3D advanced modelling of TBM excavation in squeezing rock conditions

The design analysis of tunnels to be excavated with Tunnel Boring Machines (TBMs) requires the study of the complex interaction between the rock mass, the tunnel machine and its system components, and the tunnel support. A 3D advanced model which considers all these components, as recently developed by the Rock Mechanics and Rock Engineering Group at Politecnico di Torino, will be illustrated in this lecture. Modelling is carried out by using the Finite Element Method (FEM) and with reference to the specific advanced features of the Double Shield Universal TBM. As a case example, the excavation of the Lyon-Turin Base Tunnel when crossing the Carboniferous Formation in squeezing conditions is considered. Reference is made to the characterization studies and the suite of monitoring data obtained during the excavation of the Saint Martin La Porte access adit in the same rock formation. The application of the newly developed 3D simulator to such a case will be described and the results obtained in terms of the key design parameters will be illustrated.

Keywords:

Mechanized excavation , Shielded TBMs , 3D modeling , Squeezing conditions , Lyon-Turin Base Tunnel , Carboniferous Formation