Dépouillements

Predicting the behavior of an earth and rockfill dam under construction / L. M. Costa in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 851–862 Titre : Predicting the behavior of an earth and rockfill dam under construction Type de document : texte imprimé Auteurs : L. M. Costa, Auteur ; E. E. Alonso, Auteur Année de publication : 2009 Article en page(s) : pp. 851–862 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Dams  Rockfill  Dam  construction  Soil  compaction  Unsaturated  soils  Finite  element  method  Predictions Résumé : This paper presents an application of a coupled hydromechanical formulation for compacted and rockfill materials to simulate the construction and impoundment of a zoned earth dam. The constitutive relation used to model the mechanical behavior of the shoulder, filter and core materials is the Barcelona Basic Model for unsaturated materials. The hydraulic behavior of dam materials requires the specification of their water retention characteristics and their permeabilities, which will be expressed as a function of porosity and degree of saturation. The model was used in the design stage of Lechago’s dam (Teruel, Spain), currently under construction. Soil parameters were obtained by laboratory tests performed on materials to be used in the dam. The step-by-step construction (following the sequence construction of nine horizontal layers, besides the downstream preloading layers) and subsequent impounding of the reservoir was simulated in a prediction exercise, which will be hopefully confronted with actual construction measurements in the near future. A parametric study was also performed to evaluate the effects of the compaction water content of the core material on the behavior of the dam. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000058 [article] Predicting the behavior of an earth and rockfill dam under construction [texte imprimé] / L. M. Costa, Auteur ; E. E. Alonso, Auteur . - 2009 . - pp. 851–862. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 851–862 Mots-clés : Dams  Rockfill  Dam  construction  Soil  compaction  Unsaturated  soils  Finite  element  method  Predictions Résumé : This paper presents an application of a coupled hydromechanical formulation for compacted and rockfill materials to simulate the construction and impoundment of a zoned earth dam. The constitutive relation used to model the mechanical behavior of the shoulder, filter and core materials is the Barcelona Basic Model for unsaturated materials. The hydraulic behavior of dam materials requires the specification of their water retention characteristics and their permeabilities, which will be expressed as a function of porosity and degree of saturation. The model was used in the design stage of Lechago’s dam (Teruel, Spain), currently under construction. Soil parameters were obtained by laboratory tests performed on materials to be used in the dam. The step-by-step construction (following the sequence construction of nine horizontal layers, besides the downstream preloading layers) and subsequent impounding of the reservoir was simulated in a prediction exercise, which will be hopefully confronted with actual construction measurements in the near future. A parametric study was also performed to evaluate the effects of the compaction water content of the core material on the behavior of the dam. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000058

Sensor-enabled geosynthetics / Kianoosh Hatami in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 863–874 Titre : Sensor-enabled geosynthetics : use of conducting carbon networks as geosynthetic sensors Type de document : texte imprimé Auteurs : Kianoosh Hatami, Auteur ; Brian P. Grady, Auteur ; Matthew C. Ulmer, Auteur Année de publication : 2009 Article en page(s) : pp. 863–874 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Geosynthetics  Instrumentation  Sensors  Strain Résumé : A novel technique is developed based on the piezoresistivity of electrically filled polymers to measure the tensile strain in modified geosynthetics without the need for conventional instrumentation (e.g., strain gauges). This paper reports the development of the technique and the results obtained on high-density polyethylene and polypropylene (PP) geogrid specimens filled with carbon black and carbon nanotubes (NTs). It was found that except for NT-filled PP specimens all other composites exhibited significant strain sensitivity in their conductivity. The proof-of-concept study reported in this paper has two important features: (1) strain sensitivity of electrical conductivity was demonstrated in polyolefins used to manufacture geosynthetics; and (2) this strain sensitivity was obtained and demonstrated over the range of strain values that are important in geosynthetic engineering applications. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000062 [article] Sensor-enabled geosynthetics : use of conducting carbon networks as geosynthetic sensors [texte imprimé] / Kianoosh Hatami, Auteur ; Brian P. Grady, Auteur ; Matthew C. Ulmer, Auteur . - 2009 . - pp. 863–874. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 863–874 Mots-clés : Geosynthetics  Instrumentation  Sensors  Strain Résumé : A novel technique is developed based on the piezoresistivity of electrically filled polymers to measure the tensile strain in modified geosynthetics without the need for conventional instrumentation (e.g., strain gauges). This paper reports the development of the technique and the results obtained on high-density polyethylene and polypropylene (PP) geogrid specimens filled with carbon black and carbon nanotubes (NTs). It was found that except for NT-filled PP specimens all other composites exhibited significant strain sensitivity in their conductivity. The proof-of-concept study reported in this paper has two important features: (1) strain sensitivity of electrical conductivity was demonstrated in polyolefins used to manufacture geosynthetics; and (2) this strain sensitivity was obtained and demonstrated over the range of strain values that are important in geosynthetic engineering applications. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000062

