A new concept was recently introduced for the design of shaft-tunnel junctions on the Greater Cairo metro system, whereby no ground improvement and no crosspassages are necessary. The principle lies in driving the TBM to intercept a circular slurry wall. The shaft can then be excavated in several stages, allowing for the construction of a concrete portal. While this approach entails savings, it requires adequate detailing of re-bars and shear connectors. Advanced 3D numerical modelling is used to assess structural forces for design. This example illustrates how advances in construction methods can be stimulated through improvements in the analytical tools.
展开▼
