Research and application for balance mechanism of excavation surface of slurry shield tunnel considering cutterhead thrust

In the existing balance mechanism of the excavation surface of slurry shield tunnels, the support of the excavation surface is mostly considered to be provided by mud pressure, and the role of cutterhead thrust in support is rarely mentioned. In response to the specific problems of excavation surface support in the Chuanqin slurry shield tunnel project, combined with the analysis of the main control parameters of excavation surface support, the balance mechanism of the excavation surface of the slurry shield tunnel considering the cutterhead thrust is revealed, and a specific expression of the cutterhead thrust is provided. Using the revealed equilibrium mechanism and a proposed method for estimating the external frictional resistance of the shield shell, the excavation support force and stability analysis were conducted for the three key crossing sections of the project. Research shows that in the excavation of the three key crossing sections, the cutterhead thrust accounts for 21%, 24%, and 11% of the excavation face support force, respectively; Considering both mud pressure and cutterhead thrust, the proportion of axial water and soil combined forces in the presence range in front of the excavation face increased from 0, 0, and 78% to 78%, 32%, and 88%, respectively, compared to only considering mud pressure. This indicates that cutterhead thrust plays an important role in excavation face support.