# Study on Frost Heave and Thaw Settlement Characteristics of Sanya Estuary Channel Soil Layer
## 4 Test Results and Analysis
### Analysis of Frost Heaving and Thawing Properties of Silty Clay Under Different Moisture Contents  
The displacement of the top of the silty clay during the freezing and thawing stages under different moisture contents (24%, 27%, 30%, 33%, and 36%) varies with time, as shown in Figure 7. The soil samples at the end of the thawing stage are shown in Figure 8.  
By comparing and analyzing the displacement variation curves and post-test samples under different moisture contents, the following conclusions can be drawn:  
1. The greater the moisture content in the soil, the greater the volume change of water freezing into ice during freezing. Consequently, the displacement at the stable stages of frost heaving and thawing is larger, and the frost heaving rate and thawing coefficient are higher. 2. Increasing (decreasing) the moisture content leads to an increase (decrease) in both frost heaving displacement and thawing displacement of silty clay, but the increase (decrease) in frost heaving displacement is smaller than that in thawing displacement. 3. Soil samples with higher moisture content are more likely to show damage after the test, indicating that higher moisture content leads to greater mechanical performance degradation of the soil samples after the test. The frost heaving rate and thawing coefficient of silty clay under different moisture contents (24%, 27%, 30%, 33%, and 36%) were calculated, with the results shown in Table 3, and the variation curves of frost heaving rate and thawing coefficient under different moisture contents are shown in Figure 9. From the figures and tables, the following conclusions can be reached:  
1. Under the freezing temperature of \(-\)28\({}^{\circ}\)C, the frost heaving rate of silty clay with 24% moisture content is 2.85%, and when the moisture content increases to 36%, the frost heaving rate increases to 6.84%. Within this range of moisture content change, the frost \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Serial Number** & **Soil Type** & **Frost Heave Rate/\%** & **Thaw Settlement Coefficient/\%** \\ \hline
1 & Gravel sand & 1.5 & 0.9 \\
2 & Fine sand & 2.41 & 2.98 \\
3 & Silty clay & 4.51 & 5.88 \\
4 & clay & 3.05 & 4.18 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Test Results of Frost Heaving Rate and Thawing Coefficient under Natural Moisture Content. heaving rate increases with the increase in moisture content, with the frost heaving rate rising by approximately 0.333% for every 1% increase in moisture content. 2. Under the freezing temperature of \(-28^{\circ}\)C, the thawing coefficient of silty clay with 24% moisture content is 3.81%, and when the moisture content increases to 36%, the thawing coefficient increases to 8.43%. Within this range of moisture content change, the thawing coefficient increases with the increase in moisture content, with the thawing coefficient rising by approximately 0.385% for every 1% increase in moisture content. Figure 7: _Cont._  
Figure 8: \(Cont\). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Serial Number** & **Moisture Content** & **Frost Heave Rate/\%** & **Thaw Settlement Coefficient/\%** \\ \hline
1 & 24 & 2.85 & 3.81 \\
2 & 27 & 3.83 & 4.97 \\
3 & 30 & 4.51 & 5.88 \\
4 & 33 & 5.69 & 7.08 \\
5 & 36 & 6.84 & 8.43 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Test Results of Frost Heaving Rate and Thawing Coefficient of Silty Clay under Different Moisture Contents. Figure 7: Displacement variation curves of silty clay under different moisture contents. Additionally, the displacement rate changes during the freezing phase for gravel sand, fine sand, silty clay, and clay are 0.064 mm/min, 0.083 mm/min, 0.128 mm/min, and 0.093 mm/min, respectively. During the thawing phase, the displacement rate changes are \(-\)0.046 mm/min, \(-\)0.080 mm/min, \(-\)0.158 mm/min, and \(-\)0.114 mm/min, respectively.