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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 to obtain geothermal energy while bearing the load of the upper part of the building. However, there are few researches on the thermodynamic effect of the energy pile in the cold and thermal cycles, especially in the case of thermal cycling. Based on the model test method, the heat transfer characteristics and bearing characteristics of the single U-shaped steel tubular pile subjected to multiple cooling and thermal cycles under the action of working load are studied. The displacement variation of pile top is studied. Under the effect of a single cold, thermal cycling test analysis. The experimental results show that the thermal strain of the pile caused by cold and heat cycles produces compressive stress in the pile body during heating and the tensile stress in the pile body during cooling. At the same time, the temperature causes the positive friction and the negative friction in different parts of the pile Friction resistance. Compared with the working load, the displacement of the pile increases by 41% when heated without load, while the residual displacement of the pile top under no load is about 10% under the working load after a heating and refrigeration cycle. Repeated cold and hot temperature cycle will lead to the accumulation of pile settlement.