## 5 Drift Support Analysis
### Numerical Simulation
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Location** & **Stand-Up Time** & **Q** & **RMR** & **Actual Installed** \\ \hline \multirow{3}{*}{\(-915\) m} & \multirow{3}{*}{One week\(\sim\)one month} & \multirow{3}{*}{Unsupported} & \multicolumn{3}{c}{Systematic bolt length 4 m,} & Systematic bolt length 2.2 m, spacing 1.5–2 m, shotcrete 50–100 mm on crown and 30 mm on wall} & \multicolumn{3}{c}{spacing 1.5 m, shotcrete 100 mm on crown and 50 mm on wall} \\  & & & & Local supporting, bolt length 3 m on crown, spacing 2.5 m, 50 mm concrete is sprayed on the partial crown & Systematic bolt length 2.2 m, spacing 2.0 m, shotcrete 50 mm on crown and wall} \\ \hline \multirow{3}{*}{\(-960\) m} & \multirow{3}{*}{Ten hours–one day} & \multirow{3}{*}{Transpiration by spacing 1.6 m, unreinforced shotcrete, 4 cm–10 cm} & \multicolumn{3}{c}{The whole drift is supported by anchor net, systematic bolt length 4–5 m, spacing 1–1.5 m, shotcrete 100–150 mm on crown, shotcrete 100 mm on medium steel bracket, spacing 1.5 m} & \multicolumn{3}{c}{The whole drift is supported by anchor net, systematic bolt length 2.2 m, spacing 1.0 m, shotcrete 100 mm on medium steel bracket, spacing 1.5 m} & \multicolumn{3}{c}{The whole drift is supported by anchor net, systematic bolt length 2.2 m, spacing 1.0 m, shotcrete 100 mm on medium steel bracket, spacing 1.5 m} & \multicolumn{3}{c}{The whole drift is supported by anchor net, systematic bolt length 2.2 m, spacing 1.0 m, shotcrete 100 mm on medium steel bracket, spacing 1.5 m} & \multicolumn{3}{c}{The whole drift is supported by anchor net, systematic bolt length 2.2 m, spacing 1.0 m, shotcrete 100 mm on crown and wall} \\ \cline{3-8}  & & & & The whole drift is supported by anchor net, systematic bolt length 4–5 m, spacing 1–1.5 m, shotcrete 100–150 mm on medium steel bracket, spacing 1.5 m & \multicolumn{3}{c}{The whole drift is supported by anchor net, systematic bolt length 2.2 m, spacing 1.0 m, shotcrete 100 mm on crown and wall} \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Recommended and actual installed support systems. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Study Area**} & \multirow{2}{*}{**Parameters**} & \multicolumn{5}{c}{**Pre-Supported Condition**} & \multicolumn{5}{c}{**Post-Supported Condition**} \\ \cline{3-10}  & & **Roof** & **Left** & **Right** & **Totals** & **Roof** & **Left** & **Right** & **Totals** \\ \hline \multirow{2}{*}{\(-915\) m} & Plastic zone depth (m) & 2.617 & 0.909 & 0.849 & - & 1.318 & 0.681 & 0.661 & - \\  & Plastic zone area (m\({}^{2}\)) & 10.673 & 2.054 & 2.001 & 14.728 & 3.392 & 1.231 & 1.223 & 5.846 \\ \hline \multirow{2}{*}{\(-945\) m} & Plastic zone depth (m) & 1.455 & 0.619 & 0.574 & - & 0.939 & 0.478 & 0.418 & - \\  & Plastic zone area (m\({}^{2}\)) & 5.873 & 1.336 & 1.347 & 8.556 & 2.854 & 1.070 & 1.027 & 4.951 \\ \hline \multirow{2}{*}{\(-960\) m} & Plastic zone depth (m) & 5.027 & 1.527 & 1.536 & - & 1.911 & 1.056 & 1.044 & - \\  & Plastic zone area (m\({}^{2}\)) & 30.762 & 5.090 & 5.537 & 41.389 & 7.695 & 2.424 & 2.497 & 12.616 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Detailed information on RS2 analysis. Figure 8: Comparison of plastic zones in the study area before and after support was implemented. To further analyze the reliability of the support system, the factor of safety for the drift is defined as the ratio of the bearing capacity of the support system to the total effective load of the surrounding drift. For example, if a drift is supported by rock bolts only, with a single rock bolt exhibiting a bearing capacity of 10 t and rock bolt spacing of 1 m \(\times\) 1 m, the total effective load on 1 m\({}^{2}\) of the surrounding drift is 5 t; thus, the factor of safety is 2. In theory, a factor of safety exceeding 1 may provide stability under load conditions. For temporary drifts, drift is considered unsafe when the FS is less than 1.2. For permanent drifts, drift is considered unsafe when the FS is less than 1.5.