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Journal of geotechnical and geoenvironmental engineering |
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Ajouter le résultat dans votre panierLoad testing of a closed-ended pipe pile driven in multilayered soil / Daehyeon Kim in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 4 (Avril 2009)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 463–473
Titre : Load testing of a closed-ended pipe pile driven in multilayered soil Type de document : texte imprimé Auteurs : Daehyeon Kim, Auteur ; Adriano Virgilio Bica, Auteur ; Rodrigo Salgado, Auteur Année de publication : 2009 Article en page(s) : pp. 463–473 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Bearing capacity Pipe piles Pile load tests Layered soils Résumé : Piles are often driven in multilayered soil profiles. The accurate prediction of the ultimate bearing capacity of piles driven in mixed soil is more challenging than that of piles driven in either clay or sand because the mechanical behavior of these soils is better known. In order to study the behavior of closed-ended pipe piles driven into multilayered soil profiles, fully instrumented static and dynamic axial load tests were performed on three piles. One of these piles was tested dynamically and statically. A second pile served as reaction pile in the static load test and was tested dynamically. A third pile was tested dynamically. The base of each pile was embedded slightly in a very dense nonplastic silt layer overlying a clay layer. In this paper, results of these pile load tests are presented, and the lessons learned from the interpretation of the test data are discussed. A comparison is made of the ultimate base and limit shaft resistances measured in the pile load tests with corresponding values predicted from in situ test-based and soil property-based design methods. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2846 [...] [article] Load testing of a closed-ended pipe pile driven in multilayered soil [texte imprimé] / Daehyeon Kim, Auteur ; Adriano Virgilio Bica, Auteur ; Rodrigo Salgado, Auteur . - 2009 . - pp. 463–473.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 463–473
Mots-clés : Bearing capacity Pipe piles Pile load tests Layered soils Résumé : Piles are often driven in multilayered soil profiles. The accurate prediction of the ultimate bearing capacity of piles driven in mixed soil is more challenging than that of piles driven in either clay or sand because the mechanical behavior of these soils is better known. In order to study the behavior of closed-ended pipe piles driven into multilayered soil profiles, fully instrumented static and dynamic axial load tests were performed on three piles. One of these piles was tested dynamically and statically. A second pile served as reaction pile in the static load test and was tested dynamically. A third pile was tested dynamically. The base of each pile was embedded slightly in a very dense nonplastic silt layer overlying a clay layer. In this paper, results of these pile load tests are presented, and the lessons learned from the interpretation of the test data are discussed. A comparison is made of the ultimate base and limit shaft resistances measured in the pile load tests with corresponding values predicted from in situ test-based and soil property-based design methods. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2846 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 474–486
Titre : Experimental investigation of the reinstallation of spudcan footings close to existing footprints Type de document : texte imprimé Auteurs : Mark J. Cassidy, Auteur ; Chin Kau Quah, Auteur ; Kok Seng Foo, Auteur Année de publication : 2009 Article en page(s) : pp. 474–486 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Offshore drilling Shallow foundations Clays Offshore structures Centrifuge models Installation Footings Résumé : The large footprints that remain on the seabed after offshore mobile jack-up platforms have completed operations provide hazardous conditions for any future jack-up installation at that site. The slope of the footprint and varying soil strengths below the surface cause detrimental horizontal and moment loads to be induced on the spudcan during the preloading process where only vertical loads are expected. Experimental data from 12 tests investigating the reinstallation of a spudcan footing close to an existing footprint is presented in this paper. The experiments were carried out using a geotechnical drum centrifuge at a radial acceleration level equivalent to 250 times that of Earth’s gravity. The stiffness of the loading leg and model spudcan shape were scaled to ensure conditions of stress similitude between the model and prototype. In all of the experiments, an initial footprint was created. The spudcan was then offset and reinstalled with the combined vertical, horizontal, and moment loads on the spudcan recorded. The effects of reinstallation location, preloading levels, and change in leg stiffness were investigated. The worst location for reinstallation was found to be at an offset half a spudcan diameter from the initial spudcan installation. The horizontal and moment loads were also greater when a more extensive footprint was created by the initial spudcan being embedded deeper and with a higher preload. For the range of conditions tested, changing the leg stiffness did not affect the results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2847 [...] [article] Experimental investigation of the reinstallation of spudcan footings close to existing footprints [texte imprimé] / Mark J. Cassidy, Auteur ; Chin Kau Quah, Auteur ; Kok Seng Foo, Auteur . - 2009 . - pp. 474–486.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 474–486
