Soil-Pile Interaction of Geothermal Foundation Subjected to Temperature Cycling
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2019
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ndltd-OhioLink-oai-etd.ohiolink.edu-akron15639748200496412021-08-03T07:12:04Z Soil-Pile Interaction of Geothermal Foundation Subjected to Temperature Cycling Husein, Dima A. Civil Engineering Energy In 2017, commercial and residential sectors consumed about 38 quadrillion Btu (British thermal units); which is about 39% of the total 97.7 quadrillions Btu of the U.S. energy consumption. This extensive use of energy produced from fossil fuels, a non-renewable energy source, causes the commercial and residential sectors to generate carbon emission leading to global warming and climate change. Therefore, renewable energy sources (e.g., geothermal energy) can be used to overcome this problem.Geothermal deep foundations, also known as energy piles, is an emerging environmentally friendly technology used for heating and cooling. Energy piles are used to support structures and exchange heat with the surrounding soil. The heat exchange process is comprised of extracting heat from the superstructure (building) during the summer season and injecting it into the ground, and extracting heat from the ground and injecting it into the superstructure during the winter season. These energy piles are coupled with closed-loop heat pumps that operate intermittently. This intermittent operation leads to cyclic expansion/contraction of the pile and the surrounding soil, therefore, affecting soil-pile interaction and shaft resistance of the pile. Most studies in the literature focus on the behavior of geothermal piles subjected to short-term cycles (monotonic heating or cycles less than ten). However, the long-term performance of energy pile, the effect of the operation time of GSHP, and the effect of temperature cycles on water migration and pore water pressure are still a knowledge gap that needs further investigation. Therefore, to study the effects of cyclic thermal loading on the soil-pile interface properties, a Modified Thermal-Borehole Shear Test (Modified-TBST) device was designed to perform tests in normally consolidated soil in this dissertation. The device can directly measure the shear stress versus vertical displacement curve (t-z curves), measure pore water pressure and temperature of the soil at different locations.The Modified-TBST device uses two concrete plates to simulate the pile surface with temperature changes and cycles. A series of tests were conducted to evaluate the effects of temperature change (ΔT = 5, 10, 20 °C), temperature cycles (TC = 0, 0.5, 10, 30, and 50), and to simulate different operation times in both saturated and partially saturated soil. The results obtained in this research indicate that the intermittent operation of heat pumps coupled to energy piles subject both the soil and pile to cyclic in the long run, which affects the shaft resistance. In addition, the operation times of the ground source heat pumps played a major role in the thermomechanical behavior of energy piles, where a longer running time increased the interface shear strength and a shorter stoppage time increased the temperature of the soil surrounding energy piles. Furthermore, thermally induced water flow and thermal consolidation were found to be higher in partially saturated soil, while in saturated soil, pore water pressure was critical and depended on the operation times of the heat pumps. Also, measured radial temperature distribution showed that the thermal conductivity of the soil is an important parameter that affects heat transfer around energy piles. 2019-08-29 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1563974820049641 http://rave.ohiolink.edu/etdc/view?acc_num=akron1563974820049641 restricted--full text unavailable until 2024-08-01 This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Civil Engineering Energy |
| spellingShingle |
Civil Engineering Energy Husein, Dima A. Soil-Pile Interaction of Geothermal Foundation Subjected to Temperature Cycling |
| author |
Husein, Dima A. |
| author_facet |
Husein, Dima A. |
| author_sort |
Husein, Dima A. |
| title |
Soil-Pile Interaction of Geothermal Foundation Subjected to Temperature Cycling |
| title_short |
Soil-Pile Interaction of Geothermal Foundation Subjected to Temperature Cycling |
| title_full |
Soil-Pile Interaction of Geothermal Foundation Subjected to Temperature Cycling |
| title_fullStr |
Soil-Pile Interaction of Geothermal Foundation Subjected to Temperature Cycling |
| title_full_unstemmed |
Soil-Pile Interaction of Geothermal Foundation Subjected to Temperature Cycling |
| title_sort |
soil-pile interaction of geothermal foundation subjected to temperature cycling |
| publisher |
University of Akron / OhioLINK |
| publishDate |
2019 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=akron1563974820049641 |
| work_keys_str_mv |
AT huseindimaa soilpileinteractionofgeothermalfoundationsubjectedtotemperaturecycling |
| _version_ |
1719456000706084864 |