Tunnels are obviously among the most difficult civil works to design because of the many uncertainties to deal with and their three-dimensional character. A comprehensive evaluation of the ground behavior at the excavation face of is highly important for the design and for the selection of the excavation method. It is the subject of this lecture, based on the experiences from various works in France and abroad.

I shall mainly consider deep tunnels driven in difficult ground conditions, I mean tunnels with an overburden such that the initial stresses may bring
about failures or large displacements at the excavation wall.

As a guideline I shall refer to the Convergence-Confining Method (CV-CF Method) which has become very popular at least at a preliminary stage of design analysis. The CV-CF Method stems from former studies of the interaction between the ground and the support conducted by Fenner and Pacher, but it became operational in considering the displacement which occurs before the installation of the support at some distance from the face (M. Panet, P. Guellec, 1974). The CV-CF Method was first codified by the French Tunneling Association (AFTES) in 1979.