Mots-clés : Offshore drilling Shallow foundations Clays Offshore structures Centrifuge models Installation Footings Résumé : The large footprints that remain on the seabed after offshore mobile jack-up platforms have completed operations provide hazardous conditions for any future jack-up installation at that site. The slope of the footprint and varying soil strengths below the surface cause detrimental horizontal and moment loads to be induced on the spudcan during the preloading process where only vertical loads are expected. Experimental data from 12 tests investigating the reinstallation of a spudcan footing close to an existing footprint is presented in this paper. The experiments were carried out using a geotechnical drum centrifuge at a radial acceleration level equivalent to 250 times that of Earth’s gravity. The stiffness of the loading leg and model spudcan shape were scaled to ensure conditions of stress similitude between the model and prototype. In all of the experiments, an initial footprint was created. The spudcan was then offset and reinstalled with the combined vertical, horizontal, and moment loads on the spudcan recorded. The effects of reinstallation location, preloading levels, and change in leg stiffness were investigated. The worst location for reinstallation was found to be at an offset half a spudcan diameter from the initial spudcan installation. The horizontal and moment loads were also greater when a more extensive footprint was created by the initial spudcan being embedded deeper and with a higher preload. For the range of conditions tested, changing the leg stiffness did not affect the results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2847 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 487–496
Titre : Setup Following Installation of Dynamic Anchors in Normally consolidated clay Type de document : texte imprimé Auteurs : M. D. Richardson, Auteur ; C. D. O'Loughlin, Auteur ; M. F. Randolph, Auteur Année de publication : 2009 Article en page(s) : pp. 487–496 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Anchors Offshore structures Centrifuge models Clays Soil consolidation Time dependence Pore water pressure Résumé : This paper describes a series of centrifuge model tests designed to assess the increase in capacity of dynamic anchors due to setup in normally consolidated clay. The tests involved measurement of the vertical capacity of 1:200 reduced scale model anchors following various periods of postinstallation consolidation. The short-term capacity was shown to be dependent on the anchor impact velocity. Cavity expansion solutions for consolidation around a solid driven pile were found to provide agreement with the experimental results. A simplified capacity calculation technique predicted higher friction ratio values than is typically observed for driven piles; however, these calculations were complicated by the unusual dynamic anchor load–displacement response and uncertainty regarding the true sample shear strength. Dynamic anchor consolidation proceeds at a slower rate than for suction caissons and open-ended piles of similar equivalent diameter. However, the results indicate that depending on the site conditions, dynamically installed anchors remain a viable alternative to conventional deep-water mooring techniques. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2848 [...] [article] Setup Following Installation of Dynamic Anchors in Normally consolidated clay [texte imprimé] / M. D. Richardson, Auteur ; C. D. O'Loughlin, Auteur ; M. F. Randolph, Auteur . - 2009 . - pp. 487–496.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 487–496
Mots-clés : Anchors Offshore structures Centrifuge models Clays Soil consolidation Time dependence Pore water pressure Résumé : This paper describes a series of centrifuge model tests designed to assess the increase in capacity of dynamic anchors due to setup in normally consolidated clay. The tests involved measurement of the vertical capacity of 1:200 reduced scale model anchors following various periods of postinstallation consolidation. The short-term capacity was shown to be dependent on the anchor impact velocity. Cavity expansion solutions for consolidation around a solid driven pile were found to provide agreement with the experimental results. A simplified capacity calculation technique predicted higher friction ratio values than is typically observed for driven piles; however, these calculations were complicated by the unusual dynamic anchor load–displacement response and uncertainty regarding the true sample shear strength. Dynamic anchor consolidation proceeds at a slower rate than for suction caissons and open-ended piles of similar equivalent diameter. However, the results indicate that depending on the site conditions, dynamically installed anchors remain a viable alternative to conventional deep-water mooring techniques. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2848 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 497–505
Titre : Optimization of pile groups using hybrid genetic algorithms Type de document : texte imprimé Auteurs : Chan, C. M., Auteur ; Zhang, L. M., Auteur ; Jenny T. Ng, Auteur Année de publication : 2009 Article en page(s) : pp. 497–505 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Pile foundations Pile caps Pile groups Algorithms Optimization Limit states Résumé : This paper presents an automated optimal design method using a hybrid genetic algorithm for pile group foundation design. The design process is a sizing and topology optimization for pile foundations. The objective is to minimize the material volume of the foundation taking the configuration, number, and cross-sectional dimensions of the piles as well as the thickness of the pile cap as design variables. A local search operator by the fully stressed design (FSD) approach is incorporated into a genetic algorithm (GA) to tackle two major shortcomings of a GA, namely, large computation effort in searching the optimum design and poor local search capability. The effectiveness and capability of the proposed algorithm are first illustrated by a five by five pile group subjected to different loading conditions. The proposed optimization algorithm is then applied to a large-scale foundation project to demonstrate the practicality of the algorithm. The proposed hybrid genetic algorithm successfully minimizes the volume of material consumption and the result matches the engineering expectation. The FSD operator has great improvement on both design quality and convergence rate. Challenges encountered in the application of optimization techniques to design of pile groups consisting of hundreds of piles are discussed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2849 [...] [article] Optimization of pile groups using hybrid genetic algorithms [texte imprimé] / Chan, C. M., Auteur ; Zhang, L. M., Auteur ; Jenny T. Ng, Auteur . - 2009 . - pp. 497–505.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 497–505
