Dépouillements

Deep-penetrating spudcan foundations on layered clays / M. S. Hossain in Géotechnique, Vol. 60 N° 3 (Mars 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp.157–170 Titre : Deep-penetrating spudcan foundations on layered clays : centrifuge tests Type de document : texte imprimé Auteurs : M. S. Hossain, Auteur ; M. F. Randolph, Auteur Année de publication : 2011 Article en page(s) : pp.157–170 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Bearing  capacity  Offshore  engineering  Footings/foundations  Centrifuge  modelling  Failure  Clays Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Installation of independent-legged jack-up rigs in sea-bed sediments where a strong layer overlays weaker soil can lead to catastrophic ‘punch-through', with potential leg buckling or toppling of the unit. Although approximate methods of analysis exist for estimating the penetration resistance, these do not account for the distortion of the upper layer as it punches through into the lower layer and there has been only limited visual depiction of the failure mechanism that occurs for the case of strong clay overlying weaker soil. This paper reports results of centrifuge model tests undertaken to provide insight into spudcan foundation behaviour during undrained vertical penetration through a stronger clay layer into weaker material, varying the strength ratio between lower and upper soil layers, the thickness of the upper layer relative to the spudcan diameter and the strength gradient of the lower layer. The model tests included half-spudcan tests against a transparent window, allowing the soil flow to be captured continuously by a digital camera and subsequently quantified through particle image velocimetry (PIV) analysis, and separate full-spudcan tests to measure the penetration resistance. Four interesting aspects of the soil flow mechanisms were identified: (a) vertically downwards motion of the soil and consequent deformation of the layer interface; (b) trapping of the stronger material beneath the spudcan, with this material being carried down into the underlying soft layer; (c) delayed back-flow of soil around the spudcan into the cavity formed above the spudcan; (d) eventual localised flow around the embedded spudcan. The effect of normalised layer soil properties and geometry on the soil flow mechanisms and the form of the penetration resistance profile is discussed in the context of the likelihood and severity of punch-through failure. Typical critical failure modes involved punching shear, with clear shear planes in the shape of a truncated cone forming in the upper layer below the spudcan. Potential punch-through, with a peak in penetration resistance followed by some reduction, occurred for almost all cases investigated. The reduction in resistance became more severe as the strength ratio of the underlying layer to the upper layer reduced, and also as the upper layer thickness increased. The failure modes assumed by the currently available recommended practices are not consistent with those observed from the study, suggesting a more rational approach is needed. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.039 [article] Deep-penetrating spudcan foundations on layered clays : centrifuge tests [texte imprimé] / M. S. Hossain, Auteur ; M. F. Randolph, Auteur . - 2011 . - pp.157–170. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp.157–170 Mots-clés : Bearing  capacity  Offshore  engineering  Footings/foundations  Centrifuge  modelling  Failure  Clays Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Installation of independent-legged jack-up rigs in sea-bed sediments where a strong layer overlays weaker soil can lead to catastrophic ‘punch-through', with potential leg buckling or toppling of the unit. Although approximate methods of analysis exist for estimating the penetration resistance, these do not account for the distortion of the upper layer as it punches through into the lower layer and there has been only limited visual depiction of the failure mechanism that occurs for the case of strong clay overlying weaker soil. This paper reports results of centrifuge model tests undertaken to provide insight into spudcan foundation behaviour during undrained vertical penetration through a stronger clay layer into weaker material, varying the strength ratio between lower and upper soil layers, the thickness of the upper layer relative to the spudcan diameter and the strength gradient of the lower layer. The model tests included half-spudcan tests against a transparent window, allowing the soil flow to be captured continuously by a digital camera and subsequently quantified through particle image velocimetry (PIV) analysis, and separate full-spudcan tests to measure the penetration resistance. Four interesting aspects of the soil flow mechanisms were identified: (a) vertically downwards motion of the soil and consequent deformation of the layer interface; (b) trapping of the stronger material beneath the spudcan, with this material being carried down into the underlying soft layer; (c) delayed back-flow of soil around the spudcan into the cavity formed above the spudcan; (d) eventual localised flow around the embedded spudcan. The effect of normalised layer soil properties and geometry on the soil flow mechanisms and the form of the penetration resistance profile is discussed in the context of the likelihood and severity of punch-through failure. Typical critical failure modes involved punching shear, with clear shear planes in the shape of a truncated cone forming in the upper layer below the spudcan. Potential punch-through, with a peak in penetration resistance followed by some reduction, occurred for almost all cases investigated. The reduction in resistance became more severe as the strength ratio of the underlying layer to the upper layer reduced, and also as the upper layer thickness increased. The failure modes assumed by the currently available recommended practices are not consistent with those observed from the study, suggesting a more rational approach is needed. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.039

