Integrating FBN and FDS for quantitative risk assessment of cable fire in utility tunnel

The highly integrated underground utility tunnel (UUT) is a kind of critical infrastructure for process clusters and cities. However, this integration inevitably entails potential risks, including gas leakage, explosions, cable fires, and the accumulation of toxic gases within sewage pipes, and the concern regarding cable fires supersedes others due to their multifactorial correlations and severe consequences. Especially in utility tunnels within chemical industrial parks, cable fires can precipitate the shutdown of equipment, potentially culminating in grave incidents such as chemical leaks or uncontrolled reactions, owing to failures in control systems. This paper presents a novel dynamic risk assessment model for cable compartment fire in UUTs, integrating the Fuzzy Bayesian Network (FBN), Fire Dynamic Simulator (FDS). By employing sensitivity analysis and vulnerability path analysis techniques within the FBN framework, critical hazards associated with cable compartment fires are identified. Subsequently, a comprehensive FDS analysis is conducted for a standardized UUT cable compartment fire consequence, considering the chain response of the safety barriers. The obtained results reveal that even with normal safety barrier response, the risk in the early stage of a fire cannot be disregarded. Notably, among various safety barrier failure scenarios, the failure of a single fire door has the lowest integrated risk, while sensor failure may lead to a higher peak of integrated risk, as well as a higher average integrated risk due to sprinkler failure. The results indicate that the proposed model can offer practical supports in accident mitigation, risk management, and safety barrier optimization of cable compartments in UUTs.