Journal Published Online: 21 August 2020
Volume 44, Issue 4

Developing a Sample Preparation Approach to Study the Mechanical Behavior of Unsaturated Fine/Coarse Soil Mixture

CODEN: GTJODJ

Abstract

An interlayer soil was identified in the conventional French railway substructure, corresponding to a mixture of fine soils and coarse grains. As the overall mechanical behavior of the interlayer soil can be conditioned by the microstructure of the fine soils, for the laboratory testing, it is important to develop an appropriate protocol for the sample preparation by compaction, which allows this microstructure effect to be minimized. In this study, two sample preparation approaches were considered for a fine/coarse mixture, with two distinct volumetric contents of coarse grains fv (volumetric ratio of coarse grain to total sample). The microstructure of fine soils was investigated using mercury intrusion porosimetry, and its effect on the overall mechanical behavior was examined through monotonic triaxial tests. Results showed that while compacted dry of optimum, the fine soils exhibited a bimodal porosity microstructure. By contrast, while compacted wet of optimum, the fine soils exhibited a unimodal porosity microstructure. When fv = 10 %, the sample was characterized by a fine matrix macrostructure with coarse grains floating in it. In that case, a strong effect of the microstructure of fine soils on the overall mechanical behavior was identified. On the contrary, when fv = 35 %, the sample was characterized by a coarse grain skeleton. In that case, a very limited microstructure effect of fine soils on the overall mechanical behavior was observed. Thus, while preparing samples of unsaturated fine/coarse soil mixture by compaction to study the overall mechanical behavior, it is important to account for the fv value. At low fv, the compaction at different water contents is to be avoided because of the significant effect of the microstructure of fines. On the contrary, at high fv, the samples at different water contents can be prepared by compacting the mixture at the desired water contents.

Author Information

Su, Yu
Ecole des Ponts ParisTech, Laboratoire Navier/CERMES, Cité Descartes, Champs-sur-Marne, Marne-la-Vallée cedex 2, France
Cui, Yu-Jun
Ecole des Ponts ParisTech, Laboratoire Navier/CERMES, Cité Descartes, Champs-sur-Marne, Marne-la-Vallée cedex 2, France
Dupla, Jean-Claude
Ecole des Ponts ParisTech, Laboratoire Navier/CERMES, Cité Descartes, Champs-sur-Marne, Marne-la-Vallée cedex 2, France
Canou, Jean
Ecole des Ponts ParisTech, Laboratoire Navier/CERMES, Cité Descartes, Champs-sur-Marne, Marne-la-Vallée cedex 2, France
Qi, Shuai
Department of Civil Engineering, Zhejiang University, Hangzhou, China
Pages: 17
Price: $25.00
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Details
Stock #: GTJ20190450
ISSN: 0149-6115
DOI: 10.1520/GTJ20190450