Model tests on thermo-mechanical behavior of an improved energy pile

Energy piles are now considered as an efficient energy solution for heating and cooling buildings. However, once the energy pile has a breakdown especially of the heat exchange elements, it is difficult to be repaired. Thus, a new design of energy piles with embedded steel tubes instead of two longitudinal bars is introduced. Heat exchange pipes were placed into the embedded steel tubes, instead of being attached to reinforcing cages, for the purpose of decreasing the damage to the pipes. Model tests on a conventional energy pile and an improved energy pile with and without a mechanical load were conducted in saturated sand. The thermo-mechanical behaviour of the two piles was comparatively analysed when heating and cooling. In the tests, pile temperature, soil temperature, horizontal earth pressure, strain and pile head displacement were all measured at different stages. Based on these measurements, thermal stress and mobilised side shear stress were studied to comprehensively evaluate the performance of...