Shield Tunnel

       As China continues its rapid pace urbanization, traffic jams and the deterioration of living conditions have become one of the most severe problems for the cities like Shanghai. The saturated development of the middle-shallow soil layers results in the need to build tunnels deeper with larger earth pressures and construction risks. Tunnel boring machines (TBM), which are always used in the excavation of soft soil in cities, are going through more challenges. Occasionally TBMs get stuck due to large deformation of tailskin, so understanding the mechanic property of tailskin is critical.
Research contents mainly include,
       (1) Loading models based on specification for different countries.
       (2) Calculation method of tailskin concerning the initial imperfection.
       (3) Reduction of tailskin strength caused by the structure of tailskin.
       (4) Reduction of tailskin strength and stability caused by grouting pressure and tail grease.


Figure 1 Mixshield manufactured by Herrenknecht


Figure 2 section drawing of shield machine (tailskin is circled in red)
1- cutter head 2-cutter drive 3-shield 4-cylinder 5-workshop 6-segment erector


Figure 3 Von-mises stress distribution graph of tailskin concerning initial imperfection and structure of tailskin

Copyright Tongji University Copyright Tongji University News Center, 2012