## 3 Result and Analysis
### TBM Selection Decision-Making
\begin{pmatrix}0.1016&0.1016&0.0722&0.325&0.1691&0.1524&0.0781\\ 0.0508&0.0508&0.0361&0.1625&0.08455&0.0762&0.03905\\ 0&0&0&0&0&0&0\\ 0.0762&0.1016&0.05415&0.24375&0.126825&0.0762&0.058575\end{pmatrix} \]  
Step 3. Calculate the distance between the positive and negative ideal solutions. Through Equations (11)-(13), the distance of the positive and negative ideal solution is obtained (see Table 19). Step 4. TBM selection decision-making. Using Equation (13), the closeness vector of project 1 is [0.8, 0.409188, 0, 1], \(E_{1}=0.8\), \(E_{2}=0.409188\), \(E_{3}=0\), \(E_{*}=1\) and \(E_{*}>E_{1}\). Open TBM construction is recommended for the TBM selection decision-making model. The closeness vector of project 2 is [1, 0.5, 0, 0.456063], \(E_{1}=1\), \(E_{2}=0.5\), \(E_{3}=0\), \(E_{*}=0.456063\) and \(E_{*}\in(E_{2},E_{3})\). Single-shield TBM construction is recommended for the TBM selection decision-making model. The closeness vector of project 3 is [1, 0.5, 0, 0.720969], \(E_{1}=1\) \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & & & & & & & \\ \hline Project 1 & 0.088365 & 0.35346 & 0.255175 & 0.17673 & 0.429985 & 0 & 0 & 0.429985 \\ Project 2 & 0 & 0.435205 & 0.217602 & 0.217602 & 0.435205 & 0 & 0.241131 & 0.202175 \\ Project 3 & 0 & 0.435205 & 0.217602 & 0.217602 & 0.435205 & 0 & 0.124689 & 0.322176 \\ \hline \hline \end{tabular}
\end{table} 
Table 19: Positive and negative ideal solution distance. \(E_{2}=0.5\), \(E_{3}=0\), \(E_{*}=0.720969\) and \(E_{*}\in(E_{1}\), \(E_{2})\). Double-shield TBM construction is recommended for the TBM selection decision-making model. The geological condition of Project 1 is good. The rock mass is a medium-hard rock with excellent integrity. The open TBM can be driven quickly in this stratum and it is difficult to collapse the face. In terms of adverse geology, there are few rock bursts, water inrush and fault fracture zones, which can ensure the normal excavation of open TBM. In some areas, there is large deformation of the surrounding rock. In this type of terrain, open TBM jamming can be avoided by simply accelerating through. The turning radius of the tunnel is small, and open TBM can normally pass through. To sum up, Project 1 is suitable for open TBM construction. The geological condition of Project 2 is poor. The rock mass is broken soft rock. The single-shield TBM can safely tunnel in this stratum, and the shield can provide protection when the tunnel sides and vault collapse. In terms of adverse geology, there are many small rock bursts, water inrush and fault fracture zones. Single-shield TBM can ensure normal tunnelling. Large deformation of the surrounding rock is lower, the risk of shield jamming is low, the turning radius of the tunnel is moderate, and single-shield TBM can pass through normally. To sum up, Project 2 is suitable for single-shield TBM construction. The geological condition of Project 3 is good, the rock mass is relatively complete medium hard rock, and the open TBM and double-shield TBM can safely excavate in this stratum. However, there are many rock bursts, water inrush and fault fracture zones, and the open TBM is inefficient in tunnelling in this type of stratum. The selection of double-shield TBM can ensure normal tunnelling. The surrounding rock has less large deformation and the risk of shield jamming is low. The turning radius of the tunnel is large, and the double-shield TBM can pass through normally. To sum up, Project 3 is suitable for double-shield TBM construction. The TBM decision-making model proposed in this paper is consistent with the actual situation, which proves that the decision-making model in this paper has a good decision level.