Long-term reinforcement load of geosynthetic-reinforced soil retaining walls / Huabei Liu in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 875–889 Titre : Long-term reinforcement load of geosynthetic-reinforced soil retaining walls Type de document : texte imprimé Auteurs : Huabei Liu, Auteur ; Myoung-Soo Won, Auteur Année de publication : 2009 Article en page(s) : pp. 875–889 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Geosynthetics  Retaining  walls  Soil  structures  Reinforcement  Finite  element  method  Parameters Résumé : As increasing number of geosynthetic-reinforced soil (GRS) retaining walls are built for permanent purpose, and their long-term behaviors have become one of the most critical issues in design. However, there has been very limited study on long-term reinforcement load and its relation to various parameters of GRS walls. A finite-element procedure for the long-term response of geosynthetic-reinforced soil structures with granular backfills was first validated against the long-term model test. Extensive finite-element analyses considering the viscous properties of geosynthetic reinforcements were then carried out to investigate the load distributions in geosynthetic reinforcements of GRS walls under operational condition. Construction sequence was simulated and a creep analysis of 10years was subsequently conducted on each model wall. The effects of wall parameters, including backfill soil, reinforcement length, reinforcement spacing, reinforcement stiffness, and creep rate of reinforcement were investigated. It is found from the analyses that: (1) the maximum reinforcement load of GRS walls under working stress condition was generally smaller than that estimated using the FHwA design but it is dependent on the global reinforcement stiffness Sglobal ; (2) the surface of maximum reinforcement load did not coincide with the Rankine’s surface suggested by FHwA design guidelines for vertical GRS walls and it was affected by the strength of backfill soil, reinforcement length, reinforcement spacing, and reinforcement stiffness; (3) for GRS walls under operational condition, reinforcement loads were closely related to the mobilized stiffness of backfill soil; (4) isochrone curves can be used to interpret the effects of reinforcement stiffness and creep rate on both short-term and long-term performances of GRS walls under operational condition, and with an increase in the reinforcement stiffness, the maximum reinforcement load increased; and (5) the global reinforcement stiffness Sglobal , which is related to the isochrones stiffness of reinforcement as well as reinforcement spacing was related to the total reinforcement load Tmaxtotal and with an increase in the global stiffness, the total reinforcement load increased. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000052 [article] Long-term reinforcement load of geosynthetic-reinforced soil retaining walls [texte imprimé] / Huabei Liu, Auteur ; Myoung-Soo Won, Auteur . - 2009 . - pp. 875–889. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 875–889 Mots-clés : Geosynthetics  Retaining  walls  Soil  structures  Reinforcement  Finite  element  method  Parameters Résumé : As increasing number of geosynthetic-reinforced soil (GRS) retaining walls are built for permanent purpose, and their long-term behaviors have become one of the most critical issues in design. However, there has been very limited study on long-term reinforcement load and its relation to various parameters of GRS walls. A finite-element procedure for the long-term response of geosynthetic-reinforced soil structures with granular backfills was first validated against the long-term model test. Extensive finite-element analyses considering the viscous properties of geosynthetic reinforcements were then carried out to investigate the load distributions in geosynthetic reinforcements of GRS walls under operational condition. Construction sequence was simulated and a creep analysis of 10years was subsequently conducted on each model wall. The effects of wall parameters, including backfill soil, reinforcement length, reinforcement spacing, reinforcement stiffness, and creep rate of reinforcement were investigated. It is found from the analyses that: (1) the maximum reinforcement load of GRS walls under working stress condition was generally smaller than that estimated using the FHwA design but it is dependent on the global reinforcement stiffness Sglobal ; (2) the surface of maximum reinforcement load did not coincide with the Rankine’s surface suggested by FHwA design guidelines for vertical GRS walls and it was affected by the strength of backfill soil, reinforcement length, reinforcement spacing, and reinforcement stiffness; (3) for GRS walls under operational condition, reinforcement loads were closely related to the mobilized stiffness of backfill soil; (4) isochrone curves can be used to interpret the effects of reinforcement stiffness and creep rate on both short-term and long-term performances of GRS walls under operational condition, and with an increase in the reinforcement stiffness, the maximum reinforcement load increased; and (5) the global reinforcement stiffness Sglobal , which is related to the isochrones stiffness of reinforcement as well as reinforcement spacing was related to the total reinforcement load Tmaxtotal and with an increase in the global stiffness, the total reinforcement load increased. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000052

Importance of lower-bound capacities in the design of deep foundations / Shadi S. Najjar in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 890–900 Titre : Importance of lower-bound capacities in the design of deep foundations Type de document : texte imprimé Auteurs : Shadi S. Najjar, Auteur ; Robert B. Gilbert, Auteur Année de publication : 2009 Article en page(s) : pp. 890–900 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Deep  foundations  Foundation  design  Load  and  resistance  factor  design  Reliability Résumé : There is generally a physical limit to the smallest possible capacity for a deep foundation. However, a lower bound on the capacity has rarely been accounted for in performing reliability analyses and developing reliability-based design codes. The objectives of this paper are to investigate the effect of having a lower-bound capacity on the reliability of a geotechnical engineering system and to propose a load and resistance factor design (LRFD) checking format that includes information on the lower-bound capacity in design. It is concluded that a lower-bound capacity can cause a significant increase in the calculated reliability for a geotechnical design even if it is an uncertain estimate. Two alternative LRFD formats that incorporate lower-bound capacities and that would not require substantive changes to existing codes are proposed. Real-world examples dealing with the design of onshore and offshore foundations indicate that the incorporation of a lower-bound capacity into design is expected to provide a more realistic quantification of reliability for decision-making purposes and therefore a more rational and efficient basis for design. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000044 [article] Importance of lower-bound capacities in the design of deep foundations [texte imprimé] / Shadi S. Najjar, Auteur ; Robert B. Gilbert, Auteur . - 2009 . - pp. 890–900. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 890–900 Mots-clés : Deep  foundations  Foundation  design  Load  and  resistance  factor  design  Reliability Résumé : There is generally a physical limit to the smallest possible capacity for a deep foundation. However, a lower bound on the capacity has rarely been accounted for in performing reliability analyses and developing reliability-based design codes. The objectives of this paper are to investigate the effect of having a lower-bound capacity on the reliability of a geotechnical engineering system and to propose a load and resistance factor design (LRFD) checking format that includes information on the lower-bound capacity in design. It is concluded that a lower-bound capacity can cause a significant increase in the calculated reliability for a geotechnical design even if it is an uncertain estimate. Two alternative LRFD formats that incorporate lower-bound capacities and that would not require substantive changes to existing codes are proposed. Real-world examples dealing with the design of onshore and offshore foundations indicate that the incorporation of a lower-bound capacity into design is expected to provide a more realistic quantification of reliability for decision-making purposes and therefore a more rational and efficient basis for design. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000044

