Abstract: Subway network grows rapidly in many large cities. More and more subway lines will unavoidably cross over with the further network expansion. It is critical for the operational safety of the existing subway while constructing the new crossover subway tunnel. This paper presents the numerical analysis results of a cut and cover tunnel in south Nanjing over the existing subway. The bottom heave of the existing subway during the open cut construction is predicted. The construction sequence is optimized based on the numerical analysis results. The upheaval values from the numerical simulations are compared with the observed deformation during the construction and found they were consistent. It is concluded that the numerical analysis can provide valuable guidance during the design stage.

Key words: Cut and cover tunnels, Numerical analyses, Deep excavations, Predicted values, Unloading