Dépouillements

Mechanics of lateral spreading observed in a full-scale shake test / R. Dobry 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. 115-129 Titre : Mechanics of lateral spreading observed in a full-scale shake test Type de document : texte imprimé Auteurs : R. Dobry, Auteur ; S. Thevanayagam, Auteur ; C. Medina, Auteur Année de publication : 2011 Article en page(s) : pp. 115-129 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Liquefaction  Residual  strength  Hydraulic  fill  Full-scale  tests  Lateral  displacement Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper examines in detail the mechanics of lateral spreading observed in a full-scale test of a sloping saturated fine sand deposit, representative of liquefiable, young alluvial and hydraulic fill sands in the field. The test was conducted using a 6-m tall inclined laminar box shaken at the base. At the end of shaking, nearly the whole deposit was liquefied, and the ground surface displacement had reached 32 cm. The presented analysis of lateral spreading mechanics utilizes a unique set of lateral displacement results, DH, from three independent techniques. One of these techniques—motion tracking analysis of the experiment video recording—is especially useful as it produced DH time histories for all laminar box rings and a complete picture of the lateral spreading initiation with an unprecedented degree of resolution in time and space. A systematic study of the data identifies the progressive stages of initiation and accumulation of lateral spreading, lateral spread contribution of various depth ranges and sliding zones, their relation to the simultaneous pore pressure buildup, and the soil shear strength response during sliding. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p115_s1?isAuthorized=no [article] Mechanics of lateral spreading observed in a full-scale shake test [texte imprimé] / R. Dobry, Auteur ; S. Thevanayagam, Auteur ; C. Medina, Auteur . - 2011 . - pp. 115-129. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 115-129 Mots-clés : Liquefaction  Residual  strength  Hydraulic  fill  Full-scale  tests  Lateral  displacement Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper examines in detail the mechanics of lateral spreading observed in a full-scale test of a sloping saturated fine sand deposit, representative of liquefiable, young alluvial and hydraulic fill sands in the field. The test was conducted using a 6-m tall inclined laminar box shaken at the base. At the end of shaking, nearly the whole deposit was liquefied, and the ground surface displacement had reached 32 cm. The presented analysis of lateral spreading mechanics utilizes a unique set of lateral displacement results, DH, from three independent techniques. One of these techniques—motion tracking analysis of the experiment video recording—is especially useful as it produced DH time histories for all laminar box rings and a complete picture of the lateral spreading initiation with an unprecedented degree of resolution in time and space. A systematic study of the data identifies the progressive stages of initiation and accumulation of lateral spreading, lateral spread contribution of various depth ranges and sliding zones, their relation to the simultaneous pore pressure buildup, and the soil shear strength response during sliding. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p115_s1?isAuthorized=no

Fully probabilistic framework for evaluating excavation-induced damage potential of adjacent buildings / C. Hsein Juang 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. 130-139 Titre : Fully probabilistic framework for evaluating excavation-induced damage potential of adjacent buildings Type de document : texte imprimé Auteurs : C. Hsein Juang, Auteur ; Matt Schuster, Auteur ; Chang-Yu Ou, Auteur Année de publication : 2011 Article en page(s) : pp. 130-139 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Reliability  Braced  excavation  Ground  settlement  Wall  deflection  Building  damage Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper presents a framework for a fully probabilistic analysis of the potential for damage to buildings adjacent to an excavation. Herein, the damage potential index (DPI), which is a function of angular distortion and lateral strain, is used to assess building damage potential. A serviceability limit state is established in which the resistance is expressed in terms of the “limiting” DPI, and the load is represented by the “applied” DPI. In this context, damage to the building adjacent to an excavation is said to occur deterministically if the applied DPI is greater than the limiting DPI. For the fully probabilistic analysis, both parameter and model uncertainties of the limiting and applied DPIs are first characterized. The analysis framework is then presented and demonstrated with a case history. Finally, sensitivity analysis is performed to identify the factors to which the probability of damage is most sensitive and to analyze the effect of various assumptions of the input parameters on the computed probability of building damage. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p130_s1?isAuthorized=no [article] Fully probabilistic framework for evaluating excavation-induced damage potential of adjacent buildings [texte imprimé] / C. Hsein Juang, Auteur ; Matt Schuster, Auteur ; Chang-Yu Ou, Auteur . - 2011 . - pp. 130-139. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 130-139 Mots-clés : Reliability  Braced  excavation  Ground  settlement  Wall  deflection  Building  damage Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper presents a framework for a fully probabilistic analysis of the potential for damage to buildings adjacent to an excavation. Herein, the damage potential index (DPI), which is a function of angular distortion and lateral strain, is used to assess building damage potential. A serviceability limit state is established in which the resistance is expressed in terms of the “limiting” DPI, and the load is represented by the “applied” DPI. In this context, damage to the building adjacent to an excavation is said to occur deterministically if the applied DPI is greater than the limiting DPI. For the fully probabilistic analysis, both parameter and model uncertainties of the limiting and applied DPIs are first characterized. The analysis framework is then presented and demonstrated with a case history. Finally, sensitivity analysis is performed to identify the factors to which the probability of damage is most sensitive and to analyze the effect of various assumptions of the input parameters on the computed probability of building damage. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p130_s1?isAuthorized=no

Expanded reliability-based design approach for drilled shafts / Yu Wang 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. 140-149 Titre : Expanded reliability-based design approach for drilled shafts Type de document : texte imprimé Auteurs : Yu Wang, Auteur ; Siu-Kui Au, Auteur ; Fred H. Kulhawy, Auteur Année de publication : 2011 Article en page(s) : pp. 140-149 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Uncertainty  Foundation  Pile  Limit  states  Simulations Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper develops a more general reliability-based design approach for drilled shafts that formulates the design process as an expanded reliability problem in which Monte Carlo simulations (MCS) are used in the design. Basic design parameters, such as the shaft diameter (B) and depth (D), are formulated as discrete uniform random variables. Then the design process becomes one in which failure probabilities are developed for various combinations of B and D [i.e., conditional probability p(Failure∣B,D)] and are compared with a target probability of failure pT. Equations are derived for this expanded reliability-based design (RBDE) approach, and criteria are established for the minimum number of MCS samples to ensure a desired level of accuracy. Its usefulness is illustrated using a drilled shaft design example. This RBDE approach has the following advantages: (1) it gives results that agree well with current RBD designs, but it improves the resolutions of the designs; (2) it offers design engineers insight into how the expected design performance level changes as B and D change; (3) it gives design engineers the ability to adjust pT, without additional calculation effort, to accommodate specific needs of a particular project; and (4) it is transparent and “visible” to design engineers who are given the flexibility to include uncertainties deemed appropriate. Finally, the effects of uncertainties in the at-rest horizontal soil stress coefficient (K0) and allowable displacement (ya) are illustrated using this approach. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p140_s1?isAuthorized=no [article] Expanded reliability-based design approach for drilled shafts [texte imprimé] / Yu Wang, Auteur ; Siu-Kui Au, Auteur ; Fred H. Kulhawy, Auteur . - 2011 . - pp. 140-149. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 140-149 Mots-clés : Uncertainty  Foundation  Pile  Limit  states  Simulations Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper develops a more general reliability-based design approach for drilled shafts that formulates the design process as an expanded reliability problem in which Monte Carlo simulations (MCS) are used in the design. Basic design parameters, such as the shaft diameter (B) and depth (D), are formulated as discrete uniform random variables. Then the design process becomes one in which failure probabilities are developed for various combinations of B and D [i.e., conditional probability p(Failure∣B,D)] and are compared with a target probability of failure pT. Equations are derived for this expanded reliability-based design (RBDE) approach, and criteria are established for the minimum number of MCS samples to ensure a desired level of accuracy. Its usefulness is illustrated using a drilled shaft design example. This RBDE approach has the following advantages: (1) it gives results that agree well with current RBD designs, but it improves the resolutions of the designs; (2) it offers design engineers insight into how the expected design performance level changes as B and D change; (3) it gives design engineers the ability to adjust pT, without additional calculation effort, to accommodate specific needs of a particular project; and (4) it is transparent and “visible” to design engineers who are given the flexibility to include uncertainties deemed appropriate. Finally, the effects of uncertainties in the at-rest horizontal soil stress coefficient (K0) and allowable displacement (ya) are illustrated using this approach. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p140_s1?isAuthorized=no