Deep-penetrating spudcan foundations on layered clays / M. S. Hossain in Géotechnique, Vol. 60 N° 3 (Mars 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 171–184 Titre : Deep-penetrating spudcan foundations on layered clays : numerical analysis Type de document : texte imprimé Auteurs : M. S. Hossain, Auteur ; M. F. Randolph, Auteur Année de publication : 2011 Article en page(s) : pp. 171–184 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Offshore  engineering  Numerical  modelling  Bearing  capacity  Footings/foundations  Failure  Clays Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper presents results of large deformation finite element (LDFE) analyses that investigate the penetration response of deep-penetrating spudcan foundations in stratified soil comprising a strong clay layer overlying weaker clay. Such strength profiles give rise to potential punch-through failure, with a local maximum penetration resistance followed by some reduction. The paper is a companion paper to one that presents results from centrifuge model tests of the same problem, with the overall aim being to investigate the potential for punch-through failure and its severity, as a basis for improving design methods for evaluating spudcan penetration. The LDFE analyses have simulated continuous penetration of smooth and rough spudcan foundations from the sea-bed surface. A detailed parametric study has been undertaken, exploring the relevant range of layer thickness (relative to the spudcan diameter), strength ratios and spudcan base roughness. The results have been validated against previously published results and the centrifuge test data presented in a companion paper. Excellent agreement was obtained between the results from LDFE analyses and centrifuge tests. As the ratio of the shear strength of the bottom layer to that of the top layer decreased, upwards soil flow around the spudcan shoulder became less pronounced and the failure mechanism was dominated by a steep-sided plug of soil from the top layer being forced deep into the lower layer. The potential for severe punch-through was demonstrated by a significant reduction in the resistance profile as the spudcan approached the interface between the two layers. A preliminary design chart is proposed to estimate the cavity depth above the penetrating spudcan, which was significantly greater than that for a single layer clay. The penetration responses have been presented in terms of profiles of normalised net bearing pressure for a range of layer geometries and soil properties. Potential punch-through occurred for all cases where the strength ratio was less than or equal to 0·6, with the reduction in resistance being greater the lower the strength ratio of the underlying layer to the upper layer, and the thicker the upper layer, but reducing as the strength gradient in the lower layer increased. The current approach suggested in offshore design guidelines is shown to underestimate the penetration resistance significantly, in most cases, and give poor estimates of the likelihood and severity of spudcan punch-through. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.040 [article] Deep-penetrating spudcan foundations on layered clays : numerical analysis [texte imprimé] / M. S. Hossain, Auteur ; M. F. Randolph, Auteur . - 2011 . - pp. 171–184. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 171–184 Mots-clés : Offshore  engineering  Numerical  modelling  Bearing  capacity  Footings/foundations  Failure  Clays Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper presents results of large deformation finite element (LDFE) analyses that investigate the penetration response of deep-penetrating spudcan foundations in stratified soil comprising a strong clay layer overlying weaker clay. Such strength profiles give rise to potential punch-through failure, with a local maximum penetration resistance followed by some reduction. The paper is a companion paper to one that presents results from centrifuge model tests of the same problem, with the overall aim being to investigate the potential for punch-through failure and its severity, as a basis for improving design methods for evaluating spudcan penetration. The LDFE analyses have simulated continuous penetration of smooth and rough spudcan foundations from the sea-bed surface. A detailed parametric study has been undertaken, exploring the relevant range of layer thickness (relative to the spudcan diameter), strength ratios and spudcan base roughness. The results have been validated against previously published results and the centrifuge test data presented in a companion paper. Excellent agreement was obtained between the results from LDFE analyses and centrifuge tests. As the ratio of the shear strength of the bottom layer to that of the top layer decreased, upwards soil flow around the spudcan shoulder became less pronounced and the failure mechanism