A methodology for evaluating the safety resilience of the existing tunnels induced by foundation pit excavation

The development of multifunctional and three-dimensional underground spaces is an effective approach to expanding human activity spaces in future megacities. It significantly enhances urban carrying capacity, disaster resilience, and robustness, reduces carbon emissions, and promotes harmonious coexistence between humans and nature. A methodology for evaluating the safety resilience of the existing tunnels induced by foundation pit excavation is proposed in this paper. Considering the technological and management factors, a detailed resilience index system is suggested. The composite performance Q of the studied system is consistently calculated by virtue of the combined weight method and the TOPSIS method. Specifically, the proposed Q is determined by the combination of Q_A (existing underground structures), Q_B (stratum), and Q_C (adjacent construction disturbance), each with different weights. Furthermore, a comprehensive assessment of resilience R is proposed from the perspective of maximal and cumulative damage in Q. The evaluation method was conducted on an engineering project, and the effects of the three-dimensional component of Q and the deformation limits of existing structures on the evaluation results are analyzed emphatically. The results indicate that as the deformation limits of existing structures become more strict, the Q and R decrease. The methodology proposed in this paper provides essential information for the safety resilience assessment and resilience enhancement of underground structures.