Documents disponibles écrits par cet auteur

Compacted soil liner interface strength importance / Timothy D. Stark in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 4 (Avril 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 4 (Avril 2012) . - pp. 544–550 Titre : Compacted soil liner interface strength importance Type de document : texte imprimé Auteurs : Timothy D. Stark, Auteur ; Hangseok Choi, Auteur ; Chulho Lee, Auteur Année de publication : 2012 Article en page(s) : pp. 544–550 Note générale : Géologie appliquée Langues : Anglais (eng) Mots-clés : Slope  stability  Landfills  Geomembranes  Geosynthetics  Compacted  soil  liner  Geosynthetic  lined  slopes  Interface  shear  strength Résumé : This paper describes an interesting slope failure in a liner system of a municipal solid waste containment facility during construction because the sliding interface is not the geomembrane (GM)/compacted low-permeability soil liner (LPSL) but a soil–soil interface within the LPSL. Some of the lessons learned are as follows: (1) compaction of the LPSL should ensure that each lift is kneaded into the lower lift so a weak interface is not created in the LPSL; (2) the LPSL moisture content should be controlled so it does not exceed the specified value, for example 3–4% wet of optimum, because it can lead to a weak interface in the LPSL; (3) drainage material should be placed over the GM from the slope toe to the top to reduce the shear stresses applied to the weakest interface; and (4) equipment should not move laterally across the slope if it is unsupported but up the slope while placing the cover soil from bottom to top. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000556 [article] Compacted soil liner interface strength importance [texte imprimé] / Timothy D. Stark, Auteur ; Hangseok Choi, Auteur ; Chulho Lee, Auteur . - 2012 . - pp. 544–550. Géologie appliquée Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 4 (Avril 2012) . - pp. 544–550 Mots-clés : Slope  stability  Landfills  Geomembranes  Geosynthetics  Compacted  soil  liner  Geosynthetic  lined  slopes  Interface  shear  strength Résumé : This paper describes an interesting slope failure in a liner system of a municipal solid waste containment facility during construction because the sliding interface is not the geomembrane (GM)/compacted low-permeability soil liner (LPSL) but a soil–soil interface within the LPSL. Some of the lessons learned are as follows: (1) compaction of the LPSL should ensure that each lift is kneaded into the lower lift so a weak interface is not created in the LPSL; (2) the LPSL moisture content should be controlled so it does not exceed the specified value, for example 3–4% wet of optimum, because it can lead to a weak interface in the LPSL; (3) drainage material should be placed over the GM from the slope toe to the top to reduce the shear stresses applied to the weakest interface; and (4) equipment should not move laterally across the slope if it is unsupported but up the slope while placing the cover soil from bottom to top. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000556

Pullout resistance increase of soil nailing induced by pressurized grouting / Hyung-Joon Seo in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 5 (Mai 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 5 (Mai 2012) . - pp. 604–613 Titre : Pullout resistance increase of soil nailing induced by pressurized grouting Type de document : texte imprimé Auteurs : Hyung-Joon Seo, Auteur ; Kyeong-Han Jeong, Auteur ; Hangseok Choi, Auteur Année de publication : 2012 Article en page(s) : pp. 604–613 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Pressurized  grouting  Pullout  resistance  Residual  stress  Coefficient  of  pullout  friction  Dilatancy  angle  Cavity  expansion  theory Résumé : Pressurized grouting has been frequently adopted in soil-nailing systems that are widely used to improve slope stability. In most geotechnical applications, soil nailing using pressurized grouting has been empirically performed without theoretical validation because the interaction between the pressurized grout and adjacent soil mass is very complicated. The present paper deals with a series of pilot-scale chamber tests performed on four different granite residual soils to evaluate the effect of pressurized grouting on the soil-nailing system. When grout is injected into a cylindrical cavity in the soil mass, the pressure exerted around the cavity perimeter initially increases with time up to a peak value and then gradually decreases to a residual stress. The pressure reduction may result from the seepage of water originally retained in the grout paste into the adjacent soil formation. With the application of pressurized grouting, in situ stresses can be increased by approximately 20% of the injecting pressures during the experiments. To develop a desirable residual stress in a soil-nailing system, it is necessary to select an appropriate minimum injection time for which the grout pressure should be maintained. The required minimum injection time increases with an increase in either the fine-grain content or the injection pressure. Moreover, a series of in situ pullout experiments has been performed on soil-nailing systems, using both pressurized grouting and common gravitational grouting to compare the pullout loads of both cases and to verify the effectiveness of the pressurized grouting on the soil-nailing system. The pullout load of soil nailing using pressurized grouting is approximately 36% higher than that of soil nailing using gravitational grouting. This is attributed to the additional compaction of soil by cavity expansion and to an increase in the residual stress and in the dilatancy angle by pressurized grouting. The field experimental results have been verified with analytical solutions by estimating the dilatancy angle from the pressurized grouting tests. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000622 [article] Pullout resistance increase of soil nailing induced by pressurized grouting [texte imprimé] / Hyung-Joon Seo, Auteur ; Kyeong-Han Jeong, Auteur ; Hangseok Choi, Auteur . - 2012 . - pp. 604–613. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 5 (Mai 2012) . - pp. 604–613 Mots-clés : Pressurized  grouting  Pullout  resistance  Residual  stress  Coefficient  of  pullout  friction  Dilatancy  angle  Cavity  expansion  theory Résumé : Pressurized grouting has been frequently adopted in soil-nailing systems that are widely used to improve slope stability. In most geotechnical applications, soil nailing using pressurized grouting has been empirically performed without theoretical validation because the interaction between the pressurized grout and adjacent soil mass is very complicated. The present paper deals with a series of pilot-scale chamber tests performed on four different granite residual soils to evaluate the effect of pressurized grouting on the soil-nailing system. When grout is injected into a cylindrical cavity in the soil mass, the pressure exerted around the cavity perimeter initially increases with time up to a peak value and then gradually decreases to a residual stress. The pressure reduction may result from the seepage of water originally retained in the grout paste into the adjacent soil formation. With the application of pressurized grouting, in situ stresses can be increased by approximately 20% of the injecting pressures during the experiments. To develop a desirable residual stress in a soil-nailing system, it is necessary to select an appropriate minimum injection time for which the grout pressure should be maintained. The required minimum injection time increases with an increase in either the fine-grain content or the injection pressure. Moreover, a series of in situ pullout experiments has been performed on soil-nailing systems, using both pressurized grouting and common gravitational grouting to compare the pullout loads of both cases and to verify the effectiveness of the pressurized grouting on the soil-nailing system. The pullout load of soil nailing using pressurized grouting is approximately 36% higher than that of soil nailing using gravitational grouting. This is attributed to the additional compaction of soil by cavity expansion and to an increase in the residual stress and in the dilatancy angle by pressurized grouting. The field experimental results have been verified with analytical solutions by estimating the dilatancy angle from the pressurized grouting tests. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000622

