Abstract: The Hoek-Brown strength criterion is extensively used in geotechnical engineering field because it can describe the failure characters of integral rock or jointed rock mass. The stability of tunnel rock mass was analyzed by Hoek-Brown and Mohr-Coulomb strength criterion respectively, and the results were compared. Results showed that displacements of key points, plastic radius and plastic zone size from Hoek-Brown strength criterion were larger than those from Mohr-Coulomb strength criterion. Hoek-Brown strength criterion reflects the effect of excavation disturbance on mechanical parameters of rock mass, which makes the analysis results more reasonable. Furthermore, based on the assumption that the disturbance coefficient gradually decreases from the inner wall to the outside of the tunnel, the regularity of excavation disturbance on plastic radius was analyzed by using Hoek-Brown strength criterion. Result showed that plastic radius increased nonlinearly with the increment of excavation disturbance coefficient.

Key words: tunnelling engineering, Hoek-Brown failure criterion, excavation disturbance, plastic radius