Dépouillements

Earth pressure measurements on buried HDPE pipe / M. L. Talesnick in Géotechnique, Vol. 61 N° 9 (Septembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 721-732 Titre : Earth pressure measurements on buried HDPE pipe Type de document : texte imprimé Auteurs : M. L. Talesnick, Auteur ; H.-W. Xia, Auteur ; I. D. Moore, Auteur Année de publication : 2011 Article en page(s) : pp. 721-732 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Full-scale  tests  Soil–structure  interaction  Theoretical  analysis  Sands Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An understanding of the stress distributions that act on buried pipes plays a key role in the development and use of design methods for these structures. The radial stresses that develop on buried flexible pipes have been investigated by a number of researchers through experimental, analytical and numerical methods. However, direct measurements of soil contact stresses acting on small-diameter pipes have not been possible, since commercial earth pressure cells are large, and the stiffness of the cell relative to the soil material is known to influence the measured stresses. A new technique is described for measuring the radial contact stresses acting on buried pipes, and experimental studies are reported that demonstrate the effectiveness of this new technique for measuring contact pressures for both loose and compacted sand backfills. Comparison of the measurements with computations from elastic soil–pipe interaction theory reveals significant discrepancies in the magnitude and distribution of radial pressure around the circumference of the pipe for both loose and compacted backfill conditions. The new measurement technology provides direct support for pressure distributions inferred in earlier studies from measurements of circumferential strains around the pipe circumference. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.048 [article] Earth pressure measurements on buried HDPE pipe [texte imprimé] / M. L. Talesnick, Auteur ; H.-W. Xia, Auteur ; I. D. Moore, Auteur . - 2011 . - pp. 721-732. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 721-732 Mots-clés : Full-scale  tests  Soil–structure  interaction  Theoretical  analysis  Sands Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An understanding of the stress distributions that act on buried pipes plays a key role in the development and use of design methods for these structures. The radial stresses that develop on buried flexible pipes have been investigated by a number of researchers through experimental, analytical and numerical methods. However, direct measurements of soil contact stresses acting on small-diameter pipes have not been possible, since commercial earth pressure cells are large, and the stiffness of the cell relative to the soil material is known to influence the measured stresses. A new technique is described for measuring the radial contact stresses acting on buried pipes, and experimental studies are reported that demonstrate the effectiveness of this new technique for measuring contact pressures for both loose and compacted sand backfills. Comparison of the measurements with computations from elastic soil–pipe interaction theory reveals significant discrepancies in the magnitude and distribution of radial pressure around the circumference of the pipe for both loose and compacted backfill conditions. The new measurement technology provides direct support for pressure distributions inferred in earlier studies from measurements of circumferential strains around the pipe circumference. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.048

Asymmetric ‘Newmark' sliding caused by motions containing severe ‘directivity' and ‘fling' pulses / E. Garini in Géotechnique, Vol. 61 N° 9 (Septembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 733-756 Titre : Asymmetric ‘Newmark' sliding caused by motions containing severe ‘directivity' and ‘fling' pulses Type de document : texte imprimé Auteurs : E. Garini, Auteur ; G. Gazetas, Auteur ; I. Anastasopoulos, Auteur Année de publication : 2011 Article en page(s) : pp. 733-756 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Embankments  Earthquakes  Retaining  walls  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Sliding of a rigid mass supported on an inclined, seismically shaking plane serves as a conceptual and computational model for a variety of problems in geotechnical earthquake engineering. A series of parametric analyses are presented in the paper using as excitation numerous near-fault-recorded severe ground motions and idealised wavelets, bearing the effects of ‘forward-directivity' and ‘fling-step'. Using as key parameters the angle β of the sloping plane (mimicking the sliding surface), as well as the frequency content, intensity, nature and polarity of the excitation, the paper aims at developing a deeper insight into the mechanics of the asymmetric sliding process and the role of key parameters of the excitation. It is shown that ‘directivity' and ‘fling' affected motions containing long-period acceleration pulses and large velocity steps, are particularly ‘destructive' for the examined systems. The amount of accumulating slip on a steep slope is particularly sensitive to reversal of the polarity of excitation. With some special ground motions, in particular (such as the Sakarya and Yarimca accelerograms, both recorded 3 km from the surface expression of the North Anatolian Fault that ruptured in the 1999 Kocaeli earthquake), what might at first glance appear elusively as ‘small details' in the record may turn out to exert a profound influence on the magnitude of slippage – far outweighing the effects of peak acceleration, peak velocity and Arias intensity. The results are compiled in both dimensionless and dimensional charts, and compared with classical charts from the literature. Finally, it is shown that no convincingly robust correlation could exist between accumulated slip and the Arias intensity of excitation. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.070 [article] Asymmetric ‘Newmark' sliding caused by motions containing severe ‘directivity' and ‘fling' pulses [texte imprimé] / E. Garini, Auteur ; G. Gazetas, Auteur ; I. Anastasopoulos, Auteur . - 2011 . - pp. 733-756. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 733-756 Mots-clés : Embankments  Earthquakes  Retaining  walls  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Sliding of a rigid mass supported on an inclined, seismically shaking plane serves as a conceptual and computational model for a variety of problems in geotechnical earthquake engineering. A series of parametric analyses are presented in the paper using as excitation numerous near-fault-recorded severe ground motions and idealised wavelets, bearing the effects of ‘forward-directivity' and ‘fling-step'. Using as key parameters the angle β of the sloping plane (mimicking the sliding surface), as well as the frequency content, intensity, nature and polarity of the excitation, the paper aims at developing a deeper insight into the mechanics of the asymmetric sliding process and the role of key parameters of the excitation. It is shown that ‘directivity' and ‘fling' affected motions containing long-period acceleration pulses and large velocity steps, are particularly ‘destructive' for the examined systems. The amount of accumulating slip on a steep slope is particularly sensitive to reversal of the polarity of excitation. With some special ground motions, in particular (such as the Sakarya and Yarimca accelerograms, both recorded 3 km from the surface expression of the North Anatolian Fault that ruptured in the 1999 Kocaeli earthquake), what might at first glance appear elusively as ‘small details' in the record may turn out to exert a profound influence on the magnitude of slippage – far outweighing the effects of peak acceleration, peak velocity and Arias intensity. The results are compiled in both dimensionless and dimensional charts, and compared with classical charts from the literature. Finally, it is shown that no convincingly robust correlation could exist between accumulated slip and the Arias intensity of excitation. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.070

