## 5 Conclusions  
Regarding the ambient vibration of the diversion pipeline of the PSPS, this research focused on whether the vibration of the ground exceeded the standard. The ground vibration acceleration varied under different working conditions and in different types of units.  
The conclusions are as follows:  
1. Ambient vibrations induced by the running of units constituted the primary source of vibration. The vibration of the diversion pipeline reached up to 76 cm/s\({}^{2}\) when the units were running, and the presence of mountains significantly attenuated the magnitude of vibrations. Meanwhile, a vibration acceleration of approximately 0.02 cm/s\({}^{2}\) was measured in the diversion pipeline area when no units were running.
2. The research on the ground vibrations showed that the vibration acceleration under pumping conditions was larger than that under power generation conditions. The ground vibration acceleration increased with the augmentation in power, irrespective of the power generation or pumping conditions. The ground vibration acceleration attenuated as the distance increased. The vibration of the lower flat tunnel was the largest, and the vibration of the upper inclined shaft was the smallest.
3. Within 100 Hz, the energy was primarily concentrated at 60 Hz and 70 Hz. From 100 to 200 Hz, the energy was primarily concentrated at 120 Hz and 170 Hz. From 200 to 300 Hz, the energy was primarily concentrated at 220 Hz. The theoretical calculation results were 83.33 Hz and 166.67 Hz for units 1#-4#, and 110 Hz and 220 Hz for units 5# and 6#. The test results were inconsistent with the theoretical calculation results due to mutual interference while running adjacent units and the different types of units, which led to a bias.
4. Compared to the existing urban vibration standards, the daytime vibrations in the area of the diversion pipeline should not exceed 70 dB (0.316 cm/s\({}^{2}\)), while the nighttime vibrations should not exceed 67 dB (0.224 cm/s\({}^{2}\)). The vibrations in specific regions should not exceed 75 dB (0.562 cm/s\({}^{2}\)) during the daytime and 72 dB (0.398 cm/s\({}^{2}\)) at nighttime. The vibrations of the lower flat tunnel is prone to exceed the standard, especially if the number of units running together exceeds three.  
A prototype observation method was employed in this study to monitor the ground vibration while running a PSPS. The researchers emphasized the analysis of ground vibrations in the diversion pipeline to compare with the traditional methods of monitoring plant vibrations. The prototype observation method is worth popularizing to research the vibration issue in the diversion pipeline area of a PSPS. It can reveal the inherent characteristics and propagation laws of vibration. Furthermore, the results will be helpful for future construction of PSPSs. Combining prototype observations and physical model testing may serve as a better method for research in the future and could significantly enhance the reliability of physical model testing.  
Resources, J.L.; writing--original draft preparation, L.Z.; writing--review and editing, X.W.; investigation, L.Y. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Hebei Natural Science Foundation (grant No. E2023402015) and the National Natural Science Foundation of China (grant No. U21A20164 and U20A20316).  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
**Conflicts of Interest:** The authors declare no conflicts of interest.