Analysis Method and Design Charts for Bolt Reinforcement of the Tunnel Face in Purely Cohesive Soils

The present paper proposes a limit equilibrium method for the stability analysis of reinforced tunnel faces in purely cohesive soils exhibiting constant or depth-dependent undrained shear strength. The method can be applied to arbitrary reinforcement layouts in relation to bolt spacing and length. The computational predictions are compared to the results of other models and numerical stress analyses in terms of the so-called load factor. Finally, design nomograms are presented that provide a rapid assessment of the stability of uniformly reinforced faces in soils with constant or depth-dependent undrained strength.