Seasonal ratcheting and softening in clay slopes, leading to first-time failure / W. A. Take in Géotechnique, Vol. 61 N° 9 (Septembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 757-769 Titre : Seasonal ratcheting and softening in clay slopes, leading to first-time failure Type de document : texte imprimé Auteurs : W. A. Take, Auteur ; M. D. Bolton, Auteur Année de publication : 2011 Article en page(s) : pp. 757-769 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Centrifuge  modelling  Slopes  Clays  Failure Index. décimale : 551.4 Résumé : Centrifuge tests have been carried out on kaolin clay slopes subject to variations in surface rainfall and humidity corresponding, at model scale, to successive wet and dry seasons in the field. These model slopes have been instrumented with miniature high-capacity tensiometers, and the deformations of their cross-sections have been observed by digital photography and analysed by particle image velocimetry. Sequences of swelling and shrinkage have been seen to be potentially irreversible, leading to creep in the form of down-slope ratcheting, accompanied by progressive regional softening within the zone affected by the seasonal moisture movements. Ultimately, this regional softening has been seen to lead to slope failures, in which segments of soil have separated from the mass through the opening of tension cracks and the formation of a localised shear rupture. An analysis of the phase of episodic regional softening is presented here, based on a Spencer limit-equilibrium approach. These back-analyses illustrate that clay slopes which temporarily mobilise an average stress ratio in excess of the critical state stress ratio during any portion of a typical year may eventually be brought to a long-term failure under the action of seasonal variations of pore pressure. Conversely, it is hypothesised that clay slopes which can maintain their overall equilibrium without exceeding the critical state stress ratio may not experience progressive seasonal softening. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.125 [article] Seasonal ratcheting and softening in clay slopes, leading to first-time failure [texte imprimé] / W. A. Take, Auteur ; M. D. Bolton, Auteur . - 2011 . - pp. 757-769. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 757-769 Mots-clés : Centrifuge  modelling  Slopes  Clays  Failure Index. décimale : 551.4 Résumé : Centrifuge tests have been carried out on kaolin clay slopes subject to variations in surface rainfall and humidity corresponding, at model scale, to successive wet and dry seasons in the field. These model slopes have been instrumented with miniature high-capacity tensiometers, and the deformations of their cross-sections have been observed by digital photography and analysed by particle image velocimetry. Sequences of swelling and shrinkage have been seen to be potentially irreversible, leading to creep in the form of down-slope ratcheting, accompanied by progressive regional softening within the zone affected by the seasonal moisture movements. Ultimately, this regional softening has been seen to lead to slope failures, in which segments of soil have separated from the mass through the opening of tension cracks and the formation of a localised shear rupture. An analysis of the phase of episodic regional softening is presented here, based on a Spencer limit-equilibrium approach. These back-analyses illustrate that clay slopes which temporarily mobilise an average stress ratio in excess of the critical state stress ratio during any portion of a typical year may eventually be brought to a long-term failure under the action of seasonal variations of pore pressure. Conversely, it is hypothesised that clay slopes which can maintain their overall equilibrium without exceeding the critical state stress ratio may not experience progressive seasonal softening. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.125

