13- Phased excavation of a shield tunnel GSE

The lining of a shield tunnel is often constructed using prefabricated concrete ring segments, which are bolted together within the tunnel boring machine to form the tunnel lining. During the erection of the tunnel lining the
tunnel boring machine (TBM) remains stationary. Once a tunnel lining ring has been fully erected, the excavation is resumed until enough soil has been excavated to erect the next lining ring. As a result, the construction process can be divided into construction stages with a length of a tunnel ring, often about 1.5 m long. In each of these stages, the same steps are repeated over and over again.
In order to model this, a geometry consisting of slices (or sections) each 1.5m long can be used. The calculation consists of a number of Plastic phases, each of which models the same parts of the excavation process: the
support pressure at the tunnel face needed to prevent active failure at the face, the conical shape of the TBM shield, the excavation of the soil and pore water within the TBM, the installation of the tunnel lining and the grouting of the gap between the soil and the newly installed lining. In each phase the input for the calculation phase is identical, except for its location, which will be shifted by 1.5m each phase.
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