Dépouillements

Chemo-mechanical effects in kaolinite. Part 1, Prepared samples / A. S. Wahid in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 439–447 Titre : Chemo-mechanical effects in kaolinite. Part 1, Prepared samples Type de document : texte imprimé Auteurs : A. S. Wahid, Auteur ; A. Gajo, Auteur ; R. Di Maggio, Auteur Année de publication : 2011 Article en page(s) : pp. 439–447 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Clays  permeability  Consolidation  Laboratory  tests  Chemical  properties  Shear  strength  Compressibility Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The results of laboratory tests on chemo-mechanical interactions in kaolinite samples prepared with inorganic, salt, acid and base solutions are presented. In particular, the effects of the different solutions on the liquid limit, one-dimensional compressibility, permeability and residual shear strength are considered. Kaolinite proves relatively insensitive to salt solutions, whereas variations in pore fluid pH cause large strength changes, associated with non-negligible changes in one-dimensional compressibility. The partly inconsistent effects induced by acids and bases on the residual shear strength and on the one-dimensional compressibility do not permit any easy interpretation of the experimental evidence. Mineral dissolution and the associated formation of new compounds are probably involved in the behaviour observed. These aspects will be investigated in part 2 of this paper. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.067 [article] Chemo-mechanical effects in kaolinite. Part 1, Prepared samples [texte imprimé] / A. S. Wahid, Auteur ; A. Gajo, Auteur ; R. Di Maggio, Auteur . - 2011 . - pp. 439–447. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 439–447 Mots-clés : Clays  permeability  Consolidation  Laboratory  tests  Chemical  properties  Shear  strength  Compressibility Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The results of laboratory tests on chemo-mechanical interactions in kaolinite samples prepared with inorganic, salt, acid and base solutions are presented. In particular, the effects of the different solutions on the liquid limit, one-dimensional compressibility, permeability and residual shear strength are considered. Kaolinite proves relatively insensitive to salt solutions, whereas variations in pore fluid pH cause large strength changes, associated with non-negligible changes in one-dimensional compressibility. The partly inconsistent effects induced by acids and bases on the residual shear strength and on the one-dimensional compressibility do not permit any easy interpretation of the experimental evidence. Mineral dissolution and the associated formation of new compounds are probably involved in the behaviour observed. These aspects will be investigated in part 2 of this paper. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.067

Chemo-mechanical effects in kaolinite. Part 2, Exposed samples and chemical and phase analyses / A. S. Wahid in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 449–457 Titre : Chemo-mechanical effects in kaolinite. Part 2, Exposed samples and chemical and phase analyses Type de document : texte imprimé Auteurs : A. S. Wahid, Auteur ; A. Gajo, Auteur ; R. Di Maggio, Auteur Année de publication : 2011 Article en page(s) : pp. 449–457 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Clays  Compressibility  Consolidation  Chemical  properties  Laboratory  tests Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Continuing from part 1 of this paper, the results of laboratory tests on chemo-mechanical interactions in kaolinite subjected to the diffusion of inorganic, salt, acid and base solutions under an applied stress state are presented. Chemical analyses on the surnatant and analyses on X-ray diffraction patterns, high-temperature differential scanning calorimetry thermal gravimetry scans and transmission electron microscopy micrographs led to the conclusion that the bulk of kaolinite mineral is probably only slightly affected by the chemical interactions, the chemical attack being concentrated mainly at the particle edges, where it induces a change in the shape of the edges, which become irregular and less sharp. The mechanical behaviour of kaolinite is not affected by pore fluid salinity, but it is significantly affected by pore fluid pH: both acid or base solutions under an applied stress cause significant volumetric compression. Such strains are irreversible and probably related to the particle rearrangement induced mainly by the degradation of the particle edges, in addition to the decrease in basal friction angle (described in the companion paper) and the change of strength at edge-to-face contact points. The mechanical effects are slightly related to the dielectric constant of the pore fluid and this is consistent with the general conviction that interactions between kaolinite particles are mostly mechanical. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.068 [article] Chemo-mechanical effects in kaolinite. Part 2, Exposed samples and chemical and phase analyses [texte imprimé] / A. S. Wahid, Auteur ; A. Gajo, Auteur ; R. Di Maggio, Auteur . - 2011 . - pp. 449–457. