Influence of Unsaturated Hydraulic Properties on Transient Seepage and Stability Analysis of an Earthen Dam
Publication: International Journal of Geomechanics
Volume 22, Issue 7
Abstract
Traditionally, the seepage through embankments and other geotechnical structures is estimated using the hydraulic properties of saturated soil. In most cases, the soil is not fully saturated, and the use of saturated soil properties can lead to erroneous results. A reliable assessment of slope stability needs comprehensive characterization of both unsaturated and hydraulic properties of saturated soil. The permeability coefficient of unsaturated soil is usually estimated using existing permeability models derived from the soil water characteristic curve (SWCC) of soil. The performance of these prediction models has not been consistent in the past. A proper determination of unsaturated soil permeability properties will be needed for better stability designs and checks of earth structures. In this study, an experimental program is designed to evaluate the influence of matric suction, net confining stress, and wetting and drying cycles on the hydraulic conductivity of a clayey soil over a wide range of suction values. Modified suction-controlled triaxial equipment was used to apply and maintain suction and hydraulic head in a soil specimen to measure the coefficient of permeability for drying and wetting cycles. Additionally, a series of fully coupled hydromechanic numerical analyses was performed to examine the effect of hydraulic properties of unsaturated soil on pore water pressure response and safety factors of slope for transient seepage conditions during drawdown. The effects of stress-dependent hydraulic properties and hydraulic hysteresis on transient seepage were also investigated. The findings from this study highlight the role of hydraulic properties of partially saturated soil in seepage and slope stability analysis of earthen dams.
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Acknowledgments
The authors sincerely appreciate the partial support of the National Science Foundation Industry-University Cooperative Research Center (I/UCRC) program, which funded the Center for Integration of Composites into Infrastructure (CICI) (Program Director Dr. Prakash Balan, Division of Industrial Innovation & Partnerships; Award 2017796). Any findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. We acknowledge Dr. Aritra Banerjee and Dr. Ujwalkumar Patil for their support of this study. Software support provided by PLAXIS for the numerical studies is also acknowledged.
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International Journal of Geomechanics
Volume 22 • Issue 7 • July 2022
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© 2022 American Society of Civil Engineers.
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Received: Jun 17, 2021
Accepted: Feb 7, 2022
Published online: May 10, 2022
Published in print: Jul 1, 2022
Discussion open until: Oct 10, 2022
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