# Synchronous Grouting Analysis of Shield Tunneling through High Water Pressure Fault Fracture Zone
## 5 On Site Monitoring of Soil and Water Pressure
### Analysis of Monitoring Results  
The fault zones distributed on the shield tunneling section seriously affect the construction safety of the shield tunneling, so accurately determining the relative position relationship between the fault zones and the shield tunneling section is crucial for the safe construction of the shield tunneling. Based on the geological survey results of drilling and coring, the distribution of fault fracture zones is revealed, and the relative position relationship between the fault fracture zone and the shield tunneling face is determined. The distribution of fault zones plotted based on the analysis results and the relationship between them and shield tunneling are shown in Figures 33 and 34. The inclination angle of F113 fault is relatively small, and the estimated interval between the fault fracture zone and the shield tunneling section in the profile is 1519-1538, with the intersection of faults, strongly weathered rock layers, and weakly weathered rock layers. Figure 31: Longitudinal Section of J4–J8–J10 Boreholes in the Monitoring Test Area. Figure 34: F113 fault distribution. Figure 32: Plan diagram of on-site drilling monitoring points. Figure 33: Pore pressure variation curve of monitoring points in the fractured zone. The changes in soil pressure can reflect the effects of synchronous grouting during shield tunneling. Selecting data from some drilling monitoring points, the changes in soil pressure during shield tunneling through fault fracture zones are analyzed, as shown in Figures 35 and 36. In Figure 35, the black, purple, and pink lines represent the soil pressure at the bottom, middle, and top, respectively. In Figure 36, the purple and red lines represent the soil pressure and ring number, respectively. Based on the monitoring data of J3 borehole soil pressure sensor, the trend of soil pressure changes at the top, middle, and bottom is obtained. From Figure 35, it can be seen that the variation pattern of soil pressure at the bottom, middle, and top is basically consistent. As the shield tunneling progresses, the surrounding rock and soil pressure is gradually reduced due to disturbance. When the shield tunneling machine is near the monitoring point, it has a significant impact on the rock and soil stress, with drastic changes. However, as the shield tunneling moves away, the impact on soil pressure gradually decreases. It can be seen that as shield tunneling progresses, the soil pressure varies in stages at different times and distances. Based on this division method, the impact area of shield tunneling through faults can be roughly divided into the main impact area, secondary impact area, and non-impact area. In the main affected area, the fluctuation of soil pressure is severe; however, there are secondary impact zones before and after the main impact zone, with significant fluctuations in soil pressure and a relatively small range of impact zones. The J9 borehole is close to the fault zone, and the central sensor is located on the right side of the shield, indicating a representative change in soil pressure. As shown in Figure 36, the variation of the soil pressure sensor in the middle of J9 during the entire process of shield tunneling through fault fracture zones is shown. The purple line represents the variation of soil pressure at the monitoring point with excavation time, and the red line represents the excavation ring number at that time. According to the monitoring of soil pressure changes in the middle of J9 borehole, it can be concluded that when the shield tunneling passes through the fault fracture zone and enters the 1464 ring, the soil pressure begins to fluctuate significantly and enters the  
Figure 36: Change in soil pressure in the middle of J9 hole. Figure 35: Change in soil pressure of J3 hole. secondary affected area.