Documents disponibles écrits par cet auteur

Effect of soil characteristics on relative values of piezocone, T-bar and ball penetration resistances / H. E. Low in Géotechnique, Vol. 61 N° 8 (Août 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 8 (Août 2011) . - pp. 651–664 Titre : Effect of soil characteristics on relative values of piezocone, T-bar and ball penetration resistances Type de document : texte imprimé Auteurs : H. E. Low, Auteur ; M. F. Randolph, Auteur ; T. Lunne, Auteur Année de publication : 2011 Article en page(s) : pp. 651–664 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Shear  strength  Clays  Site  investigation  In  situ  testing Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : It has been reported in the literature that net cone penetration resistance is normally higher than the penetration resistance measured using full-flow cylindrical (T-bar) or spherical (ball) penetrometers, and also that the ball penetration resistance is generally very close to the T-bar penetration resistance. In this paper, a worldwide high-quality database (three onshore sites and seven offshore sites) was used to identify soil characteristics that contribute to differences in the relative magnitudes of penetration resistance measured with cone, T-bar and ball penetrometers. For soils covered in this database, the ratio of T-bar to net cone penetration resistance (q T-bar/q net) lay between 0·75 and 1, decreasing with depth from near unity at shallow depths. For the four sites where ball penetrometer data were available, the ratio of ball to T-bar penetration resistance (q ball/q T-bar) was found to fluctuate around unity, with an average just greater than 1, but no distinguishable trend with depth. The measured q T-bar/q net and q ball/q net followed theoretical trends for the cone resistance to increase with rigidity index, G/s u, with the best quantitative agreement obtained using a rigidity index defined in terms of the small strain stiffness, G 0, as measured by in situ seismic cone tests. The resistance ratio also followed the theoretical trend predicted with certain assumptions for the effects of strength anisotropy. However, while q T-bar/q net and possibly q ball/q net appear to depend slightly on the liquidity index, liquid limit and plasticity index, the resistance ratios appeared independent of other soil parameters, including normalised in situ shear stress, sensitivity and yield stress ratio, for the soils covered in this study. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.018 [article] Effect of soil characteristics on relative values of piezocone, T-bar and ball penetration resistances [texte imprimé] / H. E. Low, Auteur ; M. F. Randolph, Auteur ; T. Lunne, Auteur . - 2011 . - pp. 651–664. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 8 (Août 2011) . - pp. 651–664 Mots-clés : Shear  strength  Clays  Site  investigation  In  situ  testing Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : It has been reported in the literature that net cone penetration resistance is normally higher than the penetration resistance measured using full-flow cylindrical (T-bar) or spherical (ball) penetrometers, and also that the ball penetration resistance is generally very close to the T-bar penetration resistance. In this paper, a worldwide high-quality database (three onshore sites and seven offshore sites) was used to identify soil characteristics that contribute to differences in the relative magnitudes of penetration resistance measured with cone, T-bar and ball penetrometers. For soils covered in this database, the ratio of T-bar to net cone penetration resistance (q T-bar/q net) lay between 0·75 and 1, decreasing with depth from near unity at shallow depths. For the four sites where ball penetrometer data were available, the ratio of ball to T-bar penetration resistance (q ball/q T-bar) was found to fluctuate around unity, with an average just greater than 1, but no distinguishable trend with depth. The measured q T-bar/q net and q ball/q net followed theoretical trends for the cone resistance to increase with rigidity index, G/s u, with the best quantitative agreement obtained using a rigidity index defined in terms of the small strain stiffness, G 0, as measured by in situ seismic cone tests. The resistance ratio also followed the theoretical trend predicted with certain assumptions for the effects of strength anisotropy. However, while q T-bar/q net and possibly q ball/q net appear to depend slightly on the liquidity index, liquid limit and plasticity index, the resistance ratios appeared independent of other soil parameters, including normalised in situ shear stress, sensitivity and yield stress ratio, for the soils covered in this study. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.018

