HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Ghezzehei, T. A. Articles by Or, D. Search for Related Content PubMed Articles by Ghezzehei, T. A. Articles by Or, D. Agricola Articles by Ghezzehei, T. A. Articles by Or, D. Related Collections Mechanical Impediance Structure and Properties Soil Physics

DIVISION S-1—SOIL PHYSICS

Pore-Space Dynamics in a Soil Aggregate Bed under a Static External Load

^a Earth Science Division, Lawrence Berkeley National Laboratory, One Cycotron Road, MS90-1116, Berkeley, CA 94720
^b Dep. of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Road, Unit 2037, Storrs, CT 06269

* Corresponding author (TAGhezzehei{at}lbl.gov)

The loose and fragmented soil structure that results from tillage operations provides favorable physical conditions for plant growth. This desirable state is structurally unstable and deteriorates with time because of overburden, external stresses, and capillary forces. The objective of this study was to model these structural changes by coupling soil intrinsic rheological properties with geometry and arrangement of aggregates represented as monosized spheres. Calculations of interaggregate stresses and strains, and associated changes in density and porosity, were performed for a rhombohedral unit cell. Soil rheological properties determined by application of steady shear stress were used for calculations of strains under steady interaggregate stresses. The models developed herein correspond to the initial stage of deformation when discrete aggregates exist. At strains exceeding 0.12 the interaggregate voids are isolated and the current model no longer applies and an alternative approach is presented elsewhere. Unit cell calculations were up scaled to an aggregate-bed scale by considering a one-dimensional stack of unit cells, which allows only vertical stress transmission. The stress acting at an interaggregate contact is fully accommodated (dissipated) by viscous flow when it exceeds the yield stress (strength) of the aggregates. The stress is fully transmitted to subsequent unit cells when it is less than the yield stress. Plausibility of the models was demonstrated by illustrative examples that highlight the different features of the models. The results were in qualitative agreement with observations from the literature for deformation of either loose structure, and for highly dense cases close to maximal bulk density.

This article has been cited by other articles:

				E.-J. Park and A. J. M. Smucker Saturated Hydraulic Conductivity and Porosity within Macroaggregates Modified by Tillage Soil Sci. Soc. Am. J., January 1, 2005; 69(1): 38 - 45. [Abstract] [Full Text] [PDF]