## 6 Conclusions  
1. In this paper, a series of fieldwork is carried out on the Shiling-Baihe fault: the core is taken out by drilling, and it is found that the surrounding rock of the tunnel is broken, and the strength is low. The surrounding rock category is extremely unstable V-type surrounding rock, and the geological conditions are poor; the high-density resistivity tomography method was used for supplementary work. It was found that the tunnel excavation path passed through a large low-resistance anomaly area, and the groundwater was relatively developed.
2. The depth of the diversion tunnel into the new diversion tunnel is deep, and the high groundwater level leads to a large head difference. It has the characteristics of large groundwater flow and strong suddenness, which brings great difficulties to tunnel construction and support.
3. The pumping test is used to explore the water storage of the tunnel excavation path. The average continuous pumping time of well #4 is 2 min, and the average water yield is 1.06 m\({}^{3}\). The continuous pumping time of adjacent well #5 is 29 min, and the average water yield is 12.76 m\({}^{3}\). In the direction of the tunnel axis, the hydraulic connection of each pumping well is weak, the formation changes greatly, the water-richness is uneven, and the water-bearing span is large.
4. In view of the high water pressure section of tunnel excavation, the working measures of \"Forecast first, mainly blocking, and combining blocking and drainage\" are put forward. When the drainage measures are implemented in the tunnel, the initial seepage field of the surrounding rock will be disturbed, but this disturbance does not spread to the whole seepage field of the surrounding rock but is generated within a certain range around the tunnel.
5. When the drainage rate reaches 66.67%, that is, the drainage volume reaches 37.43 m\({}^{3}\)/d, the external water pressure of the tunnel can be reduced to 0.3 MPa, which ensures the safety of the Earth pressure balance shield machine in the tunneling process. It provides a certain degree of basis for the variation of the external water pressure of the tunnel with the drainage rate through the numerical simulation method in the actual project.  
Methodology, H.L. ([PERSON]); formal analysis, H.L. ([PERSON]); investigation, H.L. ([PERSON]) and W.M.; data curation, W.M.; writing--original draft preparation, W.M.; writing--review and editing, M.K. and Y.F.; supervision, T.Y.; funding acquisition, H.L ([PERSON]) and B.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Research and Application of Surrounding Rock Deformation Instability Mechanism and Key Technology of High External Water Pressure Seepage Control in Xiaolangdi North Bank Irrigation Area Engineering Tunnel (grant No. XLDBAGQ-KJGG-04).  
**Informed Consent Statement**: Not applicable.  
**Data Availability Statement**: The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
**Conflicts of Interest**: Authors [PERSON], [PERSON] and [PERSON] were employed by the company Henan Water Conservancy Investment Xiaolangdi North Bank Irrigation District Engineering Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.