Abstract: The thermal conductivity of the soil is an important index for developing the shallow geothermal energy, the accuracy of its numerical value has a great influence on the utilization efficiency of the ground source heat pump. The freeze-thaw action has also the influence on the thermal conductivity of frozen soil in the seasonal frozen soil region. The study on the variation of the geothermal energy has a good reference value for the utilization of the shallow geothermal energy in the seasonal frozen soil region. This paper introduces some basic characteristics of the frozen soil in Changchun area. By analyzing the mechanism of the variation of the thermal conductivity of the frozen soil and combining the relevant experimental data, the basic characteristics that the thermal conductivity of the frozen soil will gradually decrease under the freeze-thaw action are finally determined. Based on the experimental results, the main factors that affecting the thermal conductivity of the frozen soil are determined by the moisture content, plasticity index and void ratio. The main factors that affecting the thermal conductivity of the frozen soil are preliminarily determined. According to the characteristics of the seasonal frozen soil in Changchun area, some reasonable suggestions on the use of the ground-source heat pump in this area are also proposed.

Key words: Freeze-Thaw Action, Frozen Soils, Thermal Conductivity