Influence of Back-Support Shear Wall for Shield Launching on the Mechanical Characteristics of the Reaction Frame

Objective Due to the limited space available at the shield launching site, the restricted size of the reaction frame cannot provide sufficient shield launching reaction force on its own. Therefore, it is necessary to design and install a back-support structure for the reaction frame to achieve synergistic stress between the two. Method Taking a project on Shanghai Airport Link Line as the background, the finite element analysis method is adopted to systematically study the connection method between the reaction frame and the shear wall, and the influence of the shear wall longitudinal length, thickness and height on the stress and deformation of the reaction frame structure is analyzed. Through simulation, the optimal connection method between the reaction frame and the shear wall, as well as the optimal size combination of the shear wall are screened out. Result & Conclusion The reaction frame and the shear wall are connected in a close-fitting manner to avoid the transmission of bending moment by the fitting surface of the reaction frame and the permanent structure, which has less influence on the permanent structure and can effectively release the bending moment at the unfavourable parts of the reaction frame, making the stress of the reaction frame more reasonable. As the longitudinal length of the shear wall increases, the stress and deformation capacity of the reaction frame and shear wall structure can be significantly improved; the change in the thickness of the shear wall has less influence on the stress and deformation of the reaction frame, but to some extent it can enhance the stress of the shear wall itself and reduce the deformation. The height of the shear wall has a very significant influence on the stress and deformation of the reaction frame and the shear wall structure. When the height of the shear wall is less than 13.5 m, because the top of the wall is not anchored into the center plate, resulting in the unfavorable state for the stress and deformation of the reaction frame and shear wall itself.