饱和砂土地基相变桩的热力学特性试验研究

能源桩是一种新型的能源地下结构,相变材料能够改变自身状态来提供潜热。制作相变混凝土能源桩来实施室内大尺寸模型试验,将直径为0.2 m,长度为1.5 m的相变能源桩放入长宽高分别为2.45 m×2.45 m×2 m的模型箱中,模型箱中为饱和砂土地基。随后对能源桩施加三次循环温度荷载,测量桩体内部以及桩周土体温度的分布,并对相变能源桩的力学特性进行监测和分析,研究了循环温度荷载下相变能源桩的应力应变以及桩顶位移。研究结果表明:① 能源桩在循环温度荷载作用下产生的温度变化会给桩周土体带来一定的温度累积;② 沿桩身深度方向及桩体内部同一平面内都存在着不均匀的应力应变分布;③ 桩顶位移随温度循环过程变化,温度循环结束后会产生不可恢复的塑性位移。

Investigation on Thermo-mechanical Characteristics of Phase Change-Pile in Saturated Sand Foundation by Model Tests

Energy pile is a new type of energy underground structure. Phase change material can change its state to provide latent heat. Concrete pile with phase change material was used for a large scale model test. The phase change energy pile with a diameter of 0.2 m and a length of--1.5- m was placed in a model box with a size of 2.45 m×2.45 m×2 m. The box was filled with saturated sand. Then the cyclic temperature load was applied to the energy pile, the temperature inside the pile and of the soil around the pile is measured, and the mechanical properties of the phase change energy pile, including the stress and strain and pile head displacement under cyclic temperature load, are monitored and analyzed, The results show that: (1) The temperature change of energy pile under the cyclic temperature load leads to a certain temperature accumulation in the soil around the pile; (2) Inhomogeneous stress and strain along the depth direction of the pile body and in the same cross section inside the pile body are observed; (3) The displacement of the pile changes during the temperature cycles and produces an unrecoverable plastic displacement at the end of the temperature cycles.