Study on Lining Mechanical Behavior of Super Large Diameter Shield Tunnel during Segment Opening

The mechanical behavior and risks of the lining of the super large shield tunnel during segment opening are still unclear. In order to study the characteristics of the mechanical behavior of the lining of the super-large-diameter shield tunnel during segment opening, Take the cross-passage project of Hangzhou Zhijiang Road Water Conveyance Corridor and Road Improvement Project as the engineering background. The MIDAS finite element numerical calculation model of the opening on the double-track main tunnel lining is established. The influence of the opening size and support stiffness on the mechanical behavior of the lining is analyzed separately. The main conclusions are: (1) The maximum deformation of the lining when opening occurs in the middle area directly above the opening. It is necessary to strengthen the deformation monitoring of the segment in this area during construction to prevent excessive deformation or even damage and accidents; (2) The reduction of the opening area within a certain range and the increase of the stiffness of the temporary support can reduce the deformation of the lining after the opening. Based on the determined parameters of the main tunnel lining and opening, the stiffness of the temporary support can be increased to reduce the deformation of the lining opening; (3) Setting up temporary supports and increasing the stiffness of the temporary supports cannot affect the final deformation of the lining after the temporary supports are removed. Therefore, to stabilize the lining in the open area, it is necessary to rely on pouring ring beams.