Stability analysis of tunnel surrounding rock based on different strength reduction paths

A strength reduction method(SRM) based on the generalized Hoek-Brown yield criterion was used to analyze the stability of tunnel surrounding rock.The program code of SRM was compiled by FISH language embedded in the finite difference software FLAC^3D,and the safety factor was determined according to the criteria including the convergence of numerical computation and the mutagenicity of feature points' displacement.Regarding to four basic input parameters in the generalized Hoek-Brown yield criterion,σ_ci,m_i,GSI and D,the equivalent approach index was introduced to discuss the rationality of seven strength reduction paths.It is concluded that the rationality of strength reduction paths depends on specific engineering parameters.This conclusion is verified by an engineering case.The global stability of tunnel surrounding rock decreases with the increase of D values,and the stability judging method combining the convergence of numerical computation with the mutagenicity of feature points' displacement is more reasonable than either of them.