Thermal characterization and prediction model of typical soils in Nanjing area of China

Abstract

The thermal resistivity of soil is a basic parameter to describe its heat transfer characteristic and also is a key parameter in analysis of soil heat transfer in geotechnical engineering. The thermal probe testing technology and its theory were introduced. Four different typical soils in Nanjing area were measured by non-steady-state probe. The relationship between the soil thermal resistivity and moisture content was analyzed at different dry densities. It could be concluded that the non-steady-state probe can effectively measure the thermal resistivity of soils. With an increase in both moisture content and dry density, the magnitude of thermal resistivity decreased. There is a dramatical decrease of thermal resistivity in the initial stages of adding water to the dry soil. The thermal resistivity decreases rapidly within moisture content in a relatively small range and then approach equilibrium with further increase in moisture content. The critical moisture content is a great importance index which depends on the natural properties of soils. Thermal resistivity decreases with the increase of dry density and particle size. This effect is also related to mineral composition, particle shape and other factors. Based on the existing prediction model and testing results, a new prediction model was proposed to predict the thermal resistivity of soils. The results indicate that the predicted values generally agreed with the measured values within an absolute difference of less than 15%.