Critical state friction angle of sands / A. Sadrekarimi in Géotechnique, Vol. 61 N° 9 (Septembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 771-783 Titre : Critical state friction angle of sands Type de document : texte imprimé Auteurs : A. Sadrekarimi, Auteur ; S. M. Olson, Auteur Année de publication : 2011 Article en page(s) : pp. 771-783 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Laboratory  tests  Deformation  Friction  Mineralogy  Compressibility  Sands Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The friction angle is the most important parameter used for analysing the response of sands to loading. However, its variation with stress level, fabric and particle damage has been debated. This study examines the yield and critical state friction angles of three sands using triaxial compression and ring shear tests. Only contractive responses were used to define the yield friction angles and the critical state friction angles from the triaxial tests. However, both contractive and dilative (through particle damage) specimens reached a critical state in the ring shear tests, and therefore critical state friction angles were defined from both dense and loose specimens. The yield friction angle was affected by the initial sand fabric, decreasing as the pre-shear void ratio increased. In contrast, the critical state friction angle from the ring shear tests was independent of stress paths analysed in this paper, independent of initial sand fabric, and decreased only slightly with stress level, becoming essentially constant at stresses larger than about 200 kPa. Its value depended primarily on particle mineralogy and shape (angularity). Particle damage induced in the ring shear tests increased the critical state friction angle by a few degrees, as a wider range of particle sizes and more angular particles were produced. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.090 [article] Critical state friction angle of sands [texte imprimé] / A. Sadrekarimi, Auteur ; S. M. Olson, Auteur . - 2011 . - pp. 771-783. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 771-783 Mots-clés : Laboratory  tests  Deformation  Friction  Mineralogy  Compressibility  Sands Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The friction angle is the most important parameter used for analysing the response of sands to loading. However, its variation with stress level, fabric and particle damage has been debated. This study examines the yield and critical state friction angles of three sands using triaxial compression and ring shear tests. Only contractive responses were used to define the yield friction angles and the critical state friction angles from the triaxial tests. However, both contractive and dilative (through particle damage) specimens reached a critical state in the ring shear tests, and therefore critical state friction angles were defined from both dense and loose specimens. The yield friction angle was affected by the initial sand fabric, decreasing as the pre-shear void ratio increased. In contrast, the critical state friction angle from the ring shear tests was independent of stress paths analysed in this paper, independent of initial sand fabric, and decreased only slightly with stress level, becoming essentially constant at stresses larger than about 200 kPa. Its value depended primarily on particle mineralogy and shape (angularity). Particle damage induced in the ring shear tests increased the critical state friction angle by a few degrees, as a wider range of particle sizes and more angular particles were produced. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.090

Engineered use of microbial gas production to decrease primary consolidation settlement in clayey soils / A. M. Puzrin in Géotechnique, Vol. 61 N° 9 (Septembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 785-794 Titre : Engineered use of microbial gas production to decrease primary consolidation settlement in clayey soils Type de document : texte imprimé Auteurs : A. M. Puzrin, Auteur ; J. Tront, Auteur ; A. Schmid, Auteur Année de publication : 2011 Article en page(s) : pp. 785-794 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Consolidation  Settlement Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This feasibility study examines the use of in situ microbial gas production to engineer the consolidation properties of clayey soils by changing the settlement–time profile. A simple analytical model has been proposed to assess the swelling of the soil during the steady-state gas production, and to predict immediate settlements due to loading at the end of this process. For experimental validation of the suggested technique, Clostridium acetobutylicum, an anaerobic fermentative microorganism, was mixed into clayey-sand samples, fed with a nutrient-rich medium, and allowed to produce gas in situ. A series of standard oedometer tests was performed on gas-containing and gas-free soil specimens. Results showed that, in agreement with the model predictions, in situ gas production caused negligible swelling of the samples, while shifting a significant portion (up to 50%) of total displacement from primary consolidation settlement to immediate settlement without changing total displacements or the coefficient of consolidation. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.t.023 [article] Engineered use of microbial gas production to decrease primary consolidation settlement in clayey soils [texte imprimé] / A. M. Puzrin, Auteur ; J. Tront, Auteur ; A. Schmid, Auteur . - 2011 . - pp. 785-794. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 785-794 Mots-clés : Consolidation  Settlement Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This feasibility study examines the use of in situ microbial gas production to engineer the consolidation properties of clayey soils by changing the settlement–time profile. A simple analytical model has been proposed to assess the swelling of the soil during the steady-state gas production, and to predict immediate settlements due to loading at the end of this process. For experimental validation of the suggested technique, Clostridium acetobutylicum, an anaerobic fermentative microorganism, was mixed into clayey-sand samples, fed with a nutrient-rich medium, and allowed to produce gas in situ. A series of standard oedometer tests was performed on gas-containing and gas-free soil specimens. Results showed that, in agreement with the model predictions, in situ gas production caused negligible swelling of the samples, while shifting a significant portion (up to 50%) of total displacement from primary consolidation settlement to immediate settlement without changing total displacements or the coefficient of consolidation. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.t.023