Mots-clés : Pile foundations Pile caps Pile groups Algorithms Optimization Limit states Résumé : This paper presents an automated optimal design method using a hybrid genetic algorithm for pile group foundation design. The design process is a sizing and topology optimization for pile foundations. The objective is to minimize the material volume of the foundation taking the configuration, number, and cross-sectional dimensions of the piles as well as the thickness of the pile cap as design variables. A local search operator by the fully stressed design (FSD) approach is incorporated into a genetic algorithm (GA) to tackle two major shortcomings of a GA, namely, large computation effort in searching the optimum design and poor local search capability. The effectiveness and capability of the proposed algorithm are first illustrated by a five by five pile group subjected to different loading conditions. The proposed optimization algorithm is then applied to a large-scale foundation project to demonstrate the practicality of the algorithm. The proposed hybrid genetic algorithm successfully minimizes the volume of material consumption and the result matches the engineering expectation. The FSD operator has great improvement on both design quality and convergence rate. Challenges encountered in the application of optimization techniques to design of pile groups consisting of hundreds of piles are discussed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2849 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 506–514
Titre : Lateral performance of full-scale bridge abutment wall with granular backfill Type de document : texte imprimé Auteurs : Anne Lemnitzer, Auteur ; Eric R. Ahlberg, Auteur ; Robert L. Nigbor, Auteur Année de publication : 2009 Article en page(s) : pp. 506–514 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Bridge abutments Passive pressure Seismic design Lateral pressure Backfills Granular materials Résumé : Bridge abutments typically contain a backwall element that is designed to break free of its base support when struck by a bridge deck during an earthquake event and push into the abutment backfill soils. Results are presented for a full-scale cyclic lateral load test of an abutment backwall configured to represent the dimensions ( 1.7m height), boundary conditions, and backfill materials (compacted silty sand) that are typical of California bridge design practice. An innovative loading system was utilized that operates under displacement control and that assures horizontal wall displacement with minimal vertical displacement. The applied horizontal displacement ranged from null to approximately 11% of the wall height (0.11H) . The maximum earth pressure occurred at a wall displacement of 0.03H and corresponded to a passive earth pressure coefficient of Kp=16.3 . The measured force distribution applied to the wall from hydraulic actuators allowed the soil pressure distribution to be inferred as triangular in shape and the mobilized wall-soil interface friction to be evaluated as approximately one-third to one-half of the soil friction angle. Post-test trenching of the backfill showed a log-spiral principal failure surface at depth with several relatively minor shear surfaces further up in the passive wedge. The ultimate passive resistance is well estimated by the log-spiral method and a method of slices approach. The shape of the load-deflection relationship is well estimated by models that produce a hyperbolic curve shape. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2850 [...] [article] Lateral performance of full-scale bridge abutment wall with granular backfill [texte imprimé] / Anne Lemnitzer, Auteur ; Eric R. Ahlberg, Auteur ; Robert L. Nigbor, Auteur . - 2009 . - pp. 506–514.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 506–514
Mots-clés : Bridge abutments Passive pressure Seismic design Lateral pressure Backfills Granular materials Résumé : Bridge abutments typically contain a backwall element that is designed to break free of its base support when struck by a bridge deck during an earthquake event and push into the abutment backfill soils. Results are presented for a full-scale cyclic lateral load test of an abutment backwall configured to represent the dimensions ( 1.7m height), boundary conditions, and backfill materials (compacted silty sand) that are typical of California bridge design practice. An innovative loading system was utilized that operates under displacement control and that assures horizontal wall displacement with minimal vertical displacement. The applied horizontal displacement ranged from null to approximately 11% of the wall height (0.11H) . The maximum earth pressure occurred at a wall displacement of 0.03H and corresponded to a passive earth pressure coefficient of Kp=16.3 . The measured force distribution applied to the wall from hydraulic actuators allowed the soil pressure distribution to be inferred as triangular in shape and the mobilized wall-soil interface friction to be evaluated as approximately one-third to one-half of the soil friction angle. Post-test trenching of the backfill showed a log-spiral principal failure surface at depth with several relatively minor shear surfaces further up in the passive wedge. The ultimate passive resistance is well estimated by the log-spiral method and a method of slices approach. The shape of the load-deflection relationship is well estimated by models that produce a hyperbolic curve shape. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2850 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 515–524