Pile bearing capacity factors and soil crushabiity / Keiji Kuwajima in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 901–913 Titre : Pile bearing capacity factors and soil crushabiity Type de document : texte imprimé Auteurs : Keiji Kuwajima, Auteur ; Masayuki Hyodo, Auteur ; Adrian F. Hyde, Auteur Année de publication : 2009 Article en page(s) : pp. 901–913 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Piles  Load  bearing  capacity  Friction  Sand  Silica  Calcareous  soils  Soil  compression  Model  tests Résumé : The existence of large magnitude stresses at the tip of a bearing pile is a well known phenomenon leading to crushing of soil grains and thus affecting pile behavior. Classical foundation design calculations which assume that the soil fails in shear and neglect volume change can be safely used where stress levels or particle strengths prevent crushing, however in the case of weak grains or high foundation stresses consideration should be given to the effects of grain crushing and the resulting volumetric compression. Model pile tests have been carried out in two skeletal carbonate sands and a standard silica sand with the aim of examining the variation of skin friction and end bearing capacities with degree of penetration. The mobilization of the strength of crushable soils requires a much higher strain level while at the same time the end bearing pressure on the model piles exceeded 10MPa inducing considerable particle breakage. The peak skin friction for all sands occurred at a settlement normalized by pile diameter, S∕D , of less than 0.1. At this point the carbonate sands generally had lower skin friction values than the silica sand. Further displacement caused a rapid decrease in skin friction for all three materials. At higher lateral stresses the less crushable Toyoura silica sand generated higher skin frictions. Samples of Chiibishi sand were sectioned and photographed. It was observed that a spherical plastic zone was formed at the base of the pile which expanded with increasing S∕D and a degraded layer of broken particles developed around the pile as S∕D increased. Large values of the Marsal particle breakage factor were restricted to a zone extending outwards to one pile radius. An end bearing capacity modification factor has been proposed to adapt the conventional bearing capacity equation for soil crushability. This modification factor is a function of soil compressibility and degree of penetration. The factor was shown to decrease with increasing soil compressibility and increase with normalized penetration S∕D . En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000057 [article] Pile bearing capacity factors and soil crushabiity [texte imprimé] / Keiji Kuwajima, Auteur ; Masayuki Hyodo, Auteur ; Adrian F. Hyde, Auteur . - 2009 . - pp. 901–913. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 901–913 Mots-clés : Piles  Load  bearing  capacity  Friction  Sand  Silica  Calcareous  soils  Soil  compression  Model  tests Résumé : The existence of large magnitude stresses at the tip of a bearing pile is a well known phenomenon leading to crushing of soil grains and thus affecting pile behavior. Classical foundation design calculations which assume that the soil fails in shear and neglect volume change can be safely used where stress levels or particle strengths prevent crushing, however in the case of weak grains or high foundation stresses consideration should be given to the effects of grain crushing and the resulting volumetric compression. Model pile tests have been carried out in two skeletal carbonate sands and a standard silica sand with the aim of examining the variation of skin friction and end bearing capacities with degree of penetration. The mobilization of the strength of crushable soils requires a much higher strain level while at the same time the end bearing pressure on the model piles exceeded 10MPa inducing considerable particle breakage. The peak skin friction for all sands occurred at a settlement normalized by pile diameter, S∕D , of less than 0.1. At this point the carbonate sands generally had lower skin friction values than the silica sand. Further displacement caused a rapid decrease in skin friction for all three materials. At higher lateral stresses the less crushable Toyoura silica sand generated higher skin frictions. Samples of Chiibishi sand were sectioned and photographed. It was observed that a spherical plastic zone was formed at the base of the pile which expanded with increasing S∕D and a degraded layer of broken particles developed around the pile as S∕D increased. Large values of the Marsal particle breakage factor were restricted to a zone extending outwards to one pile radius. An end bearing capacity modification factor has been proposed to adapt the conventional bearing capacity equation for soil crushability. This modification factor is a function of soil compressibility and degree of penetration. The factor was shown to decrease with increasing soil compressibility and increase with normalized penetration S∕D . En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000057

