Documents disponibles écrits par cet auteur

Arching in distribution of active load on retaining walls / Srinivasa S. Nadukuru in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 5 (Mai 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 5 (Mai 2012) . - pp. 575–584 Titre : Arching in distribution of active load on retaining walls Type de document : texte imprimé Auteurs : Srinivasa S. Nadukuru, Auteur ; Radoslaw L. Michalowski, Auteur Année de publication : 2012 Article en page(s) : pp. 575–584 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Arching  Retaining  walls  Active  load  Numerical  analysis  Discrete  element  method Résumé : Traditional methods for calculations of active loads on retaining structures provide dependable forces, but these methods do not indicate reliably the location of the resultant load on the walls. The Coulomb method does not address the load distribution because it utilizes equilibrium of forces, whereas the Rankine stress distribution provides linear increase of the load with depth. Past experimental studies indicate intricate distributions dependent on the mode of displacement of the wall before reaching the limit state. The discrete element method was used to simulate soil-retaining structure interaction, and force chains characteristic of arching were identified. Arching appears to be the primary cause affecting the load distribution. A differential slice technique was used to mimic the load distributions seen in physical experiments. The outcome indicates that rotation modes of wall movement are associated with uneven mobilization of strength on the surface separating the moving backfill from the soil at rest. Calculations show that the location of the centroid of the active load distribution behind a translating wall is approximately 0.40 of the wall height above the base, but for a wall rotating about its top point, the location of the resultant is at approximately 0.55H. In the third case, rotation about the base, the location of the calculated centroid of the stress distribution on the wall is slightly below one-third of the wall height. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000617 [article] Arching in distribution of active load on retaining walls [texte imprimé] / Srinivasa S. Nadukuru, Auteur ; Radoslaw L. Michalowski, Auteur . - 2012 . - pp. 575–584. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 5 (Mai 2012) . - pp. 575–584 Mots-clés : Arching  Retaining  walls  Active  load  Numerical  analysis  Discrete  element  method Résumé : Traditional methods for calculations of active loads on retaining structures provide dependable forces, but these methods do not indicate reliably the location of the resultant load on the walls. The Coulomb method does not address the load distribution because it utilizes equilibrium of forces, whereas the Rankine stress distribution provides linear increase of the load with depth. Past experimental studies indicate intricate distributions dependent on the mode of displacement of the wall before reaching the limit state. The discrete element method was used to simulate soil-retaining structure interaction, and force chains characteristic of arching were identified. Arching appears to be the primary cause affecting the load distribution. A differential slice technique was used to mimic the load distributions seen in physical experiments. The outcome indicates that rotation modes of wall movement are associated with uneven mobilization of strength on the surface separating the moving backfill from the soil at rest. Calculations show that the location of the centroid of the active load distribution behind a translating wall is approximately 0.40 of the wall height above the base, but for a wall rotating about its top point, the location of the resultant is at approximately 0.55H. In the third case, rotation about the base, the location of the calculated centroid of the stress distribution on the wall is slightly below one-third of the wall height. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000617