Titre : Seismic response of geocell retaining walls : experimental studies Type de document : texte imprimé Auteurs : Ling, Hoe I., Auteur ; Leshchinsky, Dov, Auteur ; Jui-Pin Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 515–524 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Seismic effects Earthquakes Retaining walls Experimentation Résumé : This paper summarizes the seismic response of five large-scale retaining walls having a geocell facing. The walls were 2.8m high and the backfill and foundation soil were a fine sand compacted to 90% standard Proctor density (relative density of 55%). The first two walls were of the same geometry, with a tapered facing made of geocells each of height 20cm , one infilled with gravel and the other with sand. In Wall 3, a facing of depth 60cm was constructed while the backfill sand was reinforced with a polyester geogrid. Wall 4 was similar to Wall 3 except that the backfill was reinforced with several geocell layers. Wall 5 had thin geocell layers of 5cm height as reinforcements in order to improve the performance compared with Wall 4. The walls were subjected to the scaled horizontal and vertical motions as recorded during the 1995 Kobe earthquake, 4.5m/s2 (450gal) and 9.0m/s2 (900gal) maximum horizontal accelerations in the first and second excitations, respectively. In an attempt to induce failure, and therefore, to investigate the failure mechanism, Walls 3–5 were subjected to a third shaking in which the horizontal accelerations were scaled to 12.0m/s2 (1,200gal) . The walls were fully instrumented with accelerometers, laser displacement transducers, force transducers, and strain gauges. All five walls performed satisfactorily under the simulated earthquake motions. An improved wall performance was seen with the geocells acting as reinforcement layers. The study showed that geocells can be used successfully to form gravity walls as well as reinforcement layers even when subjected to a very high seismic load beyond that of the Kobe earthquake. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2851 [...] [article] Seismic response of geocell retaining walls : experimental studies [texte imprimé] / Ling, Hoe I., Auteur ; Leshchinsky, Dov, Auteur ; Jui-Pin Wang, Auteur . - 2009 . - pp. 515–524.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 515–524
Mots-clés : Seismic effects Earthquakes Retaining walls Experimentation Résumé : This paper summarizes the seismic response of five large-scale retaining walls having a geocell facing. The walls were 2.8m high and the backfill and foundation soil were a fine sand compacted to 90% standard Proctor density (relative density of 55%). The first two walls were of the same geometry, with a tapered facing made of geocells each of height 20cm , one infilled with gravel and the other with sand. In Wall 3, a facing of depth 60cm was constructed while the backfill sand was reinforced with a polyester geogrid. Wall 4 was similar to Wall 3 except that the backfill was reinforced with several geocell layers. Wall 5 had thin geocell layers of 5cm height as reinforcements in order to improve the performance compared with Wall 4. The walls were subjected to the scaled horizontal and vertical motions as recorded during the 1995 Kobe earthquake, 4.5m/s2 (450gal) and 9.0m/s2 (900gal) maximum horizontal accelerations in the first and second excitations, respectively. In an attempt to induce failure, and therefore, to investigate the failure mechanism, Walls 3–5 were subjected to a third shaking in which the horizontal accelerations were scaled to 12.0m/s2 (1,200gal) . The walls were fully instrumented with accelerometers, laser displacement transducers, force transducers, and strain gauges. All five walls performed satisfactorily under the simulated earthquake motions. An improved wall performance was seen with the geocells acting as reinforcement layers. The study showed that geocells can be used successfully to form gravity walls as well as reinforcement layers even when subjected to a very high seismic load beyond that of the Kobe earthquake. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2851 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 525–532
Titre : Dynamic properties of highly organic soils from montezuma slough and clifton court Type de document : texte imprimé Auteurs : Tadahiro Kishida, Auteur ; Timothy M. Wehling, Auteur ; Ross W. Boulanger, Auteur Année de publication : 2009 Article en page(s) : pp. 525–532 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil properties Dynamic properties Organic matter Peat Shear modulus Damping Résumé : The nonlinear dynamic properties of highly organic soils from two levee sites in the Sacramento-San Joaquin Delta in California are described. Cyclic triaxial, resonant column and torsional shear tests were performed on thin-walled tube samples obtained from beneath levee crests, beneath adjacent berms, and in the free field such that the in situ vertical effective stresses (σ′vo) ranged from about 16to67kPa . These highly organic soils had considerably different organic characteristics from those used in previous studies of dynamic properties. The tested samples had organic contents of 14 to 61%, initial water contents (wo) of 88 to 496%, shear wave velocities (Vs) of 20to130m∕s , and organic components that ranged from highly fibrous to highly decomposed and amorphous. Secant shear modulus (G) , normalized secant shear modulus (G∕Gmax) , and equivalent damping ratio (ξ) versus cyclic shear strain amplitude (γc) relations are presented, and their dependence on variables such as consolidation stress, organic content, prior loading history, testing device, and loading frequency are illustrated. Findings are compared to previously published results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2852 [...] [article] Dynamic properties of highly organic soils from montezuma slough and clifton court [texte imprimé] / Tadahiro Kishida, Auteur ; Timothy M. Wehling, Auteur ; Ross W. Boulanger, Auteur . - 2009 . - pp. 525–532.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 525–532
