HR: 1400h
AN: GS23B-01    [Abstracts]
TI: The Physical Effects of an Intraaggregate Structure on Soil Shrinkage
AU: * Chertkov, V Y
EM: agvictor@tx.technion.ac.il
AF: Technion, Technion City, Haifa, 32000, Israel
AB: Clay and soil containing it have shrinkage curves that are qualitatively different in shape. These differences and their origin require a scientific explanation based on an intraaggregate soil structure. The current models are based on the approximation of an experimental shrinkage curve by some a priori taken mathematical expression and do not explain the above differences. The objective of this work is to show how a clay shrinkage curve turns into a soil shrinkage curve. Because of the crack volume the measured shrinkage curve is not the single-valued feature of a soil. We introduce a new concept of the reference shrinkage curve that is only stipulated by soil shrinkage without cracking, single-valued, and qualitatively similar to an observed shrinkage curve. We also introduce new concepts of an intraaggregate soil structure: (i) a rigid superficial layer of aggregates that loses water during shrinkage; and (ii) lacunar pores (micro-cracks) inside an intraaggregate clay that change in volume during shrinkage. Then, through a series of consecutive steps we transit from a clay shrinkage curve to a soil shrinkage curve with experimentally observed qualitative features. Thereby we demonstrate the qualitative physical impact of the intraaggregate structure on soil shrinkage. The physical understanding of the transformation of the clay shrinkage curve to the soil shrinkage curve and of the new features of the intraaggregate structure underlying this transformation, are essential for numerous applications; first of all, for the physical modeling of soil shrinkage, water retention, hydraulic conductivity, water flow, and solute transport. In addition, the concepts and results of the model can also be useful for the physical explanation of crack contribution into a measured shrinkage curve, the hysteretic shrinkage-swelling phenomenon, the effects of compaction and consolidation on soil shrinkage-swelling in the field, the effects of the non-total closing shrinkage cracks at soil wetting in field conditions, and soil crusting.
DE: 1847 Modeling
DE: 1865 Soils (0486)
DE: 1866 Soil moisture
DE: 1875 Vadose zone
DE: 3625 Petrography, microstructures, and textures
SC: Geochemical Society [GS]
MN: 2007 Joint Assembly