Thermo-mechanical behavior of energy pile under different climatic conditions

The thermal-mechanical behavior of the energy pile under three kinds of climatic conditions was investigated in this study. A small-scale floating energy pile and a small-scale end-bearing energy pile, which were embedded in normally consolidated clay, were employed. The energy piles were subjected to cyclic heating/cooling, heating/recovery and cooling/recovery to simulate the energy pile work in the regions of warm/cold balanced climate, warm-dominated climate and cold-dominated climate, respectively. The thermal response and the mechanical response of the energy pile under different climatic conditions, as well as the different response between the floating energy pile and the end-bearing energy pile, were analyzed and discussed comprehensively. The results show that the thermo-mechanical performance of energy pile depends on the types of climatic conditions, and the behavior of the floating energy pile is different from the end-bearing pile. Larger irreversible displacement could be induced by thermal cycles for the floating energy pile compared to the end-bearing energy pile, while irreversible tip resistance could be induced for end-bearing energy pile. Under warm/cold balanced climate, the largest irreversible tip resistance and pile displacement could be induced for end-bearing energy pile and floating energy pile, respectively, and the smallest thermally induced irreversible displacement was observed when the energy pile was under cold-dominated climate.