The Convergence Confinement Method (CCM) is a 2D simplified approach for resolving 3D rock-support interaction problems associated with the installation of support near a tunnel face in underground excavations. Some authors have recently put forward the idea that the behaviour of the face played a very relevant role in tunnel stability, so some new approaches to tunnel design and construction are appearing based on the study of the tunnel face. Apparently, the CCM cannot analyse these top-ics. However, the authors have observed that there is a relationship between the be-haviour of a tunnel section and the behaviour of the tunnel face. Accordingly, the authors have modelled a number of tunnel excavation processes by means of numerical modelling to study these relations. In this way, the authors have selected a series of rock masses with various rock mass behaviour properties (various rock mass qualities) and have run 2D-axisymmetric and 3D models of tunnel behaviour controlling variables such as the extent of the plastic zone around the tunnel section and in front of the tunnel face and the displacements in the tunnel section and in the centre of the tunnel face. Analysing the obtained results, expressions can be fitted that relate tunnel deformation in the spring-line to tunnel deformation in the face–or tunnel extrusion, as well as relationships between the plastic area extent around the excavation and in front of it.
The convergence-confinement method (CCM) is a method that focuses on the analysis of the stress-strain problems in tunneling. It provides a general even if simplified esti-mate of the nature of the interplay between the rock and the support installed at a dis-tance from the face. The face itself carries a significant portion of the load in its surroundings.