Mots-clés : Soil properties Dynamic properties Organic matter Peat Shear modulus Damping Résumé : The nonlinear dynamic properties of highly organic soils from two levee sites in the Sacramento-San Joaquin Delta in California are described. Cyclic triaxial, resonant column and torsional shear tests were performed on thin-walled tube samples obtained from beneath levee crests, beneath adjacent berms, and in the free field such that the in situ vertical effective stresses (σ′vo) ranged from about 16to67kPa . These highly organic soils had considerably different organic characteristics from those used in previous studies of dynamic properties. The tested samples had organic contents of 14 to 61%, initial water contents (wo) of 88 to 496%, shear wave velocities (Vs) of 20to130m∕s , and organic components that ranged from highly fibrous to highly decomposed and amorphous. Secant shear modulus (G) , normalized secant shear modulus (G∕Gmax) , and equivalent damping ratio (ξ) versus cyclic shear strain amplitude (γc) relations are presented, and their dependence on variables such as consolidation stress, organic content, prior loading history, testing device, and loading frequency are illustrated. Findings are compared to previously published results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2852 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 533–543
Titre : Regression models for dynamic properties of highly organic soils Type de document : texte imprimé Auteurs : Tadahiro Kishida, Auteur ; Ross W. Boulanger, Auteur ; Abrahamson, Norman A., Auteur Année de publication : 2009 Article en page(s) : pp. 533–543 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil properties Dynamic properties Organic matter Peat Shear modulus Damping Regression models Résumé : Regression models are presented for the dynamic properties of highly organic soils. The models are based on a database of triaxial and resonant-column/torsional-shear cyclic loading tests on thin walled tube samples mainly retrieved from the Sacramento-San Joaquin Delta. The soils in this database range from highly fibrous peat to amorphous organic clays with organic contents (OC) ranging from 14–81%, water contents ranging from 88–495%, total densities (ρ) ranging from 1.056–1.450Mg/m3 , and effective consolidation stresses (σ′vc) ranging from 11–135kPa . The secant shear modulus (G) and equivalent damping ratio (ξ) were modeled as variables dependent on the shear strain amplitude (γc) , consolidation stress (σ′vc) , and OC. The residuals of the regression models were analyzed against other predictor variables including undisturbed density (ρ) , loading frequency (f) , and number of loading cycles (N) . A regression model for ρ was developed, and conditional probabilities were used to improve the estimation of G and ξ when ρ measurements were available. The database of in situ measurements of shear wave velocity (Vs) was used to adjust the regression model for in situ conditions. Variances and correlations in the regression models are presented. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2853 [...] [article] Regression models for dynamic properties of highly organic soils [texte imprimé] / Tadahiro Kishida, Auteur ; Ross W. Boulanger, Auteur ; Abrahamson, Norman A., Auteur . - 2009 . - pp. 533–543.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 533–543
Mots-clés : Soil properties Dynamic properties Organic matter Peat Shear modulus Damping Regression models Résumé : Regression models are presented for the dynamic properties of highly organic soils. The models are based on a database of triaxial and resonant-column/torsional-shear cyclic loading tests on thin walled tube samples mainly retrieved from the Sacramento-San Joaquin Delta. The soils in this database range from highly fibrous peat to amorphous organic clays with organic contents (OC) ranging from 14–81%, water contents ranging from 88–495%, total densities (ρ) ranging from 1.056–1.450Mg/m3 , and effective consolidation stresses (σ′vc) ranging from 11–135kPa . The secant shear modulus (G) and equivalent damping ratio (ξ) were modeled as variables dependent on the shear strain amplitude (γc) , consolidation stress (σ′vc) , and OC. The residuals of the regression models were analyzed against other predictor variables including undisturbed density (ρ) , loading frequency (f) , and number of loading cycles (N) . A regression model for ρ was developed, and conditional probabilities were used to improve the estimation of G and ξ when ρ measurements were available. The database of in situ measurements of shear wave velocity (Vs) was used to adjust the regression model for in situ conditions. Variances and correlations in the regression models are presented. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2853 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 544–554
