土体温度场物理模拟用土的制备方法研究

为提高冻土模型试验对现场实际的反映程度,基于模型与原型之间的相似关系,提出了一种制备热学参数满足相似原理的模型土方法。首先,根据傅里叶方程、第三边界条件和相似理论推导出了土体冻结过程中热学参数相似准则,并依照Johansen的导热系数广义几何平均计算方法列出了模型土应满足的3个方程。在此基础上,选用高密度聚乙烯、标准砂、活性炭粉制备模型土并模拟了天津地区某粉质黏土冻结过程温度变化。根据高密度聚乙烯、标准砂、活性炭粉和天津地区粉质黏土的导热系数、比热和密度实测值,结合模型土的三个配比方程确定了模型土的相态组成。分别将配制好的模型土以及粉质黏土用于模型试验和原型试验,并将实测温度值进行了对比,验证了模型土配置方法的有效性。 该研究对于冻土温度场的跨尺度预测具有借鉴意义。

Study on the Preparation Method of Soil for the Physical Simulation of Soil Temperature Field

In order to improve the accuracy of frozen soil model test, a method of preparing model soil with thermal parameters satisfying the similarity principle is proposed based on the similar relationship between the model and prototype. According to Fourier equation, the third boundary condition and the similarity theory, the similarity criterion of thermal parameters in soil freezing process is deduced. According to Johansen's generalized geometric average calculation method of thermal conductivity, three equations that should be satisfied by the model soil are listed. High-density polyethylene, standard sand and activated carbon powder were used to prepare model soil, and the temperature variation of silty clay during freezing process was simulated. According to the measured values of thermal conductivity, specific heat and density of high-density polyethylene, standard sand, activated carbon powder and silty clay in Tianjin area, combined with the three equations of model soil, the contents of three components of model soil were obtained. The prepared model soil and silty clay were used for model test and prototype test. By comparing the measured temperature values of the two tests, the effectiveness of the model soil preparation method is verified. The study has reference significance for the cross-scale prediction of frozen soil temperature field.