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 449–457 Mots-clés : Clays  Compressibility  Consolidation  Chemical  properties  Laboratory  tests Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Continuing from part 1 of this paper, the results of laboratory tests on chemo-mechanical interactions in kaolinite subjected to the diffusion of inorganic, salt, acid and base solutions under an applied stress state are presented. Chemical analyses on the surnatant and analyses on X-ray diffraction patterns, high-temperature differential scanning calorimetry thermal gravimetry scans and transmission electron microscopy micrographs led to the conclusion that the bulk of kaolinite mineral is probably only slightly affected by the chemical interactions, the chemical attack being concentrated mainly at the particle edges, where it induces a change in the shape of the edges, which become irregular and less sharp. The mechanical behaviour of kaolinite is not affected by pore fluid salinity, but it is significantly affected by pore fluid pH: both acid or base solutions under an applied stress cause significant volumetric compression. Such strains are irreversible and probably related to the particle rearrangement induced mainly by the degradation of the particle edges, in addition to the decrease in basal friction angle (described in the companion paper) and the change of strength at edge-to-face contact points. The mechanical effects are slightly related to the dielectric constant of the pore fluid and this is consistent with the general conviction that interactions between kaolinite particles are mostly mechanical. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.068

Changes to particle characteristics associated with the compression of sands / F. N. Altuhafi in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 459–471 Titre : Changes to particle characteristics associated with the compression of sands Type de document : texte imprimé Auteurs : F. N. Altuhafi, Auteur ; M. R. Coop, Auteur Année de publication : 2011 Article en page(s) : pp. 459–471 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Particle  crushing/crushability  Microscopy  Sands Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : It is commonly accepted that the onset of particle breakage in sands during compression marks the start of yielding. Although particle breakage is strongly associated with the tensile strength of a single soil grain, initial density and initial sample grading have great influence on the probability of particle breakage. This paper examines the effect of initial grading and density on the sample behaviour during one-dimensional compression for three sands with distinct mineralogies. It was found that a unique normal compression line is the outcome of a large amount of breakage in poorly graded samples and that by changing the initial grading to a better graded sample a significant reduction in particle breakage is observed, until for very well-graded samples no significant particle breakage can be measured. At this point a difficulty in defining a unique normal compression line for the sample was found and a transitional behaviour was identified. In addition to particle size, the paper examines the changes to some important particle characteristics such as particle shape and particle surface roughness in an attempt to relate the soil behaviour to the nature of the microscopic particle damage during yielding. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.114 [article] Changes to particle characteristics associated with the compression of sands [texte imprimé] / F. N. Altuhafi, Auteur ; M. R. Coop, Auteur . - 2011 . - pp. 459–471. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 459–471 Mots-clés : Particle  crushing/crushability  Microscopy  Sands Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : It is commonly accepted that the onset of particle breakage in sands during compression marks the start of yielding. Although particle breakage is strongly associated with the tensile strength of a single soil grain, initial density and initial sample grading have great influence on the probability of particle breakage. This paper examines the effect of initial grading and density on the sample behaviour during one-dimensional compression for three sands with distinct mineralogies. It was found that a unique normal compression line is the outcome of a large amount of breakage in poorly graded samples and that by changing the initial grading to a better graded sample a significant reduction in particle breakage is observed, until for very well-graded samples no significant particle breakage can be measured. At this point a difficulty in defining a unique normal compression line for the sample was found and a transitional behaviour was identified. In addition to particle size, the paper examines the changes to some important particle characteristics such as particle shape and particle surface roughness in an attempt to relate the soil behaviour to the nature of the microscopic particle damage during yielding. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.114