Interaction of shallow foundations with reverse faults / Ahmed Waqas in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 914–924 Titre : Interaction of shallow foundations with reverse faults Type de document : texte imprimé Auteurs : Ahmed Waqas, Auteur ; Mark Fraser Bransby, Auteur Année de publication : 2009 Article en page(s) : pp. 914–924 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil-structure  interaction  Shallow  foundations  Earthquake  engineering  Geological  faults  Sand Résumé : A series of centrifuge model tests is reported that investigated the effects of foundation position on the interaction of reverse, dip-slip faults with shallow foundations resting on sand. The model tests have allowed careful examination of both the soil and foundation deformation as a shear localization (fault) propagates through a 15m thick sand layer for fault throws up to 5m . By comparing results of the tests with foundations present with those from a “free-field” test, the effect of the foundation on the faulting pattern has been observed directly. The response of the foundation is very sensitive to the exact position of the fault and even when the fault emerged remotely from the foundation it sometimes caused significant foundation movements. Detailed results are presented for the tests and it is suggested that these results are used as: (1) indications of likely foundation–soil–fault interaction mechanisms; and (2) to allow future validation of numerical models for similar problems. Finally, foundation rotations measured during the fault–foundation interaction tests are compared to those predicted using a simple method based on free-field soil displacements. This simple method makes surprisingly good prediction of maximum fault rotations for different throws. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000072 [article] Interaction of shallow foundations with reverse faults [texte imprimé] / Ahmed Waqas, Auteur ; Mark Fraser Bransby, Auteur . - 2009 . - pp. 914–924. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 914–924 Mots-clés : Soil-structure  interaction  Shallow  foundations  Earthquake  engineering  Geological  faults  Sand Résumé : A series of centrifuge model tests is reported that investigated the effects of foundation position on the interaction of reverse, dip-slip faults with shallow foundations resting on sand. The model tests have allowed careful examination of both the soil and foundation deformation as a shear localization (fault) propagates through a 15m thick sand layer for fault throws up to 5m . By comparing results of the tests with foundations present with those from a “free-field” test, the effect of the foundation on the faulting pattern has been observed directly. The response of the foundation is very sensitive to the exact position of the fault and even when the fault emerged remotely from the foundation it sometimes caused significant foundation movements. Detailed results are presented for the tests and it is suggested that these results are used as: (1) indications of likely foundation–soil–fault interaction mechanisms; and (2) to allow future validation of numerical models for similar problems. Finally, foundation rotations measured during the fault–foundation interaction tests are compared to those predicted using a simple method based on free-field soil displacements. This simple method makes surprisingly good prediction of maximum fault rotations for different throws. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000072

Stability charts for the collapse of residual soil in karst / Eric C. Drumm in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 925–931 Titre : Stability charts for the collapse of residual soil in karst Type de document : texte imprimé Auteurs : Eric C. Drumm, Auteur ; Özgür Aktürk, Auteur ; Haluk Akgün, Auteur Année de publication : 2009 Article en page(s) : pp. 925–931 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Karst  Residual  soils  Finite  element  method  Void  Stability  Shear  strength Résumé : Collapse of the residual soil over bedrock cavities often occurs during construction in karst terrain, particularly when the thickness of the residuum is reduced during excavation. Even if an estimate of the strength of the residual soil is known, uncertainty with respect to the size/geometry of the subterranean voids makes a detailed analysis difficult, and straightforward methods to check the stability are needed. In this study, numerical analyses were performed to develop a stability chart expressed in terms of a dimensionless stability number and the geometry of a potential void in the residual soil. The stability charts include the effect of friction angle, and are also developed to allow the investigation of the effect of the inverted strength profile typically observed in karst terrain. Such stability numbers may be useful to estimate the stability of a given site based on the expected thickness of the soil overburden and the likely range of anticipated soil void diameters. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000066 [article] Stability charts for the collapse of residual soil in karst [texte imprimé] / Eric C. Drumm, Auteur ; Özgür Aktürk, Auteur ; Haluk Akgün, Auteur . - 2009 . - pp. 925–931. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 925–931 Mots-clés : Karst  Residual  soils  Finite  element  method  Void  Stability  Shear  strength Résumé : Collapse of the residual soil over bedrock cavities often occurs during construction in karst terrain, particularly when the thickness of the residuum is reduced during excavation. Even if an estimate of the strength of the residual soil is known, uncertainty with respect to the size/geometry of the subterranean voids makes a detailed analysis difficult, and straightforward methods to check the stability are needed. In this study, numerical analyses were performed to develop a stability chart expressed in terms of a dimensionless stability number and the geometry of a potential void in the residual soil. The stability charts include the effect of friction angle, and are also developed to allow the investigation of the effect of the inverted strength profile typically observed in karst terrain. Such stability numbers may be useful to estimate the stability of a given site based on the expected thickness of the soil overburden and the likely range of anticipated soil void diameters. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000066

