Bearing Performance of Geothermal Energy Pile Subjected to Thermal Loading

Abstract

As a kind of Ground Source Heat Pump (GSHP), geothermal energy piles is the economic, stable, efficient, and environmentally friendly way of cooling and heating building. Though the usage of geothermal energy piles has rapidly increased in the past three decades, there is so far limited understanding of their thermo-mechanical performance, and its application is earlier than theoretical investigation. Based on four published research findings, the bearing capacity and the mobilized shaft resistance of pile under thermal loading are analyzed. When geothermal energy pile (GEP) is heated, its bearing capacity will be increased, and the friction resistance of the upper section will be decreased. At the same time, friction resistance of the lower section is increased, and the axial force along pile will be enlarged. Whilst geothermal energy pile is cooled, friction resistance of the upper section will be increased, and that of the low pile is decreased. The mobilized strain, stress and shaft resistance profile are related to the constraint condition of pile ends. There is even tensile stress in pile under the special case with cooling load, which is adverse to its bearing capacity. The results is reference to design geothermal energy pile under similar circumstance.