Thermal conductivity of Toyoura sand at various moisture and stress conditions

Thermal conductivity of soils is a crucial characteristic in various geotechnical applications, such as geothermal pumps, energy piles and buried pipelines. Previous researchers have done extensive works on the factors that may affect the soil thermal conductivity, including soil porosity, degree of saturation, mineralogy, testing temperatures, particle size and gradation. A modified oedometer frame that can incorporate the transient heat probe method is adopted to investigate the influence of stress state on thermal conductivity of Toyoura sand. Preliminary test under 1-D compression shows that the thermal conductivity of sand increases with the rise of vertical stress, and the variation exhibits hysteresis during a loading and unloading cycle. In addition, the effects of void ratio and water content were also studied and test results agreed well with previous values reported in the literature.