Internal erosion and rehabilitation of an earth-rock dam / Raul Flores-Berrones 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. 150-160 Titre : Internal erosion and rehabilitation of an earth-rock dam Type de document : texte imprimé Auteurs : Raul Flores-Berrones, Auteur ; Martín Ramirez-Reynaga, Auteur ; Emir José Macar, Auteur Année de publication : 2011 Article en page(s) : pp. 150-160 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Earth-rock  dam  Internal  erosion  Piping  Dam  failure  Rehabilitation Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper describes an earth-rock dam whose filters’ characteristics did not comply with the design criterion. In addition, the degree of compaction and the water content in the impervious core consisted of highly plastic residual clay. Although Terzaghi’s filter design criterion was used, the as-built grain size distribution did not comply with such criterion. Several problems arose right after the first filling of the dam, including the following: (1) water leak at a rate of 200 L/s was observed along the downstream slope, in the vicinity of the outlet pipeline; the dark color of the observed water implied that the core material was being eroded; (2) two sinkholes near the crest (20 m apart) were observed along the outlet axis, one on the upstream and the other on the downstream slopes; right after the occurrence of these two sinkholes, the water leakage decreases significantly, noticing a plugged effect of the material that falls down through the sinkholes. To avoid piping, a notch was installed on the spillway to quickly reduce the reservoir level. A site investigation around the affected zone was performed to find the causes of the observed seepage through the dam. The paper presents a detailed description of the site investigation. In addition, the paper presents the instrumentation, laboratory, and field tests employed as part of the site investigation. After analyzing the information produced in the site investigation, the following conclusions were derived: (1) large variation in the water content was used during the compaction of each lift of the impervious core which resulted in a highly heterogeneous core of the dam; (2) stress analysis of the zones around the outlet pipe demonstrated that the hydrostatic pressure in such zones exceeded the sum of the transverse normal and tensile stresses, inducing hydraulic fracturing; and (3) because of the grain size segregation during the placement of the filter material, the upstream and downstream filters did not satisfy the design criterion. Description of the stabilization of the damage zones through a grouting process, together with the construction of a diaphragm wall and an interface grouting, is presented. Finally, this paper reviews existing criteria for designing filters to protect earth and rockfill dams against internal erosion or piping and applies these criteria to the described dam. A special discussion on this topic is also presented. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p150_s1?isAuthorized=no [article] Internal erosion and rehabilitation of an earth-rock dam [texte imprimé] / Raul Flores-Berrones, Auteur ; Martín Ramirez-Reynaga, Auteur ; Emir José Macar, Auteur . - 2011 . - pp. 150-160. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 150-160 Mots-clés : Earth-rock  dam  Internal  erosion  Piping  Dam  failure  Rehabilitation Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper describes an earth-rock dam whose filters’ characteristics did not comply with the design criterion. In addition, the degree of compaction and the water content in the impervious core consisted of highly plastic residual clay. Although Terzaghi’s filter design criterion was used, the as-built grain size distribution did not comply with such criterion. Several problems arose right after the first filling of the dam, including the following: (1) water leak at a rate of 200 L/s was observed along the downstream slope, in the vicinity of the outlet pipeline; the dark color of the observed water implied that the core material was being eroded; (2) two sinkholes near the crest (20 m apart) were observed along the outlet axis, one on the upstream and the other on the downstream slopes; right after the occurrence of these two sinkholes, the water leakage decreases significantly, noticing a plugged effect of the material that falls down through the sinkholes. To avoid piping, a notch was installed on the spillway to quickly reduce the reservoir level. A site investigation around the affected zone was performed to find the causes of the observed seepage through the dam. The paper presents a detailed description of the site investigation. In addition, the paper presents the instrumentation, laboratory, and field tests employed as part of the site investigation. After analyzing the information produced in the site investigation, the following conclusions were derived: (1) large variation in the water content was used during the compaction of each lift of the impervious core which resulted in a highly heterogeneous core of the dam; (2) stress analysis of the zones around the outlet pipe demonstrated that the hydrostatic pressure in such zones exceeded the sum of the transverse normal and tensile stresses, inducing hydraulic fracturing; and (3) because of the grain size segregation during the placement of the filter material, the upstream and downstream filters did not satisfy the design criterion. Description of the stabilization of the damage zones through a grouting process, together with the construction of a diaphragm wall and an interface grouting, is presented. Finally, this paper reviews existing criteria for designing filters to protect earth and rockfill dams against internal erosion or piping and applies these criteria to the described dam. A special discussion on this topic is also presented. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p150_s1?isAuthorized=no

