长期循环温度下能源桩‑土热传播特性研究∗

开展了桩长 52.5 m、桩径 1.05 m 的能源桩?土热传导离心模型试验，揭示了三十个周期的冷热循环温度作用下能源桩?土传热规律，基于 ABAQUS 有限元数值模拟，建立了桩周土体温度场长期数值计算模型，并将其与离心模型试验结果进行了对比验证。结果表明：各循环温度区间变化模拟值与实测值整体波动具有很好的一致性，各周期内最大相对误差为 5.6%，整体误差较小，验证了模型的合理性；长期冷热循环温度作用下，能源桩整体运行效率存在降低趋势；桩端土体的温度变化滞后于桩体中部区域土体，因此在进行能源桩内管道布设时可以考虑桩端部分区域内适当加密，提高能源桩的换热性能；热循环阶段，模拟值变温区峰值高于实测变温区峰值，而在冷循环末期，模拟值较小，且距桩不同距离位置处实测值相对应的变温时间区间，相较模拟值变温区间均存在一定程度的后延，且循环周期越多时间区间后延效应越明显。

Study on the Heat Propagation Characteristics of Energy Pile‑Soil under Long‑Term Cycling Temperature

A centrifugal model test was conducted on an energy pile-soil heat conduction system, featuring a pile length of 52.5 meters and a pile diameter of 1.05 meters. This study investigated the heat transfer patterns between the energy pile and the surrounding soil over 30 cycles of cold and hot temperature. A long-term numerical model for the temperature field around the pile was established using ABAQUS finite element simulations and validated against centrifugal model test results. The following conclusions were drawn: the simulated temperature variations within each cycle closely matched the measured values, exhibiting consistent overall fluctuations and a maximum relative error of 5.6%, confirming the model''s accuracy. The overall operational efficiency of the energy pile showed a declining trend under long-term thermal cycling. Temperature changes in the soil at the pile end lagged behind those in the soil at the mid-section of the pile. To enhance the heat exchange performance of the energy pile, it was suggested to increase the density of the pipeline layout within the pile end area. During the heating stage of the thermal cycling, the peak temperature in the simulated variable temperature zone was higher than the measured peak temperature. Conversely, at the end of the cold cycle, the simulated values were lower. Additionally, the measured temperature variation time intervals at different distances from the pile lagged behind the simulated time intervals. This lag effect became more pronounced with an increasing number of cycles.