关键词: 能量桩, 现浇混凝土大直径管桩（PCC桩）, 循环温度场, 热-力耦合, 模型试验

Abstract: PCC energy pile is based on one of new type energy pile technology methods developed by Geotechnical Engineering Institute of Hohai University. On the basis of traditional static load test of pile, PCC energy piles are embedded into Nanjing typical sand. Thermal field of model pile is simulated through water circulation in the cyclic pipe. The characteristic and mechanism of bearing capacity of PCC energy pile in operation are studied. The PCC energy pile is firstly loaded to the working load (half of the ultimate load) and then the heating and cooling cycle is applied. After that the model pile is loaded to the ultimate load. The curves of load-displacement and stress-strain of pile shaft under different temperatures are measured. The results show that the heat can easily transfer from pile to soil (summer mode). The displacement of pile top changes obviously during heating and cooling cycles. The change of temperature brings plastic deformation in the soil, which can harm the upper structure. The thermal stress in the PCC pile caused by temperature field is relatively large. The change of thermal stress is different under different constraint conditions. Under cooling cycle, tensile strain even appears on the bottom of pile.

Key words: energy pile, cast-in-place concrete large diameter pipe pile (PCC pile), cyclic temperature field, thermomechanical coupling, model test