Thermohydraulic Responses of Unsaturated Sand around a Model Energy Pile
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 147, Issue 10
Abstract
This paper examines the effects of monotonic and cyclic temperature changes of a model energy pile (, ) on the variations in temperature and volumetric water content of surrounding unsaturated sand. Water flowed away from the pile during heating to 36°C and toward the pile during cooling to 5°C, causing soil drying and wetting near the pile, respectively. The change in volumetric water content was time-dependent, nonlinear, and slower than the change in soil temperature and continued to evolve after the soil temperature changes stabilized. Cyclic heating/cooling induced lower thermohydraulic changes in the soil than monotonic heating and cooling. The most significant changes in soil temperatures and volumetric water content were closest to the pile at a radial distance of 20 mm from the edge of the pile and reduced with increasing radial distance for all cases. The largest change in the degree of saturation was near the pile and was up to 6% for monotonic heating. Cyclic heating/cooling induced irreversible cyclic hydraulic responses near the pile with consecutive thermal cycles and caused a permanent reduction in the soil volumetric water content. However, these irreversible cyclic effects were dominant at a radius of 20 mm and reduced with increasing radial distance from the energy pile. The change in volumetric water content was time-dependent, indicating that the ratio of heating to cooling times during cyclic heating/cooling will have a significant effect on the reversibility of hydraulic responses under temperature cycles.
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Data Availability Statement
All data, models, and code generated or used during the study appear in the published article.
Acknowledgments
This research project was supported by the Australian Research Council’s Linkage Projects funding scheme (Project No. LP120200613). A US National Science Foundation grant (Grant No. CMMI-1054190) supported the third author. The support of all the sponsors (Geotechnical Engineering Pty. Ltd., Golder Associates Pty Ltd., Geoexchange Australia Pty. Ltd., and Brookfield-Multiplex) is gratefully acknowledged. The opinions expressed in this paper are those of the authors alone.
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Journal of Geotechnical and Geoenvironmental Engineering
Volume 147 • Issue 10 • October 2021
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© 2021 American Society of Civil Engineers.
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Received: Jun 2, 2020
Accepted: Jun 15, 2021
Published online: Aug 10, 2021
Published in print: Oct 1, 2021
Discussion open until: Jan 10, 2022
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