Analysis of Structural Interaction in Tunnels using the Convergence-Confinement Approach

The rock-support interaction in tunnels is studied through the use ofthe convergence–confinement method. The equations that characterize the behaviour ofthe most important support types are given together with a set of conceptual interaction schemes. As far as the behaviour of the support is concerned, reference is made to the ultimate limit state concept, which is widely used in civil engineering. This approach is linked to the classical convergence–confinement method. The interaction between the temporary support system and the final lining is dealt with, and the noteworthy case of presupport ahead of the face, followed by a further internal support (usually steel sets and shotcrete) is also included. Finally, the ‘ground reaction curve ofthe reinforced tunnel’, which allows one to analyse the interaction between the reinforcement around the tunnel and supports, is introduced.