Critical pool level and stability of slopes in granular soils / Radoslaw L. Michalowski in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N°3 (Mars 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°3 (Mars 2009) . - pp. 444–448 Titre : Critical pool level and stability of slopes in granular soils Type de document : texte imprimé Auteurs : Radoslaw L. Michalowski, Auteur Année de publication : 2009 Article en page(s) : pp. 444–448 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Slopes  Limit  states  Failures  Submerging  Pore  water  pressure Résumé : The influence of pore-water pressure and the pool water pressure on stability of submerged slopes was investigated using the kinematic approach of limit analysis. For soils with some cohesive component of strength, the critical pool level is slightly below half of the slope height, whereas for slopes built of purely granular soils the critical pool level is not well defined. The most critical mechanism of failure for submerged granular slopes was found to have the failure surface intersecting the face of the slope, with one intersection point above, and the other one below the pool level. The solution to the stability problem was found to be independent of the length scale (slope height), and equally critical mechanisms of failure can be triggered “locally” with any water level in the pool. The safety factor associated with these mechanisms is lower than the well-known factor defined by a planar failure surface approaching the slope face. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A3%2844 [...] [article] Critical pool level and stability of slopes in granular soils [texte imprimé] / Radoslaw L. Michalowski, Auteur . - 2009 . - pp. 444–448. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°3 (Mars 2009) . - pp. 444–448 Mots-clés : Slopes  Limit  states  Failures  Submerging  Pore  water  pressure Résumé : The influence of pore-water pressure and the pool water pressure on stability of submerged slopes was investigated using the kinematic approach of limit analysis. For soils with some cohesive component of strength, the critical pool level is slightly below half of the slope height, whereas for slopes built of purely granular soils the critical pool level is not well defined. The most critical mechanism of failure for submerged granular slopes was found to have the failure surface intersecting the face of the slope, with one intersection point above, and the other one below the pool level. The solution to the stability problem was found to be independent of the length scale (slope height), and equally critical mechanisms of failure can be triggered “locally” with any water level in the pool. The safety factor associated with these mechanisms is lower than the well-known factor defined by a planar failure surface approaching the slope face. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A3%2844 [...]

Expanding collapse in partially submerged granular soil slopes / Radoslaw L. Michalowski in Canadian geotechnical journal, Vol. 46 N° 12 (Décembre 2009) 

