Titre : Influence of temperature on the permeability of rocks Type de document : texte imprimé Auteurs : A. Kozusnikova, Auteur ; P. Konecny, Auteur Année de publication : 2012 Article en page(s) : pp. 1081–1085 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Permeability  Temperature  effects  Rocks/rock  mechanics Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Changes in physical properties due to temperature increase have been investigated for three generically different types of rock: marble, sandstone and granite. The Hg-porosity and permeability of the rocks were analysed. The permeability of the specimens was determined during axial loading at a constant triaxial state of stress. Greater permeability changes were registered for rocks with compact structure and low porosity. These types of rock are characterised by line contacts between the grains. They are more sensitive to temperature increase; pores with a radius greater than 500 nm increase due to the temperature influence, with the permeability increasing considerably. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.t.034 [article] Influence of temperature on the permeability of rocks [texte imprimé] / A. Kozusnikova, Auteur ; P. Konecny, Auteur . - 2012 . - pp. 1081–1085. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1081–1085 Mots-clés : Permeability  Temperature  effects  Rocks/rock  mechanics Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Changes in physical properties due to temperature increase have been investigated for three generically different types of rock: marble, sandstone and granite. The Hg-porosity and permeability of the rocks were analysed. The permeability of the specimens was determined during axial loading at a constant triaxial state of stress. Greater permeability changes were registered for rocks with compact structure and low porosity. These types of rock are characterised by line contacts between the grains. They are more sensitive to temperature increase; pores with a radius greater than 500 nm increase due to the temperature influence, with the permeability increasing considerably. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.t.034

Relating the maximum radial stress on pile shaft to pile base resistance / J. Yang in Géotechnique, Vol. 61 N° 12 (Décembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1087–1092 Titre : Relating the maximum radial stress on pile shaft to pile base resistance Type de document : texte imprimé Auteurs : J. Yang, Auteur ; F. Mu, Auteur Année de publication : 2012 Article en page(s) : pp. 1087–1092 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Piles  Bearing  capacity  Sands  stiffness  Compressibility Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An approximate analytic relationship is developed between the maximum radial stress on the shaft of a displacement pile in sand and the base resistance of the pile. Using the cavity expansion analogy, together with a confined failure mechanism, the ratio between the two quantities, defined as a factor S t, is established as a function of the friction angle, shear stiffness, compressibility and mean effective stress of the sand near the pile tip. It is shown that, given otherwise identical input parameters, the value of S t will decrease with increasing friction angle, and with decreasing mean stress level. It also tends to decrease with an increase in relative density. It is predicted that S t has typical values between 0·03 and 0·05, in broad agreement with the range of empirically derived values in the literature. The relationship also predicts that S t may take much higher values (∼0·1) for piles installed in dense sand or in highly compressible sand. Because of the analytical nature, the established relationship provides useful insights into the mechanisms involved and important implications for design practice. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.10.t.006 [article] Relating the maximum radial stress on pile shaft to pile base resistance [texte imprimé] / J. Yang, Auteur ; F. Mu, Auteur . - 2012 . - pp. 1087–1092. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 12 (Décembre 2011) . - pp. 1087–1092 Mots-clés : Piles  Bearing  capacity  Sands  stiffness  Compressibility Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An approximate analytic relationship is developed between the maximum radial stress on the shaft of a displacement pile in sand and the base resistance of the pile. Using the cavity expansion analogy, together with a confined failure mechanism, the ratio between the two quantities, defined as a factor S t, is established as a function of the friction angle, shear stiffness, compressibility and mean effective stress of the sand near the pile tip. It is shown that, given otherwise identical input parameters, the value of S t will decrease with increasing friction angle, and with decreasing mean stress level. It also tends to decrease with an increase in relative density. It is predicted that S t has typical values between 0·03 and 0·05, in broad agreement with the range of empirically derived values in the literature. The relationship also predicts that S t may take much higher values (∼0·1) for piles installed in dense sand or in highly compressible sand. Because of the analytical nature, the established relationship provides useful insights into the mechanisms involved and important implications for design practice. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.10.t.006

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