Progressive failure of Aznalcóllar dam using the material point method / F. Zabala in Géotechnique, Vol. 61 N° 9 (Septembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 795-808 Titre : Progressive failure of Aznalcóllar dam using the material point method Type de document : texte imprimé Auteurs : F. Zabala, Auteur ; E. E. Alonso, Auteur Année de publication : 2011 Article en page(s) : pp. 795-808 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Numerical  models  Pore  pressures  Case  history  Dams  Strain  localisation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The material point method, which combines features of finite-element and particle discretisation methods, has been extended to solve coupled flow-deformation problems in granular media. The method is applied to simulate the construction and failure of the Aznalcóllar dam. The brittle foundation clay is characterised by means of a strain-softening Mohr–Coulomb elasto-plastic model. The rupture process of the foundation is associated with a progressive failure mechanism. The model predicts the development of a localised shearing band that initiates at the toe of the dam at some intermediate stage of construction, and propagates downstream and upstream. The shape and position of the failure surface reproduce actual field observations. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.134 [article] Progressive failure of Aznalcóllar dam using the material point method [texte imprimé] / F. Zabala, Auteur ; E. E. Alonso, Auteur . - 2011 . - pp. 795-808. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 795-808 Mots-clés : Numerical  models  Pore  pressures  Case  history  Dams  Strain  localisation Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The material point method, which combines features of finite-element and particle discretisation methods, has been extended to solve coupled flow-deformation problems in granular media. The method is applied to simulate the construction and failure of the Aznalcóllar dam. The brittle foundation clay is characterised by means of a strain-softening Mohr–Coulomb elasto-plastic model. The rupture process of the foundation is associated with a progressive failure mechanism. The model predicts the development of a localised shearing band that initiates at the toe of the dam at some intermediate stage of construction, and propagates downstream and upstream. The shape and position of the failure surface reproduce actual field observations. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.134

Cross-anisotropic elastic parameters of two natural stiff clays / S. Yimsiri in Géotechnique, Vol. 61 N° 9 (Septembre 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 809-814 Titre : Cross-anisotropic elastic parameters of two natural stiff clays Type de document : texte imprimé Auteurs : S. Yimsiri, Auteur ; K. Soga, Auteur Année de publication : 2011 Article en page(s) : pp. 809-814 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Anisotropy  Constitutive  relations  Elasticity  Laboratory  tests  Stiffness Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An experimental study of the cross-anisotropic elastic parameters was performed on two heavily overconsolidated clays: London Clay and Gault Clay. The study utilised a special triaxial testing apparatus that incorporates local strain measuring system and elastic wave velocity measurement system. Isotropically consolidated drained compression tests and shear wave velocity measurements were undertaken on both vertically and horizontally cut specimens. The experiments were performed under in situ isotropic stresses to study the inherent anisotropic characteristics of the clays in terms of the elastic stiffness. The deformation characteristics during triaxial compression were carefully investigated to obtain various elastic moduli and Poisson ratios. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.072 [article] Cross-anisotropic elastic parameters of two natural stiff clays [texte imprimé] / S. Yimsiri, Auteur ; K. Soga, Auteur . - 2011 . - pp. 809-814. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 9 (Septembre 2011) . - pp. 809-814 Mots-clés : Anisotropy  Constitutive  relations  Elasticity  Laboratory  tests  Stiffness Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An experimental study of the cross-anisotropic elastic parameters was performed on two heavily overconsolidated clays: London Clay and Gault Clay. The study utilised a special triaxial testing apparatus that incorporates local strain measuring system and elastic wave velocity measurement system. Isotropically consolidated drained compression tests and shear wave velocity measurements were undertaken on both vertically and horizontally cut specimens. The experiments were performed under in situ isotropic stresses to study the inherent anisotropic characteristics of the clays in terms of the elastic stiffness. The deformation characteristics during triaxial compression were carefully investigated to obtain various elastic moduli and Poisson ratios. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.072

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