Abstract: Thermal property is one of the basic physical properties of rock and soil, and it is widely used to evaluate the retention, conduction and distribution of the heat. Thermal conductivity, specific heat capacity and thermal conductivity are the most common parameters, and they are also used in geothermal energy management and development, engineering freezing excavation and construction design in cold areas. The existing studies have shown that soil thermal parameters are associate to some factors such as the soil types, source, water content, density. In this study, the thermal parameters of silty clay and clay at a construction site in Zhanjiang, Guangdong province were tested. The results show that with increasing water contents, the thermal conductivity and thermal diffusivity of silty clay increase to a maximum value and then decrease, while the specific heat capacity increases linearly. The effect of dry density on thermal conductivity of silty clay depends on the moisture. When the water content is less than 20.0%, the thermal conductivity increases with the increase of dry density, while the water content is over 27.5%, it decreases with the increase of dry density. At the water content of about 24.5% (liquid limit), there is no law to follow. The effect of dry density on thermal diffusivity of silty clay is not obvious. Both the thermal conductivity and specific heat capacity of clay increase with the increase of water content and dry density. As the water content increases, the thermal diffusivity increases nonlinearly until it is stable. Under a low water content, the dry density does not significantly affect the thermal diffusivity; however the thermal diffusivity increases firstly and then decreases with increasing dry densities under the high water content. In addition, it is also found that the existence of large particles can cause the thermal conductivity of silty clay to be more complicated than that of clay.

Key words: thermal conductivity, volume specific heat capacity, thermal diffusivity, moisture content, dry density