Bayesian framework for characterizing geotechnical model uncertainty / J. Zhang in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 932–940 Titre : Bayesian framework for characterizing geotechnical model uncertainty Type de document : texte imprimé Auteurs : J. Zhang, Auteur ; Zhang, L. M., Auteur ; Wilson H. Tang, Auteur Année de publication : 2009 Article en page(s) : pp. 932–940 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Bayesian  analysis  Uncertainty  principles  Slope  stability  Centrifuge  model  Reliability Résumé : As any model is only an abstraction of the real world, model uncertainty always exists. The magnitude of model uncertainty is important for geotechnical decision making. If model uncertainty is not considered, the geotechnical predictions and hence the decisions based on the geotechnical predictions might be biased. In this study, a framework for characterizing geotechnical model uncertainty using observation data is proposed. The framework is based on the concept of multivariable Bayesian updating, in which the statistics of model uncertainty are updated using observed performance data. Uncertainties in both input parameters and observed data can be considered in the proposed framework. To bypass complex computational works involved in the proposed framework, a practical approximate solution is presented. The proposed framework is illustrated by characterizing the model uncertainty of four limit equilibrium methods for slope stability analysis using quality centrifuge test data. Parametric study in the illustrative example shows that both quality and quantity of the performance data could affect the determination of the model uncertainty, and that such effects can be systematically quantified with the proposed method. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000018 [article] Bayesian framework for characterizing geotechnical model uncertainty [texte imprimé] / J. Zhang, Auteur ; Zhang, L. M., Auteur ; Wilson H. Tang, Auteur . - 2009 . - pp. 932–940. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 932–940 Mots-clés : Bayesian  analysis  Uncertainty  principles  Slope  stability  Centrifuge  model  Reliability Résumé : As any model is only an abstraction of the real world, model uncertainty always exists. The magnitude of model uncertainty is important for geotechnical decision making. If model uncertainty is not considered, the geotechnical predictions and hence the decisions based on the geotechnical predictions might be biased. In this study, a framework for characterizing geotechnical model uncertainty using observation data is proposed. The framework is based on the concept of multivariable Bayesian updating, in which the statistics of model uncertainty are updated using observed performance data. Uncertainties in both input parameters and observed data can be considered in the proposed framework. To bypass complex computational works involved in the proposed framework, a practical approximate solution is presented. The proposed framework is illustrated by characterizing the model uncertainty of four limit equilibrium methods for slope stability analysis using quality centrifuge test data. Parametric study in the illustrative example shows that both quality and quantity of the performance data could affect the determination of the model uncertainty, and that such effects can be systematically quantified with the proposed method. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000018

Strain rate, creep, and stress drop-creep experiments on crushed coral sand / Poul V. Lade in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 941–953 Titre : Strain rate, creep, and stress drop-creep experiments on crushed coral sand Type de document : texte imprimé Auteurs : Poul V. Lade, Auteur ; Carl D. Liggio Jr., Auteur ; Jungman Nam, Auteur Année de publication : 2009 Article en page(s) : pp. 941–953 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Creep  Granular  materials  Sand  Soil  properties  Strain  rate  Time  dependence  Triaxial  tests Résumé : The part of sand behavior that is affected by time, such as creep, relaxation, and loading rate effects are not similar to those observed for clay. To throw more light on the time effects in sand, many series of drained triaxial compression experiments have been performed on crushed coral sand. These tests were all performed with a constant effective confining pressure of 200kPa . The test series included experiments with specimens loaded at five different strain rates with a 256-fold ratio between the extreme rates, tests with sudden changes in strain rate from slow to fast and vice versa, and tests in which axial and volumetric creep strains were observed at stress differences of 500, 700, and 900kPa . Creep creates structuration and this has to be overcome to produce further plastic straining. Experiments were also performed in which the stress difference was dropped quickly from three different values of 500, 700, and 900kPa followed by creep. In these stress drop-creep tests five different magnitudes of stress drops were employed: 0, 100, 200, 300, and 400kPa . The results involving conventional creep effects and stress drop-creep effects are presented and analyzed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000067 [article] Strain rate, creep, and stress drop-creep experiments on crushed coral sand [texte imprimé] / Poul V. Lade, Auteur ; Carl D. Liggio Jr., Auteur ; Jungman Nam, Auteur . - 2009 . - pp. 941–953. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 941–953 Mots-clés : Creep  Granular  materials  Sand  Soil  properties  Strain  rate  Time  dependence  Triaxial  tests Résumé : The part of sand behavior that is affected by time, such as creep, relaxation, and loading rate effects are not similar to those observed for clay. To throw more light on the time effects in sand, many series of drained triaxial compression experiments have been performed on crushed coral sand. These tests were all performed with a constant effective confining pressure of 200kPa . The test series included experiments with specimens loaded at five different strain rates with a 256-fold ratio between the extreme rates, tests with sudden changes in strain rate from slow to fast and vice versa, and tests in which axial and volumetric creep strains were observed at stress differences of 500, 700, and 900kPa . Creep creates structuration and this has to be overcome to produce further plastic straining. Experiments were also performed in which the stress difference was dropped quickly from three different values of 500, 700, and 900kPa followed by creep. In these stress drop-creep tests five different magnitudes of stress drops were employed: 0, 100, 200, 300, and 400kPa . The results involving conventional creep effects and stress drop-creep effects are presented and analyzed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000067

