Comparisons on the response of shallow geothermal energy pile embedded in soft and firm soils

Abstract

Shallow geothermal energy pile, particularly the one used in tropical countries, is a sustainable geostructure system that transforms the soil surrounding the geostructure as a heat sink, for building cooling purposes. Thermal loads stored in the soil will cause thermally induced settlement. A series of laboratory tests were performed to study the behaviour of model energy piles installed in kaolin soil with soft and firm consistencies. Twelve tests which included thermal load tests (35˚C and 40˚C) and thermo-axial load tests (100 N and 200 N, combined with thermal loads) were performed. The pile response to thermal and thermo-axial loads were attributed to the soil consistency and the magnitude of the loads applied to the pile head. Firm soils produce lower thermally induced settlement, due to higher level of restraint compared to soft soils. To ensure that the thermo-axial settlement does not exceed the limiting settlement, the recommended global factor of safety used for soft soil and firm soils subjected to 40˚C thermal load should be more than 4.0 and 2.5, respectively.