was dominated by a steep-sided plug of soil from the top layer being forced deep into the lower layer. The potential for severe punch-through was demonstrated by a significant reduction in the resistance profile as the spudcan approached the interface between the two layers. A preliminary design chart is proposed to estimate the cavity depth above the penetrating spudcan, which was significantly greater than that for a single layer clay. The penetration responses have been presented in terms of profiles of normalised net bearing pressure for a range of layer geometries and soil properties. Potential punch-through occurred for all cases where the strength ratio was less than or equal to 0·6, with the reduction in resistance being greater the lower the strength ratio of the underlying layer to the upper layer, and the thicker the upper layer, but reducing as the strength gradient in the lower layer increased. The current approach suggested in offshore design guidelines is shown to underestimate the penetration resistance significantly, in most cases, and give poor estimates of the likelihood and severity of spudcan punch-through. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.040

Numerical modelling of discrete pile rows for slope stability and generic guidance for design / E. A. Ellis in Géotechnique, Vol. 60 N° 3 (Mars 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 185–195 Titre : Numerical modelling of discrete pile rows for slope stability and generic guidance for design Type de document : texte imprimé Auteurs : E. A. Ellis, Auteur ; I. K. Durrani, Auteur ; D. J. Reddish, Auteur Année de publication : 2011 Article en page(s) : pp. 185–195 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Piles  Soil–structure  interaction  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Discrete (spaced) pile rows are an established method of improving slope stability, or ‘dowelling' an existing slip. The piles predominantly provide horizontal restraint to the potentially unstable mass of the slope. The method becomes more cost effective as the pile spacing increases, but there is also increasing risk that the soil will ‘flow' through the gap between piles, rather than arching across it. Two- and three-dimensional numerical analyses of a generic slope with piles at various locations are undertaken. A simple model of the stabilising force required for a given increase in factor of safety of the slope is then combined with a model of limiting pile row interaction to allow direct estimation of the effect of piles at a particular spacing ratio in improving the factor of safety. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00090 [article] Numerical modelling of discrete pile rows for slope stability and generic guidance for design [texte imprimé] / E. A. Ellis, Auteur ; I. K. Durrani, Auteur ; D. J. Reddish, Auteur . - 2011 . - pp. 185–195. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 185–195 Mots-clés : Piles  Soil–structure  interaction  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Discrete (spaced) pile rows are an established method of improving slope stability, or ‘dowelling' an existing slip. The piles predominantly provide horizontal restraint to the potentially unstable mass of the slope. The method becomes more cost effective as the pile spacing increases, but there is also increasing risk that the soil will ‘flow' through the gap between piles, rather than arching across it. Two- and three-dimensional numerical analyses of a generic slope with piles at various locations are undertaken. A simple model of the stabilising force required for a given increase in factor of safety of the slope is then combined with a model of limiting pile row interaction to allow direct estimation of the effect of piles at a particular spacing ratio in improving the factor of safety. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00090

Smear zone identification and soil properties around stone columns constructed in-flight in centrifuge model tests / T. M. Weber in Géotechnique, Vol. 60 N° 3 (Mars 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 197–206 Titre : Smear zone identification and soil properties around stone columns constructed in-flight in centrifuge model tests Type de document : texte imprimé Auteurs : T. M. Weber, Auteur ; M. Plotze, Auteur ; J. Laue, Auteur Année de publication : 2011 Article en page(s) : pp. 197–206 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Ground  improvement  Model  tests  Clay  Microscopy  Fabric/structure  of  soil Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Stone columns are primarily used for the purpose of ground improvement in fine grained soils in order to reduce settlements and the risk of bearing failure. They are also designed to improve the drainage conditions in the ground and to accelerate the consolidation processes within the clay. However, smear and disturbing effects caused during the construction of stone columns result in degradation of consolidation performance in comparison with the theoretically ideal conditions. Model stone columns are constructed in-flight under 50 times gravity in centrifuge tests and the soil micro-structure in the vicinity of these columns is investigated by applying different methods, including environmental scanning electron microscopy and mercury intrusion porosimetry. The results of these tests confirm that smear and disturbance occur owing to stone column installation and the region influenced can be divided into three sections: a penetration zone (1) where the sand particles are squeezed through the clay; a smear zone (2) where the soil particles have experienced a significant reorientation; and a densification zone (3) where the structure of the clay does not appear to change, but compaction of the clay is measurable. The extremes of the disturbed zone around model stone columns are determined to extend to about 2·5 times the column radius. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.098 [article] Smear zone identification and soil properties around stone columns constructed in-flight in centrifuge model tests [texte imprimé] / T. M. Weber, Auteur ; M. Plotze, Auteur ; J. Laue, Auteur . - 2011 . - pp. 197–206. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 197–206 Mots-clés : Ground  improvement  Model  tests  Clay  Microscopy  Fabric/structure  of  soil Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Stone columns are primarily used for the purpose of ground improvement in fine grained soils in order to reduce settlements and the risk of bearing failure. They are also designed to improve the drainage conditions in the ground and to accelerate the consolidation processes within the clay. However, smear and disturbing effects caused during the construction of stone columns result in degradation of consolidation performance in comparison with the theoretically ideal conditions. Model stone columns are constructed in-flight under 50 times gravity in centrifuge tests and the soil micro-structure in the vicinity of these columns is investigated by applying different methods, including environmental scanning electron microscopy and mercury intrusion porosimetry. The results of these tests confirm that smear and disturbance occur owing to stone column installation and the region influenced can be divided into three sections: a penetration zone (1) where the sand particles are squeezed through the clay; a smear zone (2) where the soil particles have experienced a significant reorientation; and a densification zone (3) where the structure of the clay does not appear to change, but compaction of the clay is measurable. The extremes of the disturbed zone around model stone columns are determined to extend to about 2·5 times the column radius. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.098

Kinematics and rheology of a major landslide based on signal analysis / S. I. Pytharouli in Géotechnique, Vol. 60 N° 3 (Mars 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 207–222 Titre : Kinematics and rheology of a major landslide based on signal analysis Type de document : texte imprimé Auteurs : S. I. Pytharouli, Auteur ; S. C. Stiros, Auteur Année de publication : 2011 Article en page(s) : pp. 207–222 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Creep  Statistical  analysis  Deformation  Slopes  Landslides  Monitoring Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A detailed geodetic record, which is over 23 years old and describes the kinematics of the Mandria (or Left Bank Upstream) landslide – a major deep-seated landslide close to the Polyphyton dam, Greece – was analysed on the basis of advanced signal analysis techniques without any geotechnical constraints. It was found that all points share the same pattern of displacement, which characterises both short and longer records. The overall behaviour of the landslide can be described as viscoelastic and viscous or elastoviscous, with multi-annual periodic effects superimposed on the creep, as the results of spectral analysis indicate. The landslide seems insensitive to seasonal variations of precipitation and to annual fluctuations of the reservoir level, although the first filling of the reservoir is likely to have had an important role in its movement. There is a lack of subsurface information, but the available data indicate that the landslide corresponds to a rigid mass dominated by brittle behaviour and internal shearing, with its kinematics controlled by thin mylonitic layers along low- and high-angle faults. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.049 [article] Kinematics and rheology of a major landslide based on signal analysis [texte imprimé] / S. I. Pytharouli, Auteur ; S. C. Stiros, Auteur . - 2011 . - pp. 207–222. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 207–222 Mots-clés : Creep  Statistical  analysis  Deformation  Slopes  Landslides  Monitoring Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A detailed geodetic record, which is over 23 years old and describes the kinematics of the Mandria (or Left Bank Upstream) landslide – a major deep-seated landslide close to the Polyphyton dam, Greece – was analysed on the basis of advanced signal analysis techniques without any geotechnical constraints. It was found that all points share the same pattern of displacement, which characterises both short and longer records. The overall behaviour of the landslide can be described as viscoelastic and viscous or elastoviscous, with multi-annual periodic effects superimposed on the creep, as the results of spectral analysis indicate. The landslide seems insensitive to seasonal variations of precipitation and to annual fluctuations of the reservoir level, although the first filling of the reservoir is likely to have had an important role in its movement. There is a lack of subsurface information, but the available data indicate that the landslide corresponds to a rigid mass dominated by brittle behaviour and internal shearing, with its kinematics controlled by thin mylonitic layers along low- and high-angle faults. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.049

