Documents disponibles écrits par cet auteur

Numerical study of reinforced soil segmental walls using three different constitutive soil models / Bingquan Huang in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 10 (Octobre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 10 (Octobre 2009) . - pp. 1486–1498 Titre : Numerical study of reinforced soil segmental walls using three different constitutive soil models Type de document : texte imprimé Auteurs : Bingquan Huang, Auteur ; Richard J. Bathurst, Auteur ; Kianoosh Hatami, Auteur Année de publication : 2009 Article en page(s) : pp. 1486–1498 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  stabilizationWallsConstitutive  modelsNumerical  modelsReinforcement Résumé : A numerical finite-difference method (FLAC) model was used to investigate the influence of constitutive soil model on predicted response of two full-scale reinforced soil walls during construction and surcharge loading. One wall was reinforced with a relatively extensible polymeric geogrid and the other with a relatively stiff welded wire mesh. The backfill sand was modeled using three different constitutive soil models varying as follows with respect to increasing complexity: linear elastic-plastic Mohr-Coulomb, modified Duncan-Chang hyperbolic model, and Lade’s single hardening model. Calculated results were compared against toe footing loads, foundation pressures, facing displacements, connection loads, and reinforcement strains. In general, predictions were within measurement accuracy for the end-of-construction and surcharge load levels corresponding to working stress conditions. However, the modified Duncan-Chang model which explicitly considers plane strain boundary conditions is a good compromise between prediction accuracy and availability of parameters from conventional triaxial compression testing. The results of this investigation give confidence that numerical FLAC models using this simple soil constitutive model are adequate to predict the performance of reinforced soil walls under typical operational conditions provided that the soil reinforcement, interfaces, boundaries, construction sequence, and soil compaction are modeled correctly. Further improvement of predictions using more sophisticated soil models is not guaranteed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000092 [article] Numerical study of reinforced soil segmental walls using three different constitutive soil models [texte imprimé] / Bingquan Huang, Auteur ; Richard J. Bathurst, Auteur ; Kianoosh Hatami, Auteur . - 2009 . - pp. 1486–1498. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 10 (Octobre 2009) . - pp. 1486–1498 Mots-clés : Soil  stabilizationWallsConstitutive  modelsNumerical  modelsReinforcement Résumé : A numerical finite-difference method (FLAC) model was used to investigate the influence of constitutive soil model on predicted response of two full-scale reinforced soil walls during construction and surcharge loading. One wall was reinforced with a relatively extensible polymeric geogrid and the other with a relatively stiff welded wire mesh. The backfill sand was modeled using three different constitutive soil models varying as follows with respect to increasing complexity: linear elastic-plastic Mohr-Coulomb, modified Duncan-Chang hyperbolic model, and Lade’s single hardening model. Calculated results were compared against toe footing loads, foundation pressures, facing displacements, connection loads, and reinforcement strains. In general, predictions were within measurement accuracy for the end-of-construction and surcharge load levels corresponding to working stress conditions. However, the modified Duncan-Chang model which explicitly considers plane strain boundary conditions is a good compromise between prediction accuracy and availability of parameters from conventional triaxial compression testing. The results of this investigation give confidence that numerical FLAC models using this simple soil constitutive model are adequate to predict the performance of reinforced soil walls under typical operational conditions provided that the soil reinforcement, interfaces, boundaries, construction sequence, and soil compaction are modeled correctly. Further improvement of predictions using more sophisticated soil models is not guaranteed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000092

Response analysis of field-scale fully grouted standard cable bolts using a coupled ANN–FDM approach / Roozbeh Grayeli in Journal of engineering mechanics, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 135 N° 6 (Juin 2009) . - pp. 561-570 Titre : Response analysis of field-scale fully grouted standard cable bolts using a coupled ANN–FDM approach Type de document : texte imprimé Auteurs : Roozbeh Grayeli, Auteur ; Kianoosh Hatami, Auteur Article en page(s) : pp. 561-570 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Neural  networks  Finite  difference  method  Bolts  Rocks  Axial  loads  Stabilization  Pull-out  resistance. Résumé : This paper presents a coupled approach using an artificial neural network (ANN) and the finite difference method (FDM) that has been developed to predict the distribution of axial load along fully grouted standard cable bolts in the field using laboratory pullout test data. A back-propagation training algorithm was used in ANN to determine axial loads in the cables tested in the laboratory. The ANN component of the computational model was trained using two different types of data sets. At first, the ANN was trained to predict the axial loads in a series of short cables grouted with Portland cement at a specific water-to-cement ratio and subjected to different radial confining stiffness values. Next, the ANN model was trained for an expanded case to include the influence of lateral confining stress on the distribution of axial load in the cable reinforcement. Finally, the ANN model was implemented into a widely used, FDM-based geotechnical software (FLAC). The accuracy of the ANN–FDM model is demonstrated in this paper against measured data from laboratory and field tests. The analysis approach introduced in this study is a valuable computational tool that can be used to determine the axial load distribution in long standard cable bolts, which are commonly installed to stabilize rock masses in various geotechnical, transportation, and mining applications. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...] [article] Response analysis of field-scale fully grouted standard cable bolts using a coupled ANN–FDM approach [texte imprimé] / Roozbeh Grayeli, Auteur ; Kianoosh Hatami, Auteur . - pp. 561-570. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 135 N° 6 (Juin 2009) . - pp. 561-570 Mots-clés : Neural  networks  Finite  difference  method  Bolts  Rocks  Axial  loads  Stabilization  Pull-out  resistance. Résumé : This paper presents a coupled approach using an artificial neural network (ANN) and the finite difference method (FDM) that has been developed to predict the distribution of axial load along fully grouted standard cable bolts in the field using laboratory pullout test data. A back-propagation training algorithm was used in ANN to determine axial loads in the cables tested in the laboratory. The ANN component of the computational model was trained using two different types of data sets. At first, the ANN was trained to predict the axial loads in a series of short cables grouted with Portland cement at a specific water-to-cement ratio and subjected to different radial confining stiffness values. Next, the ANN model was trained for an expanded case to include the influence of lateral confining stress on the distribution of axial load in the cable reinforcement. Finally, the ANN model was implemented into a widely used, FDM-based geotechnical software (FLAC). The accuracy of the ANN–FDM model is demonstrated in this paper against measured data from laboratory and field tests. The analysis approach introduced in this study is a valuable computational tool that can be used to determine the axial load distribution in long standard cable bolts, which are commonly installed to stabilize rock masses in various geotechnical, transportation, and mining applications. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...]

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

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