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The Applicability of Dual Gamma Scanning to Freezing Soils and the Problem of Stratification
Author(s) -
Goit J. B.,
Groenevelt P. H.,
Kay B. D.,
Loch J. G. P.
Publication year - 1978
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1978.03615995004200060003x
Subject(s) - attenuation , stratification (seeds) , soil water , beam (structure) , plane (geometry) , homogeneous , mechanics , soil science , mineralogy , materials science , geology , physics , optics , geometry , mathematics , thermodynamics , seed dormancy , germination , dormancy , biology , botany
The attenuation of a dual energy gamma beam provides a powerful technique for studying the swelling phenomenon associated with soil freezing. However, the development of a stratified system due to the formation of a discrete ice lens in the same plane as the gamma beam requires special attention. Erroneous results are obtained when attenuation equations which are developed for homogeneous mixtures are applied to stratified media. The calculated dry bulk densities are then always lower than the averaged actual dry bulk densities and sometimes even negative. The calculated water contents are then always higher than the averaged actual water contents and sometimes in excess of 1 g/cm 3 . Stratification may also occur during the shrinking of unfrozen soil when cracks form in the same plane as the gamma beam. The equation describing the attenuation of a gamma beam in a stratified medium is formulated. A technical modification in the scanning procedure is suggested in order to solve the appropriate equations and to locate the interface.