It is necessary to establish the energy conservation equation to research the thermodynamical properties of unsaturated soil; the determination of two representative parameters (volumetric specific parameter and thermal conductive parameter) of fundamental physico-mechanical parameters is a key factor to obtain the results of the energy conservation equation. The effective thermal conductive coefficients of dry soil grain are analyzed for different composition geomaterials; and the thermodynamical properties of porous media with water and gas are researched; the comparative analyses of different calculation methods of thermal conductive coefficient have been conducted; an available calculating method is proposed to determine the thermodynamical parameters; the comparisons among the results of the proposed method

the volumetric average method

the self consist method

the Hashin-Strikman method have been made; the proposed method is of the good agreement with the testing result; and it fits to describe the main properties of thermal mechanical conductivity.