能量桩是一种在承载上部建筑荷载的同时获取地热能源的新技术。但目前对于能量桩在冷、热循环过程中尤其多次冷、热循环情况下的热力学效应研究较少。基于模型试验方法，针对预埋钢管单U型新型能量桩，开展工作荷载作用下多次冷、热循环时的传热特性和承载特性，尤其是桩顶位移变化规律的研究；并开展无荷载作用下单次冷、热循环试验进行分析。试验结果表明，冷、热循环引起的桩体热应变，在加热时桩体内部产生压应力，而在制冷时桩体内部产生拉应力，同时温度引起桩侧不同部位分别产生正摩阻力和负摩阻力。相较于工作荷载，无荷载作用下加热会使桩体位移上升约41%，而一次加热与制冷循环作用后，无荷载作用下桩顶残余位移约为工作荷载作用下的10%。多次冷、热温度循环会导致桩体沉降不断积累。

Energy pile is a new technology which supports the upper building load and extracts geothermal energy from its surrounding simultaneously. However, there is only little research available on the thermal-mechanical behavior of the piles subject to heating-cooling cycles and particularly repeated cycles. Model tests are carried out to examine the heat transfer performance and bearing characteristics of energy pile with embedded steel tube under working loading conditions over repeated temperature cycling, and especially the law of pile head displacement. Moreover, the displacement is also observed and analyzed under no load over one cycle of heating and cooling for comparative analysis. The results show that the heating-cooling cycles produce thermal strain in the pile shaft, heating generates compressive stress and cooling induces the tensile stress. Meanwhile, the positive and negative frictions are yielded in different parts of the pile side due to temperature. The upward displacement magnitude of pile top under no working load is 41% greater than that under working load, but the final displacement of pile top is approximately 10% of that under working load after one heating-cooling cycle. The repeated temperature cycling can lead to continuous accumulation of settlement.