# Numerical Analysis of an Upstream Tailings Dam Subjected to Pond Filling Rates
## 5 Conclusions  
In this study, a numerical analysis of an upstream tailings dam subjected to pond filling rates was conducted. A finite element software was used to simulate the time-dependent pond filling process and the staged dam construction under various pond filling rates. An advanced constitutive model was adopted in the finite element models to capture the nonlinearity in the elastic deformations of the tailings materials. Based on the results of this study, the following conclusions can be drawn:  
* Excess pore water pressure increased after every raising phase and then decreased after every subsequent consolidation phase in the numerical models. However, excess pore water pressure remained after every consolidation phase, leading to the build-up of excess pore water pressure and, eventually, a potentially critical situation in the stability of the dam (i.e., especially for the dam without strengthening).
* The stability of the dam decreased during the raising phase but increased during the consolidation phase. This is due to the changes of excess pore water pressure, i.e., increased values with the raising phase and decreased values with the consolidation phase. In addition, it is also vital to mention that the strengthening of an upstream tailings dam with rockfill berms at the downstream slope could improve the stability of the dam. The basic concept of excess pore water pressure build-up during the stage of construction was presented based on the remaining excess pore water pressure after every consolidation phase. The remaining excess pore water pressure varied depending on the pond filling rates, being larger in high filling rates and smaller in low filling rates. A very high pond filling rate is, therefore, not recommended for an upstream tailings dam as the dissipation of excess pore water pressure usually takes a long time.
* This study provided an in-depth analysis of the build-up of excess pore water pressure and slope stability during the stage of construction (pond filling and dam raising) of an upstream tailings dam. It is believed that the finite element method could be used to study how an upstream tailings dam should be built in order to be stable for different pond filling rates.  
**Author Contributions:** Conceptualization, [PERSON]; [PERSON]; [PERSON]; methodology, [PERSON]; [PERSON]; software, [PERSON]; H.M.; validation, [PERSON]; [PERSON]; [PERSON]; Q.J.; formal analysis, [PERSON]; [PERSON]; H.M.; investigation, [PERSON]; [PERSON]; [PERSON]; writing--original draft preparation, [PERSON]; writing--review and editing, [PERSON]; [PERSON]; H.M.; Q.J.; supervision, [PERSON]; H.M.; Q.J.; project administration, [PERSON]; funding acquisition, J.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by Svenskt Vattenkraftcentrum, SVC (\"The Swedish Hy-dropower Center\").  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The research presented in this paper was carried out as a part of the Swedish Hydropower Center (Svenskt Vattenkraftcentrum, SVC). SVC has been established by the Swedish Energy Agency, Energiforsk, and Svenska Kraftnat, together with the Lulea University of Technology, KTH Royal Institute of Technology, Chalmers University of Technology, Uppsala University, and Lund University. The participating companies and industry associations are: Andritz Hydro, Boliden, Fortum Sweden, Holmen Energi, Jamtkraft, Karlstads Energi, LKAB, Malarenergi, Norconsult, Rainbower, Skellefeta Kraft, Sollefetaforsens, Statkraft Sverige, Sweco Sverige, Tekniska vorken i Linkoping, Uniper, Vattenfall R&D, Vattenfall Vattenkraft, Voth Hydro, WSP Sverige, Zink-grnvan, and F Industry. This research was funded by SVC and the Lulea University of Technology.  
**Conflicts of Interest:** The authors declare no conflict of interest.