ON THE PREDICTION OF THE THERMAL CONDUCTIVITY OF SATURATED CLAYEY SOILS: EFFECT OF THE SPECIFIC SURFACE AREA

The models for predicting thermal conductivity of soils are usually sensitive to the chosen value of the soil solid conductivity.s. Existing approaches of estimating.s, in some cases, may lead to significant biases in predictions of overall thermal conductivities. It is postulated in the paper that the value of.s can be estimated using the information on the microstructural, intrinsic soil property, namely the specific surface area (SSA). The new model is validated against thirty-four laboratory measurements of thermal conductivity performed on silt and clay soils. For validation purposes five widely known models, predicting overall soil thermal conductivity, are used. The analyses are performed with the use of four different values of solid thermal conductivity. The best agreement between predicted and measured conductivities is obtained when the new model is incorporated into the Johansen's method, i. e. root mean square error (RMSE) and bias are 0.172 Wm(-1)K(-1) and -0.040 Wm(-1)K(-1), respectively.