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土壤导热率是重要的热参数之一,为了获得预测导热率的准确方法,该文对比分析了确定土壤导热率的热脉冲直接测定法和模型间接推求法。根据热脉冲原理在相同体积质量下,测定了不同质地和含水率土壤的导热率值。结果表明在相同含水率条件下,砂粒含量越高,土壤的导热率越大,土壤导热能力越强。利用Horton经验公式对实测值进行了拟合,结果显示Horton经验模型基本可以反映土壤导热率变化特征,并得到了Horton公式经验系数。利用实测值与Campbell模型计算值进行了比较,结果显示Campbell模型计算结果偏差较大,并对其进行了修正。并且用实测值与Johansen模型及其2种改进模型(Coté-Konrad模型和Lu-Ren模型)的计算值进行了对比分析,结果表明Johansen模型计算结果与实测值偏差较大,2种改进型模型的计算结果与实测值更接近。该研究表明土壤导热率可以利用土壤质地、含水率、孔隙度和体积质量进行计算,3种理论模型的计算值与实测值的相关系数均值分别为:0.643、0.937、0.943,推荐使用Coté-Konrad模型和Lu-Ren模型计算土壤导热率,Lu-Ren模型比Coté-Konrad模型的适用范围更广。
Soil thermal conductivity is one of the important thermal parameters. In order to get an accurate method of predicting the thermal conductivity, this paper comparatively analyzes the direct measurement of thermal conductivity and the indirect model in determining soil thermal conductivity. According to the theory of thermal pulse, the thermal conductivity of soils with different textures and moisture contents was measured under the same volumetric mass. The results show that under the same moisture content, the higher the content of sand, the greater the thermal conductivity of soil, the stronger the thermal conductivity of soil. Horton empirical formula was used to fit the measured data. The results show that the Horton empirical model can basically reflect the changing characteristics of soil thermal conductivity and obtain the empirical coefficient of Horton’s formula. Comparisons between the calculated results and Campbell model results show that the calculated results of Campbell model deviate greatly and their corrections are made. Compared with the Johansen model and its two improved models (Coté-Konrad model and Lu-Ren model), the measured values are compared with the measured values. The results show that the calculated results of Johansen model deviate from the measured values significantly. Two improved models The calculated result is closer to the measured value. The study shows that soil thermal conductivity can be calculated by soil texture, water cut, porosity and volumetric mass. The calculated correlations of the three theoretical models and the measured values are 0.643, 0.937 and 0.943, respectively. Coté-Konrad Model and the Lu-Ren model to calculate the soil thermal conductivity, the Lu-Ren model is more applicable than the Coté-Konrad model.