Cyclic stress–strain response of compacted gravel / G. Modoni in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 473–485 Titre : Cyclic stress–strain response of compacted gravel Type de document : texte imprimé Auteurs : G. Modoni, Auteur ; J. Koseki, Auteur ; L. Q. Anh Dan, Auteur Année de publication : 2011 Article en page(s) : pp. 473–485 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Elasticity  Plasticity  Compaction  Gravels Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The positive effect of artificial densification on the stress–strain performance of granular materials is acknowledged from very ancient times but its importance greatly increased after the development of powerful machineries for the construction of large earth and rockfill dams. It is, however, pointed out that the extensive exploitation of gravelly soil is rarely supported by a thorough analytical assessment of the compaction effects on the constitutive relationships of materials, as would be desirable considering the massive dimension of these works and the complexity of typical loading conditions. The present research aims to fill this gap by means of a detailed experimental investigation and a theoretical analysis on the stress–strain response of dense gravels under monotonic and cyclic loading. The experimental campaign consists of a large number of triaxial tests performed at different initial mean effective stresses, following different stress paths and sequences, on artificially reconstituted samples of large dimensions compacted at different initial densities. The great care placed in the accuracy of laboratory instrumentation enables a high repeatability of experimental results, which is necessary to provide a clear focus on non-linearity in the limited strain range of the pre-failure response of the gravel. Based on the curve-fitting method the ingredients of an elasto-plastic constitutive model have been defined to predict the response of gravel under monotonic and cyclic loading. Elastic stiffness is simulated with a model derived from the literature which assumes a dependency on soil density together with inherent and stress-induced anisotropy. Plastic strain development from different initial stress and volume states of gravel is simulated by a critical state, multiple yielding constitutive model. Hardening and flow rules for the latter have been obtained by modifying previously existing laws in order better to reproduce the observations under monotonic compression, extension and cyclic loading. Validation of the proposed model is finally provided by comparing simulations and experimental results in a variety of testing conditions. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00150 [article] Cyclic stress–strain response of compacted gravel [texte imprimé] / G. Modoni, Auteur ; J. Koseki, Auteur ; L. Q. Anh Dan, Auteur . - 2011 . - pp. 473–485. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 473–485 Mots-clés : Elasticity  Plasticity  Compaction  Gravels Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The positive effect of artificial densification on the stress–strain performance of granular materials is acknowledged from very ancient times but its importance greatly increased after the development of powerful machineries for the construction of large earth and rockfill dams. It is, however, pointed out that the extensive exploitation of gravelly soil is rarely supported by a thorough analytical assessment of the compaction effects on the constitutive relationships of materials, as would be desirable considering the massive dimension of these works and the complexity of typical loading conditions. The present research aims to fill this gap by means of a detailed experimental investigation and a theoretical analysis on the stress–strain response of dense gravels under monotonic and cyclic loading. The experimental campaign consists of a large number of triaxial tests performed at different initial mean effective stresses, following different stress paths and sequences, on artificially reconstituted samples of large dimensions compacted at different initial densities. The great care placed in the accuracy of laboratory instrumentation enables a high repeatability of experimental results, which is necessary to provide a clear focus on non-linearity in the limited strain range of the pre-failure response of the gravel. Based on the curve-fitting method the ingredients of an elasto-plastic constitutive model have been defined to predict the response of gravel under monotonic and cyclic loading. Elastic stiffness is simulated with a model derived from the literature which assumes a dependency on soil density together with inherent and stress-induced anisotropy. Plastic strain development from different initial stress and volume states of gravel is simulated by a critical state, multiple yielding constitutive model. Hardening and flow rules for the latter have been obtained by modifying previously existing laws in order better to reproduce the observations under monotonic compression, extension and cyclic loading. Validation of the proposed model is finally provided by comparing simulations and experimental results in a variety of testing conditions. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00150

