# Numerical Simulation of Seepage Surface and Analysis of
## 5 Conclusions  
The seepage stability of tailings dams is very important for their stability. At present, numerical simulation is widely used in the simulation of a tailings dam seepage flow field to accurately determine seepage stability and reduce online monitoring costs. Therefore, studying the seepage problem of tailings dams and simulating the seepage field of tailings dams is an important task. In this study, the engineering profile and geological conditions of the tailings dam were provided, from which a finite element model was developed, and the physical and mechanical parameters of the tailings sand in different layers were measured by carrying out indoor experiments, which were then used as the basis for inverse analyses, and the results were further used for numerical simulations. Total head, phreatic lines, and seepage safety coefficients under different working conditions were derived. The main conclusions are summarized below:  
1. This study used seepage back analysis to obtain the permeability coefficients of tailings in different layers and conducted an analysis of the mutual influence law of seepage field by the coefficients, revealing the key areas and reasons, and proposed countermeasures for seepage control. These findings will provide reference and guidance for the construction and daily safety management of high pile tailings dams with fine-grained tailings under similar complex terrain conditions. The next study will investigate the impact of different drainage measures on the control of seepage in sensitive areas and conduct on-site practice. 2. Back analysis using drilling data to establish a finite element model was a very practical and effective method in practical engineering, which could accurately reflect the actual permeability coefficient of each partition of tailings dams and lay the foundation for the later seepage calculation of the tailings dam. 3. Due to the comprehensive influence of complicated geography conditions such as multiple areas of seepage accumulation, large valley corners, and narrowing of the dam axis, there was a significant difference in the spatial seepage characteristics of a high fine-grained tailings dam. In the region of 1220 m to 1250 m a.s.l. on the left shoulder of the tailing dam, the phreatic line was elevated by 2 m\(\sim\)3 m compared to the surrounding area and was the most critical region of the tailings dam seepage control. 4. The seepage gradient of the starter dam at the inner slope foot was the largest, which was smaller than the critical seepage gradient, and seepage failure could not occur. When the tailings dam was 210 m high, the depth of the phreatic line was controlled to be 23 m, which could be easily controlled by setting corresponding drainage facilities. 5. In addition to strengthening the daily monitoring of the key areas of the tailings dam, it was critical to control the local phreatic line and ensure the safe of the tailings dam by adopting local horizontal seepage drainage measures or radiation wells. It is recommended to carry out determination tests of the permeability coefficient and particle size at regular intervals, and ensure that the permeability coefficient of the tailing sand does not change accordingly, and strengthen the monitoring of the exfiltration facilities. The research results can possibly be applied to a tailing dam with similar geological conditions, particle size distribution, sedimentation pattern, and permeability coefficient as this tailing dam. **Author Contributions:** Conceptualization, Y.H., G.W., X.Z. and B.Z. ; methodology, Y.H. and G.W. ; software, Y.H. and B.Z. ; validation, X.Z. ; formal analysis, Y.H. and B.Z. ; investigation, Y.H. and X.Z. ; data curation, Y.H. ; writing--original draft preparation, Y.H. and B.Z. ; writing--review and editing, Y.H. ; supervision, G.W. and B.Z. All authors have read and agreed to the published version of the manuscript. **Funding:** This research received no external funding. **Institutional Review Board Statement:** Not applicable.