Titre : Development of dissipation model of excess pore pressure in liquefied sandy ground Type de document : texte imprimé Auteurs : Sung-Ryul Kim, Auteur ; Jae-Ik Hwang, Auteur ; Hon-Yim Ko, Auteur Année de publication : 2009 Article en page(s) : pp. 544–554 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil liquefaction Soil consolidation Solidification Centrifuge models Sand Résumé : Recently, several studies on the dissipation of excess pore pressure in liquefied sandy grounds have been reported on evaluation of postliquefaction behavior of structures. To further contribute to the understanding of this complicated dynamic phenomenon, centrifuge tests were performed in this research to analyze the liquefaction behavior of level saturated sandy grounds. The test results showed that the excess pore pressure in the liquefied sand was dissipated by the combined process of the solidification of the sand grains and the consolidation of the solidified layer. Based on the test results, a nonlinear model for the solidified layer thickness versus time, i.e., the solidification velocity, was developed. A new dissipation model was also developed by combining the nonlinear solidification model with Scott’s theory to improve the prediction for the time history of excess pore pressure. In addition, a method for evaluating the input parameters in the dissipation model was proposed by relating the parameters to the particle size and the relative density of soils. The proposed dissipation model properly estimated the dissipation of excess pore pressure with time observed in the centrifuge experiments. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2854 [...] [article] Development of dissipation model of excess pore pressure in liquefied sandy ground [texte imprimé] / Sung-Ryul Kim, Auteur ; Jae-Ik Hwang, Auteur ; Hon-Yim Ko, Auteur . - 2009 . - pp. 544–554.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 544–554
Mots-clés : Soil liquefaction Soil consolidation Solidification Centrifuge models Sand Résumé : Recently, several studies on the dissipation of excess pore pressure in liquefied sandy grounds have been reported on evaluation of postliquefaction behavior of structures. To further contribute to the understanding of this complicated dynamic phenomenon, centrifuge tests were performed in this research to analyze the liquefaction behavior of level saturated sandy grounds. The test results showed that the excess pore pressure in the liquefied sand was dissipated by the combined process of the solidification of the sand grains and the consolidation of the solidified layer. Based on the test results, a nonlinear model for the solidified layer thickness versus time, i.e., the solidification velocity, was developed. A new dissipation model was also developed by combining the nonlinear solidification model with Scott’s theory to improve the prediction for the time history of excess pore pressure. In addition, a method for evaluating the input parameters in the dissipation model was proposed by relating the parameters to the particle size and the relative density of soils. The proposed dissipation model properly estimated the dissipation of excess pore pressure with time observed in the centrifuge experiments. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2854 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 555–565
Titre : Effects of principal stress rotation on permanent deformation in rail track foundations Type de document : texte imprimé Auteurs : P. J. Gräbe, Auteur ; C. R. Clayton, Auteur Année de publication : 2009 Article en page(s) : pp. 555–565 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Cyclic loads Laboratory tests Shear tests Railroad tracks Stress Résumé : A realistic assessment of the whole life cost of rail track foundations requires analysis of the effects of the repeated loadings applied by trains. This paper reports the effects of principal stress rotation (PSR) during cyclic loading on the permanent deformations measured in a series of hollow cylinder tests. The tests were carried out on a number of reconstituted soils selected in order to simulate foundation materials on an existing heavy haul railway line. Typical loadings and track geometry together with dynamic finite-element analyses were used to define representative stress changes to be applied to these soils, which were then tested with and without principal stress rotation during loading. It is shown that principal stress rotation has a significant and deleterious impact on permanent deformation of some materials. Therefore, it is concluded that cyclic triaxial testing, which cannot impose principal stress rotation, will not necessarily give good estimates of the long-term performance of rail track foundations. As PSR cannot be ignored when evaluating permanent displacements of rail track foundations, the use of more appropriate (realistic) testing methods such as the cyclic hollow cylinder or the cyclic simple shear apparatus is required. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2855 [...] [article] Effects of principal stress rotation on permanent deformation in rail track foundations [texte imprimé] / P. J. Gräbe, Auteur ; C. R. Clayton, Auteur . - 2009 . - pp. 555–565.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 555–565
Mots-clés : Cyclic loads Laboratory tests Shear tests Railroad tracks Stress Résumé : A realistic assessment of the whole life cost of rail track foundations requires analysis of the effects of the repeated loadings applied by trains. This paper reports the effects of principal stress rotation (PSR) during cyclic loading on the permanent deformations measured in a series of hollow cylinder tests. The tests were carried out on a number of reconstituted soils selected in order to simulate foundation materials on an existing heavy haul railway line. Typical loadings and track geometry together with dynamic finite-element analyses were used to define representative stress changes to be applied to these soils, which were then tested with and without principal stress rotation during loading. It is shown that principal stress rotation has a significant and deleterious impact on permanent deformation of some materials. Therefore, it is concluded that cyclic triaxial testing, which cannot impose principal stress rotation, will not necessarily give good estimates of the long-term performance of rail track foundations. As PSR cannot be ignored when evaluating permanent displacements of rail track foundations, the use of more appropriate (realistic) testing methods such as the cyclic hollow cylinder or the cyclic simple shear apparatus is required. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2855 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 566–572
