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 (17) 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. GeoRef GeoRef Citation Agricola Articles by Ghezzehei, T. A. Articles by Or, D. Related Collections Flow Soil Models Soil Physics

DIVISION S-1 - SOIL PHYSICS

Rheological Properties of Wet Soils and Clays under Steady and Oscillatory Stresses

Dep. of Plants, Soils and Biometeorology, Utah State Univ., Logan, UT 84322

Corresponding author (dani{at}mendel.usu.edu)

Tilled agricultural soils are in a constant state of change induced by variations in soil strength due to wetting and drying and compaction by farm implements. Changes in soil structure affect many hydraulic and transport properties; hence their quantification is critical for accurate hydrological and environmental modeling. This study highlights the role of soil rheology in determining time-dependent stress–strain relationships that are essential for prediction and analysis of structural changes in soils. The primary objectives of this study were (i) to extend a previously proposed aggregate-pair model to prediction of compaction under external steady or transient stresses and (ii) to provide experimentally determined rheological information for the above models. Rheological properties of soils and clay minerals were measured with a rotational rheometer with parallel-plate sensors. These measurements, under controlled steady shear stress application, have shown that wet soils have viscoplastic behavior with well-defined yield stress and nearly constant plastic viscosity. In contrast, rapid transient loading (e.g., passage of a tractor) is often too short for complete viscous dissipation of applied stress, resulting in an elastic (recoverable) component of deformation (viscoelastic behavior). Measured viscoelastic properties were expressed by complex viscosity and shear modulus whose components denote viscous energy dissipation, and energy storage (elastic). Results show that for low water contents and fast loading (tractor speed), the elastic component of deformation increases, whereas with higher water contents, viscosity and shear modulus decrease. Steady and oscillatory stress application to an aggregate pair model illustrates potential use of rheological properties towards obtaining predictions of strains in soils.

Abbreviations: CR, controlled shear rate • CS, controlled stress • OSC, sinusoidal (oscillatory) shear stress

This article has been cited by other articles:

				B. Augeard, L. M. Bresson, S. Assouline, C. Kao, and M. Vauclin Dynamics of Soil Surface Bulk Density: Role of Water Table Elevation and Rainfall Duration Soil Sci. Soc. Am. J., January 25, 2008; 72(2): 412 - 423. [Abstract] [Full Text] [PDF]

				X. Peng, R. Horn, and A. Smucker Pore Shrinkage Dependency of Inorganic and Organic Soils on Wetting and Drying Cycles Soil Sci. Soc. Am. J., June 8, 2007; 71(4): 1095 - 1104. [Abstract] [Full Text] [PDF]

				W. Markgraf and R. Horn Scanning Electron Microscopy-Energy Dispersive Scan Analyses and Rheological Investigations of South-Brazilian Soils Soil Sci. Soc. Am. J., May 16, 2007; 71(3): 851 - 859. [Abstract] [Full Text] [PDF]

				M. Berli, C. G. Eggers, M. L. Accorsi, and D. Or Theoretical Analysis of Fluid Inclusions for In Situ Soil Stress and Deformation Measurements Soil Sci. Soc. Am. J., August 3, 2006; 70(5): 1441 - 1452. [Abstract] [Full Text] [PDF]

				L. R. Ahuja, L. Ma, and D. J. Timlin Trans-Disciplinary Soil Physics Research Critical to Synthesis and Modeling of Agricultural Systems Soil Sci. Soc. Am. J., February 2, 2006; 70(2): 311 - 326. [Abstract] [Full Text] [PDF]

				T. A. Ghezzehei and D. Or Pore-Space Dynamics in a Soil Aggregate Bed under a Static External Load Soil Sci. Soc. Am. J., January 1, 2003; 67(1): 12 - 19. [Abstract] [Full Text] [PDF]

				F. J. Leij, T. A. Ghezzehei, and D. Or Analytical Models for Soil Pore-Size Distribution After Tillage Soil Sci. Soc. Am. J., July 1, 2002; 66(4): 1104 - 1114. [Abstract] [Full Text] [PDF]