# Study on Disintegration and Infiltration Characteristics of Nanjing Jiangxinzhou Embankment Soil
## 5 Conclusions  
Long-term flooding of the embankment's soil has caused partial or complete degradation of the soil structure at parts of the terrain's naturally low slopes. This study's test variables were the soil's water content and dry density in the Nanjing Jiangxinzhou embankment. The disintegration and infiltration characteristics of the modified Jiangxinzhou embankment soil under hydrostatic immersion were investigated through indoor tests. The key findings are the following:  
1. The pattern of the dry density effect on soil disintegration can be found in Figure 5. In Figure 12, with the rise of dry density, it can be observed that the number of soil particles per unit space of the sample increases, the number of pores decreases, and the structure becomes more compact. Furthermore, increased dry density leads to increased capillary force and matrix suction. The increase in potential energy difference will have a more significant hindering effect on water infiltration and the slower disintegration rate of the sample. Therefore, the disintegration rate decreases with increasing dry density for soil samples with the same water content. 2. Based on Figure 5a-c, when the water content was low, the water absorption of the sample was more significant than the disintegration amount due to the large matrix suction, and the sample gained weight for a short time. When the water content of the test reached a particular value, there was almost no cementing ability between the soil particles of the sample. The softened sample wedged into the metal mesh under gravity, causing cracking and sudden disintegration. Moreover, there is a threshold  
Figure 15: SEM results of the test at different immersion days. (**a**) 0 d; (**b**) 20 d.  
water content of around 20%, and it is assumed that the disintegration pattern of the soil may be significantly different depending on the optimum moisture content. The effect of moisture content on the disintegration of the samples was more significant. 3. The results of the indoor test showed that there were three main disintegration modes of the samples. When the water content was low, including 5%, 10%, and 15%, the disintegration process mainly showed a weight gain disintegration mode (Figure 8). The samples showed continuous and rapid disintegration when the water content rose to 20% and 25% (Figure 9). The samples showed a constant and stable disintegration when the water content was up to 30% (Figure 10). This phenomenon was independent of the dry density of the samples. The disintegration pattern of the samples under different water content conditions is shown in Figure 13.
4. Infiltration significantly affects the soil's permeability. After 20 days of immersion, the degree of change in the permeability coefficient weakens as the dry density increases. With the increase in water immersion days, the dissolution of cementing material between soil particles occurs and the particles move to fill the intergranular pore space. The result of pore structure reduction can better explain the phenomenon of soil permeability decreasing with the increase in immersion time. 5. The disintegration characteristics of soil are affected by many factors, such as initial water content, dry density, temperature, dry and wet cycles, and immersion height. In this paper, only two factors, initial water content and dry density, are considered. Future research can consider the comprehensive influence of multiple factors on the disintegration characteristics. This paper's comparative analysis of microstructure before and after immersion reveals the microscopic mechanism of permeability change. Therefore, the use of other advanced scientific techniques needs to be considered to achieve further revelation of the microstructural evolution patterns during the permeation process. The current study is mainly an indoor experiment, which needs to be better integrated with the actual problems in the field, and the research scale should be enlarged to combine with the actual engineering problems. Conceptualization, K.Z.