Experimental study and modelling of the thermal conductivity of frozen sandy soil at different water contents

Abstract

In a wide range of earthworks and engineering applications such as ground heat exchanger piles and energy piles, radioactive waste disposal in deep underground locations, installation of underground power cables, etc., a better understanding of soil thermal conductivity is required in cold regions. The thermal conductivity (lambda) of frozen sandy soils in eastern Turkey was measured for five volumetric water contents (theta = 0.219, 0.230, 0.246, 0.260, and 0.320 m(3)/m(3)) at six frozen temperatures (Tf = 4, 0, -7, -12, -20 and -25 degrees C). Moreover, six proposed models were analyzed to determine the lambda. The results demonstrated that a decrease in the Tf increased the lambda and reached a plateau at a very low Tf for all theta. Increasing the theta increases the lambda at the same Tf. Also, the de Vries model provided for the highest precision, followed by the Chen, the Parallel, the Johansen, the Cote and Konrad, and the serial models, respectively. Further, the changes of volume in the soil were incorporated into the parallel and series models, and a new model was developed to estimate the lambda of the frozen soil. The new model can be effectively used to estimate the lambda.