Abstract
This paper presents the development of an elastic model for partially saturated granular materials based on micromechanical factor consideration. A granular material is considered as an assembly of particles. The stress-strain relationship for an assembly can be determined by integrating the behavior at all interparticle contacts and by using a static hypothesis, which relates the average stress of the granular assembly to a mean field of particle contact forces. As for the nonsaturated state, capillary forces at grain contacts are added to the contact forces created by an external load. These are then calculated as a function of the degree of saturation, depending on the grain size distribution and on the void ratio of the granular assembly. Hypothesizing a Hertz-Mindlin law for the grain contacts leads to an elastic nonlinear behavior of the particulate material. The prediction of the stress-strain model is compared to experimental results obtained from several different granular materials in dry, partially saturated and fully saturated states. The numerical predictions demonstrate that the model is capable of taking into account the influence of key parameters, such as degree of saturation, void ratio, and mean stress.
Highlights
A granular material can be considered as a collection of particles of different sizes and shapes
Two different approaches can be followed based on the so-called kinematic hypothesis, which states that every particle displaces in accordance with a uniform deformation fieldChang 1988͒, or on the static hypothesis, which relates the average stress of the granular assembly to a mean field of particle contact forcesCambou et al 1995; Chang and Gao 1996; Liao et al 1997͒
Where fcap= capillary force between two neighboring grains, not necessarily in contact; fmax= value of fcap for two grains in contact; and R = mean grain radius; d = distance between two grains and is equal to l − 2R, l being the branch length given as a distribution function of the grain size and the void ratio; c = material parameter, dependent on the grain morphology and on the water content; fmax depends on the capillary pressure defined as the pressure jump across the liquid-air interface, on the liquid-air interface surface tension, as well as on the geometry of the menisci governed by the solid-liquid contact angle and the filling angle
Summary
To cite this version: Pierre-Yves Hicher, Ching Chang. Elastic model for partially saturated granular materials. Journal of Engineering Mechanics - ASCE, American Society of Civil Engineers, 2008, 134 (6), pp.505513. HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés
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