Abstract: In recent years, the demand of exploiting and utilizing new resources is increasing significantly as the consumption of traditional energy resources increases. As a result, the study of thermal properties of geotechnical materials has drawn more attention because geothermal energy is a kind of clean, sustainable and renewable energy resource. Soil thermal property consists of thermal conductivity, thermal diffusivity and heat capacity. Thermal conductivity is the most important soil thermal property, and it not only determines the speed of heat conduction and temperature field in soils, but also is a primary design parameter for various kinds of geothermal heat pumps, geothermal energy piles and other geothermal related structures. The engineering background and research motivation of soil thermal conductivity is firstly introduced, and followed by the definition of soil thermal conductivity and the analysis of its influence factors including moisture content, density, mineral component, temperature, etc. Based on the literature review, the summary of soil thermal conductivity prediction models is also presented. Model assessments including the advantages, disadvantages and applicability of each model are also presented afterward. Finally, some recommendations and suggestions have been provided for future research regarding geothermal applications.

Key words: thermal conductivity, prediction model, research status, recommendations and suggestions