Evolution of Unsaturated Shear Strength and Microstructure of a Compacted Silty Clay on Wetting Paths
Publication: International Journal of Geomechanics
Volume 21, Issue 12
Abstract
Silty clay is a common embankment material whose moisture increases over time due to soil–atmosphere interactions and climate changes. The objective of this study is to investigate the unsaturated shear strength and microstructural evolution of compacted silty clay on wetting paths. Suction-controlled triaxial tests, scanning electron microscopy (SEM) observations, and mercury intrusion porosimetry (MIP) tests were performed on compacted silty clay specimens at various matric suctions and net confining pressures. The results show that both the matric suction and the net confining pressure have positive effects on the unsaturated shear strength of compacted silty clay. Nevertheless, they tend to cause different failure forms of the specimens, indicating distinct mechanisms behind their contributions to the soil shear strength on wetting paths. A change in matric suction does not lead to obvious evolution of clay particle orientation, but an increase in net confining pressure causes a weaker preferential orientation of clay particles. The shape of pore size distribution curves is slightly affected by the matric suction on wetting paths, while an increase in net confining pressure obviously reduces the proportion of large pores. The brittle failure of compacted silty clay appears due to the presence of open microcracks at high matric suctions.
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Acknowledgments
This work was supported by the National Natural Science Foundation of China (Grant Nos. 52008041, 51838001, 51878070, 51908069, 51908073, and 51978085), the Key Research and Development Program of Hunan Province (Grant No. 2019SK2171), the Double First-Class Scientific Research International Cooperation Expansion Project of Changsha University of Science and Technology (Project No. 2019IC04), and the Changsha Municipal Natural Science Foundation (Grant No. kq2014110).
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International Journal of Geomechanics
Volume 21 • Issue 12 • December 2021
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© 2021 American Society of Civil Engineers.
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Received: Feb 22, 2021
Accepted: Jul 29, 2021
Published online: Sep 29, 2021
Published in print: Dec 1, 2021
Discussion open until: Mar 1, 2022
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