Use of A = 0 as a failure criterion for weakly cemented soils / Christopher D. P. Baxter 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. 161-170 Titre : Use of A = 0 as a failure criterion for weakly cemented soils Type de document : texte imprimé Auteurs : Christopher D. P. Baxter, Auteur ; M. S. Ravi Sharma, Auteur ; Kathryn Moran, Auteur Année de publication : 2011 Article en page(s) : pp. 161-170 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Portland  cement  Silts  Sand  Shear  strength  Dilatancy  Stiffness Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : There is considerable uncertainty in the determination of effective stress strength parameters of cemented soils from undrained triaxial tests. Large negative excess pore pressures are generated at relatively large strains (typically 4–5% for cemented silty sand) in isotropically consolidated undrained (CIU) tests, which results in gas coming out of solution during shear and significant variability in the measured peak deviator stress. In this study, different failure criteria for weakly cemented sands were evaluated based on the results of CIU and isotropically consolidated drained triaxial compression tests conducted on samples of artificially cemented sand. The use of math = 0 as a failure criterion eliminates the variability between the undrained tests and also ensures that the mobilized failure strength is not based on the highly variable negative excess pore pressures. In addition, the resulting strains to failure are comparable to the strains to failure for the drained tests. Mohr-Coulomb strength parameters thus estimated from the undrained tests are generally lower than strength parameters obtained from drained tests, and the difference between the failure envelopes from undrained tests increases as the level of cementation increases. This divergence is attributed to differences in the stiffness of the cemented soil under the different loading conditions. The stiffness under undrained loading conditions decreases with increasing cementation due to an increase in the generation of positive excess pore pressure at low strains. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p161_s1?isAuthorized=no [article] Use of A = 0 as a failure criterion for weakly cemented soils [texte imprimé] / Christopher D. P. Baxter, Auteur ; M. S. Ravi Sharma, Auteur ; Kathryn Moran, Auteur . - 2011 . - pp. 161-170. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 161-170 Mots-clés : Portland  cement  Silts  Sand  Shear  strength  Dilatancy  Stiffness Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : There is considerable uncertainty in the determination of effective stress strength parameters of cemented soils from undrained triaxial tests. Large negative excess pore pressures are generated at relatively large strains (typically 4–5% for cemented silty sand) in isotropically consolidated undrained (CIU) tests, which results in gas coming out of solution during shear and significant variability in the measured peak deviator stress. In this study, different failure criteria for weakly cemented sands were evaluated based on the results of CIU and isotropically consolidated drained triaxial compression tests conducted on samples of artificially cemented sand. The use of math = 0 as a failure criterion eliminates the variability between the undrained tests and also ensures that the mobilized failure strength is not based on the highly variable negative excess pore pressures. In addition, the resulting strains to failure are comparable to the strains to failure for the drained tests. Mohr-Coulomb strength parameters thus estimated from the undrained tests are generally lower than strength parameters obtained from drained tests, and the difference between the failure envelopes from undrained tests increases as the level of cementation increases. This divergence is attributed to differences in the stiffness of the cemented soil under the different loading conditions. The stiffness under undrained loading conditions decreases with increasing cementation due to an increase in the generation of positive excess pore pressure at low strains. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p161_s1?isAuthorized=no

Behavior of cemented paste backfill in two mine stopes: measurements and modeling / Matthew Helinski 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. 171-182 Titre : Behavior of cemented paste backfill in two mine stopes: measurements and modeling Type de document : texte imprimé Auteurs : Matthew Helinski, Auteur ; Martin Fahey, Auteur ; Andy Fourie, Auteur Année de publication : 2011 Article en page(s) : pp. 171-182 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Stope  mining  Paste  backfill  Consolidation  In  situ  monitoring Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Over the past decade there has been increasing use of “paste” for backfilling of mined-out voids (“stopes”) in underground mines. Paste backfill is generated from full stream tailings and is almost always placed underground with cement. This paper presents field measurements and back analysis of two different cemented paste backfill (CPB) cases. Using the collected data and subsequent back analysis, the writers show that these two cases demonstrate considerably different consolidation behaviors, which in turn influence critical design and management aspects such as applied barricade stresses and choice of an appropriate curing technique for laboratory control specimens. The paper presents pore pressure and total stress monitoring data gathered from two different CPBs during the deposition process. Both filling cases are modeled using Minefill-2D, which is a finite-element (FE) model capable of fully coupling the time-dependent processes of fill accretion, consolidation, cement hydration, and stress arching. Input parameters for the model are obtained from independent laboratory tests. Comparison between measured values and those calculated based on laboratory measurements verifies that, in general, the model provides a good representation of the process. However, there are some significant difficulties relating to modeling a three-dimensional stope with a two-dimensional plane-strain FE program, and some ways of accounting for these difficulties are explored. The model is then used to extrapolate the measured results to investigate the influence of varying filling rate, cement content, and number of drawpoints on critical design aspects. