# Experimental and Theoretical Study of the Influence of Saline Soils on Frozen Wall Formation
## 1 Introduction
The works [16,17] present the results of  
Figure 1: Scheme of the frozen wall (**a**) and an example of the location of control boreholes in a transverse horizontal section (**b**). laboratory studies on the effects of salinity on freezing temperatures in sand samples. In addition, the results of an experiment on the effects of water filtration and the artificial freezing of soil samples using two freeze pipes with different levels of salt content in the porewater are presented. However, these studies consider only the effect of salinity on the freezing temperature of porewater, while an analysis of the effect of salinity on the changes in the entire complex of basic thermophysical properties of soils was not implemented. The work [7] contains the results of laboratory studies on the effects of the salinity and initial water content on the freezing temperature of porewater, specific heat capacity, thermal conductivity, and unfrozen water content. However, as in the case of works [16; 17], this study addresses only one type of soil--argillite-like clay--rather than sand. At the same time, the importance of studying a set of different soil types should be noted because the construction of underground structures often involves penetrating various types of soil layers. Dissolved salt can have different effects on the freezing processes of different types of soils. Recently, there has been a tendency toward increased research using the numerical simulation of heat and mass transfer during AGF. This may be due to the growing need to design the construction of FWs in difficult hydrogeological conditions. For example, works [18; 19] present the results of a study on the numerical modeling of AGF in saline soils, regarding the construction of underground tunnels. Based on the literature data on the experimentally measured thermal conductivity of frozen soils, [PERSON] et al. [20] proposed a new neural network model for determining the dependence of thermal conductivity on temperature and other soil properties. [PERSON] et al. [21] presents an analytical model for evaluating the thermal conductivity of sodium sulfate soils based on a generalized thermal conductivity theory of geomaterials. At the same time, only a few works can be found that consider the presence of soils and their transfer via porewater during soil freezing. For example, in [22; 23; 24], complex, coupled thermo-hydro-mechanical models were developed with consideration given to changes in the soil salinity. However, the models presented in these works contain many equations, relationships, and unknown parameters. As a result, they are difficult to implement, and therefore, it is problematic to use them for the practical tasks of designing and controlling FW formation. Most often, when monitoring the state of an FW, carrying out a quick, near-real-time calculation of the temperature field in frozen soil is required. These calculations also usually require preliminary parametrization of the model according to experimental data from control boreholes. The process of parameterizing and adjusting the model also requires a series of trial calculations. For these reasons, in our work, to analyze the state of the FW, we tried to choose models that would be easy to implement, would be less demanding on computational resources, and would have fewer calibrated parameters. However, at the same time, these models should include the most significant physical processes during AGF and the formation of FWs. Thus, based on all of the above-described considerations, it can be concluded that, at present, it is possible to find a lot of experimental studies on the effect of salinity on soil freezing in relation to permafrost problems, but only a small portion of the studies are directly related to AGF, and even fewer are directly related to the analysis of FW formation. In addition, the issue of the numerical simulation of heat and mass transfer processes in solving applied problems of monitoring and predicting FW formation in saline soils remains poorly covered.