# Experimental and Theoretical Study of the Influence of Saline Soils on Frozen Wall Formation
## 2 Experimental Study on the Effect of Salinity on Soil Thermophysical Properties
### Results and Processing of Experimental Measurements  
Table 1 shows the measured density of the wet soils and the specific heat capacity of the dry skeleton. Table 2 shows the dependence of the freezing temperature of the porewater with different levels of NaCl content in units of g/100 g of moisture. (Hereafter, \"NaCl content\" is replaced with \"salinity\"). In Tables 1 and 2, clay parameters are presented only for one value of water content: 0.26 kg/kg. These parameters appear to be the most interesting from the point of view of comparative analysis with the thermophysical properties of chalk, which has nearly the same water content: 0.25 kg/kg. The results of  
the experimental measurements of clay parameters with other water content values can be found in [7]. The obtained experimental dependencies for the freezing temperatures of the porewater were approximated by a linear dependence (see Figure 2). It should be noted that, in general, the freezing temperature of water may depend nonlinearly on salinity [27]. However, subsequently, the numerical simulation of the heat and mass transfer in the saline soils was implemented with salinity values in the range of 0.01 g/100 g to 13.8 g/100 g. For this range, the error of the linear approximation relative to the nonlinear one, according to the data from [27], was about 0.2 \({}^{\circ}\)C, which can be considered insignificant. \begin{table}
\begin{tabular}{c c c} \hline
**Soil** & **Soil Density (kg/m\({}^{3}\))** & **Specific Heat Capacity of Dry Skeleton (J/(kg-\({}^{\circ}\)C))** \\ \hline
**Clay** & 2070 & 757 \\ \hline
**Chalk** & 1985 & 798 \\ \hline
**Sand** & 1730 & 692 \\ \hline \end{tabular}
\end{table} 
Table 1: Experimental measurements of soil density and specific heat capacity of dry skeleton. \begin{table}
\begin{tabular}{c c c c} \hline
**Soil** & **NaCl (g/100 g)** & **Moisture (kg/kg)** & **Freezing Temperature (\({}^{\circ}\)C)** \\ \hline \multirow{3}{*}{**Clay**} & 0.00 & & \(-\)0.23 \\ \cline{2-4}  & 3.46 & 0.26 & \(-\)2.55 \\ \cline{2-4}  & 6.90 & & \(-\)5.00 \\ \hline \multirow{3}{*}{**Chalk**} & 0.00 & & \(-\)0.30 \\ \cline{2-4}  & 3.46 & 0.25 & \(-\)2.31 \\ \cline{2-4}  & 6.90 & & \(-\)4.51 \\ \hline \multirow{2}{*}{**Sand**} & 0.00 & & \(-\)0.09 \\ \cline{2-4}  & 5.20 & 0.11 & \(-\)3.59 \\ \hline \end{tabular}
\end{table} 
Table 2: Experimental measurements of the dependence of the freezing temperature of porewater on the NaCl content. Figure 2: Dependence of the freezing temperature of porewater on salinity. (Experimental measurements are indicated by dots.) Table 3 shows the results of the experimental measurements of the dependence of the unfrozen water content on temperature and salinity, and Table 4 shows the results for the measurements of thermal conductivity. The functional dependence of the unfrozen water on temperature and salinity is given by a well-known empirical dependence [28; 29]:  
\[\gamma=\left[1+\left(\frac{T_{\mathit{I}iq}-T}{\omega}\right)^{\frac{1}{1-m}} \right]^{-m} \tag{7}\]