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Capillary force and water retention between two uneven-sized particles / Jeremy Lechman in Journal of engineering mechanics, Vol. 134 N°5 (Mai 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°5 (Mai 2008) . - pp.374–384. Titre : Capillary force and water retention between two uneven-sized particles Type de document : texte imprimé Auteurs : Jeremy Lechman, Auteur ; Ning Lu, Auteur Année de publication : 2008 Article en page(s) : pp.374–384. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Absorption  Interfacial  tension  Unsaturated  soils  Granular  materials  Tensile  stress  Theory  Particles Résumé : Capillary force and water retention between two uneven-sized spherical particles are investigated. Previous studies have been limited to systems with even-sized particles. The appropriate definition of the boundary value problem for a water lens between two uneven-sized particles is presented under the consideration of thermodynamic free energy at the microscopic level. Capillary force and water retention under the consideration of toroidal approximation are also derived for a system with two uneven-sized particles. Comparison of normalized capillary force and water retention calculated by the free energy approach and toroidal approximation are conducted. The quantitative analysis shows that for a system with two identical particles, the behavior of water retention and normalized capillary force is very similar to some recent studies by others, confirming that the toroidal approximation provides reasonably good estimations for both capillary force and water retention. For a system with uneven-sized particles, it is shown that error in normalized capillary force could be significant as the matric suction approaches zero and the particle sizes become very different. The errors for the mean curvature of the meniscus for the toroidal approximation are significant where the matric suction is near zero. Thus for soils with varying particle sizes, it may be necessary to employ the exact solution to meniscus shape in order to accurately quantify normalized capillary force and water retention. The induced normalized capillary force increases inversely with the particle size, and is generally insensitive to the water content. For soil assembly with particle size of 0.01mm , the normalized capillary force could reach 10kPa , whereas for soil assembly with particle size of 1mm , the normalized capillary force is on the order of 100Pa . ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A5%2837 [...] [article] Capillary force and water retention between two uneven-sized particles [texte imprimé] / Jeremy Lechman, Auteur ; Ning Lu, Auteur . - 2008 . - pp.374–384. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°5 (Mai 2008) . - pp.374–384. Mots-clés : Absorption  Interfacial  tension  Unsaturated  soils  Granular  materials  Tensile  stress  Theory  Particles Résumé : Capillary force and water retention between two uneven-sized spherical particles are investigated. Previous studies have been limited to systems with even-sized particles. The appropriate definition of the boundary value problem for a water lens between two uneven-sized particles is presented under the consideration of thermodynamic free energy at the microscopic level. Capillary force and water retention under the consideration of toroidal approximation are also derived for a system with two uneven-sized particles. Comparison of normalized capillary force and water retention calculated by the free energy approach and toroidal approximation are conducted. The quantitative analysis shows that for a system with two identical particles, the behavior of water retention and normalized capillary force is very similar to some recent studies by others, confirming that the toroidal approximation provides reasonably good estimations for both capillary force and water retention. For a system with uneven-sized particles, it is shown that error in normalized capillary force could be significant as the matric suction approaches zero and the particle sizes become very different. The errors for the mean curvature of the meniscus for the toroidal approximation are significant where the matric suction is near zero. Thus for soils with varying particle sizes, it may be necessary to employ the exact solution to meniscus shape in order to accurately quantify normalized capillary force and water retention. The induced normalized capillary force increases inversely with the particle size, and is generally insensitive to the water content. For soil assembly with particle size of 0.01mm , the normalized capillary force could reach 10kPa , whereas for soil assembly with particle size of 1mm , the normalized capillary force is on the order of 100Pa . ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A5%2837 [...]

