## 2 Statistical Analysis for the Determination of Operating Parameter Requirements
### Estimation of Requirements for Operating Parameters
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{2}{c}{**Variable Type**} & \multicolumn{1}{c}{**Variable Name**} & \multicolumn{1}{c}{**Symbol**} & \multicolumn{1}{c}{**Note**} \\ \hline \multirow{4}{*}{Dependent variable (Output variables)} & \multicolumn{2}{c}{Thrust requirement} & \(y_{1}\) & \\ \cline{3-5}  & & \multicolumn{1}{c}{Cutterhead torque} & \(y_{2}\) & Unit: \% \\ \cline{3-5}  & & \multicolumn{1}{c}{Requirement} & \(y_{3}\) & \\ \cline{3-5}  & & \multicolumn{1}{c}{Rotation speed requirement} & \(y_{3}\) & \\ \cline{3-5}  & & \multicolumn{1}{c}{Advance rate requirement} & \(y_{4}\) & Unit: mm/min \\ \hline \multirow{4}{*}{Independent variable (Input variables)} & \multirow{4}{*}{Qualitative variable} & Boulder and cobble & \(S_{1}\) & If a variable is present, its corresponding value is set to 1, otherwise 0 \\ \cline{3-5}  & & \multicolumn{1}{c}{Clay} & \(S_{3}\) & \\ \cline{3-5}  & & \multicolumn{1}{c}{} & & \\ \cline{3-5}  & & \multicolumn{1}{c}{} & & \\ \cline{3-5}  & & \multicolumn{1}{c}{} & & \\ \cline{3-5}  & & \multicolumn{1}{c}{} & & \\ \cline{3-5}  & & \multicolumn{1}{c}{} & & \\ \cline{3-5}  & & \multicolumn{1}{c}{} & & \\ \cline{3-5}  & & \multicolumn{1}{c}{} & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Dependent and independent variables used for multiple regression to estimate four operating parameters. Figure 3: Verification of regression equations for soil excavation. Estimations of the required (**a**) thrust, (**b**) cutterhead torque, (**c**) rotation speed, and (**d**) advance rate. Figure 2: Results of multiple regression analysis for soil excavation. Estimations of required (**a**) thrust, (**b**) cutterhead torque, (**c**) rotation speed, and (**d**) advance rate. Table 2 summarizes the regression equations estimating the operating parameters for soil excavation. The estimated operating parameters will vary with the soil conditions. As the soil type changes from \"boulder and cobble\" to \"clay\" through \"gravel, sand, and silt,\" the estimated thrust and cutterhead torque requirements decrease. In contrast, the estimated rotation speed and advance rate requirements increase gradually. If the ground is composed of more than two soil types, the intensity of the variation should be higher. Overall, the soil type substantially affects the estimation of operating parameters during soil excavation. Operating parameters should be estimated differently depending on the TBM type. The thrust and cutterhead torque requirements for an EPB TBM are estimated to be higher than those for a slurry TBM. The TBM's diameter also influences its estimated operating parameters. The estimated thrust and cutterhead torque requirements increase with increasing diameter, whereas the estimated rotation speed and advance rate requirements decrease. The estimated thrust and cutterhead torque requirements increase as the ratio of their maximum values increases. All operating parameters are expected to decrease as the maximum capacity of the rotation speed increases. However, more data should be acquired to estimate the operating parameters. Statistical Analysis for the Determination of Interactions between Operational Actions and Mechanical Responses  
The operator closely monitors the TBM's operating parameters and controls its entire operation in response to them. The operating parameters can be divided into two types: operational actions and mechanical responses. After the six operational actions and ten mechanical responses were defined, their correlations were determined for use in the interaction system of the operating model.