Safety Risk Immunization Strategies for Subway Shield Construction in Water-Rich Silty Fine Sand Layers: A Complex Network Approach

To mitigate safety risks in subway shield construction within water-rich silty fine sand layers, a risk immunization strategy based on complex network theory was proposed.Safety risk factors were systematically identified through literature review and expert consultation, and their relationships were modeled as a complex network.Unlike traditional single-index analyses, this study integrated degree centrality, betweenness centrality, eigenvector centrality, and clustering coefficient centrality to comprehensively evaluate the importance of risk factors.Results indicated that targeted immunization strategies significantly outperformed random immunization, with degree centrality (DC) and betweenness centrality (BC) immunization demonstrating the best performance.Key risk sources included stratum stability, allowable surface deformation, surface settlement monitoring, and shield tunneling control.Furthermore, the optimal two-factor coupling immunization strategy was found to be the combination of DC and BC strategies, which provided the most effective risk prevention.This study is the first to apply complex network immunization simulation to safety risk management in subway shield construction, enhancing the risk index system and validating the impact of different immunization strategies on overall safety.The findings offer scientific guidance for risk management in complex geological conditions and provide theoretical support and practical insights for improving construction safety.