Experimental verification of capillary force and water retention between uneven-sized spheres / Ning Lu in Journal of engineering mechanics, Vol. 134 N°5 (Mai 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°5 (Mai 2008) . - pp.385–395. Titre : Experimental verification of capillary force and water retention between uneven-sized spheres Type de document : texte imprimé Auteurs : Ning Lu, Auteur ; Jeremy Lechman, Auteur ; Kelly T. Miller, Auteur Année de publication : 2008 Article en page(s) : pp.385–395. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Absorption  Interfacial  tension  Unsaturated  soils  Granular  materials  Tensile  stress  Experimentation  Verification Résumé : The recently established theoretical results of the solid-water characteristic curve (SWCC) and capillary force characteristic curve (CFCC) are experimentally verified for mechanical and hydrologic interaction between uneven-sized spherical particles under partially saturated conditions. It is shown that the theoretical framework, based on the minimization of the free energy of the liquid meniscus between the two uneven-sized particles, can predict both water retention and capillary force accurately for spherical particles ranging in radius from 165to252μm . The experimental technique is novel and the results at such scale are valuable for the understanding of gas-solid-liquid interaction among granular media, since there is very limited experimental data available in the literature. The comparisons between the theoretical and experimental predictions of the SWCC and CFCC indicate that the agreements are generally very good, confirming the validity of the theory. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A5%2838 [...] [article] Experimental verification of capillary force and water retention between uneven-sized spheres [texte imprimé] / Ning Lu, Auteur ; Jeremy Lechman, Auteur ; Kelly T. Miller, Auteur . - 2008 . - pp.385–395. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°5 (Mai 2008) . - pp.385–395. Mots-clés : Absorption  Interfacial  tension  Unsaturated  soils  Granular  materials  Tensile  stress  Experimentation  Verification Résumé : The recently established theoretical results of the solid-water characteristic curve (SWCC) and capillary force characteristic curve (CFCC) are experimentally verified for mechanical and hydrologic interaction between uneven-sized spherical particles under partially saturated conditions. It is shown that the theoretical framework, based on the minimization of the free energy of the liquid meniscus between the two uneven-sized particles, can predict both water retention and capillary force accurately for spherical particles ranging in radius from 165to252μm . The experimental technique is novel and the results at such scale are valuable for the understanding of gas-solid-liquid interaction among granular media, since there is very limited experimental data available in the literature. The comparisons between the theoretical and experimental predictions of the SWCC and CFCC indicate that the agreements are generally very good, confirming the validity of the theory. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A5%2838 [...]

Hysteresis of Matric Suction and Capillary Stress in Monodisperse Disk-Shaped Particle / Jeremy Lechman in Journal of engineering mechanics, Vol. 132 N°5 (Mai 2006) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 132 N°5 (Mai 2006) . - 565-577 p. Titre : Hysteresis of Matric Suction and Capillary Stress in Monodisperse Disk-Shaped Particle Titre original : L'Hystérésis de l'Effort Matriciel d'Aspiration et de Capillaire dans le Disque mono-dispersion a Formé la Particule Type de document : texte imprimé Auteurs : Jeremy Lechman, Auteur ; Ning Lu, Auteur ; Wu, David ; Ooi, J. Y., Editeur scientifique Article en page(s) : 565-577 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Unsaturated  soils  Granular  media  Hysteresis  Suction  Effective  stress  Sols  insaturés  Médias  granulaires  Aspiration  d'hystérésis  Effort  efficace Index. décimale : 621.34 Résumé : The dependences of matric suction and capillary stress on the degree of saturation in monodisperse disk-shaped particles are established for the full range of the degree of saturation. A thermodynamic free energy approach is employed to obtain both the soil-water characteristic curve (SWCC) and the capillary stress characteristic curve (CSCC) for both wetting and drying processes. It is shown that the thermodynamic energy