Thermal conductivity is a key parameter for many soil applications, especially for dimensioning shallow and very shallow geothermal systems based on the possible heat extraction rate and for modelling heat transfer processes around high voltage underground cables. Due to the limited purview of direct thermal conductivity measurements, for an investigation of extensive areas, usually other geophysical methods like electrical resistivity tomography measurements are applied. To derive thermal conductivity of soil from geoelectrical measurements a relation between electrical and thermal conductivity is needed. Until now only few approaches worked on a direct correlation between both conductivities. Due to the difficulties of a direct relation, within this study a modular approach of a mediate correlation between electrical and thermal conductivity was investigated. Therefore, a direct relationship between a corrected electrical conductivity and water content as well as the standard and simple thermal conductivity model of Kersten (Bull of the Univ Minnesota 28:1–227, 1949) was used. To develop this concept soil types of sand, silt loam and clay were investigated where different saturation steps and pressure loads were applied. For each configuration electrical and thermal conductivity as well as water content and bulk density was determined. To refine the results of the calculated water content a corrective factor was applied. Furthermore, bulk density as an inlet parameter of the Kersten equation was also derived based on electrical conductivity. The suggested proceeding enables the determination of thermal conductivity solely based on electrical conductivity without prior soil property information.

中文翻译：

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土壤电导率与导热率之间的中介关系

导热系数是许多土壤应用的关键参数，尤其是根据可能的热量提取速率确定浅层和极浅层地热系统的尺寸以及对高压地下电缆周围的传热过程进行建模时。由于直接热导率测量的范围有限，为了研究广阔的区域，通常采用其他地球物理方法，例如电阻层析成像测量。为了从地电测量中得出土壤的热导率，需要电导率和热导率之间的关系。到目前为止，只有两种方法可以在两种电导率之间建立直接关联。由于直接关系的困难，在这项研究中，研究了电导率和导热率之间中介关系的模块化方法。因此，使用校正后的电导率和水含量之间的直接关系，以及Kersten的标准和简单的热导率模型（明尼苏达州牛市报28：1-227，1949年）。为了发展这个概念，研究了在不同的饱和步骤和压力载荷作用下的砂，粉壤土和粘土的土壤类型。对于每种配置，确定了电导率和导热率以及水含量和堆积密度。为了改进计算出的水含量的结果，应用了校正因子。此外，还基于电导率推导了堆积密度作为Kersten方程的入口参数。