Abstract: The deep buried tunnels are the fundamental and dominating projects in the implementation of transportation routes, they have been developing rapidly and vigorously in the last decade. At present, the failure criterion of rock mass adopted in the elasto-plastic analysis of a circular opening is the Hoek–Brown strength criterion, in which only the maximum and minimum principal stress are considered. Obviously, the Hoek-Brown strength criterion is not compatible with the rock mass of a deep buried tunnel which bears high-level three-dimensional geostresses. On the basis of numerical procedure proposed by Lee and Pietruszczak, the deformation and stresses considering the generalized Zhang-Zhu strength criterion(GZZ) of rock mass around a circular opening are analyzed in this paper. It is found that the tunnel wall displacement and plastic radius are reduced, and both of the radical stress and hoop stress in the plastic zone are increased. It is also proved that a greater intermediate principal stress coefficient leads to higher stresses. Compared to another approach, theoretical solutions considering the effect of out-of-plane stress, the tunnel wall displacement calculated by GZZ strength criterion is reduced by 26.6% and the plastic radii are approximately the same. Finally, the GZZ strength criterion is applied as a practical approach to estimate the critical tunnel wall displacements of Jianping tunnel, then the triple bench cut method is modified to improve the advance rates of type Ⅳ and type Ⅴ rock mass, the safe and efficient cut of Jianping tunnel is achieved with outstanding engineering performance.

Key words: deep buried tunnels, GZZ strength criterion, strain-softening rock mass, safe and efficient cut