stability concept can lead to the establishment of hysteresis in both the SWCC and CSCC without explicit involvement of the contact angle and ink-bottle hysteresis. The air-entry pressure value and capillary condensation pressure value are quantified and their functional dependencies on the average pore sizes are established. For particle sizes ranging between 0.001 and 1 mm, the air-entry and capillary condensation pressures decrease from several hundred kPa to several kPa and capillary forces are found to range between tens and hundreds of micronewtons. Les dépendances de l'effort matriciel d'aspiration et de capillaire à légard le degré de saturation dans les particules en forme de disque de monodisperse sont établies pour la gamme complète du degré de saturation. Une approche libre thermo-dynamique d'énergie est utilisée pour obtenir la courbe caractéristique de l'sol-eau (SWCC) et la courbe caractéristique d'effort capillaire (CSCC) pour le mouillage et les processus de séchage. On lui montre que le concept thermo-dynamique de stabilité d'énergie peut mener à l'établissement de l'hystérésis dans le SWCC et CSCC sans participation explicite de l'angle de contact et de l'hystérésis d'encre-bouteille. La valeur de valeur de pression d'air-entrée et de pression de condensation de capillaire sont mesurées et leurs dépendances fonctionnelles sur les tailles moyennes de pore sont établies. Pour des dimensions particulaires s'étendant entre 0.001 et 1 millimètre, l'air-entrée et les pressions de condensation de capillaire diminuent des plusieurs centaines le kPa aux plusieurs kPa et des forces de capillaire s'avèrent pour s'étendre entre les dizaines et les centaines de micronewtons. En ligne : ninglu@mines.edu [article] Hysteresis of Matric Suction and Capillary Stress in Monodisperse Disk-Shaped Particle = L'Hystérésis de l'Effort Matriciel d'Aspiration et de Capillaire dans le Disque mono-dispersion a Formé la Particule [texte imprimé] / Jeremy Lechman, Auteur ; Ning Lu, Auteur ; Wu, David ; Ooi, J. Y., Editeur scientifique . - 565-577 p. Génie Mécanique Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 132 N°5 (Mai 2006) . - 565-577 p. Mots-clés : Unsaturated  soils  Granular  media  Hysteresis  Suction  Effective  stress  Sols  insaturés  Médias  granulaires  Aspiration  d'hystérésis  Effort  efficace Index. décimale : 621.34 Résumé : The dependences of matric suction and capillary stress on the degree of saturation in monodisperse disk-shaped particles are established for the full range of the degree of saturation. A thermodynamic free energy approach is employed to obtain both the soil-water characteristic curve (SWCC) and the capillary stress characteristic curve (CSCC) for both wetting and drying processes. It is shown that the thermodynamic energy stability concept can lead to the establishment of hysteresis in both the SWCC and CSCC without explicit involvement of the contact angle and ink-bottle hysteresis. The air-entry pressure value and capillary condensation pressure value are quantified and their functional dependencies on the average pore sizes are established. For particle sizes ranging between 0.001 and 1 mm, the air-entry and capillary condensation pressures decrease from several hundred kPa to several kPa and capillary forces are found to range between tens and hundreds of micronewtons. Les dépendances de l'effort matriciel d'aspiration et de capillaire à légard le degré de saturation dans les particules en forme de disque de monodisperse sont établies pour la gamme complète du degré de saturation. Une approche libre thermo-dynamique d'énergie est utilisée pour obtenir la courbe caractéristique de l'sol-eau (SWCC) et la courbe caractéristique d'effort capillaire (CSCC) pour le mouillage et les processus de séchage. On lui montre que le concept thermo-dynamique de stabilité d'énergie peut mener à l'établissement de l'hystérésis dans le SWCC et CSCC sans participation explicite de l'angle de contact et de l'hystérésis d'encre-bouteille. La valeur de valeur de pression d'air-entrée et de pression de condensation de capillaire sont mesurées et leurs dépendances fonctionnelles sur les tailles moyennes de pore sont établies. Pour des dimensions particulaires s'étendant entre 0.001 et 1 millimètre, l'air-entrée et les pressions de condensation de capillaire diminuent des plusieurs centaines le kPa aux plusieurs kPa et des forces de capillaire s'avèrent pour s'étendre entre les dizaines et les centaines de micronewtons. En ligne : ninglu@mines.edu