Stress–dilatancy relation for Mohr–Coulomb soils following a non-associated flow rule / J. Zhang in Géotechnique, Vol. 60 N° 3 (Mars 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 223–226 Titre : Stress–dilatancy relation for Mohr–Coulomb soils following a non-associated flow rule Type de document : texte imprimé Auteurs : J. Zhang, Auteur ; R. Salgado, Auteur Année de publication : 2011 Article en page(s) : pp. 223–226 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Constitutive  relations  Failure  Shear  strength  Friction  Deformation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Rowe's stress–dilatancy relation for frictional (cohesionless) materials has been a cornerstone of soil mechanics. The original derivation of this relationship was based on incorrect energy minimisation considerations, but the relationship was proven later by De Josselin de Jong using friction laws, and has been confirmed by a large body of experimental results. In contrast, the validity of Rowe's stress–dilatancy relation for cohesive-frictional materials, which has also been used, although not as extensively, was never verified. This paper shows that Rowe's stress–dilatancy relation for Mohr–Coulomb soils (cohesive-frictional materials) is in fact incorrect. The paper also provides a correct stress–dilatancy relationship for non-associated Mohr–Coulomb soils that have both cohesive and frictional strength components. The derivation of the relationship for cohesive-frictional soils presented in this paper relies on use of the sawtooth model together with the application of the laws of friction. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.t.039 [article] Stress–dilatancy relation for Mohr–Coulomb soils following a non-associated flow rule [texte imprimé] / J. Zhang, Auteur ; R. Salgado, Auteur . - 2011 . - pp. 223–226. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 223–226 Mots-clés : Constitutive  relations  Failure  Shear  strength  Friction  Deformation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Rowe's stress–dilatancy relation for frictional (cohesionless) materials has been a cornerstone of soil mechanics. The original derivation of this relationship was based on incorrect energy minimisation considerations, but the relationship was proven later by De Josselin de Jong using friction laws, and has been confirmed by a large body of experimental results. In contrast, the validity of Rowe's stress–dilatancy relation for cohesive-frictional materials, which has also been used, although not as extensively, was never verified. This paper shows that Rowe's stress–dilatancy relation for Mohr–Coulomb soils (cohesive-frictional materials) is in fact incorrect. The paper also provides a correct stress–dilatancy relationship for non-associated Mohr–Coulomb soils that have both cohesive and frictional strength components. The derivation of the relationship for cohesive-frictional soils presented in this paper relies on use of the sawtooth model together with the application of the laws of friction. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.t.039

Modelling realistic shape and particle inertia in DEM / J. Ferellec in Géotechnique, Vol. 60 N° 3 (Mars 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 227–232 Titre : Modelling realistic shape and particle inertia in DEM Type de document : texte imprimé Auteurs : J. Ferellec, Auteur ; G. McDowell, Auteur Année de publication : 2011 Article en page(s) : pp. 227–232 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Numerical  modelling  Friction  Dynamics Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The use of clumps of overlapping spheres in DEM can be used to represent realistic particle shapes. This Technical Note discusses a method that is simple and fast, and highlights the key parameters influencing particle resolution. However, the problem with overlapping mass is that the density is non-uniform, which leads to incorrect moments of inertia and therefore rotational resistance. This Technical Note addresses this issue, and proposes a simple method to reduce the error in the principal moments of inertia. The effect on a falling heap of ballast particles is shown; the method improves not only behaviour, but also computational time. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.t.015 [article] Modelling realistic shape and particle inertia in DEM [texte imprimé] / J. Ferellec, Auteur ; G. McDowell, Auteur . - 2011 . - pp. 227–232. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 3 (Mars 2010) . - pp. 227–232 Mots-clés : Numerical  modelling  Friction  Dynamics Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The use of clumps of overlapping spheres in DEM can be used to represent realistic particle shapes. This Technical Note discusses a method that is simple and fast, and highlights the key parameters influencing particle resolution. However, the problem with overlapping mass is that the density is non-uniform, which leads to incorrect moments of inertia and therefore rotational resistance. This Technical Note addresses this issue, and proposes a simple method to reduce the error in the principal moments of inertia. The effect on a falling heap of ballast particles is shown; the method improves not only behaviour, but also computational time. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.t.015

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