## 4 The Influence of Different Factors on the Development of Temperature Field Patterns
### The Impact of the Salt Content on the New Pipe Curtain Freezing Method  
In frozen engineering in coastal formations, not only does the impact of the groundwater flow need to be considered, but the influence of changes in the salt content in the underground soil layers caused by seawater infiltration on frozen engineering also needs to be taken into account. In order to study the influence of different salt content in various soil layers on the new pipe curtain freezing method under seepage conditions, this study adopts four different salt content values of 0%, 2%, 4%, and 6% and conducts a numerical analysis on models with different salt content. The calculated results provide a reference for similar engineering projects. In frozen engineering, specific attention needs to be paid to the freezing effect in predominantly water-rich sand layers or in formations with flowing water. In order to simplify the model calculations, only sand layers are used in this model to simulate the permeable layers with different salt content. Additionally, to enhance the display of the calculation results, a seepage velocity of 4.27 m/d is set. Based on the experimental research by [PERSON] [17], the thermal physical parameters of salt solutions with different salt content are obtained. The thermal physical parameters are listed in Table 2. Table 3 shows the parameters of ice after a phase change [32; 33; 34; 35]. A temperature curve analysis is conducted on temperature measurement point DGJ-4-2 located in the freezing interval of temperature measurement path DGJ-4, as well as temperature measurement points DGJ-4-1 and DGJ-4-3 located at 1 m on each side of DGJ-4-2. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Salt Content** & **Density** & **Thermal** & **Specific** & **Freezing Point** \\
**/\%** & **Kg/m\({}^{\text{5}}\)** & **Conductivity** & **Heat Capacity** & **Temperature** \\  & & **W/(m\(\cdot\)K)** & **J/(kg\(\cdot\)K)** & \({}^{\circ}\)**C** \\ \hline
0 & 1000 & 0.630 & 4180 & 0 \\
2 & 1013 & 0.598 & 4074 & \(-1.47\) \\
4 & 1027 & 0.594 & 3958 & \(-3.01\) \\
6 & 1041 & 0.591 & 3894 & \(-4.02\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Thermal physical parameters of salt solution with different salt content. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Ice** & **Density** & **Thermal** & **Specific Heat** & **Latent Heat** \\
**Kg/m\({}^{\text{3}}\)** & **Conductivity** & **Capacity** & **Kg/m** \\  & & **W/(m\(\cdot\)K)** & **J/(kg\(\cdot\)K)** & **Kg/m** \\ \hline  & 918 & 2.31 & 2050 & 330 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Parameters of ice after phase transition. Figure 9 shows the temperature variation curves of the temperature measurement points with different salt content. The curves clearly indicate that temperature measurement point DGJ-4-1 upstream of the freezing pipe is most affected by the salt content. The freezing time of the measurement point increases with higher salt content, and the final freezing temperature also rises. The different salt content also affects the encircling time of the frozen soil curtain in the new pipe curtain freezing method, with the freezing time of DGJ-4-2 increasing with the salt content. In contrast, the freezing condition at temperature measurement point DGJ-4-3, located downstream of the freezing pipe, shows the opposite result to that of DGJ-4-1, which is upstream. As the salt content increases, the freezing time at DGJ-4-3 decreases, and the final temperature also drops. This indicates that the variation in the salt content not only affects the final freezing effect of the frozen soil curtain but also influences the formation process of the frozen soil curtain. Before the temperature reaches the freezing point, due to the flow of the groundwater and the presence of large ions in the salt solution, the free ions freeze only when they reach the downstream region, disrupting the normal formation of the frozen soil curtain.