## 3 Results and Discussion  
### Results of Numerical Simulation  
The seepage analysis was calculated using the unsaturated soil seepage theory on the Seep/W module in the GeoStudio platform, and the rainfall duration of each rainfall curve was set to 150 years. In this study, nine rainfall conditions corresponding to the bottom slope of \(i\) = 0.1 were used to investigate the evolution law of seepage field in dry-stack tailings ponds. Combined with the results of the bottom slope of \(i\) = 0.05 and \(i\) = 0.15, the influencing factors of the evolution of seepage field in dry-stack tailings ponds were analyzed. In the study of the evolution law of seepage field, the typical positions in the tailings pond (the distribution of the points is shown in Figure 1) were used to study the changing process of pore water pressure at different positions with time in the process of rainfall, so as to analyze the evolution process of the seepage field in the tailings pond. In order to properly express the evolution characteristics of the seepage field in dry-stack tailings ponds, the variation in the saturation line with time and its influencing factors were analyzed. 1.1 The Spatial-Temporal Evolution Process of the Seepage Field in Dry-Stack Tailings Ponds under the Action of Multi-Year Rainfall  
Considering that there are many working conditions and that the laws revealed by working condition 1, working condition 2, and working condition 3 are similar, the author arbitrarily selected condition II to explain the evolution process of the seepage field in dry-stack tailings ponds in this paper. The evolution process of pore pressure at typical points A, B, and C (marked in Figure 2) in dry-stack tailings ponds is shown in Figure 5. \begin{table}
\begin{tabular}{c c c c c} \hline \multicolumn{2}{c}{**Rainfall Parameters**} & \multicolumn{1}{c}{**Bottom Slope of 0.05**} & \multicolumn{1}{c}{**Bottom Slope of 0.1**} & \multicolumn{1}{c}{**Bottom Slope of 0.15**} \\ \hline \multicolumn{2}{c}{**Annual Rainfall**} & \multicolumn{1}{c}{**Rainfall Pattern**} & & \\ \hline \multirow{3}{*}{400 mm} & Taiyuan 2018 & Case: I-a & Case: II-a & Case: III-a \\  & Taiyuan 2019 & Case: I-b & Case: II-b & Case: III-b \\  & Taiyuan 2020 & Case: I-c & Case: II-c & Case: III-c \\ \hline \multirow{3}{*}{800 mm} & Zhengzhou 2018 & Case: I-d & Case: II-d & Case: III-d \\  & Zhengzhou 2019 & Case: I-e & Case: II-e & Case: III-e \\  & Zhengzhou 2020 & Case: I-f & Case: II-f & Case: III-f \\ \hline \multirow{3}{*}{1200 mm} & Guiyang 2018 & Case: I-g & Case: II-g & Case: III-g \\  & Guiyang 2019 & Case: I-h & Case: II-h & Case: III-h \\ \cline{1-1}  & Guiyang 2020 & Case: I-i & Case: II-i & Case: III-i \\ \hline \end{tabular}
\end{table} 
Table 1: Calculation table of working conditions. Figure 5: Pore pressure curves of the seepage field in a dry-stack tailings pond under different rainfall patterns: (**a**) Taiyuan: 2018, 2019, and 2020; (**b**) Zhengzhou: 2018, 2019, and 2020; (**c**) Guiyang: 2018, 2019, and 2020. It can be seen from Figure 5 that under different working conditions, the growth modes of pore water pressure at various points at the bottom of the dry-stack tailings pond are basically the same. In the case of a certain amount of annual rainfall, the variation law of pore water pressure at the same position of the tailings pond under different rainfall patterns is the same. Correspondingly, the numerical difference is not large. The final pore pressure of each point at the bottom of the tailings pond grows with the increase in annual rainfall. According to the growth curve of pore water pressure at each point, the changing process of pore water pressure can be divided into three stages: the rapid, the slow, and the relatively stable increase stages of pore pressure with rainfall years of 0-20a, 20-50a, and 50-150a, respectively. The changes in pore water pressure values in the corresponding three stages are shown in Tables 2-4.