Public ISBD [article]  in Canadian geotechnical journal > Vol. 46 N° 12 (Décembre 2009) . - pp. 1371–1378 Titre : Expanding collapse in partially submerged granular soil slopes Type de document : texte imprimé Auteurs : Radoslaw L. Michalowski, Auteur Année de publication : 2010 Article en page(s) : pp. 1371–1378 Note générale : Sciences de la Terre Langues : Anglais (eng) Mots-clés : Slopes  Limit  state  analysis  Progressive  failure  Submerged  slopes  Pentes  Analyse  de  l’état  limite  Rupture  progressive  Pentes  submergées Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : The traditional approach to stability analysis of granular slopes leads to the safety factor that is associated with a planar failure surface approaching the slope face, whether the slope is “dry” or submerged. However, for partially submerged slopes, a more critical, nonplanar failure surface can be formed. A family of geometrically similar surfaces can be found that is characterized by the same safety factor. If the safety factor drops down to unity and the slope becomes unstable, then a mechanism of any size can form. Alternatively, the failure may start at some small region and then the volume of the mechanism of failure can expand, giving rise to a progressive failure of a different kind that is typically associated with slopes. This progression has the character of a “disturbance” or a shock-like kinematic discontinuity propagating into the soil at rest. A quantitative analysis is presented and it is demonstrated that the soil dilates while the mechanism expands, leaving the slope weakened and susceptible to a deep failure. This is a plausible mode of failure of partially submerged slopes, the type that is most likely responsible for large subaqueous landslides, and is similar to the well-documented instability propagation in “quick clay.” L’approche traditionnelle pour l’analyse de stabilité des pentes faites de matériaux granulaires permet d’obtenir un facteur de sécurité associé à une surface de rupture plane, près de la surface de la pente, que ce soit pour une pente « sèche » ou submergée. Cependant, dans le cas des pentes partiellement submergées, une surface de rupture non plane, et plus critique, peut être formée. Une famille de surface ayant une géométrie similaire, et caractérisée par le même facteur de sécurité, peut être formée. Si le facteur de sécurité descend à une valeur de 1 et que la pente devient instable, alors n’importe quelle taille de mécanisme peut se former. D’un autre côté, la rupture peut débuter dans une petite région, ensuite le volume du mécanisme de rupture peut prendre de l’expansion, ce qui amène à un type différent de rupture progressive qui est normalement associée aux pentes. Cette progression ressemble à une perturbation ou une discontinuité cinétique de type onde de choc qui se propage à travers le sol au repos. Une analyse quantitative est présentée, et démontre que le sol se dilate à mesure que le mécanisme prend de l’expansion, laissant ainsi la pente affaiblie et susceptible à une rupture en profondeur. Ce mode de rupture est plausible pour des pentes partiellement submergées et est probablement responsable des importants glissements de terrains sous-marins, en plus d’être similaire à la propagation des instabilités dans l’ « argile rapide » qui elle est bien documentée. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...] [article] Expanding collapse in partially submerged granular soil slopes [texte imprimé] / Radoslaw L. Michalowski, Auteur . - 2010 . - pp. 1371–1378. Sciences de la Terre Langues : Anglais (eng) in Canadian geotechnical journal > Vol. 46 N° 12 (Décembre 2009) . - pp. 1371–1378 Mots-clés : Slopes  Limit  state  analysis  Progressive  failure  Submerged  slopes  Pentes  Analyse  de  l’état  limite  Rupture  progressive  Pentes  submergées Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : The traditional approach to stability analysis of granular slopes leads to the safety factor that is associated with a planar failure surface approaching the slope face, whether the slope is “dry” or submerged. However, for partially submerged slopes, a more critical, nonplanar failure surface can be formed. A family of geometrically similar surfaces can be found that is characterized by the same safety factor. If the safety factor drops down to unity and the slope becomes unstable, then a mechanism of any size can form. Alternatively, the failure may start at some small region and then the volume of the mechanism of failure can expand, giving rise to a progressive failure of a different kind that is typically associated with slopes. This progression has the character of a “disturbance” or a shock-like kinematic discontinuity propagating into the soil at rest. A quantitative analysis is presented and it is demonstrated that the soil dilates while the mechanism expands, leaving the slope weakened and susceptible to a deep failure. This is a plausible mode of failure of partially submerged slopes, the type that is most likely responsible for large subaqueous landslides, and is similar to the well-documented instability propagation in “quick clay.” L’approche traditionnelle pour l’analyse de stabilité des pentes faites de matériaux granulaires permet d’obtenir un facteur de sécurité associé à une surface de rupture plane, près de la surface de la pente, que ce soit pour une pente « sèche » ou submergée. Cependant, dans le cas des pentes partiellement submergées, une surface de rupture non plane, et plus critique, peut être formée. Une famille de surface ayant une géométrie similaire, et caractérisée par le même facteur de sécurité, peut être formée. Si le facteur de sécurité descend à une valeur de 1 et que la pente devient instable, alors n’importe quelle taille de mécanisme peut se former. D’un autre côté, la rupture peut débuter dans une petite région, ensuite le volume du mécanisme de rupture peut prendre de l’expansion, ce qui amène à un type différent de rupture progressive qui est normalement associée aux pentes. Cette progression ressemble à une perturbation ou une discontinuité cinétique de type onde de choc qui se propage à travers le sol au repos. Une analyse quantitative est présentée, et démontre que le sol se dilate à mesure que le mécanisme prend de l’expansion, laissant ainsi la pente affaiblie et susceptible à une rupture en profondeur. Ce mode de rupture est plausible pour des pentes partiellement submergées et est probablement responsable des importants glissements de terrains sous-marins, en plus d’être similaire à la propagation des instabilités dans l’ « argile rapide » qui elle est bien documentée. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...]

