Abstract: Shielded tunnel excavation adjacent to the foundation deep excavation might induce the adverse effect to the safety of excavation supporting structures; on the other hand, the foundation and supper structure construction might also affect the deformation of the excavated tunnel. To maintain the safety of the tunnel excavation, the effect of deep excavation on the underlying shielded tunnel was evaluated. These study aspects include: 1) the effect of shielded tunnel excavation on bottom of the foundation excavation area as well as the supporting structures was analyzed by using finite element method. The results indicate that, if the shielded tunnel excavation is directly underneath the deep excavation, the deformation at the bottom of the deep excavation will be greatly affected; whereas, if the shielded tunnel is excavated beside the foundation excavation, the supporting structure of the deep excavation will then be influenced. 2) The influence building structure on the shielded tunnel construction was also investigated and it was concluded that the weight of the superstructure is carried by the pile foundation and the impact on the tunnel excavation is minimal. 3) When the deep excavation and the shielded tunnel is vertically aligned, proper construction sequence is needed to ensure the safe excavation of both the tunnel and the excavation.

Key words: foundation pit, underlying shield tunnel, deformation, interaction