Hydraulic and Mechanical Behavior of Unsaturated Silt: Experimental and Theoretical Characterization
Publication: International Journal of Geomechanics
Volume 16, Issue 6
Abstract
A series of experiments were performed to investigate the hydraulic and mechanical behavior of an unsaturated silt obtained from the Yellow River Delta. To identify the key factors that influence the soil-water characteristics (SWC), an experimental program was designed to study the SWC of the soil at different void ratios and vertical pressures. It was shown that an that that apparent hysteresis phenomenon occurred on the SWC curves when the soil experienced drying/wetting cycles. It was also shown that the influence of void ratio on the SWC was significant, and the stress state influenced the SWC only through changing the void ratio. Isotropic compression tests were conducted at different constant matric suctions, using a suction-controlled double cell triaxial apparatus. The soil under shearing showed apparent dilatant and softening behavior, in a way similar to medium to dense sand. In addition, the hardening effect of matric suction was significant, and both the stiffness and peak strength of the soil increased with matric suction. Based on the experimental observations, an elastoplastic constitutive model coupling capillary hysteresis and plastic deformation was developed, in which a hysteretic SWC relationship was introduced to characterize the influence of hydraulic history on the skeletal deformation. To better simulate the volumetric change of the soil, a nonassociated flow rule was adopted. The effect of the plastic volumetric strain on water-retention behavior was also taken into consideration. The proposed model was used to simulate the behavior of unsaturated silt under constant-suction, isotropic compression and constant-suction, triaxial shearing conditions, showing the capability of the new model in describing the behavior of unsaturated silt.
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Acknowledgments
The research was supported by the National Key Basic Research Program of China under Grant 2012CB026102, the Natural Science Foundation of China under Grant 51239010, and the Natural Science Foundation of Guangxi under Grant 2012GXNSFGA060001.
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Information & Authors
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Published In
International Journal of Geomechanics
Volume 16 • Issue 6 • December 2016
Copyright
© 2015 American Society of Civil Engineers.
History
Received: May 28, 2014
Accepted: Jun 29, 2015
Published online: Dec 31, 2015
Discussion open until: May 31, 2016
Published in print: Dec 1, 2016
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