## 4 Analysis of the Effect of TBM Crossing Fault Fracture Zone Under Different Treatment Methods  
### Calculation Condition Setting  
To ensure the safe and efficient crossing of fault zones by TBM, four treatment measures are proposed for discussion and analysis, starting from two methods of treatment inside and outside the tunnel. These four treatment measures correspond to four working conditions:  
Figure 4: Schematic diagram of grouting effect after TBM passes through. (After the TBM passage, the figure clearly shows that the rock fractures have been effectively filled, the cross-section is smooth and even, and the surrounding rock conditions have been significantly improved). (**a**) Single-layer pipe shed grouting on site. (**b**) Site grouting of double-layer pipe sheds.  
Figure 5: Schematic diagram of TBM stuck theoretical model prediction. (Figure 5 shows TBM excavation data, with the red area indicating the jamming warning zone. When the cutterhead torque reached 4200 kN/m, the TBM entered the warning zone, causing jamming. There is a high risk of jamming at location 1 in the gully, requiring urgent analysis of pre-reinforcement schemes for Gully 2).  
Condition I involves chemical grouting of the palm face, grouting of the deep pipe shed, and grouting of the shield tail small conduit, as shown in Figure 6a. Condition II is the grouting of the pipe shed (control group), as shown in Figure 6b. Condition III is the construction of a double-layered pipe shed for grouting in a manually expanded pilot tunnel, as shown in Figure 6c. Condition IV is surface pre-grouting, as shown in Figure 6d.e. Analyze the treatment effects of the above four working conditions through numerical analysis. The detailed parameter settings for the above operating conditions are listed in Table 2.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{Case I} & Reinforcement & Grouting Pipe & \multirow{2}{*}{Spacing} & \multirow{2}{*}{Note} \\  & depth & Diameter & & & \\ \hline Shallow hole chemical & & & & & \\  & grouting on palm face & & & & \\  & Deep pipe shed & & & & \\  & grouting & & & & \\  & Shield tail small & & & & \\  & conduit grouting & & & & \\ \cline{2-5}  & \multirow{2}{*}{Case II (control group)} & Reinforcement & \multirow{2}{*}{Diffusion Radius} & \multirow{2}{*}{Spacing} & \multirow{2}{*}{Note} \\  & depth & & & & \\ \hline Pipe Shelter Grouting & & & & & \\ \hline Case III & Number of layers & & & & \\  & of pipe scaffolding & & & & \\ \cline{2-5}  & Hand-expanded & & & & \\  & double-layer pipe shed & & & & \\ \hline \multirow{4}{*}{Surface Grouting} & \multirow{2}{*}{Case IV} & Reinforcement & Grouting Pipe & \multirow{2}{*}{spacing} & \multirow{2}{*}{diffusion radius} \\  & area (H \(\times\) L \(\times\) W) & Diameter & & & \\ \cline{2-5}  & \multirow{2}{*}{Surface pre-grouting} & 16 m \(\times\) 60 m \(\times\) & \multirow{2}{*}{90 mm} & \multirow{2}{*}{1 m} & \multirow{2}{*}{0.65 m} \\  & & 22 m & & & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Working condition setting.  
Figure 6: Schematic diagram of four treatment measures for TBM passing through faults (working condition I: chemical grouting on the face of the tunnel + pipe shed + shield tail small conduit; working condition II: pipe shed; working condition III: double-layer pipe shed; working condition IV: surface grouting). (**a**) Case I. (**b**) Case II. (**c**) Case III. (**d**) Case IV.