Titre : Seepage-induced acoustic emission in granular soils Type de document : texte imprimé Auteurs : Meng-Hsi Hung, Auteur ; Gerald C. Lauchle, Auteur ; Mian C. Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 566–572 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Acoustic emission Seepage Granular materials Soils Monitoring Résumé : This technical paper presents the results of a study on detecting excessive seepage in granular soils by monitoring the seepage-induced acoustic emission (AE). The laboratory experiments and data analyses were performed using specially designed data acquisition instruments and computer-based data analysis devices. The monitored data were analyzed using three methods, namely, amplitude, time, and frequency domain analyses. The analysis results showed that the seepage-induced AE in the test soils were broadband Gaussian signals which were zero mean, normally distributed, and leptokurtic. All of the measured autospectral density functions showed that the most prominent AE activities occurred within a frequency range of about 0.8–10kHz . Based on acoustic similarity laws and a graphical fitting method, the test results were subjected to dimensional analysis. The results of this analysis provided a relationship between a nondimensional sound pressure level and a nondimensional frequency, in which AE intensity, seepage velocity, soil, and permeant properties were interrelated. This relationship provided a fundamental basis for detecting excessive seepage using the monitored seepage-induced AE intensity. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2856 [...] [article] Seepage-induced acoustic emission in granular soils [texte imprimé] / Meng-Hsi Hung, Auteur ; Gerald C. Lauchle, Auteur ; Mian C. Wang, Auteur . - 2009 . - pp. 566–572.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 566–572
Mots-clés : Acoustic emission Seepage Granular materials Soils Monitoring Résumé : This technical paper presents the results of a study on detecting excessive seepage in granular soils by monitoring the seepage-induced acoustic emission (AE). The laboratory experiments and data analyses were performed using specially designed data acquisition instruments and computer-based data analysis devices. The monitored data were analyzed using three methods, namely, amplitude, time, and frequency domain analyses. The analysis results showed that the seepage-induced AE in the test soils were broadband Gaussian signals which were zero mean, normally distributed, and leptokurtic. All of the measured autospectral density functions showed that the most prominent AE activities occurred within a frequency range of about 0.8–10kHz . Based on acoustic similarity laws and a graphical fitting method, the test results were subjected to dimensional analysis. The results of this analysis provided a relationship between a nondimensional sound pressure level and a nondimensional frequency, in which AE intensity, seepage velocity, soil, and permeant properties were interrelated. This relationship provided a fundamental basis for detecting excessive seepage using the monitored seepage-induced AE intensity. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2856 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 573–589
Titre : Structuration and destructuration behavior of cement-treated singapore marine clay Type de document : texte imprimé Auteurs : A. H. Kamruzzaman, Auteur ; S. H. Chew, Auteur ; F. H. Lee, Auteur Année de publication : 2009 Article en page(s) : pp. 573–589 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Microstructure Fabrics Cements Clays Singapore Résumé : This paper examines the structuration and destructuration characteristics of cement-treated Singapore marine clay and their relation to the observed microstructural behavior. The pozzolanic reaction is found to be very significant up to curing periods of 1year , and thus the unconfined compressive strength increases notably leading to the formation of more structured treated clay. Due to the effect of structuration (existing of cementation bond), the yield stress increases resulting in an expansion of the yield surface and failure envelope under compression and shearing. The microstructural observation of treated clay structure at various stress levels from one-dimensional consolidation shows that destructuration (breaking of cementation bond) is progressive; the largest intercluster voids being the first affected. As the consolidation proceeds, both inter and intracluster voids are affected. Consolidated undrained triaxial results reveal that complete destructuration only takes place on the shear plane at which the clay–cement cluster crushes. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2857 [...] [article] Structuration and destructuration behavior of cement-treated singapore marine clay [texte imprimé] / A. H. Kamruzzaman, Auteur ; S. H. Chew, Auteur ; F. H. Lee, Auteur . - 2009 . - pp. 573–589.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 573–589
Mots-clés : Microstructure Fabrics Cements Clays Singapore Résumé : This paper examines the structuration and destructuration characteristics of cement-treated Singapore marine clay and their relation to the observed microstructural behavior. The pozzolanic reaction is found to be very significant up to curing periods of 1year , and thus the unconfined compressive strength increases notably leading to the formation of more structured treated clay. Due to the effect of structuration (existing of cementation bond), the yield stress increases resulting in an expansion of the yield surface and failure envelope under compression and shearing. The microstructural observation of treated clay structure at various stress levels from one-dimensional consolidation shows that destructuration (breaking of cementation bond) is progressive; the largest intercluster voids being the first affected. As the consolidation proceeds, both inter and intracluster voids are affected. Consolidated undrained triaxial results reveal that complete destructuration only takes place on the shear plane at which the clay–cement cluster crushes. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2857 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 590–594