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p171_s1?isAuthorized=no [article] Behavior of cemented paste backfill in two mine stopes: measurements and modeling [texte imprimé] / Matthew Helinski, Auteur ; Martin Fahey, Auteur ; Andy Fourie, Auteur . - 2011 . - pp. 171-182. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 171-182 Mots-clés : Stope  mining  Paste  backfill  Consolidation  In  situ  monitoring Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Over the past decade there has been increasing use of “paste” for backfilling of mined-out voids (“stopes”) in underground mines. Paste backfill is generated from full stream tailings and is almost always placed underground with cement. This paper presents field measurements and back analysis of two different cemented paste backfill (CPB) cases. Using the collected data and subsequent back analysis, the writers show that these two cases demonstrate considerably different consolidation behaviors, which in turn influence critical design and management aspects such as applied barricade stresses and choice of an appropriate curing technique for laboratory control specimens. The paper presents pore pressure and total stress monitoring data gathered from two different CPBs during the deposition process. Both filling cases are modeled using Minefill-2D, which is a finite-element (FE) model capable of fully coupling the time-dependent processes of fill accretion, consolidation, cement hydration, and stress arching. Input parameters for the model are obtained from independent laboratory tests. Comparison between measured values and those calculated based on laboratory measurements verifies that, in general, the model provides a good representation of the process. However, there are some significant difficulties relating to modeling a three-dimensional stope with a two-dimensional plane-strain FE program, and some ways of accounting for these difficulties are explored. The model is then used to extrapolate the measured results to investigate the influence of varying filling rate, cement content, and number of drawpoints on critical design aspects. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p171_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

Minimum foundation mass for vibration control / A. J. Anyaegbunam 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. 190-195 Titre : Minimum foundation mass for vibration control Type de document : texte imprimé Auteurs : A. J. Anyaegbunam, Auteur Année de publication : 2011 Article en page(s) : pp. 190-195 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Foundation  vibration  Analog  solution  Damping  ratio  Minimum  mass  Ideal  optimum  solution  Best  nonoptimum  solution Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This note utilizes the analog models of forced vibration to express the mass of foundation block in terms of damping ratio and thereafter obtains the expression for the minimum foundation mass required to limit vertical machine vibration amplitude to a prescribed limit. The resulting formula, which accounts for internal damping, is constrained by the limitations of the original analog solutions. Moreover, formulas are derived for determining the damping ratio for conditions different from optimum that enable the evaluation of the nonoptimum foundation mass required to limit vibration. Since the ideal optimum solution may not be practical, an expression has been derived for the best nonoptimum foundation mass. The method presented in this note is believed to be easier to implement and to yield smaller foundation blocks than the existing traditional method, and thus will enable cheaper machine foundations to be constructed. It is believed that the proposed optimal solution may lead to the near elimination of machine vibration nuisance produced by high-frequency machines during operation. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p190_s1?isAuthorized=no [article] Minimum foundation mass for vibration control [texte imprimé] / A. J. Anyaegbunam, Auteur . - 2011 . - pp. 190-195. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 190-195 Mots-clés : Foundation  vibration  Analog  solution  Damping  ratio  Minimum  mass  Ideal  optimum  solution  Best  nonoptimum  solution Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This note utilizes the analog models of forced vibration to express the mass of foundation block in terms of damping ratio and thereafter obtains the expression for the minimum foundation mass required to limit vertical machine vibration amplitude to a prescribed limit. The resulting formula, which accounts for internal damping, is constrained by the limitations of the original analog solutions. Moreover, formulas are derived for determining the damping ratio for conditions different from optimum that enable the evaluation of the nonoptimum foundation mass required to limit vibration. Since the ideal optimum solution may not be practical, an expression has been derived for the best nonoptimum foundation mass. The method presented in this note is believed to be easier to implement and to yield smaller foundation blocks than the existing traditional method, and thus will enable cheaper machine foundations to be constructed. It is believed that the proposed optimal solution may lead to the near elimination of machine vibration nuisance produced by high-frequency machines during operation. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p190_s1?isAuthorized=no

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