饱和砂土地基中碳化硅能源桩的传热特性测试与分析

Test and analysis of heat transfer characteristics of silicon carbide energy piles in saturated sandy soil foundations

采用标准试块测试与模型试验,对碳化硅能源桩的传热特性进行研究。通过桩基混凝土试块导热系数和力学性能测试,确定碳化硅能源桩的桩身材料配合比;通过饱和砂土地基中能源桩高温释热工况模型试验,分析饱和砂土地基中碳化硅能源桩的传热性能以及轴向和径向温度分布及变化规律。结果表明:碳化硅代砂率达到16.0%时,桩基混凝土试块的导热系数、抗压强度以及抗折强度会分别提升64.1%、19.9%和11.4%,该代砂率下的碳化硅能源桩桩身材料配合比为最佳配合比。碳化硅能源桩的最高温度出现在桩体中部。相较于普通能源桩,碳化硅能源桩具有更高的桩体温度、温度增长速率和换热功率,表现出更优的传热性能。在碳化硅能源桩进行热循环时,桩土间的热量传递效率自桩身向外沿径向递减;热循环后,桩周土体呈现热量堆积现象,且这种现象随着接近桩身区域而逐渐增强。研究结果可为碳化硅能源桩的设计及其在饱和砂土地基中的应用提供试验依据。

Based on standardized specimen blocks and model experimental tests,heat transfer characteristics of silicon carbide energy piles were investigated.The pile body material ratio of silicon carbide energy piles was determined through the test of thermal conductivity and mechanical properties of pile concrete specimen.Through the high-temperature heat release working condition model test of energy piles in saturated sand foundations,the heat transfer performance of silicon carbide energy piles in saturated sand foundations,as well as the axial-radial temperature distribution and change rule were analyzed.The results show that the thermal conductivity compressive strength and flexural strength of the concrete specimen of pile base are increased by 64.1%,19.9%and 11.4%,respectively when the sand substitution rate of silicon carbide reaches 16.0%,and the ratio of this sand substitution rate is the optimal ratio for the material of the pile body of silicon carbide energy piles.The highest temperature of the silicon carbide energy piles occurs in the middle of the pile body.Compared with ordinary energy piles,the silicon carbide energy piles have higher pile body temperatures,temperature growth rates,and heat transfer power,and show better heat transfer performance.The heat transfer efficiency between pile and soil decreases radially from the pile body to the outside during thermal cycling of the silicon carbide energy piles;after thermal cycling,the soil around the pile shows the phenomenon of heat accumulation,and this phenomenon is gradually strengthened with the approach to the pile body region.The results of the study are expected to provide a test basis for the design and application of silicon carbide energy piles in saturated sandy soil foundations.