## 7 Conclusions  
The variable weight theory is introduced to enhance and modernize the risk assessment process for tunnel TBM construction. This modification aims to address evaluation deviations caused by fluctuating index values, ultimately improving the accuracy and applicability of the evaluation method. Additionally, fuzzy analysis is utilized to demonstrate that changes in construction risk index values directly impact the weight factor. The degree of influence of different indicators on risk assessment results when values change is analyzed, aiding in identifying the most important indicators. The key findings can be summarized as follows:  
1. The WBS-RBS method is utilized to establish a comprehensive risk evaluation index system for TBM construction sections, which compensates for the shortcomings of risk identification that may result in omissions and incomplete identification in expert evaluation methods. This results in a more refined risk evaluation index system that can comprehensively reflect the actual risks at all levels of TBM construction. Furthermore, this approach fully considers the randomness and fuzziness of the risk grade boundary values while directly utilizing original engineering data, thereby avoiding data normalization processes and reducing information loss possibilities. 2. The method mentioned in the original text applies a variable weight theory based on the extensible model of physical elements, incorporating both subjective and objective evaluation factors, namely, the analytic hierarchy process (AHP) and an improved variable weight theory. This approach takes into consideration the impact of indicator value volatility on indicator weights, thereby accounting for fluctuations in traditional fixed weights. By employing this model to assess the risk of eight tunnel sections in the KS Tunnel, more precise results are obtained compared to utilizing the traditional method with fixed weights. 3. It is evident from the importance analysis that the change in rock mass classification during TBM excavation has a significant impact on the risk assessment of tunnel TBM construction, while the influence of the guidance monitoring system is relatively minor. This is not only because a TBM is a large-scale equipment integrating multiple functions, but also because, when evaluating the construction risk of a TBM, its own ability to deal with risks and the effectiveness of on-site construction management should also be taken into account. By considering these factors in the model's calculations, the model can be made more closely aligned with reality, and the results will be more accurate. 4. The modified variable weight matter-element extension model is used to evaluate the risk of eight TBM construction sections of the KS tunnel, and the comparison and analysis with the traditional risk assessment model are carried out to verify the reasonability and feasibility of constructing the new model. The risk evaluation based on the KS tunnel verifies that the new model has good operability in the risk analysis of TBM construction. 5. In application, a series of strategies can be adopted to optimize the model: firstly, the model is applied in a small range of engineering sites to improve the application ability of the model; secondly, the data system is optimized to ensure the comprehensiveness and immediacy of the data required by the model. We hope that this model can be promoted in more infrastructure construction projects in the future to further verify its universality and reliability. **Author Contributions:** Conceptualization, T.F. and K.S. ; methodology, R.S. ; resources, Z.L. ; data curation, J.Z. ; writing--original draft preparation, K.S. ; writing--review and editing, T.F. All authors have read and agreed to the published version of the manuscript. **Funding:** This research received no external funding. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.