|
Model | Advantages | Disadvantages | Comments |
Kersten (1949) | Simple formula; for every type of soil | Equations do not take into account the quartz content which has the largest contribution in overall value of λ | Thermal conductivity in dry state cannot be determined |
Johansen (1975) | Can be used for frozen soils; relatively high quality of prediction; for every type of soil | Possible inaccuracy for dry soil (±20%) | Empirical relations valid for Sr>0.05 (coarse-grained soil) and Sr>0.01 (fine-grained soil) |
Donazzi et al. (1979) | Simple formula; for every type of soil | Weak prediction for soils with low water content | The shape of the λ − Sr curve does not fully comply with the test results and with most other models presented in literature |
Côté and Konrad (2005b) | For every type of soil; includes the type of soil and the shape of grains | The course of the Ke − Sr curve is not entirely consistent with common knowledge for fine-grained soils with low water content | Modification of the Johansen method (1975) with respect to the Kersten number and dry soil conductivity |
Lu et al. (2007) | For every type of soil; very good reflection of thermal conductivity for fine-grained soils with very low water content; the type of soil is taken into account | Unknown influence of the type of soil on the conductivity in the dry state | Modification of the Johansen method with respect to the Kersten number and dry soil conductivity |
Chen (2008) | Simple formula; good quality of prediction | Limited applicability | Only for sands with a high quartz content |
Lu et al. (2014) | Simple formula; for every type of soil; includes the effect of the dry density on thermal conductivity | For the analysed soils, the model clearly overestimated the values of λ in the entire range of water content | Dry soil conductivity should be computed using empirical relation proposed in Lu et al. (2007); possible weaker prediction for soils with high content of sand separate |
He at al. (2017) | Simple formula; for every type of soil; good quality of prediction | Lack of correlation formulas for determining model parameters | Modification of the Johansen method with respect to the Kersten number |