## 4 Analysis of the Tunnel Construction Simulation Results
### Vault Settlement and Tunnel Perimeter Convergence  
The deformation surveying is carried out in the left tunnel and the right tunnel, and the deformation curve of each surveying point is obtained by analyzing the simulation results. B1 and B2 are the surveying points at the top of the tunnel, and S1, S2, S3, and S4 are the surveying points for the horizontal convergence of the tunnel. Data analysis is performed on the deformation around the tunnel at 0 m, 20 m, 40 m, and 60 m. The simulation at 0 m represents the tunnel opening excavation. The simulation at 20 m and 40 m represents the excavation process in the middle of the tunnel, and the simulation at 60 m represents the excavation at its end. The deformation curves of each surveying point of different excavation methods are obtained (Figure 6). It can be deduced that the roof subsidence is negative, and the horizontal convergence around the hole is also negative. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Material Properties**} & **Test Weight** & **Elastic Modulus** & **Poisson’s Ratio** & **Cohesion** & **Internal Friction** \\  & \(\boldsymbol{\gamma}\)**/KN**\(\cdot\)**m\({}^{-3}\)** & **E/MPa** & \(\boldsymbol{\mu}\) & **c/KPa** & **Angle** \\ \hline Fully weathered crushed rock & 19.7 & 7 & 0.3 & 12.6 & 16.2 \\ Strongly weathered rock & 23 & 500 & 0.3 & 20 & 33 \\ Medium weathered rock & 25 & 2000 & 0.25 & 200 & 35 \\ Initial support & 24 & 15,000 & 0.2 & / & / \\ Secondary lining & 22 & 31,500 & 0.3 & / & / \\ Anchor & 78.5 & 210,000 & 0.3 & / & / \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Material physical and mechanical parameters. Figure 5: Layout drawing of the separated tunnel surveying points. It can be seen from Figure 6 that the full-section method is the fastest one, and the CD and CRD methods have the same construction speed. The shapes of the vault settlement curves surveyed at different positions are different. More precisely, the surveying curve at 0 m is an inverse curve, while the settlement curves surveyed at 20 m, 40 m, and 60 m are first gentle, then sharp, and finally flattened. The curve at 60 m has the largest deformation rate because the deformation curve at the end of the tunnel excavation is simulated at 60 m. The settlement curve of the full-section method has the largest slope, and it is the most difficult to support, while the CD and CRD methods have relatively gentle settlement curves, which are relatively easy to support and the most favorable for the overall maintenance of the tunnel. The CRD excavation method has the smallest settlement, which presents its largest advantage. It is the most complicated in construction and excavation but the most favorable for the stability of the surrounding rock around the tunnel. The full-section method excavates the entire tunnel section, the stability of the surrounding rock is the most difficult to control, and the settlement is the largest. Through the analysis of the tunnel settlement map of different excavation methods, it is found the position of the maximum settlement of the vault occurs in the excavation of the full-section method, and the maximum settlement value is 13.7 mm. After the first part of the tunnel was excavated, the maximum settlement of the vault reached 5.04 mm, which accounts for 36.79% of the total settlement. When excavating 10 m back from the surveying point, the maximum settlement of the vault reached 11.3 mm, the settlement increased by 45.69%, and the stability of the surrounding rock was destroyed the most. The CRD method has the smallest excavation settlement of 12.2 mm. After the first part of the tunnel excavation, settling the tunnel vault reaches 1.74 mm, which accounts for  
Figure 6: Deformation diagram of tunnels with different excavation methods. 14.26% of the total settlement. After excavating 10 m back from the surveying point, the maximum settlement of the vault increased by 4.21 mm, and the settlement increased by 34.49%, which had the least impact on the stability of the surrounding rock.