Titre : Short-term electrical conductivity and strength development of lime kiln dust modified soils Type de document : texte imprimé Auteurs : Renpeng Chen, Auteur ; Vincent P. Drnevich, Auteur ; Radha Krishna Daita, Auteur Année de publication : 2009 Article en page(s) : pp. 590–594 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Dust Electrical conductivity Penetration resistance Clays Résumé : Lime kiln dust (LKD) is used for modifying pavement subgrades to expedite construction on wet clayey soils. This paper describes the short-term development (typically, over the first 3to7days ) of electrical conductivity and penetration resistance of LKD-modified soils. The normalized net change of electrical conductivity is solely related to the LKD dosage. The decrease of electrical conductivity with time coincides with the increase of penetration resistance with time. The correlations of electrical conductivity with strength gain in LKD and lime-modified soils suggest that electrical conductivity measurements can potentially be useful for quality control in field applications. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2859 [...] [article] Short-term electrical conductivity and strength development of lime kiln dust modified soils [texte imprimé] / Renpeng Chen, Auteur ; Vincent P. Drnevich, Auteur ; Radha Krishna Daita, Auteur . - 2009 . - pp. 590–594.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 590–594
Mots-clés : Dust Electrical conductivity Penetration resistance Clays Résumé : Lime kiln dust (LKD) is used for modifying pavement subgrades to expedite construction on wet clayey soils. This paper describes the short-term development (typically, over the first 3to7days ) of electrical conductivity and penetration resistance of LKD-modified soils. The normalized net change of electrical conductivity is solely related to the LKD dosage. The decrease of electrical conductivity with time coincides with the increase of penetration resistance with time. The correlations of electrical conductivity with strength gain in LKD and lime-modified soils suggest that electrical conductivity measurements can potentially be useful for quality control in field applications. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2859 [...]
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 595–604
Titre : Interference of two closely spaced strip footings on sand using model tests Type de document : texte imprimé Auteurs : Jyant Kumar, Auteur ; Manas Kumar Bhoi, Auteur Année de publication : 2009 Article en page(s) : pp. 595–604 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Bearing capacity Failures Foundations Model tests Scale effect Sand Résumé : By using small scale model tests, the interference effect on the ultimate bearing capacity of two closely spaced strip footings, placed on the surface of dry sand, was investigated. At any time, the footings were assumed to (1) carry exactly the same magnitude of load; and (2) settle to the same extent. No tilt of the footing was allowed. The effect of clear spacing (s) between two footings was explicitly studied. An interference of footings leads to a significant increase in their bearing capacity; the interference effect becomes even more substantial with an increase in the relative density of sand. The bearing capacity attains a peak magnitude at a certain (critical) spacing between two footings. The experimental observations presented in this technical note were similar to those given by different available theories. However, in a quantitative sense, the difference between the experiments and theories was seen to be still significant and it emphasizes the need of doing a further rigorous analysis in which the effect of stress level on the shear strength parameters of soil mass can be incorporated properly. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2859 [...] [article] Interference of two closely spaced strip footings on sand using model tests [texte imprimé] / Jyant Kumar, Auteur ; Manas Kumar Bhoi, Auteur . - 2009 . - pp. 595–604.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 595–604
Mots-clés : Bearing capacity Failures Foundations Model tests Scale effect Sand Résumé : By using small scale model tests, the interference effect on the ultimate bearing capacity of two closely spaced strip footings, placed on the surface of dry sand, was investigated. At any time, the footings were assumed to (1) carry exactly the same magnitude of load; and (2) settle to the same extent. No tilt of the footing was allowed. The effect of clear spacing (s) between two footings was explicitly studied. An interference of footings leads to a significant increase in their bearing capacity; the interference effect becomes even more substantial with an increase in the relative density of sand. The bearing capacity attains a peak magnitude at a certain (critical) spacing between two footings. The experimental observations presented in this technical note were similar to those given by different available theories. However, in a quantitative sense, the difference between the experiments and theories was seen to be still significant and it emphasizes the need of doing a further rigorous analysis in which the effect of stress level on the shear strength parameters of soil mass can be incorporated properly. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2859 [...]
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