Analysis of model sheet pile walls with plastic hinges / P. J. Bourne-Webb in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 487–499 Titre : Analysis of model sheet pile walls with plastic hinges Type de document : texte imprimé Auteurs : P. J. Bourne-Webb, Auteur ; D. M. Potts, Auteur ; D. Konig, Auteur Année de publication : 2011 Article en page(s) : pp. 487–499 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Limit  state  design/analysis  Numerical  modelling  Centrifuge  modelling  Standards  Sheet  piles  and  cofferdams Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : As part of a wider project investigating the implications of Eurocode 3, Design of steel structures – Part 5: Piling, centrifuge testing of model sheet pile walls and numerical back-analysis were undertaken. The aims of the study were to examine the effect of plastic hinging on embedded retaining wall response, and to verify calculation methods for use in wider generic calculations. Physical modelling of an anchored wall embedded in dry sand was undertaken. In some of the tests a hinge zone was introduced into the wall in order to reproduce a kinematic mechanism similar to that associated with plastic hinge formation. Finite-element calculations were undertaken using Lade's double-hardening cap model to represent the behaviour of the sand. The analyses generally yielded good accord with the test results in many aspects of the wall behaviour. In terms of the aims of the testing, the study of the effect of plastic hinging was not realistically captured, because the hinge zone was present from the outset of the test, allowing greater than expected earth pressure redistribution, and because the moment–curvature characteristic of the notched wall did not reproduce the buckling effects seen in the plastic bending response of steel sheet piles. On the other hand, the satisfactory agreement between the test observations and the numerical predictions gave confidence in the use of the calculation model for further generic calculations using realistic steel sheet pile moment–plastic curvature characteristics. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.061 [article] Analysis of model sheet pile walls with plastic hinges [texte imprimé] / P. J. Bourne-Webb, Auteur ; D. M. Potts, Auteur ; D. Konig, Auteur . - 2011 . - pp. 487–499. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 487–499 Mots-clés : Limit  state  design/analysis  Numerical  modelling  Centrifuge  modelling  Standards  Sheet  piles  and  cofferdams Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : As part of a wider project investigating the implications of Eurocode 3, Design of steel structures – Part 5: Piling, centrifuge testing of model sheet pile walls and numerical back-analysis were undertaken. The aims of the study were to examine the effect of plastic hinging on embedded retaining wall response, and to verify calculation methods for use in wider generic calculations. Physical modelling of an anchored wall embedded in dry sand was undertaken. In some of the tests a hinge zone was introduced into the wall in order to reproduce a kinematic mechanism similar to that associated with plastic hinge formation. Finite-element calculations were undertaken using Lade's double-hardening cap model to represent the behaviour of the sand. The analyses generally yielded good accord with the test results in many aspects of the wall behaviour. In terms of the aims of the testing, the study of the effect of plastic hinging was not realistically captured, because the hinge zone was present from the outset of the test, allowing greater than expected earth pressure redistribution, and because the moment–curvature characteristic of the notched wall did not reproduce the buckling effects seen in the plastic bending response of steel sheet piles. On the other hand, the satisfactory agreement between the test observations and the numerical predictions gave confidence in the use of the calculation model for further generic calculations using realistic steel sheet pile moment–plastic curvature characteristics. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.061

Ultrasonic transducers characterisation for evaluation of stiff geomaterials / F. Tallavo in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 501–510 Titre : Ultrasonic transducers characterisation for evaluation of stiff geomaterials Type de document : texte imprimé Auteurs : F. Tallavo, Auteur ; G. Cascante, Auteur ; Pandey, M. D., Auteur Année de publication : 2011 Article en page(s) : pp. 501–510 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Laboratory  tests  Numerical  modelling  Dynamics  Waves  and  wave  loading Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The pulse velocity test (PVT) is an ASTM standard for the dynamic characterisation of geomaterials such as stiff clays, cemented sands, rooks and concrete. The PVT is based on the first arrival of the compressional wave. The analysis of full waveforms in ultrasonic testing is important in evaluating the variation with frequency of the dynamic properties of materials (phase velocity and material damping). Reliable full waveforms are also required to calibrate numerical simulations for the interpretation of ultrasonic wave propagation in viscoelastic materials. However, the analysis of full waveforms is rarely performed in practice because of the difficulties involved in the characterisation of ultrasonic transducers and their coupling with the medium. This paper presents a new methodology for measurement of the frequency response and impulse response functions of ultrasonic transducers. The proposed methodology uses the complex exponential method to extract dynamic properties from impulse response functions. Ultrasonic tests and numerical simulations are conducted on a calibration aluminium bar and a cemented sand specimen to demonstrate the applicability of the new methodology. The results show that this methodology can be successfully used for dynamic characterisation of ultrasonic transducers for evaluation of the wave velocity and damping ratio of stiff geomaterials. