双U型埋管能源桩桩周岩土体温度场分布特征试验研究

Experimental analysis of ground temperature distribution of double-U type energy piles

以信阳地区两根相邻的双U型埋管能源桩为研究对象,通过较长时间的TRT增温测试地温恢复TPT制冷测试模拟了能源桩的间歇性运行状态,在能源桩桩壁和岩土体中埋设传感器实测获得了能源桩运行过程中的桩周岩土体温度场分布。研究成果显示,能源桩运行过程中的传热表现为三维传热特征,桩端岩土体的温度变化滞后于桩体中间区域岩土体,建议能源桩设计时在桩端部位适当增加埋管量,以提高能源桩的换热效率;测试结果显示在经过172h的TRT测试并进行约25d的地温恢复后,桩周岩土体温度整体升高了约1℃,验证了岩土体温度扩散的缓慢性及其具有良好的热储性,同时也预示了地源热泵运行过程中存在冷热失衡的可能性。

Two double U-type buried tube energy piles in Xinyang region were investiguted.Long time TRT tests and temperature recovery-TPT test are conducted to simulate the operating state of energy piles under intermittent conditions.Sensors are prepared in the energy pile wall and soil,the distribution of temperature field during the operation of energy piles is measured.？The research results show energy piles in the operating process of heat transfer performs three-dimensional characteristics,the soil temperature in pile end position changes lag to the middle region of the pile body.It is hence suggested that the increace of the buried pipe in pile end position could increase energy pile heat exchange efficiency.The test results show the temperature of the soil around the pile is increased about 1℃after temperature recovery about 25 days after the 172 hTRT,verifying the slow conduction and good heat storage of the rock and soil body.At the same time,the importance of the cold and heat imbalance of the ground source heat pump system is also predicted.