# Experimental and Theoretical Study of the Influence of Saline Soils on Frozen Wall Formation
## 4 Conclusions  
In the course of this work, laboratory and theoretical studies were implemented on the effects of porewater salinity on the artificial freezing of three soils: clay, chalk, and sand.  
Conducting laboratory studies made it possible to determine the dependencies of the freezing temperature of porewater, the unfrozen water content, the specific heat capacity, and the thermal conductivity on the salinity of the considered soils. The experimental data obtained were approximated using analytical functions known in the literature. The obtained dependencies were later used for theoretical research: the numerical simulation  
Figure 15: The dependence of the FW’s thickness on time for sand in the inner frozen zone (**a**) and in the outer frozen zone (**b**), and on the total thickness (**c**).  
of the AGF process for the conditions of the construction of the frozen wall around the designed mineshaft at a potash salt deposit.  
The analysis of the simulation results shows that, with an increase in the initial salinity, the temperature of the soil decreases because more saline soils contain a larger quantity of unfrozen water content (which was also shown by the simulation results), and, therefore, to lower their temperature by a given amount, less heat must be removed. However, this effect is less pronounced in clay. In addition, for all the soils under consideration, the opposite local effect was noted: at low values of initial salinity, the soil temperature increases. Since this effect manifests itself only at small initial salinities, we can discuss the insignificance of this effect.  
The dependence of the FW's thickness on the initial salinity was found. The thickness was calculated from the isotherm of the freezing temperature of the porewater. The obtained results show that, in the case of clay, a natural process occurs: an increase in initial salinity leads to a decrease in the FW's thickness since the water's freezing temperature decreases. In the case of both chalk and sand, it was found that, at certain values of initial salinity, the FW's thickness becomes independent of the initial salinity. However, with the continued increase in initial salinity, at some point, the FW's thickness begins to decrease. This can be explained by the fact that, at some values of initial salinity, the two processes are balanced: a decrease in ground temperature leads to an increase in the FW's thickness, and a decrease in the freezing temperature of porewater leads to a decrease in the FW's thickness.  
The relationships and simulation results acquired in this study hold significant practical importance: they will contribute to the enhancement of existing tools for the design and monitoring of frozen walls under the circumstances involving saline soil layers near the water-protective salt stratum.  
Conceptualization, S.B., M.S., L.L., A.B. and I.D.; methodology, M.S., A.B. and I.D.; software, S.B. and M.S.; validation, S.B., M.S. and L.L.; formal analysis, S.B., M.S. and L.L.; investigation S.B., M.S., L.L., A.B. and I.D.; resources, S.B., M.S., L.L., A.B. and I.D.; data curation, M.S., A.B. and I.D.; writing--original draft preparation, S.B.; writing--review and editing, M.S.; visualization, S.B.; supervision, M.S. and L.L.; project administration, M.S. and L.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Ministry of Science and Higher Education of Russia within the framework of project No. C-26/563.  
Not applicable.  
The authors declare no conflict of interest.