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.087 [article] Ultrasonic transducers characterisation for evaluation of stiff geomaterials [texte imprimé] / F. Tallavo, Auteur ; G. Cascante, Auteur ; Pandey, M. D., Auteur . - 2011 . - pp. 501–510. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 501–510 Mots-clés : Laboratory  tests  Numerical  modelling  Dynamics  Waves  and  wave  loading Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The pulse velocity test (PVT) is an ASTM standard for the dynamic characterisation of geomaterials such as stiff clays, cemented sands, rooks and concrete. The PVT is based on the first arrival of the compressional wave. The analysis of full waveforms in ultrasonic testing is important in evaluating the variation with frequency of the dynamic properties of materials (phase velocity and material damping). Reliable full waveforms are also required to calibrate numerical simulations for the interpretation of ultrasonic wave propagation in viscoelastic materials. However, the analysis of full waveforms is rarely performed in practice because of the difficulties involved in the characterisation of ultrasonic transducers and their coupling with the medium. This paper presents a new methodology for measurement of the frequency response and impulse response functions of ultrasonic transducers. The proposed methodology uses the complex exponential method to extract dynamic properties from impulse response functions. Ultrasonic tests and numerical simulations are conducted on a calibration aluminium bar and a cemented sand specimen to demonstrate the applicability of the new methodology. The results show that this methodology can be successfully used for dynamic characterisation of ultrasonic transducers for evaluation of the wave velocity and damping ratio of stiff geomaterials. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.087

A field study of stress-dependent soil–water characteristic curves and permeability of a saprolitic slope in Hong Kong / C. W.W. Ng in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 511–521 Titre : A field study of stress-dependent soil–water characteristic curves and permeability of a saprolitic slope in Hong Kong Type de document : texte imprimé Auteurs : C. W.W. Ng, Auteur ; H. N. Wong, Auteur ; Y. M. Tse, Auteur Année de publication : 2011 Article en page(s) : pp. 511–521 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Field  instrumentation  Permeability  Pore  pressures  Suction  In  Situ  testing  Partial  saturation  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : It is well recognised that field measurements of stress-dependent soil–water characteristic curves (SDSWCCs) and the permeability function (coefficient of permeability with respect to the water phase) are vital for assessing transient seepage, pore water pressure changes and the stability of unsaturated soil slopes. In this study, SDSWCCs and the permeability function were measured by using the instantaneous profile method on a saprolitic hillside in Tung Chung, Hong Kong. The ground profile comprises colluvium and completely decomposed tuff (CDT). A 3 m diameter circular plot was instrumented and subjected to two wetting–drying cycles. Throughout a 48-day monitoring period, variations of volumetric water content and matrix suction in the uppermost 3 m of soil were measured continuously using time-domain reflectometry moisture probes and jet-fill tensiometers, respectively. The field observations reveal that there is a clear trend of decreasing sizes of hysteretic loops of SDSWCCs with depth. In a comparison of the field- and laboratory-measured SDSWCCs, general agreement can be seen in the first wetting–drying cycle but not in the second cycle. The field-observed unsaturated permeability function is highly dependent on suction history (wetting–drying cycles). The field-measured permeability ranges from 4 × 10−7 m/s to 3 × 10−4 m/s in the colluvium, whereas the corresponding measured values vary from 4 × 10−7 m/s to 1 × 10−4 m/s in the CDT. Predictions of SWCC and permeability function using existing empirical approaches based on particle size distributions (PSDs) should be treated with caution. There is a clear qualitative and quantitative inconsistency between predictions of permeability function from PSD and field measurements. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.157 [article] A field study of stress-dependent soil–water characteristic curves and permeability of a saprolitic slope in Hong Kong [texte imprimé] / C. W.W. Ng, Auteur ; H. N. Wong, Auteur ; Y. M. Tse, Auteur . - 2011 . - pp. 511–521. