Investigation of Soil–Structure Interface Properties under Temperature Cycles and Different Operation Time of a Ground Source Heat Pump
Publication: IFCEE 2021
ABSTRACT
Geothermal deep foundations (energy piles) are used for heating and cooling of buildings. The intermittent operation of the ground source heat pumps (GSHP) connected to energy pile subjects the soil–pile interface and the surrounding soil to cyclic temperature changes affecting soil–pile interaction and shaft resistance of the pile. To evaluate the effects of cyclic thermal loading on the soil–pile interface properties and effect of temperature cycles on pore water pressure, a fully automated modified thermal-borehole shear test (Modified-TBST) device was utilized to perform tests in saturated normally consolidated clayey soil. In addition to directly measuring the shear stress-vertical displacement curves (t–z curves), the soil temperature at different locations and the pore water pressure were monitored. The fully automated Modified-TBST device uses two concrete plates to simulate the pile surface with temperature and expansion/contraction controls. A series of tests were conducted to evaluate the effects of intermittent operation times for temperature change (ΔT = 10°C) and temperature cycles (N = 10 heating cycles). It was observed that the operation time of the GSHPs connected to energy piles has significant effects on thermally induced pore water pressure when installed in saturated clayey soil.
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IFCEE 2021
Pages: 567 - 575
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© 2021 American Society of Civil Engineers.
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Published online: May 6, 2021
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