Abstract: A new method based on Pair-Copula Bayesian network (PCBN) model is proposed to accurately evaluate the interaction risk of shield tunneling underneath an existing tunnel. First, a relatively perfect risk evaluation system is established for shield tunneling underneath existing tunnels. Second, the uncertain reasoning of the Bayesian network model is enhanced using Copula theory to deal with correlations, establishing a PCBN model of construction risk evaluation for shield tunneling underneath the existing tunnel, thus realizing the accurate modeling of complex dependent relations of risk factors and providing a practical safety analysis and management of shield tunneling adjacent to buildings/structures. Finally, the model is implemented on a shield tunnel crossing underneath an existing tunnel to conduct risk and index correlation analysis. The results show the construction risk state of the project and critical risk factors highly correlated with the construction risk and verify the effectiveness and rationality of the proposed evaluation method.

Key words: shield tunnel, underpass construction, existing tunnel, safety risk, Pair-Copula Bayesian model, risk assessment, key risk factors