Using the Reference Shrinkage Curve to Estimate the Corrected Crack Volume of a Soil Layer
To estimate the correct soil crack volume based on the shrinkage geometry factor, in addition to measurements with core samples, one also needs to know the shrinkage curve of the soil matrix without cracks. For such a curve one can use the soil reference shrinkage curve that is only stipulated by intraaggregate clay shrinkage without interaggregate cracking. The objective of this work is to illustrate such use of the reference shrinkage curve and, in addition, to argue the necessity to correct the usual estimates of the shrinkage geometry factor in order to correctly estimate the soil crack vol- ume. The illustration is based on available data and reference shrinkage curves for eight soils.
Step-by-Step Transition from Clay to Soil Shrinkage Curve
Clay and soil containing it have shrinkage curves that are qualitatively different in shape. The objective of this work is to qualitatively show with maximum simplicity, how a clay shrinkage curve turns into a soil shrinkage curve. Be- cause of the crack volume the measured shrinkage curve is not the single-valued feature of a soil. We use a concept of the reference shrinkage curve that is only stipulated by soil shrinkage without cracking, single-valued, and qualitatively simi- lar to an observed shrinkage curve. We also use new concepts of an intra-aggregate soil structure: (i) a deformable, but non-shrinking surface layer of aggregates that loses water during shrinkage; and (ii) lacunar pores (micro-cracks) inside an intra-aggregate clay that increase in volume during shrinkage. Then, through a series of consecutive steps, illustrating each step by a separate graphic presentation, we move from a clay shrinkage curve to a soil shrinkage curve with pre- dicted qualitative features that coincide with those experimentally observed in numerous soil shrinkage publications. We thereby demonstrate the qualitative physical impact of the intra-aggregate structure on soil shrinkage.
Physical Chemistry for the Life Sciences
PART 1 - BIOCHEMICAL THERMODYNAMICS PART 2- THE KINETICS OF LIFE PROCESSES PART 3 - BIOMOLECULAR STRUCTURE PART 4 - BIOMOLECULAR SPECTROSCOPY