## 3 Analysis of Water-Bearing Characteristics in Water-Rich Region
### Water Pumping Test  
In order to explore the water storage situation in the water-rich area, five pumping wells were constructed on the ground to carry out pumping tests. The pumping wells are cross-arranged at a distance of 7 m from the middle line of the tunnel in the range of pile number 8 + 416 \(\sim\) 8 + 673. The diameter of the well is 60 cm, and the bottom hole construction depth of the pumping well is 20 m below the tunnel floor. The depths of the No. 1 well to the No. 5 well are 130.5 m, 123 m, 101.2 m, 101.6 m, and 125 m. The well location layout is shown in Figure 8.  
The water level meter was used to observe the static and dynamic water levels manually, the water meter was used to measure the water inflow, and the stopwatch was used to time. The static water level was observed before pumping, and the dynamic water level was observed at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 40, 50, and 60 min after pumping, and then observed every 30 min. The recovery water level observation was the same as the above pumping test observation time until the water level returned to the natural static water level. Three kinds of pumping tests with variable flow were designed. The #1 to #4 wells are pumping at the same time, #1, #2, and #5 wells are pumping at the same time, and #3, #4, and #5 are pumping at the same time. When the amount of pumping water is 0, stop pumping and record the duration of pumping and the amount of pumping during this period. According to the recorded data, the change diagram of pumping amount-cumulative time is drawn, as shown in Figure 9.  
The pumping volume and pumping duration of four times from well #1 to well #4 roughly showed a law of decreasing first, then increasing, and then decreasing. Among them, the four pumping durations and variation ranges of well #1 and well #2 are relatively close, but the total pumping volume of #1 is much larger than that of well #2. The total pumping volume of well #1 and well #2 is 12.2 m\({}^{3}\) and 6.69 m\({}^{3}\), respectively. The pumping duration line chart of well #3 is relatively flat, and the third and fourth pumping volumes are on the rise. The total pumping volume reached 15.33 m\({}^{3}\), indicating that the water storage and recharge rate of the aquifer where well #3 was located is greater than that of well #1 and well #2. The average pumping volume of well #4 is 0.78 m\({}^{3}\), and the third pumping volume is even 0 m\({}^{3}\). It was inferred that the water richness of the layer where well #4 was located was relatively poor. Figure 8: Layout of pumping test well (unit: m). which is 7 times and 28 times that of well #3 and well #2, respectively. Compared with the first pumping test data, the variation in pumping time and pumping volume of well #1, well #2, and well #4 is small, and it is inferred that the hydraulic connection between well #1, well #2, and well #5 was weak. The pumping volume of well #3 was affected by the pumping of well #5, which was greatly reduced compared with the first pumping test. The five pumping wells were cross-arranged at 7 m from the center line of the tunnel. Well #3 and well #5 were 30 m away from well #4 in the direction of the center line of the tunnel, but the hydraulic connection was very weak, and the water yield was uneven, resulting in a polarization of pumping water. Analysis of the Distribution Law of Water Pressure Outside the Tunnel under Water Plugging and Drainage Restriction  
The geological structure around the fault zone is complex and changeable, and there are high water pressure and high permeability rock mass sections inside. When the tunnel passes through the Shiling-Baihe fault, the distance between the top of the tunnel and the groundwater level is about 80 m, and the external water pressure that may be generated after the reduction is 0.54-0.56 MPa, which is greater than the 0.3 MPa that the Earth pressure balance shield machine can withstand. There is a large risk of destruction and construction safety risk.