Publication Date:
2014-05-28
Description:
For the saturated case with only one pore fluid, either water or air, the roles of both the intergranular stress tensor and the pore fluid stress can be distinguished easily. In the unsaturated case, the capillary water is recognized to induce capillary suction in the pores and capillary-suction-induced interparticle forces. At the macroscale, volume averaging of these forces would lead to the capillary-suction-induced intergranular stress tensor. In its approximate formulation, the concept of the fabric stress tensor is applied, enabling the effect of the spatial distribution of the intergranular fabric on the capillary water bridges as occurring in the drier pendular saturation phase to be accounted for. Subsequently, the combined intergranular stress tensor and the combined pore fluid stress tensor can be derived directly. The constitutive relation of a granular skeleton, composed of elastic particles with mainly frictional interaction, like quartz sands and silts, is considered to remain independent of the degree of saturation. Under such restrictive conditions, only the additional physical parameters of the capillary-suction-induced intergranular stress tensor need to be determined, which can be achieved by means of inverse modeling, taking advantage of all macroscale experimental data and physical modeling for the whole unsaturated range. For clays and peats, with potential physicochemical and biochemical actions and double porosity and/or fibrous microstructures, the constitutive models can be expected to be physically more complicated, thus involving more physically relevant parameters. Hence, clays and peats must be considered to fall outside the scope of the proposed model framework.
Electronic ISSN:
1539-1663
Topics:
Geosciences
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Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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