# Deformation Analysis of the Rock Surrounding a Tunnel Excavated through a Gently Dipping Bed
## 4 Engineering Application
### Comparison of Measurements and Simulation Results  
Based on the comparison between the actual measured deformation values and the simulated values presented in the last section, the excavation of bedding planes with different bedding inclination angles (\(0^{\circ},30^{\circ},60^{\circ}\), and \(90^{\circ}\)) was carried out in a direction perpendicular to the direction of the tunneling. A schematic diagram of the bedding excavation is shown in Table 3.  
When the tunnel section was transfixed at the monitored points in both the entrance side and the exit side (y = 3 m, y = -3 m), the cumulative vault settlement was determined. The simulation results are shown in Figure 6:0 \begin{table}
\begin{tabular}{c c c} \hline
**Dip Angle** & **Ways of Penetration** \\ \hline
0\({}^{\circ}\) & Through excavation side & Stopping excavation side \\ \hline
30\({}^{\circ}\) & Through excavation side & Stopping excavation side \\ \hline
60\({}^{\circ}\) & Through excavation side & Stopping excavation side \\ \hline
90\({}^{\circ}\) & Through excavation side & Stopping excavation side \\ \hline \end{tabular}
\end{table} 
Table 3: Schematic diagram of the tunnel excavation. Table 4 shows the following results: (1) the excavation on the construction entrance side resulted in significant disturbance on construction exit side. The disturbance initially increased and then decreased as the bedding angle increased, and the peak value appeared in the case of a gentle dip (about 30\({}^{\circ}\)). Therefore, for tunnel construction in surrounding rock with gently dipping bedding, it is necessary to strengthen the control measures for surrounding rock deformation. (2) Through comparison of the final cumulative settlement percentage of the vault on both the construction entrance side and exit side, we found that, when adopting the join-through construction scheme, the temporary support of the construction exit side should be strengthened to ensure the deformation stability of the surrounding rock mass. Comparative Analysis of the Tunnel Excavation of CIS and Inverse Layers in Gently Inclined Surrounding Rocks  
It can be seen from Table 4 that the disturbance from the construction entrance side to the construction exit side of the gently inclined rock strata (0-30\({}^{\circ}\)) increased with the increase of the bedding dip angle, and the influence range of excavation in both the CIS layer (\(-\)30\({}^{\circ}\)) and inverse layer (30\({}^{\circ}\)) was investigated when the direction of the slowly inclined bedding plane was perpendicular to the tunnel boring direction. Table 5 presents a schematic diagram of the different excavation directions (CIS and inverse). Figure 12 shows the schematic diagram of excavation from 5 m rock pillars left on the construction entrance side to tunnel penetration. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Dip Angle**} & \multicolumn{4}{c}{**Settlement of Vault (cm)**} \\ \cline{2-5}  & **Through Construction Side** & **Stopping Construction** & \multirow{2}{*}{**Difference**} & \multirow{2}{*}{**Relative Difference**} \\  & **(y = 3 m)** & **Side (y = \(-\)3 m)** & & \\ \hline
0\({}^{\circ}\) & 16.5 & 26.7 & 10.2 & 61.82\% \\
30\({}^{\circ}\) & 9.82 & 19.5 & 9.68 & 98.57\% \\
60\({}^{\circ}\) & 7.54 & 13.3 & 5.76 & 76.39\% \\
90\({}^{\circ}\) & 7.92 & 13.6 & 5.68 & 71.72\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Cumulative vault settlement from the cross-section of the tunnel under the influence of different inclination angles. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Dip Angle** & **Ways of Penetration** \\ \hline
30\({}^{\circ}\) (inverse layer) & Through excavation side & Stopping excavation side \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Schematic diagram of through excavation cis-layer and inverse layer. Figure 13 shows the cumulative settlement of the tunnel vault when the rock mass pillar was either retained or excavated. The rock mass pillar was 5 m, which is about 0.5 times the tunnel span.