# The Impact of Fine-Layering of Tailings Dam on the Variation Pattern of Infiltration Lines
## 3 Results and Discussion
### Distribution of the Infiltration Line during the Rainfall Strategy  
Under the rainfall strategy, a continuous rainfall of 9 days was implemented with moderate intensity. The constant head boundary was deactivated, and the rainfall boundary was defined as the upper boundary of the tailings dam (including the initial outer slope). After 9 days of rainfall, the distribution of the infiltration lines of the three schemes were illustrated in Figures 8-10. Figures 8-10 demonstrate the distribution of pore water pressure after 9 days rainfall in each scheme. The upper boundary represents the infiltration line with zero pore water pressure, which is defined as the infiltration line. Under the rainfall strategy, drainage is not allowed, and the analysis is performed under transient conditions involving both horizontal and vertical seepage. The initial embankment infiltration lines for all three schemes exhibit a slight slope in a linear distribution, while the reservoir infiltration lines show noticeable fluctuations. It is evident that the infiltration lines for all three schemes have increased compared to the constant head strategy, with the highest infiltration line observed in scheme 3, followed by scheme 2, and then scheme 1. Figure 11 records the changes in the height of the infiltration line between lines A and E, with the origin at the  
Figure 8: Distribution of the infiltration line in scheme 1 during the rainfall strategy. Figure 10: Distribution of the infiltration line in scheme 3 during the rainfall strategy. Figure 9: Distribution of the infiltration line in scheme 2 during the rainfall strategy. left end point of the model bottom, the model bottom boundary as the x-axis, and a line passing through the origin and perpendicular to the bottom boundary as the y-axis. In scheme 1, the tailings dam consists of uniformly deposited tailings fine sand \(\textcircled{3}_{1}\) without any layering. In scheme 2, the dam body is divided into layers based on the type of soil, including the surface fill soil, tailings fine sand \(\textcircled{3}_{1}\), tailings silty sand, tailings silty clay \(\textcircled{5}_{1}\), and tailings silty clayy silt. Meanwhile, in scheme 3, the dam body is further divided into layers based on the compaction density of the tailings sand, incorporating additional layers of tailings fine sand \(\textcircled{3}_{2}\) and tailings silty clay \(\textcircled{5}_{2}\) compared to scheme 2. According to Figure 11, the average increase in the height of the infiltration line after 9 days of rainfall for scheme 1, scheme 2, and scheme 3 is 46.20%, 65.88%, and 85.32%, respectively. It is apparent that the percentage increase in lines B, C, and D is relatively large, while lines A and E have comparatively smaller percentage increases. Among them, scheme 3 has the highest average increase in infiltration line, which is 85.32%, surpassing scheme 2 (65.88%) and scheme 1 (46.20%), which indicates that the upper layers of the tailings dam in all three schemes are fine tailings, and the difference in rainfall infiltration capacity is relatively small. However, as the compactness of the tailings layers increases, the permeability coefficient of the tailings sand decreases [18; 30], resulting in a decrease in the water permeability of the tailings sand and a slower seepage velocity, consequently leading to an increase in the infiltration line. The compactness of the tailings dam for scheme 1, scheme 2, and scheme 3 follows the order of scheme 3 \(>\) scheme 2 \(>\) scheme 1. Therefore, after 9 days of rainfall, the percentage increase in the infiltration line for the three schemes also follows the pattern of scheme 3 \(>\) scheme 2 \(>\) scheme 1.