Limit analysis and stability charts for 3D slope failures / Radoslaw L. Michalowski in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 4 (Avril 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 4 (Avril 2010) . - pp. 583-593 Titre : Limit analysis and stability charts for 3D slope failures Type de document : texte imprimé Auteurs : Radoslaw L. Michalowski, Auteur Année de publication : 2010 Article en page(s) : pp. 583-593 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Slope  stability  Limit  analysis  Landslides  Plasticity  Failure  Three-dimensional  analysis  Loaded  slopes Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The kinematic approach of limit analysis is explored in three-dimensional (3D) stability analysis of slopes. A formal derivation is first shown indicating that, in a general case, the approach yields an upper bound to the critical height of the slope or an upper bound on the safety factor. A 3D failure mechanism is used to produce stability charts for slopes. The slope safety factor can be read from the charts without the need for iterations. While two-dimensional (2D) analyses of uniform slopes lead to lower safety factors than 3D analyses do, a 3D calculation is justified in cases where the width of the collapse mechanism has physical limitations, for instance, in the case of excavation slopes, or when the analysis is carried out to back-calculate the properties of the soil from 3D failure case histories. Also, a 3D failure can be triggered by a load on a portion of the surface area of the slope. Calculations indicate that for the 3D safety factor of the loaded slope to become lower than the 2D factor for the same slope (but with a load-free surface), the load has to be very significant and equal to the weight of a soil column of the order 10−1 of the slope height. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i4/p583_s1?isAuthorized=no [article] Limit analysis and stability charts for 3D slope failures [texte imprimé] / Radoslaw L. Michalowski, Auteur . - 2010 . - pp. 583-593. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 4 (Avril 2010) . - pp. 583-593 Mots-clés : Slope  stability  Limit  analysis  Landslides  Plasticity  Failure  Three-dimensional  analysis  Loaded  slopes Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The kinematic approach of limit analysis is explored in three-dimensional (3D) stability analysis of slopes. A formal derivation is first shown indicating that, in a general case, the approach yields an upper bound to the critical height of the slope or an upper bound on the safety factor. A 3D failure mechanism is used to produce stability charts for slopes. The slope safety factor can be read from the charts without the need for iterations. While two-dimensional (2D) analyses of uniform slopes lead to lower safety factors than 3D analyses do, a 3D calculation is justified in cases where the width of the collapse mechanism has physical limitations, for instance, in the case of excavation slopes, or when the analysis is carried out to back-calculate the properties of the soil from 3D failure case histories. Also, a 3D failure can be triggered by a load on a portion of the surface area of the slope. Calculations indicate that for the 3D safety factor of the loaded slope to become lower than the 2D factor for the same slope (but with a load-free surface), the load has to be very significant and equal to the weight of a soil column of the order 10−1 of the slope height. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i4/p583_s1?isAuthorized=no

Stability charts for 3D failures of steep slopes subjected to seismic excitation / Radoslaw L. Michalowski in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 183-189 Titre : Stability charts for 3D failures of steep slopes subjected to seismic excitation Type de document : texte imprimé Auteurs : Radoslaw L. Michalowski, Auteur ; Tabetha Marte, Auteur Année de publication : 2011 Article en page(s) : pp. 183-189 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Slopes  Stability  Seismic  analysis  Limit  state  analysis  3D  analysis  Failure Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Design of slopes and analysis of existing slopes subjected to seismic shaking are carried out routinely using approximations of plane strain and substitution of a quasi-static load for the seismic excitation. A three-dimensional (3D) analysis of slopes is carried out, based on the kinematic theorem of limit analysis. A rotational failure mechanism is used with the failure surface in the shape of a curvilinear cone sector passing through the slope toe, typical of steep slopes. A quasi-static approach is used to develop stability charts allowing assessment of the factor of safety of slopes without the need for an iterative procedure. The charts are of practical importance in cases of excavation slopes and whenever a slope is physically constrained, preventing a plane failure. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p183_s1?isAuthorized=no [article] Stability charts for 3D failures of steep slopes subjected to seismic excitation [texte imprimé] / Radoslaw L. Michalowski, Auteur ; Tabetha Marte, Auteur . - 2011 . - pp. 183-189. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 183-189 Mots-clés : Slopes  Stability  Seismic  analysis  Limit  state  analysis  3D  analysis  Failure Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Design of slopes and analysis of existing slopes subjected to seismic shaking are carried out routinely using approximations of plane strain and substitution of a quasi-static load for the seismic excitation. A three-dimensional (3D) analysis of slopes is carried out, based on the kinematic theorem of limit analysis. A rotational failure mechanism is used with the failure surface in the shape of a curvilinear cone sector passing through the slope toe, typical of steep slopes. A quasi-static approach is used to develop stability charts allowing assessment of the factor of safety of slopes without the need for an iterative procedure. The charts are of practical importance in cases of excavation slopes and whenever a slope is physically constrained, preventing a plane failure. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p183_s1?isAuthorized=no

Static fatigue, time effects, and delayed increase in penetration resistance after dynamic compaction of sands / Radoslaw L. Michalowski in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 5 (Mai 2012) 

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