Documents disponibles écrits par cet auteur

Spatial variability of in situ weathered soil / S. M. Dasaka in Géotechnique, Vol. 62 N° 5 (Mai 2012) 

Public ISBD [article]  in Géotechnique > Vol. 62 N° 5 (Mai 2012) . - pp. 375 –384 Titre : Spatial variability of in situ weathered soil Type de document : texte imprimé Auteurs : S. M. Dasaka, Auteur ; Zhang, L. M., Auteur Année de publication : 2012 Article en page(s) : pp. 375 –384 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Sampling  Piles  Site  investigation  Statistical  analysis  Geology  Residual  soils Résumé : The founding depths of pile foundations depend primarily on the loading conditions of the superstructure and the strength of subsoil. The depth of Grade III weathered rock, the top of completely decomposed granite (CDG), and standard penetration test N-value of 200 (SPT-200) are often used as indicators for decision-making in arriving at the preliminary founding depth of piles in Hong Kong. The work reported in this paper focuses on evaluation of the spatial variability characteristics of the above founding depth indicators at a construction site, using statistical models based on random field theory. Spatial variability characteristics are evaluated using the measured data in terms of scale of fluctuation. Geostatistics is used to obtain additional data at unsampled locations for mapping profiles of founding depth indicators over the site, using the measured data from borehole records and site investigation results. It is observed from the results that, if faults are not present, the depth of the Grade III surface exhibits the largest scale of fluctuation among the three indicators, and the variability of the ground is observed to increase with the weathering grade. The effect of the size of the sampling domain on the autocorrelation characteristics of the founding depth indicators is also studied. The results demonstrate that the scale of fluctuation increases with increase in the size of the sampling domain. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.P.151.3786 [article] Spatial variability of in situ weathered soil [texte imprimé] / S. M. Dasaka, Auteur ; Zhang, L. M., Auteur . - 2012 . - pp. 375 –384. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 62 N° 5 (Mai 2012) . - pp. 375 –384 Mots-clés : Sampling  Piles  Site  investigation  Statistical  analysis  Geology  Residual  soils Résumé : The founding depths of pile foundations depend primarily on the loading conditions of the superstructure and the strength of subsoil. The depth of Grade III weathered rock, the top of completely decomposed granite (CDG), and standard penetration test N-value of 200 (SPT-200) are often used as indicators for decision-making in arriving at the preliminary founding depth of piles in Hong Kong. The work reported in this paper focuses on evaluation of the spatial variability characteristics of the above founding depth indicators at a construction site, using statistical models based on random field theory. Spatial variability characteristics are evaluated using the measured data in terms of scale of fluctuation. Geostatistics is used to obtain additional data at unsampled locations for mapping profiles of founding depth indicators over the site, using the measured data from borehole records and site investigation results. It is observed from the results that, if faults are not present, the depth of the Grade III surface exhibits the largest scale of fluctuation among the three indicators, and the variability of the ground is observed to increase with the weathering grade. The effect of the size of the sampling domain on the autocorrelation characteristics of the founding depth indicators is also studied. The results demonstrate that the scale of fluctuation increases with increase in the size of the sampling domain. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.P.151.3786

Uncertainties in geologic profiles versus variability in pile founding depth / Zhang, L. M. in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 11 (Novembre 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 11 (Novembre 2010) . - pp. 1475-1488 Titre : Uncertainties in geologic profiles versus variability in pile founding depth Type de document : texte imprimé Auteurs : Zhang, L. M., Auteur ; S. M. Dasaka, Auteur Année de publication : 2011 Article en page(s) : pp. 1475-1488 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Geology  Pile  foundations  Pile  driving  Reliability  Site  investigation  Spatial  analysis  Uncertainty  principles Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : How the design and actual founding depths of foundations correspond to the variability of geological conditions has long been a concern. This paper evaluates the spatial variability characteristics of as-built and estimated founding depths of driven steel H piles with reference to the spatial variability characteristics of geologic profiles at a weathered soil site in Hong Kong. Spatial variability characteristics are evaluated in terms of variance and scale of fluctuation. The variability of three founding depth indicators, i.e., the depth of Grade-III bedrock, the depth of standard penetration test blow count “N” of 200 blows/0.3 m (SPT-200), and the depth of completely decomposed granite over the site was estimated. It is found that pile founding depths exhibit greater variations than those of the geologic profiles due to the presence of design model errors, judgment errors, and construction effects. The as-built founding depths are mostly between the SPT-200 profile and the Grade-III bedrock profile. The variances of as-built pile length are similar to those with depth of SPT-200 but less than those with depth of Grade-III bedrock. The scale of fluctuation of as-built pile length is on the order of 20 m when kriging is used and 10 m when kriging is not used, which are less than those with depths of SPT-200 and Grade-III bedrock. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...] [article] Uncertainties in geologic profiles versus variability in pile founding depth [texte imprimé] / Zhang, L. M., Auteur ; S. M. Dasaka, Auteur . - 2011 . - pp. 1475-1488. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 11 (Novembre 2010) . - pp. 1475-1488 Mots-clés : Geology  Pile  foundations  Pile  driving  Reliability  Site  investigation  Spatial  analysis  Uncertainty  principles Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : How the design and actual founding depths of foundations correspond to the variability of geological conditions has long been a concern. This paper evaluates the spatial variability characteristics of as-built and estimated founding depths of driven steel H piles with reference to the spatial variability characteristics of geologic profiles at a weathered soil site in Hong Kong. Spatial variability characteristics are evaluated in terms of variance and scale of fluctuation. The variability of three founding depth indicators, i.e., the depth of Grade-III bedrock, the depth of standard penetration test blow count “N” of 200 blows/0.3 m (SPT-200), and the depth of completely decomposed granite over the site was estimated. It is found that pile founding depths exhibit greater variations than those of the geologic profiles due to the presence of design model errors, judgment errors, and construction effects. The as-built founding depths are mostly between the SPT-200 profile and the Grade-III bedrock profile. The variances of as-built pile length are similar to those with depth of SPT-200 but less than those with depth of Grade-III bedrock. The scale of fluctuation of as-built pile length is on the order of 20 m when kriging is used and 10 m when kriging is not used, which are less than those with depths of SPT-200 and Grade-III bedrock. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...]