Impact of Partition Method in Pit Construction Adjacent to Existing Metro Shield Tunnel

In order to ensure the structural safety and normal operation of pit construction occurring adjacent to an existing metro shield tunnel, research on a longitudinal equivalent rigidity model of a shield tunnel was performed to establish the relationship between the tunnel's longitudinal deformation curvature and the bolt's bearing condition, and to set the requirements for a normal operation of the track. Subsequently, the actual engineering conditions of a particular deep-large pit in Shenyang, which is adjacent to an existing subway shield tunnel, were used to create a three-dimensional numerical analog. By changing the spatial position of the newly constructed pit near the existing shield tunnel with pile-anchor support, zoning charts were drawn and divided into zones of strong, weak, or no influence. Settlement measured in the field confirmed the efficiency of zoning standards based on influence and control technology. The results show that the longitudinal deformation curvature of the shield tunnel is the key index for determining the safety and normal operation of pit construction adjacent to the existing metro shield tunnel. Consequently, the tunnel's longitudinal deformation curvature can be used as a zoning standard for the influence of the adjacent subway shield tunnel. Finally, the critical state of the track alignment and the longitudinal deformation curvature of the tunnel joint within the limit state can be used to define the thresholds for zoning charts divided into zones of strong, weak, and no influence.