Centrifuge modelling of the effect of temperature on the capacity of novel thermal piles in clay

The HIPER™ pile is a novel cast in situ or precast hollow pile that reduces the amount of concrete normally required for a pile of a given capacity, facilitates reuse of foundations in the long term and can be used as a thermal pile. When used as a thermal pile the central cavity is filled with water in which the heat exchange pipes are placed. This ensures that exchange of heat with the surrounding ground is significantly more efficient than for a conventional solid concrete pile, both when the pile is being used for cooling and heating. A series of tests has been undertaken using a geotechnical centrifuge to investigate whether changing the temperature of the pile and surrounding soil affects the ultimate capacity and load displacement response of the pile. The soil used was Speswhite kaolin clay and the pile was heated and cooled by circulating water through the pile in flight. The temperature gradient in the soil and in the pile was monitored by temperature sensors. The paper will report the apparatus used and the results of the study.