Reliability-Based Economic Design Optimization of Spread Foundations / Yu Wang in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 954–959 Titre : Reliability-Based Economic Design Optimization of Spread Foundations Type de document : texte imprimé Auteurs : Yu Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 954–959 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Foundation  design  Economic  factors  Costs  Reliability  Uncertainty  principles  Optimization Résumé : This technical note develops a design approach that integrates economic design optimization with reliability-based methodologies to rationally account for geotechnical-related uncertainties. The geotechnical related uncertainties are addressed using a reliability-based approach in the assessment of ultimate limit state (ULS) and serviceability limit state (SLS) requirements. This design approach is illustrated using an example of spread foundation under drained uplift loading. Comparison of the economically optimized design with conventional designs shows that cost of the economically optimized design is lower than that of other feasible designs, and increasing foundation depth is a relatively effective way to increase uplift capacity. Impacts of geotechnical property uncertainties on foundation construction costs are quantified, and the results form a basis of a quantitative cost-benefit analysis of reducing geotechnical property uncertainties. Operative horizontal stress coefficient (K) is shown to be the key parameter that significantly affects the design of a spread foundation under drained uplift, and therefore, deserves attention in site investigation. For a typical allowable uplift displacement ya=25mm , the spread foundation design is dictated by the ULS requirement, and the effect of ya , or SLS requirement, is negligible. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000013 [article] Reliability-Based Economic Design Optimization of Spread Foundations [texte imprimé] / Yu Wang, Auteur . - 2009 . - pp. 954–959. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 954–959 Mots-clés : Foundation  design  Economic  factors  Costs  Reliability  Uncertainty  principles  Optimization Résumé : This technical note develops a design approach that integrates economic design optimization with reliability-based methodologies to rationally account for geotechnical-related uncertainties. The geotechnical related uncertainties are addressed using a reliability-based approach in the assessment of ultimate limit state (ULS) and serviceability limit state (SLS) requirements. This design approach is illustrated using an example of spread foundation under drained uplift loading. Comparison of the economically optimized design with conventional designs shows that cost of the economically optimized design is lower than that of other feasible designs, and increasing foundation depth is a relatively effective way to increase uplift capacity. Impacts of geotechnical property uncertainties on foundation construction costs are quantified, and the results form a basis of a quantitative cost-benefit analysis of reducing geotechnical property uncertainties. Operative horizontal stress coefficient (K) is shown to be the key parameter that significantly affects the design of a spread foundation under drained uplift, and therefore, deserves attention in site investigation. For a typical allowable uplift displacement ya=25mm , the spread foundation design is dictated by the ULS requirement, and the effect of ya , or SLS requirement, is negligible. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000013

Simple energy-based method for nonlinear analysis of incompressible pile groups in clays / Assaf Klar in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 960–965 Titre : Simple energy-based method for nonlinear analysis of incompressible pile groups in clays Type de document : texte imprimé Auteurs : Assaf Klar, Auteur ; Yat-Fai Leung, Auteur Année de publication : 2009 Article en page(s) : pp. 960–965 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Pile  groups  Pile  foundations  Clays  Energy  methods  Nonlinear  analysis Résumé : This note presents a method for predicting nonlinear response of pile groups in clays, subjected to vertical loads. The method is based on mobilizable strength design (MSD) concepts, in which the mobilized strength is associated with the shear strains developed in the soil. The suggested procedure is incremental, and requires evaluation of a displacement field. A simple procedure of superposition of pattern functions is suggested for the construction of a complete displacement field. The incremental procedure allows for the variation of the displacement field throughout the loading process, according to principles of minimum energy and compatibility requirements among the piles. Essentially, the procedure allows consideration of a nonlinear continuum between the piles. The pattern functions are an adaptive form of the logarithmic function suggested by Randolph and Wroth in 1979. Under small load levels, when the soil is essentially elastic, the procedure yields values comparable to those from the elastic solution of Randolph and Wroth. At larger strain levels, nonlinear pile group response is simulated based on the soil constitutive models specified by the practitioner. The method is applicable to cases where shaft loading does not induce volume changes in the soil. The method is compared with three dimensional finite difference simulation of undrained loading of pile groups with a nonlinear soil constitutive model. Fair agreement is observed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000002 [article] Simple energy-based method for nonlinear analysis of incompressible pile groups in clays [texte imprimé] / Assaf Klar, Auteur ; Yat-Fai Leung, Auteur . - 2009 . - pp. 960–965. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 960–965 Mots-clés : Pile  groups  Pile  foundations  Clays  Energy  methods  Nonlinear  analysis Résumé : This note presents a method for predicting nonlinear response of pile groups in clays, subjected to vertical loads. The method is based on mobilizable strength design (MSD) concepts, in which the mobilized strength is associated with the shear strains developed in the soil. The suggested procedure is incremental, and requires evaluation of a displacement field. A simple procedure of superposition of pattern functions is suggested for the construction of a complete displacement field. The incremental procedure allows for the variation of the displacement field throughout the loading process, according to principles of minimum energy and compatibility requirements among the piles. Essentially, the procedure allows consideration of a nonlinear continuum between the piles. The pattern functions are an adaptive form of the logarithmic function suggested by Randolph and Wroth in 1979. Under small load levels, when the soil is essentially elastic, the procedure yields values comparable to those from the elastic solution of Randolph and Wroth. At larger strain levels, nonlinear pile group response is simulated based on the soil constitutive models specified by the practitioner. The method is applicable to cases where shaft loading does not induce volume changes in the soil. The method is compared with three dimensional finite difference simulation of undrained loading of pile groups with a nonlinear soil constitutive model. Fair agreement is observed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000002

