Journal Published Online: 17 January 2014
Volume 37, Issue 2

Getting Information from Modal Decomposition of Grain Size Distribution Curves



Soil samples may be difficult-to-identify mixtures of different layers. For environmental and groundwater projects, a detailed stratigraphy is needed because the coarse layers are highways for both water and dissolved contaminants. The paper proposes a method to decompose a grain size distribution curve (GSDC) into its 1, 2, or 3 log-normal components and their proportions. The proposed method can accurately decompose synthetic mixes of three lognormal modes, except when a mode contributes for less than about 2 %. In such a case, it is suggested to ignore this mode and describe the mix as a two mode mix. An example is given for an experimental site with many split-spoon soil samples. The suspected stratification was confirmed by the decomposition method, which found mixtures of only two soil components, fine sand and clayey silt, each of them with little variability. The large-scale permeability, as provided by a pumping test, corresponds to the horizontally composed permeability of the soil components: thus, it confirms the adequacy of the soil sample decomposition method.

Author Information

Chapuis, Robert
Department CGM, Ecole Polytechnique, Montreal, QC, CA
Dallaire, Véronique
Department CGM, Ecole Polytechnique, Montreal, QC, CA Golder Associates Ltd., Montreal, QC, CA
Saucier, Antoine
Department MAGI, Ecole Polytechnique, Montreal, QC, CA
Pages: 15
Price: $25.00
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Stock #: GTJ20120218
ISSN: 0149-6115
DOI: 10.1520/GTJ20120218