Measurement and prediction of temperature effects of thermal conductivity of soils

 Currently, there is an extreme deficiency of complete data of thermal conductivity of soils under high temperature around the world, tests are thus conducted through KD2 Pro on the silty clay loam and fine sand within a wide range of temperatures (5 ℃～ 88 ℃ ) and water contents. The results indicate that the thermal conductivity under 88 ℃ is 3 or 4 times as high as that under 5 ℃ due to the latent heat transfer effect caused by condensation and evaporation of vapor. The critical water content, which depends on texture, exists as thermal conductivity changes with the water content. According to the verification and comparison of de V-1 and Campbell theoretical models from de Vries’s hypothesis, improvements are needed on some parameters and the applicability of achieving them in the references. However, the modified models can comparatively better predict the change of the thermal conductivity under different temperatures (RMSE ＜ 30%). The closer to 40 ℃ , the lower the error. It is suggested that a mass transfer enhancement factor of 2.5 should be multiplied under 58 ℃～ 88 ℃ within θ_AWC ～ θ _PWP for silty clay loam. Judged by the complexity of these two models, the more convenient empirical models are expected to be established based on this foundation.