Uncertainties of field pullout resistance of soil nails / L. L. Zhang in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 966–972 Titre : Uncertainties of field pullout resistance of soil nails Type de document : texte imprimé Auteurs : L. L. Zhang, Auteur ; Zhang, L. M., Auteur ; W. H. Tang, Auteur Année de publication : 2009 Article en page(s) : pp. 966–972 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  nailing  Slope  stability  Pull-out  In  situ  tests  Uncertainty  principles  Soil  suction Résumé : A large number of field pullout tests on soil nails have been carried out to provide valuable information for enhancing the understanding of pullout resistance of soil-grout interface and for reliability evaluation of soil-nailed slopes. In this paper, a data set of 167 field pullout tests performed in 23 nailed completely decomposed granite cut slopes is used for a statistical evaluation of four factors influencing the pullout resistance of soil nails, namely overburden pressure, grout length, soil suction, and soil dilatancy. For the tests in which nails were pulled out, the measured pullout resistance is essentially independent of the effective overburden pressure. A bias factor r∗ is defined as the ratio of the measured pullout resistance and the calculated value using a design equation. The mean value of r∗ is 4.30 and the coefficient of variation is 47%. When the uncertainties in grout length, soil suctions around nails, and the soil shear dilatancy are considered, the mean value of r∗ can finally be reduced to 0.99. The quantification of the uncertainties provides a better physical understanding of the working mechanisms of soil nails. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000014 [article] Uncertainties of field pullout resistance of soil nails [texte imprimé] / L. L. Zhang, Auteur ; Zhang, L. M., Auteur ; W. H. Tang, Auteur . - 2009 . - pp. 966–972. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 966–972 Mots-clés : Soil  nailing  Slope  stability  Pull-out  In  situ  tests  Uncertainty  principles  Soil  suction Résumé : A large number of field pullout tests on soil nails have been carried out to provide valuable information for enhancing the understanding of pullout resistance of soil-grout interface and for reliability evaluation of soil-nailed slopes. In this paper, a data set of 167 field pullout tests performed in 23 nailed completely decomposed granite cut slopes is used for a statistical evaluation of four factors influencing the pullout resistance of soil nails, namely overburden pressure, grout length, soil suction, and soil dilatancy. For the tests in which nails were pulled out, the measured pullout resistance is essentially independent of the effective overburden pressure. A bias factor r∗ is defined as the ratio of the measured pullout resistance and the calculated value using a design equation. The mean value of r∗ is 4.30 and the coefficient of variation is 47%. When the uncertainties in grout length, soil suctions around nails, and the soil shear dilatancy are considered, the mean value of r∗ can finally be reduced to 0.99. The quantification of the uncertainties provides a better physical understanding of the working mechanisms of soil nails. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000014

Investigation of tunnel-soil-pile interaction in cohesive soils / Mohamed A. Meguid in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 973–979 Titre : Investigation of tunnel-soil-pile interaction in cohesive soils Type de document : texte imprimé Auteurs : Mohamed A. Meguid, Auteur ; Joe Mattar, Auteur Année de publication : 2009 Article en page(s) : pp. 973–979 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Tunneling  Piles  Soil-structure  interaction  Cohesive  soils Résumé : Underground tunnels are considered to be a vital infrastructure component in most cities around the world. Careful planning is always necessary to ensure minimum impact on nearby surface and subsurface structures. This study describes the experimental investigation carried out to examine the effect of existing piles installed in cohesive soil and extended to bedrock on the circumferential stresses developing in a newly constructed tunnel supported by a flexible lining system. A small scale testing facility was designed and built to simulate the process of tunnel excavation and lining installation in the close vicinity of preinstalled model piles. Lining stresses were measured for different separation distances between the lining and the existing piles Consistent decrease in the lining load was observed when the piles are located within a distance of one tunnel diameter from the tunnel. The results presented in this study indicated that measuring the lining response near existing pile foundations may be used to evaluate the extent of the interaction between the lining and the surrounding piles. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000004 [article] Investigation of tunnel-soil-pile interaction in cohesive soils [texte imprimé] / Mohamed A. Meguid, Auteur ; Joe Mattar, Auteur . - 2009 . - pp. 973–979. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 973–979 Mots-clés : Tunneling  Piles  Soil-structure  interaction  Cohesive  soils Résumé : Underground tunnels are considered to be a vital infrastructure component in most cities around the world. Careful planning is always necessary to ensure minimum impact on nearby surface and subsurface structures. This study describes the experimental investigation carried out to examine the effect of existing piles installed in cohesive soil and extended to bedrock on the circumferential stresses developing in a newly constructed tunnel supported by a flexible lining system. A small scale testing facility was designed and built to simulate the process of tunnel excavation and lining installation in the close vicinity of preinstalled model piles. Lining stresses were measured for different separation distances between the lining and the existing piles Consistent decrease in the lining load was observed when the piles are located within a distance of one tunnel diameter from the tunnel. The results presented in this study indicated that measuring the lining response near existing pile foundations may be used to evaluate the extent of the interaction between the lining and the surrounding piles. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000004

