Dépouillements

Response of stiff piles in sand to long-term cyclic lateral loading / C. Leblanc in Géotechnique, Vol. 60 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 79–90 Titre : Response of stiff piles in sand to long-term cyclic lateral loading Type de document : texte imprimé Auteurs : C. Leblanc, Auteur ; Houlsby, G. T., Auteur ; B. W. Byrne, Auteur Année de publication : 2011 Article en page(s) : pp. 79–90 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Stiffness  Piles  Settlement  Repeated  loading  Laboratory  tests  Sands Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The driven monopile is currently the preferred foundation type for most offshore wind farms. While the static capacity of the monopile is important, a safe design must also address issues of accumulated rotation and changes in stiffness after long-term cyclic loading. Design guidance on this issue is limited. To address this, a series of laboratory tests were conducted where a stiff pile in drained sand was subjected to between 8000 and 60 000 cycles of combined moment and horizontal loading. A typical design for an offshore wind turbine monopile was used as a basis for the study, to ensure that pile dimensions and loading ranges were realistic. A complete non-dimensional framework for stiff piles in sand is presented, and applied to interpret the test results. The accumulated rotation was found to be dependent on relative density, and was strongly affected by the characteristics of the applied cyclic load. Particular loading characteristics were found to cause a significant increase in the accumulated rotation. The pile stiffness increased with number of cycles, which contrasts with the current methodology where static load–displacement curves are degraded to account for cyclic loading. Methods are presented to predict the change in stiffness and the accumulated rotation of a stiff pile due to long-term cyclic loading. The use of the methods developed is demonstrated for a typical full-scale monopile. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00196 [article] Response of stiff piles in sand to long-term cyclic lateral loading [texte imprimé] / C. Leblanc, Auteur ; Houlsby, G. T., Auteur ; B. W. Byrne, Auteur . - 2011 . - pp. 79–90. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 79–90 Mots-clés : Stiffness  Piles  Settlement  Repeated  loading  Laboratory  tests  Sands Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The driven monopile is currently the preferred foundation type for most offshore wind farms. While the static capacity of the monopile is important, a safe design must also address issues of accumulated rotation and changes in stiffness after long-term cyclic loading. Design guidance on this issue is limited. To address this, a series of laboratory tests were conducted where a stiff pile in drained sand was subjected to between 8000 and 60 000 cycles of combined moment and horizontal loading. A typical design for an offshore wind turbine monopile was used as a basis for the study, to ensure that pile dimensions and loading ranges were realistic. A complete non-dimensional framework for stiff piles in sand is presented, and applied to interpret the test results. The accumulated rotation was found to be dependent on relative density, and was strongly affected by the characteristics of the applied cyclic load. Particular loading characteristics were found to cause a significant increase in the accumulated rotation. The pile stiffness increased with number of cycles, which contrasts with the current methodology where static load–displacement curves are degraded to account for cyclic loading. Methods are presented to predict the change in stiffness and the accumulated rotation of a stiff pile due to long-term cyclic loading. The use of the methods developed is demonstrated for a typical full-scale monopile. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00196

Shear mechanisms and viscoplastic effects during impulsive shearing / G. Grelle in Géotechnique, Vol. 60 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 91–103 Titre : Shear mechanisms and viscoplastic effects during impulsive shearing Type de document : texte imprimé Auteurs : G. Grelle, Auteur ; M. Guadagno, Auteur Année de publication : 2011 Article en page(s) : pp. 91–103 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Viscoplastic  behaviour  Impulsive  shear  strength  Clays  Landslides Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : In clay formations, the co-seismic reactivation of pre-existing landslides involves dynamic shear actions on sliding surfaces characterised by attritive states. Impulsive shear motions were applied, after the attainment of the fully softened and residual conditions, by means of an appropriately modified ring-shear apparatus. The kinematics parameters that characterise shear motions are related to co-seismic displacements of rigid landslide bodies, as defined by Newmark's approach. The results of the tests, performed on clay samples with different index properties, highlight the influence of the initial spatial disposition of particles on the shear mechanisms. In addition, it seems that these mechanisms control both the inviscid and viscous components of the shear stress. For high shear rates, an increase of the viscous strength in the residual condition determines a greater viscoplastic strength than that in the fully softened condition. On this basis, different behaviours in seismically induced reactivation of landslides can be explained. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.019 [article] Shear mechanisms and viscoplastic effects during impulsive shearing [texte imprimé] / G. Grelle, Auteur ; M. Guadagno, Auteur . - 2011 . - pp. 91–103. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 91–103 Mots-clés : Viscoplastic  behaviour  Impulsive  shear  strength  Clays  Landslides Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : In clay formations, the co-seismic reactivation of pre-existing landslides involves dynamic shear actions on sliding surfaces characterised by attritive states. Impulsive shear motions were applied, after the attainment of the fully softened and residual conditions, by means of an appropriately modified ring-shear apparatus. The kinematics parameters that characterise shear motions are related to co-seismic displacements of rigid landslide bodies, as defined by Newmark's approach. The results of the tests, performed on clay samples with different index properties, highlight the influence of the initial spatial disposition of particles on the shear mechanisms. In addition, it seems that these mechanisms control both the inviscid and viscous components of the shear stress. For high shear rates, an increase of the viscous strength in the residual condition determines a greater viscoplastic strength than that in the fully softened condition. On this basis, different behaviours in seismically induced reactivation of landslides can be explained. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.019

