# Compression Law and Settlement Calculation Method of Over-Wet Soil Based on Large Samples
## 3 Results and Discussion
### Analysis of Water Changes in Different Compression Stages of Over-Wet Soil  
The strain of soil was significantly affected by water [20]. To further analyze the water variation law with different binding forces during the compression process of excessively wet soil, the durations of the primary and secondary consolidation stages under loads of 200 kPa (below the pre-consolidation pressure) and 400 kPa (above the pre-consolidation pressure) were calculated using compression curve 5. The results are summarized in Table 7.  
A small amount of soil was collected from the consolidated sample at the end of the different stages of thermogravimetric analysis based on the data in Table 7. The test data at \begin{table}
\begin{tabular}{l l l} \hline \hline
**Load** & \(\varepsilon_{c}\) & \(\mathbf{R^{2}}\) \\ \hline
50 & \(\varepsilon_{c}=6.0\times 10^{-6}w\) & 0.961 \\
100 & \(\varepsilon_{c}=7.1\times 10^{-6}w\) & 0.943 \\
200 & \(\varepsilon_{c}=1.9\times 10^{-5}w\) & 0.944 \\
300 & \(\varepsilon_{c}=4.8\times 10^{-5}w\) & 0.981 \\
400 & \(\varepsilon_{c}=6.5\times 10^{-4}w\) & 0.999 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Fitting curve for the creep strain of over-wet soil. Figure 13: Creep strain under different loads. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Load/kPa** & **Primary Consolidation Stage/h** & **Secondary Consolidation Stage/h** & **Tertiary Consolidation Stage** \\ \hline
200 & 1.54 & 10.3 \\
400 & 6.08 & 359.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: End time of the three compression stages. 200 kPa are used as an example for the analysis because the variation patterns of all curves are similar, as shown in Figure 14. The Y-axis in Figure 14 represents the percentage of remaining sample mass (TG), while the Y-axis in Figure 14 represents the derivative of the percentage of remaining sample mass (DTG). As the temperature increases, the mass percentage of over-wet soil rapidly decreases in the early stage of heating (Figure 14a). When the temperature exceeds approximately 60 \({}^{\circ}\)C (point A), the weight loss rate of the over-wet soil reduces and remains stable. When the temperature exceeds approximately 110 \({}^{\circ}\)C (point B), the rate gradually reduces and stabilizes. In thermogravimetric analysis, the mass changes during the heating process of a sample are measured, distinguishing different components based on the trough position of the differential curve (DTG). Because the weight loss temperatures of free and bound water in the soil samples were relatively continuous, the DTG curve shows a continuous trough (Figure 14b). Conventional methods cannot accurately distinguish between free and weakly bound water. Therefore, researchers have proposed distinguishing between different types of water in soil using critical temperatures [21; 22; 23; 24]. [PERSON] et al. [25] proposed through the analysis of the thermogravimetric curve that free water loses weight before approximately 60 \({}^{\circ}\)C, while weakly bound water loses weight between 60 \({}^{\circ}\)C and 108 \({}^{\circ}\)C. At this point, the TG curve is a straight line, and when the temperature exceeds 108 \({}^{\circ}\)C, the main loss is owing to strongly bound water. This conclusion is consistent with the results of wet soil tests. Based on the data presented in Figure 14a, the temperature range for weight loss of free water in over-wet soil is from room temperature to 60 \({}^{\circ}\)C, the weight loss temperature range for weakly bound water is from 60 \({}^{\circ}\)C to 110 \({}^{\circ}\)C, and the weight loss temperature range for strongly bound water is above 110 \({}^{\circ}\)C. The variation in water with different binding forces in over-wet soil is calculated as shown in Figure 15.  
Figure 15 shows that the changes in free water, weakly bound water, and strongly bound water exhibit strong regularity. Free water decreases significantly in the primary consolidation stage, with an average decrease of approximately 81% (200 kPa) and 64% (400 kPa) for the two sets of data (Figure 15a).