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 511–521 Mots-clés : Field  instrumentation  Permeability  Pore  pressures  Suction  In  Situ  testing  Partial  saturation  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : It is well recognised that field measurements of stress-dependent soil–water characteristic curves (SDSWCCs) and the permeability function (coefficient of permeability with respect to the water phase) are vital for assessing transient seepage, pore water pressure changes and the stability of unsaturated soil slopes. In this study, SDSWCCs and the permeability function were measured by using the instantaneous profile method on a saprolitic hillside in Tung Chung, Hong Kong. The ground profile comprises colluvium and completely decomposed tuff (CDT). A 3 m diameter circular plot was instrumented and subjected to two wetting–drying cycles. Throughout a 48-day monitoring period, variations of volumetric water content and matrix suction in the uppermost 3 m of soil were measured continuously using time-domain reflectometry moisture probes and jet-fill tensiometers, respectively. The field observations reveal that there is a clear trend of decreasing sizes of hysteretic loops of SDSWCCs with depth. In a comparison of the field- and laboratory-measured SDSWCCs, general agreement can be seen in the first wetting–drying cycle but not in the second cycle. The field-observed unsaturated permeability function is highly dependent on suction history (wetting–drying cycles). The field-measured permeability ranges from 4 × 10−7 m/s to 3 × 10−4 m/s in the colluvium, whereas the corresponding measured values vary from 4 × 10−7 m/s to 1 × 10−4 m/s in the CDT. Predictions of SWCC and permeability function using existing empirical approaches based on particle size distributions (PSDs) should be treated with caution. There is a clear qualitative and quantitative inconsistency between predictions of permeability function from PSD and field measurements. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.157

A comparison of dynamic and quasi-static results for the flow towards a well / J. J. Nader in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 523–524 Titre : A comparison of dynamic and quasi-static results for the flow towards a well Type de document : texte imprimé Auteurs : J. J. Nader, Auteur Année de publication : 2011 Article en page(s) : pp. 523–524 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Permeability  Water  flow  Groundwater  Seepage Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The present analysis takes into account the acceleration term in the differential equation of motion to obtain exact dynamic solutions concerning the groundwater flow towards a well in a confined aquifer. The results show that the error contained in the traditional quasi-static solution is very small in typical situations. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.10.t.007 [article] A comparison of dynamic and quasi-static results for the flow towards a well [texte imprimé] / J. J. Nader, Auteur . - 2011 . - pp. 523–524. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 523–524 Mots-clés : Permeability  Water  flow  Groundwater  Seepage Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The present analysis takes into account the acceleration term in the differential equation of motion to obtain exact dynamic solutions concerning the groundwater flow towards a well in a confined aquifer. The results show that the error contained in the traditional quasi-static solution is very small in typical situations. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.10.t.007

Cone penetration tests in a virtual calibration chamber / M. Arroyo in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 525–531 Titre : Cone penetration tests in a virtual calibration chamber Type de document : texte imprimé Auteurs : M. Arroyo, Auteur ; J. Butlanska, Auteur ; A. Gens, Auteur Année de publication : 2011 Article en page(s) : pp. 525–531 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Sands  Laboratory  testing  In  Situ  testing  Numerical  modelling Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A virtual calibration chamber was built using a three-dimensional model based on the discrete-element method. The chamber was then filled with a scaled granular equivalent of Ticino sand, the material properties of which were selected by curve-fitting triaxial tests. Cone penetration tests were then performed under different initial densities and isotropic stresses. Penetration resistance in the virtual calibration chamber was affected by the same cone/chamber size effect that affects physical calibration chambers and was corrected accordingly. The corrected cone resistance obtained from the virtual calibration chamber cone penetration tests shows good quantitative agreement with correlations that summarise previous physical results. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.067 [article] Cone penetration tests in a virtual calibration chamber [texte imprimé] / M. Arroyo, Auteur ; J. Butlanska, Auteur ; A. Gens, Auteur . - 2011 . - pp. 525–531. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 525–531 Mots-clés : Sands  Laboratory  testing  In  Situ  testing  Numerical  modelling Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : A virtual calibration chamber was built using a three-dimensional model based on the discrete-element method. The chamber was then filled with a scaled granular equivalent of Ticino sand, the material properties of which were selected by curve-fitting triaxial tests. Cone penetration tests were then performed under different initial densities and isotropic stresses. Penetration resistance in the virtual calibration chamber was affected by the same cone/chamber size effect that affects physical calibration chambers and was corrected accordingly. The corrected cone resistance obtained from the virtual calibration chamber cone penetration tests shows good quantitative agreement with correlations that summarise previous physical results. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.067

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