Mechanical properties of reconstituted australian black coal / D. Jasinge in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 980–985 Titre : Mechanical properties of reconstituted australian black coal Type de document : texte imprimé Auteurs : D. Jasinge, Auteur ; P. G. Ranjith, Auteur ; S. K. Choi, Auteur Année de publication : 2009 Article en page(s) : pp. 980–985 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Coal  Australia  Mechanical  properties Résumé : Coal is usually highly heterogeneous. Great variation in properties can exist among samples obtained even at close proximity within the same seam or within the same core sample. This makes it difficult to establish a correlation between uniaxial compressive strength (UCS) and point load index for coal. To overcome this problem, a method for making reconstituted samples for laboratory tests was developed. Samples were made by compacting particles of crushed coal mixed with cement and water. These samples were allowed to cure for four days. UCS and point load tests were performed to measure the geomechanical properties of the reconstituted coal. After four days curing, the average UCS was found to be approximately 4MPa . This technical note outlines some experimental results and correlations that were developed to predict the mechanical properties of the reconstituted black coal samples. By reconstituting the samples from crushed coal, it is hoped that the samples will retain the important mechanical and physicochemical properties of coal, including the swelling, fluid transport, and gas sorption properties of coal. The aim is to be able to produce samples that are homogeneous with properties that are highly reproducible, and the reconstituted coal samples can be used for a number of research areas related to coal, including the long-term safe storage of CO2 in coal seams. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000010 [article] Mechanical properties of reconstituted australian black coal [texte imprimé] / D. Jasinge, Auteur ; P. G. Ranjith, Auteur ; S. K. Choi, Auteur . - 2009 . - pp. 980–985. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 980–985 Mots-clés : Coal  Australia  Mechanical  properties Résumé : Coal is usually highly heterogeneous. Great variation in properties can exist among samples obtained even at close proximity within the same seam or within the same core sample. This makes it difficult to establish a correlation between uniaxial compressive strength (UCS) and point load index for coal. To overcome this problem, a method for making reconstituted samples for laboratory tests was developed. Samples were made by compacting particles of crushed coal mixed with cement and water. These samples were allowed to cure for four days. UCS and point load tests were performed to measure the geomechanical properties of the reconstituted coal. After four days curing, the average UCS was found to be approximately 4MPa . This technical note outlines some experimental results and correlations that were developed to predict the mechanical properties of the reconstituted black coal samples. By reconstituting the samples from crushed coal, it is hoped that the samples will retain the important mechanical and physicochemical properties of coal, including the swelling, fluid transport, and gas sorption properties of coal. The aim is to be able to produce samples that are homogeneous with properties that are highly reproducible, and the reconstituted coal samples can be used for a number of research areas related to coal, including the long-term safe storage of CO2 in coal seams. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000010

Membrane effects in biaxial compression tests / J. David Frost in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 986–991 Titre : Membrane effects in biaxial compression tests Type de document : texte imprimé Auteurs : J. David Frost, Auteur ; T. Matthew Evans, Auteur Année de publication : 2009 Article en page(s) : pp. 986–991 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Membranes  Strain  Localization  Compression  tests Résumé : The effects of the confining membrane in laboratory tests on soil specimens have been the subject of numerous experimental, analytical, and numerical studies over the past half-century. This technical note expands the existing knowledge base by presenting a methodology and the associated results from an experimental study that has quantified the effect of the confining membrane in biaxial shear tests conducted on medium sand. The applicability of the method of biaxial tests on clay specimens is also presented. The results show that for both tests on sands and clays, the effect of the membrane on the shear stress on the failure plane are significant and should be accounted for in the interpretation of biaxial shear test results where localization occurs. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000011 [article] Membrane effects in biaxial compression tests [texte imprimé] / J. David Frost, Auteur ; T. Matthew Evans, Auteur . - 2009 . - pp. 986–991. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 986–991 Mots-clés : Membranes  Strain  Localization  Compression  tests Résumé : The effects of the confining membrane in laboratory tests on soil specimens have been the subject of numerous experimental, analytical, and numerical studies over the past half-century. This technical note expands the existing knowledge base by presenting a methodology and the associated results from an experimental study that has quantified the effect of the confining membrane in biaxial shear tests conducted on medium sand. The applicability of the method of biaxial tests on clay specimens is also presented. The results show that for both tests on sands and clays, the effect of the membrane on the shear stress on the failure plane are significant and should be accounted for in the interpretation of biaxial shear test results where localization occurs. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000011

Best-fit models to estimate modified proctor properties of compacted soil / Lucio Di Matteo in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 992–996 Titre : Best-fit models to estimate modified proctor properties of compacted soil Type de document : texte imprimé Auteurs : Lucio Di Matteo, Auteur ; Federica Bigotti, Auteur ; Remo Ricco, Auteur Année de publication : 2009 Article en page(s) : pp. 992–996 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  properties  Mechanic  properties  Soil  compaction  Geostatistics Résumé : Regression models were developed to estimate the optimum moisture content and maximum dry density of clayey and fine-grained soils using physical and index properties from 30 soil samples collected in Central Italy and 41 soils described in the literature. The liquid limit of the soils analyzed ranged between 18 and 82%, the plasticity index between 1 and 51%, and specific gravity between 2.47 and 3.09. The most significant regression variables were the specific gravity and the Atterberg limits. The developed models are accurate and can be used as a simple tool to approximate the maximum dry density and optimum water content of clayey and fine-grained soils. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000022 [article] Best-fit models to estimate modified proctor properties of compacted soil [texte imprimé] / Lucio Di Matteo, Auteur ; Federica Bigotti, Auteur ; Remo Ricco, Auteur . - 2009 . - pp. 992–996. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 992–996 Mots-clés : Soil  properties  Mechanic  properties  Soil  compaction  Geostatistics Résumé : Regression models were developed to estimate the optimum moisture content and maximum dry density of clayey and fine-grained soils using physical and index properties from 30 soil samples collected in Central Italy and 41 soils described in the literature. The liquid limit of the soils analyzed ranged between 18 and 82%, the plasticity index between 1 and 51%, and specific gravity between 2.47 and 3.09. The most significant regression variables were the specific gravity and the Atterberg limits. The developed models are accurate and can be used as a simple tool to approximate the maximum dry density and optimum water content of clayey and fine-grained soils. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000022

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