Convergence-confinement approach for designing tunnel face reinforcement by horizontal bolting

The ground reinforcement by bolting is a technique in strong development. Bringing a perennial supplement of resistance to the ground, this technique permits to use poor grounds in a sensitive environment. It can be particularly, used for the reinforcement of tunnel faces.The full numerical simulation of such works remains a heavy and expensive process, notably in terms of geometrical complexity and various scale levels. During the preliminary project stage, it appears necessary to have simplified models, making possible to simply appreciate the effectiveness of the reinforcement.The existing simplified methods being not well adapted for the optimal conception of these reinforcement systems, a new method based on the convergence confinement approach is proposed and tested in this paper.

► Validation of 3D numerical calculations on the maximum displacement of the tunnel face.
► Proposition of a convergence-confinement type method for the design.
► The confinement brought by the reinforcement can be reasonably summarized by a single curve.
► Easy use for the design of reinforced tunnel by horizontal bolts.