Estimation of intact and remoulded undrained shear strengths from penetration tests in soft clays / H. E. Low in Géotechnique, Vol. 60 N° 11 (Novembre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 11 (Novembre 2010) . - pp. 843–859 Titre : Estimation of intact and remoulded undrained shear strengths from penetration tests in soft clays Type de document : texte imprimé Auteurs : H. E. Low, Auteur ; T. Lunne, Auteur ; K. H. Andersen, Auteur Année de publication : 2011 Article en page(s) : pp. 843–859 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Shear  strength  in  situ  testing  Clays Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Difficulties in obtaining high-quality soil samples from deepwater sites have necessitated increasing reliance on piezocone, T-bar and ball penetration tests to determine soil properties for design purposes. This paper reports the results of an international collaborative project in which a worldwide high-quality database of lightly overconsolidated clays was assembled and used to evaluate resistance factors for the estimation of intact and remoulded undrained shear strength from the penetration resistance of each device. The derived factors were then compared with existing theoretical solutions to evaluate the influence of particular soil characteristics. The overall statistics showed similar levels of variability of the resistance factors, with low coefficients of variation, for all three types of penetrometer. However, correlations of the resistance factors with specific soil characteristics indicated that the resistance factors for the piezocone were more influenced by soil stiffness, or rigidity index, than for the T-bar and ball, while the effect of strength anisotropy was only apparent in respect of resistance factors for the T-bar and ball relative to shear strengths measured in triaxial compression. In the correlation between the remoulded penetration resistance and remoulded strength, the resistance factors for remoulded strength were found to be higher than those for intact strength and with a slight tendency to increase with increasing strength sensitivity but insensitive to soil index properties. Based on an assessment of the influence of various soil characteristics, resistance factors are recommended for the estimation of intact and remoulded undrained shear strength from the penetration resistances of each device for soil with strength sensitivity less than six. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.017 [article] Estimation of intact and remoulded undrained shear strengths from penetration tests in soft clays [texte imprimé] / H. E. Low, Auteur ; T. Lunne, Auteur ; K. H. Andersen, Auteur . - 2011 . - pp. 843–859. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 11 (Novembre 2010) . - pp. 843–859 Mots-clés : Shear  strength  in  situ  testing  Clays Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Difficulties in obtaining high-quality soil samples from deepwater sites have necessitated increasing reliance on piezocone, T-bar and ball penetration tests to determine soil properties for design purposes. This paper reports the results of an international collaborative project in which a worldwide high-quality database of lightly overconsolidated clays was assembled and used to evaluate resistance factors for the estimation of intact and remoulded undrained shear strength from the penetration resistance of each device. The derived factors were then compared with existing theoretical solutions to evaluate the influence of particular soil characteristics. The overall statistics showed similar levels of variability of the resistance factors, with low coefficients of variation, for all three types of penetrometer. However, correlations of the resistance factors with specific soil characteristics indicated that the resistance factors for the piezocone were more influenced by soil stiffness, or rigidity index, than for the T-bar and ball, while the effect of strength anisotropy was only apparent in respect of resistance factors for the T-bar and ball relative to shear strengths measured in triaxial compression. In the correlation between the remoulded penetration resistance and remoulded strength, the resistance factors for remoulded strength were found to be higher than those for intact strength and with a slight tendency to increase with increasing strength sensitivity but insensitive to soil index properties. Based on an assessment of the influence of various soil characteristics, resistance factors are recommended for the estimation of intact and remoulded undrained shear strength from the penetration resistances of each device for soil with strength sensitivity less than six. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.017

Geotechnical characterisation and engineering properties of Burswood clay / H. E. Low in Géotechnique, Vol. 61 N° 7 (Juillet 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 7 (Juillet 2011) . - pp. 575–591 Titre : Geotechnical characterisation and engineering properties of Burswood clay Type de document : texte imprimé Auteurs : H. E. Low, Auteur ; M. Landon Maynard, Auteur ; M. F. Randolph, Auteur Année de publication : 2011 Article en page(s) : pp. 575–591 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : In  situ  testing  Laboratory  tests  Clays  Stiffness  Compressibility  Shear  strength Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The Burswood clay is a lightly overconsolidated and sensitive silty clay of high to extremely high plasticity. In two extensive characterisation studies, a wide range of in situ tests were carried out at the Burswood site, including full-flow penetrometer tests (T-bar, ball and plate). In addition, thin-wall tube samples and high-quality Sherbrooke block samples were collected for laboratory testing. The stress–strain–strength, consolidation and compressibility characteristics of Burswood clay were investigated, and the performance of various penetrometers in characterising the soft Burswood clay was assessed. The paper compares values of stiffness and shear strength measured by different in situ and laboratory tests, quantifying the degree of non-linearity of the stress–strain response, the effect of sample disturbance on the measured mechanical properties, the degree of strength anisotropy, and the influence of strain rate on the measured shear strength. In addition, factors relating the net penetration resistance measured by cone, T-bar and ball penetrometers to yield stress, small-strain shear modulus and different measures of undrained shear strength are also provided. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.035 [article] Geotechnical characterisation and engineering properties of Burswood clay [texte imprimé] / H. E. Low, Auteur ; M. Landon Maynard, Auteur ; M. F. Randolph, Auteur . - 2011 . - pp. 575–591. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 7 (Juillet 2011) . - pp. 575–591 Mots-clés : In  situ  testing  Laboratory  tests  Clays  Stiffness  Compressibility  Shear  strength Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The Burswood clay is a lightly overconsolidated and sensitive silty clay of high to extremely high plasticity. In two extensive characterisation studies, a wide range of in situ tests were carried out at the Burswood site, including full-flow penetrometer tests (T-bar, ball and plate). In addition, thin-wall tube samples and high-quality Sherbrooke block samples were collected for laboratory testing. The stress–strain–strength, consolidation and compressibility characteristics of Burswood clay were investigated, and the performance of various penetrometers in characterising the soft Burswood clay was assessed. The paper compares values of stiffness and shear strength measured by different in situ and laboratory tests, quantifying the degree of non-linearity of the stress–strain response, the effect of sample disturbance on the measured mechanical properties, the degree of strength anisotropy, and the influence of strain rate on the measured shear strength. In addition, factors relating the net penetration resistance measured by cone, T-bar and ball penetrometers to yield stress, small-strain shear modulus and different measures of undrained shear strength are also provided. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.035

Geotechnical characterisation and engineering properties of Burswood clay / H. E. Low in Géotechnique, Vol. 62 N° 7 (Juillet 2012) 

Public ISBD [article]  in Géotechnique > Vol. 62 N° 7 (Juillet 2012) . - pp. 653 –656 Titre : Geotechnical characterisation and engineering properties of Burswood clay Type de document : texte imprimé Auteurs : H. E. Low, Auteur ; M. Landon Maynard, Auteur ; M. F. Randolph, Auteur Année de publication : 2012 Article en page(s) : pp. 653 –656 Note générale : Génie Civil Langues : Anglais (eng) Note de contenu : Discussion ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.11.D.007 [article] Geotechnical characterisation and engineering properties of Burswood clay [texte imprimé] / H. E. Low, Auteur ; M. Landon Maynard, Auteur ; M. F. Randolph, Auteur . - 2012 . - pp. 653 –656. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 62 N° 7 (Juillet 2012) . - pp. 653 –656 Note de contenu : Discussion ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.11.D.007