Modified Côté-Konrad model for describing relationship between thermal conductivity and water content of coral calcareous sand

The artificial freezing construction process is determined through the thermal properties of coral calcareous sand in the South China Sea, however, the heat transfer among calcareous sand particles is still unclear. The classic Côté-Konrad (CK) model is difficult to be directly used in calcareous sand because of the irregular shape, high angularity and long heat transfer path among particles. To fill this gap, a relative particle evaluation parameter ($\mu$) is defined, and a modified CK (MCK) model is established with consideration of $\mu$. The MCK model is used to describe the relationship between water content and thermal conductivity in unfrozen calcareous sand. A serious of laboratory tests are conducted to verify the MCK model. The results indicate that the mean absolute error, root mean square error and mean absolute percentage error are 0.098 W/m℃, 0.011 W/m℃ and about 10%, respectively, which are much less than those of CK model (0.286 W/m℃, 0.098 W/m℃ and 40%). In the frozen calcareous sand, the CK model is still applicable because ice can fill the surface pores of solid particles and enhance connectivity, which reduces the influences of particle shape on thermal conductivity.