# Study on Disintegration and Infiltration Characteristics of Nanjing Jiangxinzhou Embankment Soil
## 2 Materials and Methods
### Disintegration Test  
Disintegration tests are often performed by the float method [24] and the tensiometer method [10]. Due to the soil shedding disturbance and the bubble escape effect causing the float to float, the float method could be more stable during the measurement process. In this paper, the tensiometer method was chosen. As shown in Figure 2, a simple disintegration test device was designed, allowing the sample to deform freely in all directions. The samples were placed on a wire mesh grid of 1 cm \(\times\) 1 cm. Moreover, a spring dynamometer (Range: 1 N, Accuracy: 0.02 N) weighed the samples during disintegration. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Specific Gravity** & **Maximum Dry** & **Optimum Water** & **Liquid Limit \(w_{L}\)** & **Plastic Limit \(w_{p}\)** & **Plasticity Index \(I_{p}\)** \\
**\(Gs\)** & **Density** & **Content** & & & \\ \hline
2.72 & \(1.68\)g/cm\({}^{3}\) & 19.86\% & 39.17\% & 19.48\% & 19.69 \\ \hline \end{tabular}
\end{table} 
Table 1: Basic physical characteristics. Figure 1: Sampling site in Nanjing, China. After drying and cooling the samples with different immersion times, they were ground into fine particles using a grinding rod and then sieved through a 2 mm screen. The prepared samples were stored in preservation bags. Deionized water was used to prepare soil samples with water contents of 5%, 10%, 15%, 20%, 25%, and 30% before they were sealed in plastic bags and left for 24 h. Considering disintegration occurs in shallow soils, standard ring knives with smaller thicknesses and larger cross-sectional areas were used to press the samples ($61.8 mm \(\times\) 20.0 mm). This produced samples with different dry densities (1.4 g/cm\({}^{3}\), 1.5 g/cm\({}^{3}\), 1.6 g/cm\({}^{3}\)). The disintegration test design is shown in Table 2.  
The equipment was assembled according to Figure 2 and the pushers were used to remove the soil sample from the ring knife to ensure the integrity of the soil sample. The container was filled with a fixed volume of deionized water to provide a hydrostatic environment for the disintegration of the sample, and the suspension height of the spring force gauge was fixed to ensure that the test device was not disturbed during the entire test. During the test, the ring knife sample was placed smoothly on the wire mesh and quickly submerged in water while immediately starting the timer and recording the spring force meter readings. When the spring dynamometer reading remained unchanged, it indicated that the sample had been completely disintegrated, and the test was terminated. Based on the literature [9; 13] and norms [4], the soil's disintegration properties were assessed using the disintegration quantity and rate. The general equations for both are shown below. Real-time disintegration volume \(\Delta_{m_{t}}\) (%):  
\[\Delta_{m_{t}}=\frac{F_{0}-F_{t}}{F_{0}}\times 100\%, \tag{1}\]  
In the formula, \(F_{0}\) is the spring force gauge reading when the ring knife sample and the metal mesh are submerged in water and just stabilized(N), and \(F_{t}\) is the spring dynamometer reading after time t(N). \begin{table}
\begin{tabular}{c c c} \hline
**Experiment No.** & **Water Content (\%)** & **Dry Density (g/cm\({}^{3}\))** \\ \hline
1–3 & 5 & \\
4–6 & 10 & \\
7–9 & 15 & \\
10–12 & 20 & \\
13–15 & 25 & \\
16–18 & 30 & \\ \hline \end{tabular}
\end{table} 
Table 2: Experimental schemes. Figure 2: Disintegration test device. Real-time disintegration rate \(v\) (%/s):  
\[v=\frac{\Delta_{i+1}-\Delta_{i}}{t_{i+1}-t_{i}} \tag{2}\]  
In the formula, \(\Delta_{i+1}\) and \(\Delta_{i}\) correspond to the real-time disintegration volume of the adjacent recording times \(t_{i+1}\) and \(t_{i}\). Equation (2) is the formula for the real-time disintegration rate. It reflects the speed of disintegration of the soil after water immersion. Observing the mass time variation curves shows that it has some linearity and can be fitted by a straight line.