ABSTRACT
Shield tunneling beneath existing shield tunnel is a common recurring problem. Excessive settlement and severe disease might occur for the existing tunnel if no appropriate countermeasure is adopted. Evolution of the upward soil arching induced by the shield tunneling is a key factor influencing the responses of the existing tunnel. This research develops a theoretical model to describe the developing upward soil arching associated with the magnitude of ground volume loss. Furthermore, the theory for depicting the interaction between the soil arching and existing shield tunnel is proposed. The nonlinear bending and shearing stiffness of the assembled tunnel is considered. Technologies regarding deformation control for the overlying existing shield tunnels are suggested by mitigating the expansion of the loosened zone and reinforcing the loosened zone. Finally, engineering applications of the technologies are also introduced.