Slug test analysis in vertical cutoff walls with consideration of filter cake / The-Bao Nguyen in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 8 (Août 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 8 (Août 2011) . - pp. 785-797 Titre : Slug test analysis in vertical cutoff walls with consideration of filter cake Type de document : texte imprimé Auteurs : The-Bao Nguyen, Auteur ; Chulho Lee, Auteur ; Hangseok Choi, Auteur Année de publication : 2011 Article en page(s) : pp. 785-797 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Core  walls  Backfills  Filter  cake  Bentonite  Hydraulic  conductivity Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : In constructing a vertical cutoff wall, bentonite-water slurry is frequently used to maintain the stability of sidewalls during excavation before backfilling the trench with less permeable materials to complete the cutoff wall construction. This procedure leads to a thin but relatively impermeable layer, called a filter cake, on the excavation surface. The aim of this paper is to examine the effect of a filter cake on evaluating hydraulic conductivity of the cutoff wall backfill through a slug test analysis with the aid of the verified numerical program, Slug_3D. As an upper bound solution for evaluation of the hydraulic conductivity of the cutoff wall backfill, no-flux boundary conditions for the boundaries of cutoff walls are imposed to consider the effect of filter cakes. The type-curve method and modified line-fitting method are employed to reanalyze the case of EMCON/OWT, Inc., as an example. The previous analysis, without consideration of a filter cake, is compared with the current results that consider the filter cake to reveal the necessity of considering the effect of a filter cake in the slug test analysis. The comparison shows that the hydraulic conductivity of the cutoff wall backfill will be underestimated in a slug test analysis if the filter cake is not properly considered. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i8/p785_s1?isAuthorized=no [article] Slug test analysis in vertical cutoff walls with consideration of filter cake [texte imprimé] / The-Bao Nguyen, Auteur ; Chulho Lee, Auteur ; Hangseok Choi, Auteur . - 2011 . - pp. 785-797. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 8 (Août 2011) . - pp. 785-797 Mots-clés : Core  walls  Backfills  Filter  cake  Bentonite  Hydraulic  conductivity Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : In constructing a vertical cutoff wall, bentonite-water slurry is frequently used to maintain the stability of sidewalls during excavation before backfilling the trench with less permeable materials to complete the cutoff wall construction. This procedure leads to a thin but relatively impermeable layer, called a filter cake, on the excavation surface. The aim of this paper is to examine the effect of a filter cake on evaluating hydraulic conductivity of the cutoff wall backfill through a slug test analysis with the aid of the verified numerical program, Slug_3D. As an upper bound solution for evaluation of the hydraulic conductivity of the cutoff wall backfill, no-flux boundary conditions for the boundaries of cutoff walls are imposed to consider the effect of filter cakes. The type-curve method and modified line-fitting method are employed to reanalyze the case of EMCON/OWT, Inc., as an example. The previous analysis, without consideration of a filter cake, is compared with the current results that consider the filter cake to reveal the necessity of considering the effect of a filter cake in the slug test analysis. The comparison shows that the hydraulic conductivity of the cutoff wall backfill will be underestimated in a slug test analysis if the filter cake is not properly considered. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i8/p785_s1?isAuthorized=no