## 5 Field Application Cases  
To prevent the recurrence of the same machine jamming accident in Gully 1, surface pre-grouting reinforcement should be carried out promptly for the rock mass exposed by the TBM in Gully 2. To test the grouting effect, core inspection holes were arranged around  
Figure 16: Stratographic displacement pattern at the location of the fault fracture zone.  
Figure 17: Structural stress calculation cloud map. (**a**) Axial force cloud of cable structural unit at the location of the fault fracture zone. (**b**) Axial force cloud of beam structural unit at the location of the fault fracture zone.  
the original drilling core location after grouting was completed. The depth of the inspection holes was consistent with the grouting depth. By taking cores from the inspection holes, it was found that a complete stone body with a length of about 10 cm could be obtained in the grouting area. The core sampling results indicate that defects such as cracks and voids have been effectively filled, and the overall integrity of the grouted stone body has been significantly improved. The compression test was conducted on the complete core sample, and the results showed that the consolidation strength of the slurry exceeded 0.4 MPa. The average compressive strength of the rock mass after 28 days reached 7.8 MPa, meeting the requirement of not less than 5.8 MPa in the specifications and achieving the purpose of grouting. The schematic diagram of the grouting filling effect during construction is shown in Figure 18a.  
To assess the impact of grouting on TBM excavation performance, excavation parameters from the grouting section were compared with those from adjacent sections with favorable geological conditions. The main comparison between cutterhead speed and cutterhead thrust for the two sections is shown in Figure 19.  
Figure 19 shows that in the normal section with intact surrounding rock, the TBM cutter head speed is maintained at 5-7 r/min, with cutter head thrust between 14,000 and 18,000 kN. In the surface pre-grouting section, the cutter head speed increases significantly, ranging from 3 to 6 r/min, while thrust drops to 6000-9000 kN. To prevent TBM jamming from excessive thrust, both speed and thrust are reduced when entering the pre-grouting section. As excavation progresses, both speed and thrust generally increase, positively  
Figure 19: Comparison of parameters.  
Figure 18: On-site verification of grouting effect. (**a**) Post-construction grouting and filling effect in Case IV. (**b**) Grouting effect revealed during TBM digging process.  
correlating with the surrounding rock's strength and integrity, indicating effective grouting reinforcement.  
To validate the numerical simulation, three test sections (K116 + 148, K116 + 440, and K119 + 460) were set up in the YE tunnel. Deformation monitoring of the arch crown, waist, and bottom was conducted to verify the numerical model's calculation results, as shown in Table 5.  
Real-time monitoring of arch settlement and peripheral convergence was conducted in three sections: K116 + 148, K116 + 440, and K119 + 460. The monitoring data, shown in Figure 20, indicate no sudden deformation in the surrounding rock during excavation, with the deformation data eventually stabilizing, confirming a good pre-grouting effect on the tunnel surface. A comparison of the data reveals that the numerical simulation predicted an arch settlement of 7.32 mm, while the measured value was 9.14 mm, resulting in a 19% error. For the arch waist deformation, the error was 15%, and for the bottom slab uplift, it was 13%. Overall, the errors were all below 20%, demonstrating that the numerical simulation design is reasonably accurate.