## 2 Materials and Methods
### Test Protocols and Devices  
In this study, 48 groups of one-dimensional consolidation/permeability tests were established to clarify the effects of granular gradation and lime dosage on the compressibility and permeability of lime-stabilized slurry with high water content, as shown in Table 2 below. The soil sample had a diameter of 61.8 mm (area of 30 cm\({}^{2}\)) and a height of 40 mm. Due to the extremely high initial water content of the test soil samples, if a conventional one-dimensional consolidation instrument with an initial loading stress of 12.5 kPa had been used, the loading would easily have led to the destruction of the soil sample and affected the test accuracy. Therefore, an ultra-low stress consolidation/permeability tester with a minimum consolidation pressure of 1 kPa was used for this test, as shown in Figure 1 below [23]. The test loading sequence was as follows: 1 kPa, 2 kPa, 3 kPa, 5 kPa, 7 kPa, 9 kPa, 12.5 kPa, 25 kPa, 50 kPa, 100 kPa, 200 kPa, 400 kPa, 800 kPa, and 1600 kPa. After the completion of each loading level and stabilization for over 24 h, the specimens were considered stable once they were settling by no more than 0.01 mm per hour, and the settlement of the soil sample was measured.  
The permeability test was carried out after each level of loading was completed [24]. The water head height was strictly controlled throughout the permeability test. When the vertical effective stress was below 12.5 kPa, the initial water head height was 500 mm.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sampling Site** & **Wenzhou** & **Taizhou** & **Zhoushan** & **Hangzhou** \\ \hline Initial water content \(w_{0}\) (\%) & 104 & 122 & 94 & 90 \\ Liquid limit \(w_{\text{L}}\) (\%) & 56 & 40 & 31 & 38 \\ Plastic limit \(w_{\text{P}}\) (\%) & 32 & 27 & 18 & 27 \\ Relative density G\({}_{\text{S}}\) & 2.55 & 2.63 & 2.72 & 2.62 \\ Plastic index \(I_{\text{P}}\) & 24 & 13 & 15 & 11 \\ \textless{}0.002 mm & 2 & 2.5 & 23.1 & 25.9 \\ Granular & 0.002–0.075 mm & 54.7 & 66.1 & 32.5 & 60.7 \\ gradation & 0.075–0.425 mm & 43.2 & 25.3 & 41.8 & 13.4 \\  & 0.425–0.2 mm & 0.1 & 6.1 & 2.6 & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Basic physical properties of the four types of soil samples.  
Figure 1: Ultra-low stress consolidation/permeability tester.  
When the vertical effective stress was greater than 12.5 kPa but less than 200 kPa, it was 1000 mm. When the vertical effective stress was greater than 200 kPa, it was 2000 mm. During the test, the change of water head with time was measured at a certain time interval, and the permeability coefficient was calculated based on this.  
After consolidation/permeability tests, the compacted soil samples were made into the size required for MIP tests and SEM tests. The sample size of the MIP test and SEM test were 10 mm \(\times\) 5 mm \(\times\) 5 mm and 10 mm \(\times\) 10 mm \(\times\) 20 mm (length \(\times\) width \(\times\) height), respectively. All soil samples were immersed in liquid nitrogen for 10 min and freeze-dried for 24 h [25]. For the MIP test, the soil samples needed vacuum treatment before injecting mercury. The instrument settings in this MIP test are as follows: the surface tension of mercury was 485 dynes/cm, the contact angle was 130\({}^{\circ}\), and the maximum pressure was 60,000 psia. For the SEM test, the soil samples were observed by a scanning electron microscope after spray-gold treatment.