Evolution of microstructure in compacted London Clay during wetting and loading / R. Monroy in Géotechnique, Vol. 60 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 105–119 Titre : Evolution of microstructure in compacted London Clay during wetting and loading Type de document : texte imprimé Auteurs : R. Monroy, Auteur ; L. Zdravkovic, Auteur ; A. Ridley, Auteur Année de publication : 2011 Article en page(s) : pp. 105–119 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Compaction  Partial  saturation  Laboratory  tests  Microscopy Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The influence of fabric on mechanical behaviour is explicitly considered in some of the current constitutive models for unsaturated soils. These are based on assumptions regarding the interaction between different levels of structure, which still require experimental validation. A study has been carried out to investigate the evolution of fabric in a compacted natural clay during wetting and loading, and the results are presented in this paper. Samples of London Clay were statically compacted to the same initial conditions, dry of optimum moisture content in a Proctor plot, and subsequently taken along complex stress paths involving wetting, loading, or a combination of both. Mercury intrusion porosimetry (MIP) and environmental scanning electron microscopy (ESEM) microstructure investigations were carried out to observe and quantify the change in fabric associated with each path. The soil fabric was observed to change from an aggregate to a matrix type structure along all wetting paths. This transition was found to take place only when the suction was reduced to a value close to zero kPa. Results also showed that fabric changes during yielding were stress path-dependent. It was not possible to find a correspondence between the volume of free porosity and the volume of intra-aggregate pores, as suggested by some authors. Finally, the volume of pore water was found to agree closely with the volume of intra-aggregate pores, providing support to the assumption that in an unsaturated aggregate microstructure the clay aggregations are saturated. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.125 [article] Evolution of microstructure in compacted London Clay during wetting and loading [texte imprimé] / R. Monroy, Auteur ; L. Zdravkovic, Auteur ; A. Ridley, Auteur . - 2011 . - pp. 105–119. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 105–119 Mots-clés : Compaction  Partial  saturation  Laboratory  tests  Microscopy Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The influence of fabric on mechanical behaviour is explicitly considered in some of the current constitutive models for unsaturated soils. These are based on assumptions regarding the interaction between different levels of structure, which still require experimental validation. A study has been carried out to investigate the evolution of fabric in a compacted natural clay during wetting and loading, and the results are presented in this paper. Samples of London Clay were statically compacted to the same initial conditions, dry of optimum moisture content in a Proctor plot, and subsequently taken along complex stress paths involving wetting, loading, or a combination of both. Mercury intrusion porosimetry (MIP) and environmental scanning electron microscopy (ESEM) microstructure investigations were carried out to observe and quantify the change in fabric associated with each path. The soil fabric was observed to change from an aggregate to a matrix type structure along all wetting paths. This transition was found to take place only when the suction was reduced to a value close to zero kPa. Results also showed that fabric changes during yielding were stress path-dependent. It was not possible to find a correspondence between the volume of free porosity and the volume of intra-aggregate pores, as suggested by some authors. Finally, the volume of pore water was found to agree closely with the volume of intra-aggregate pores, providing support to the assumption that in an unsaturated aggregate microstructure the clay aggregations are saturated. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.125

Physical modelling of pile penetration in clay using transparent soil and particle image velocimetry / Q. Ni in Géotechnique, Vol. 60 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 121–132 Titre : Physical modelling of pile penetration in clay using transparent soil and particle image velocimetry Type de document : texte imprimé Auteurs : Q. Ni, Auteur ; C. C. Hird, Auteur ; Guymer, I., Auteur Année de publication : 2011 Article en page(s) : pp. 121–132 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Clays  Model  tests  Deformation  Piles Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A small-scale physical modelling method was developed to study the movement of clay during pile installation. The clay was simulated using a mixture of amorphous silica and mineral oil, which becomes almost transparent when the refractive indices of the oil and the silica are well matched. After adding reflective particles and consolidating the mixture in a transparent container, cylindrical model piles were driven vertically at the centre. A vertical section aligned with the pile centreline was illuminated by a laser light sheet, and a sequence of digital images was recorded. These were analysed using particle image velocimetry, and the complete displacement distribution during the pile installation was obtained. Notwithstanding some discrepancies at shallow depths, the observed displacements generally showed fairly good agreement with the theoretical predictions of the shallow strain path method (SSPM) once the effect of some soil trapped beneath the flat pile tip was taken into account. Normalisation of the horizontal and vertical components of movement employing both the pile length and radius, based on SSPM theory, was shown to be valid. The normalised vertical displacement contours were similar to those published by previous researchers. The results of this study could be used to assess the impact of disturbance due to pile installation on, for example, buried services or archaeology. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.052 [article] Physical modelling of pile penetration in clay using transparent soil and particle image velocimetry [texte imprimé] / Q. Ni, Auteur ; C. C. Hird, Auteur ; Guymer, I., Auteur . - 2011 . - pp. 121–132. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 121–132 Mots-clés : Clays  Model  tests  Deformation  Piles Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A small-scale physical modelling method was developed to study the movement of clay during pile installation. The clay was simulated using a mixture of amorphous silica and mineral oil, which becomes almost transparent when the refractive indices of the oil and the silica are well matched. After adding reflective particles and consolidating the mixture in a transparent container, cylindrical model piles were driven vertically at the centre. A vertical section aligned with the pile centreline was illuminated by a laser light sheet, and a sequence of digital images was recorded. These were analysed using particle image velocimetry, and the complete displacement distribution during the pile installation was obtained. Notwithstanding some discrepancies at shallow depths, the observed displacements generally showed fairly good agreement with the theoretical predictions of the shallow strain path method (SSPM) once the effect of some soil trapped beneath the flat pile tip was taken into account. Normalisation of the horizontal and vertical components of movement employing both the pile length and radius, based on SSPM theory, was shown to be valid. The normalised vertical displacement contours were similar to those published by previous researchers. The results of this study could be used to assess the impact of disturbance due to pile installation on, for example, buried services or archaeology. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.052

