EXPERIMENTAL STUDY ON VARIATION OF THERMAL CONDUCTIVITY OF RED CLAY AT HIGH TEMPERATURE

Currently, there is a lack of experimental study and model prediction of thermal conductivity of soil under high temperature around the world. Tests are conducted through KD2 Pro on two kinds of lateritic clay within a wide range of temperatures(5~90℃) and water contents. Meanwhile, the IPCHT model is chosen to predict the variation of the volumetric water content and thermal conductivity under high temperature. The results of test indicate that the sensitivity of the thermal conductivity on the two kinds of lateritic clay to the volumetric water content is related to the temperature. The thermal conductivity increases with the increase of temperature. The thermal conductivity under 90℃ is 3 or 4 times as high as that under 5℃. The change of thermal conductivity with volumetric water content has obvious critical water content under 60~90℃(correspond to the plasticity index of soil). However, the latent heat transfer effect of water vapor in the lateritic clay of Liuzhou is more obvious than that in the lateritic clay of Guilin under the same temperature and volumetric water content. The results of model fit show that the prediction results of IPCHT model are not ideal except for the silty clay loam, after modification of the mass transfer enhancement factor ξ. The simulated values of the thermal conductivity of lateritic clay in Liuzhou and fine sand are in good agreement with the measured values(RMSE < 30%). However, the overall prediction effect of the lateritic clay in Guilin is still not ideal.