## 6 Numerical Simulation of Monitoring Equipment in Non-Cohesive Soil
### Analysis of Computational Results  
Following the numerical simulation parameters for the linear heat source, finite element simulation models were established for iron-based and PVC-based linear heat sources in fine sand with 5% moisture content, fine sand with 15% moisture content, fine sand with 25% moisture content, coarse sand with 5% moisture content, coarse sand with 15% moisture content, and coarse sand with 25% moisture content. The temperature variation in the linear heat source with time was determined, as shown in Figures 16-21. Furthermore, the temperature distribution in the surrounding soil near the linear heat source was plotted for iron-based and PVC-based linear heat sources in cohesive soil with 45% moisture content, as depicted in Figures 22 and 23. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Serial Number** & **Category** & **Category Moisture** & \(\rho\) **(kg/m3)** & **C** & **Thermal Conductivity** \\  & & **Content (\%)** & & **[J/(kg.\({}^{\circ}\)C)]** & **[J/(m.\({}^{\circ}\)C\(\cdot\)s)]** \\ \hline T-1 & & 5 & 1700 & 1050 & 0.65 \\ T-2 & Powder, & 15 & 1800 & 1250 & 1 \\ T-3 & Fine sand & 25 & 1950 & 1450 & 1.55 \\ \hline T-4 & & 5 & 1980 & 950 & 0.75 \\ T-5 & Medium, & 15 & 2000 & 1200 & 1.15 \\ T-6 & Coarse sand & 25 & 2100 & 1400 & 1.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Thermodynamic parameters of non-cohesive soil medium. Figure 16: The results for 5% moisture content fine-powdered sand: (**a**) ferrous heat source; (**b**) PVC heat source. Figure 17: The results for 15% moisture content fine-powdered sand: (**a**) ferrous heat source; (**b**) PVC heat source. Figure 21: The results for 25% water content medium–coarse sand: (**a**) ferrous heat source; (**b**) PVC heat source. Figure 19: The results for 5% moisture content medium–coarse sand: (**a**) ferrous heat source; (**b**) PVC heat source. Figure 20: The results for 15% water content medium–coarse sand: (**a**) ferrous heat source; (**b**) PVC heat source. 2. The temperature increase patterns of iron-based linear heat sources and PVC-based linear heat sources were calculated in eight types of cohesive soils and six types of non-cohesive soils. It was observed that there were significant differences in temperature distribution between the iron-based and PVC-based linear heat sources in both seawater and cohesive soils. Specifically, a notable temperature gradient was present at the interface between water and soil, and this gradient became increasingly pronounced with time. This phenomenon could be attributed to the fact that, when the linear heat source was situated within the soil medium, the low thermal diffusivity of the soil resulted in a slower rate of temperature increase on the surface of the linear heat source. Conversely, when the linear heat source was submerged in the water medium, the efficient thermal diffusion properties of water led to a rapid increase in surface temperature. Consequently, by monitoring the changes in the surface temperature of the heat source, the temperature trends in different media could be analyzed, allowing for the identification of the water-soil interface within cohesive soils. 3. An analysis was conducted on the temperature distribution patterns and their propagation range in eight types of cohesive soils and six types of non-cohesive soils for both types of linear heat sources. It was observed that the temperature distribution in the soil surrounding the linear heat source increased gradually with time for both types. However, there was a notable difference in the impact range of the iron-based linear heat source compared to the PVC-based linear heat source for the same duration. Specifically, the temperature rise in the soil near the iron-based linear heat source was faster than that near the PVC-based linear heat source within the same time frame.