A comparison of critical state models for sand under conditions of axial symmetry / A. R. Russell in Géotechnique, Vol. 60 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 133–140 Titre : A comparison of critical state models for sand under conditions of axial symmetry Type de document : texte imprimé Auteurs : A. R. Russell, Auteur ; D. Muir Wood, Auteur Année de publication : 2011 Article en page(s) : pp. 133–140 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Sands  Constitutive  relations  Elasticity  Plasticity  Stiffness  Numerical  modelling  and  analysis Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Three constitutive models constructed within the spirit of critical state soil mechanics are summarised and compared under conditions of axial symmetry. The models have been calibrated using drained and undrained triaxial compression tests on Hostun sand. The quality of the individual simulations is strongly influenced by the shape chosen for the critical state line at high stresses. Stress response envelopes have been produced in order to contrast the incremental stiffnesses that the models predict for stress and strain paths other than those used for simulation. Plots of second-order work have also been presented for each model. Negative second-order work for certain strain paths indicates the potential for instability and bifurcation of response. Non-associated flow is a basic feature of these models and potentially unstable states were found to occur at mobilised friction angles lower than the peak of the stress–strain response. The hardening moduli of the models are similar, even though they were developed from different starting assumptions. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/search?value1='sands'&option1=fulltext [article] A comparison of critical state models for sand under conditions of axial symmetry [texte imprimé] / A. R. Russell, Auteur ; D. Muir Wood, Auteur . - 2011 . - pp. 133–140. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 133–140 Mots-clés : Sands  Constitutive  relations  Elasticity  Plasticity  Stiffness  Numerical  modelling  and  analysis Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Three constitutive models constructed within the spirit of critical state soil mechanics are summarised and compared under conditions of axial symmetry. The models have been calibrated using drained and undrained triaxial compression tests on Hostun sand. The quality of the individual simulations is strongly influenced by the shape chosen for the critical state line at high stresses. Stress response envelopes have been produced in order to contrast the incremental stiffnesses that the models predict for stress and strain paths other than those used for simulation. Plots of second-order work have also been presented for each model. Negative second-order work for certain strain paths indicates the potential for instability and bifurcation of response. Non-associated flow is a basic feature of these models and potentially unstable states were found to occur at mobilised friction angles lower than the peak of the stress–strain response. The hardening moduli of the models are similar, even though they were developed from different starting assumptions. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/search?value1='sands'&option1=fulltext

Analytical and combined numerical methods evaluating pore water pressure on tunnels / J. H. Shin in Géotechnique, Vol. 60 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 141–145 Titre : Analytical and combined numerical methods evaluating pore water pressure on tunnels Type de document : texte imprimé Auteurs : J. H. Shin, Auteur Année de publication : 2011 Article en page(s) : pp. 141–145 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Tunnels  Numerical  modelling  Pore  pressure  Groundwater Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : One of the main issues in tunnel maintenance is the hydraulic deterioration of the drainage system. In this study, simple methods to evaluate pore water pressures on existing tunnels were proposed. The methods involve an indirect and non-destructive approach while providing a convenient and easy method to evaluate the residual pore water pressure on the lining. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.t.035 [article] Analytical and combined numerical methods evaluating pore water pressure on tunnels [texte imprimé] / J. H. Shin, Auteur . - 2011 . - pp. 141–145. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 2 (Fevrier 2010) . - pp. 141–145 Mots-clés : Tunnels  Numerical  modelling  Pore  pressure  Groundwater Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : One of the main issues in tunnel maintenance is the hydraulic deterioration of the drainage system. In this study, simple methods to evaluate pore water pressures on existing tunnels were proposed. The methods involve an indirect and non-destructive approach while providing a convenient and easy method to evaluate the residual pore water pressure on the lining. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.t.035

Exemplaires

Bibliothèque Ecole Nationale Polytechnique d'Alger

Accueil

Se connecter

Météo

Adresse