间歇与持续加热下含承台能量桩基础现场试验  

Field thermal response test of energy pile foundation with cap under intermittent and continuous heating

作　　者：陈玉 孔纲强 孟永东[1] 王乐华[1] 刘红程[1] CHEN Yu;KONG Gangqiang;MENG Yongdong;WANG Lehua;LIU Hongcheng(Key Laboratory of Geological Hazards on Three Gorges Reservoir Area of Ministry of Education,China Three Gorges University,Yichang 443002,Hubei Province,P.R.China;Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210098,Jiangsu Province,P.R.China)

机构地区：[1]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002 [2]河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京210098

出　　处：《深圳大学学报（理工版）》2022年第1期75-84,共10页Journal of Shenzhen University(Science and Engineering)

基　　金：国家自然科学基金资助项目(51922037)。

摘　　要：能量桩基础兼具承担上部荷载和浅层地温能利用的双重功能,基础埋深条件和运行模式对能量桩的换热性能及热力响应均有一定影响.依托中国三峡大学水科学与工程楼桩基础工程,针对3.0 m埋深条件下含承台能量桩基础,开展时长各16 d的两组现场对比试验,每日对应的运行模式分别为16 h加热-8 h自冷的间歇循环加热(IH-16)和持续24 h加热(CH-24),实测能量桩及承台的温度、热致应变等的变化.结果表明,该试验条件下,CH-24和IH-16试验加热稳定阶段的换热效率值分别约为5.32 kW和5.38 kW,中性点均出现在距桩顶0.78倍桩长处,桩顶位移分别为0.38 mm及0.19 mm,对应的桩身平均温度升幅分别为8.9℃和4.7℃,热扰动范围约1.7 m;CH-24试验桩身最大约束应力为-3.01 MPa,比IH-16试验的最大约束应力-1.68 MPa提升了79%. IH-16试验在非运行对角桩对应的承台部位产生了约1.75 MPa的附加拉应力,约为C40混凝土抗拉强度值的73.2%.两组运行模式下承台均出现了细微的差异变形,在设计运行时应予以考虑.Energy pile foundation has dual functions of bearing capacity and the utilization of shallow geothermal energy,the depth of foundation and operation modes have a certain impact on the heat transfer performance of the energy pile. Relying on the energy pile foundation with cap under the condition of 3.0 m buried depth,which belongs to the Hydraulic and Engineering Building of China Three Gorges University(Yichang city,Hubei province),two series of field thermal response tests are conducted with 16-day test duration,the operation modes are 16 h heating-8 h self-cooling intermittent heating process(IH-16)and continuous 24 h heating process(CH-24),respectively. The temperature,thermal induced strain of energy piles and cap are measured. The heat transfer efficiency values in the stable heating stage under CH-24 and IH-16 heating modes are about 5.32 kW and 5.38 kW,respectively. The neutral points of both CH-24 and IH-16 test conditions are appeared at 0.78 times the length of the pile from pile top,resulting in pile top displacements of 0.38 mm and 0.19 mm,the average temperature rise of the pile body is 8.9 ℃ and 4.7 ℃,respectively;and the thermal disturbance range is about 1.7 m. The maximum constraint stress of pile body under CH-24 test condition is-3.01 MPa,which is 79% higher than that under IH-16 mode of -1.68 MPa. The IH-16 test produced an additional tensile stress of about 1.75 MPa at the position of the cap corresponding to the non-operating diagonal pile,which was about 73.2% of the C40 concrete tensile strength value.There were slight deformation differences in the cap under both two operating modes,which should be considered during design and operation.

关 键 词：岩土工程 能量桩 基础埋深 间歇循环加热 热力学响应 现场试验 

分 类 号：TU443[建筑科学—岩土工程]