Study On The Water-temperature-salt Coupling Effect On The Thermal Properties Of Red Clay

This paper selects two kinds of representative red clay in Guangxi as the main research object,its thermal properties for research purposes,through thermal test,comprehensively reveal the soil thermal conductivity and volumetric heat capacity and the thermal diffusivity with water content changes,and respectively used Johanson formula,Kersten formula and IPCHT model to simulate the state of normal and high temperature.The main research results were as follows:1.The results show that the change of water content in the soil is the same as that of the two kinds of red clay under different volume and water content.Under the same dry density,with the increase of volume water content,Thermal conductivity,volume specific heat capacity and thermal diffusivity are increased.2.through the different temperature of the two red clay thermal properties test,the soil thermal properties with the temperature changes in the law:In the case of constant dry density and volume water content,the thermal conductivity of soil increases with the increase of temperature(5~60?),and the growth slope decreases with the increase of water content,even at high temperature(60~90?)a critical water content after a negative value,this time the soil water vaporization phenomenon,thus affecting the soil thermal conductivity.3.through the different salt concentration of two red clay thermal properties test,the soil thermal properties with salt(NaCl)solution concentration changes in the law:In the case of the same dry density,the salt concentration in the case of lower volume water content has little effect on the thermal conductivity of the soil,with the gradual increase of water content,the thermal conductivity of soil decreases with the increase of salt concentration,however,the thermal conductivity of soil increased with the increase of salt concentration after a critical water content(0.21cm~3/cm~3 in Guilin red clay and 0.29 cm~3/cm~3 in Liuzhou red clay).4.Based on the theory of double electric layer,the double electric layer thickness of two kinds of red clay in Guilin and Liuzhou were tested by means of water vapor isothermal adsorption test.On this basis,the law of thermal conductivity of red clay with water,heat and salt was explained.with the increase in water content,soil particles combined with the thickness of the water film also increases.the temperature has some influence on the thermal movement of water molecules.The temperature increases the partial permeation combined with water into free water,which improves the heat transfer efficiency.the presence of Na~+decreases the thickness of the bound water film on the surface of the soil particles,resulting in a decrease in the heat transfer channel and a decrease in the thermal conductivity of the red clay.5.The simulation results show that,the measured values of the two red clays fall within±30%of the predicted Johanson formula,the measured value of Guilin red clay falls within±30%of the calculated value of the Kersten formula.the IPCHT model modified by the mass enhancement factor can better simulate the weak development of Liuzhou red clay,but for the development of aggregates in Guilin red clay prediction results are a large deviation.Therefore,the IPCHT model does not well reflect the specific structure of the aggregates within the developmental medium.