Strength-reduction Finite Element Analysis for Stability of Surrounding Rock Mass with Primary Shotcrete and Rock Bolts

The overall stability evaluation of tunnel surrounding rock mass with primary shotcrete and rock bolts in construction stage is very important for construction safety.Based on geologic conditions of class IV surrounding rock mass in one constructing tunnel,the safety factor of the overall stability of tunnel surrounding rock mass with shotcrete and rock bolts is investigated using ABAQUS through three-dimensional(3D)finite element strength reduction technique coupled with the Hyperbolic Drucker-Prager elasto-plastic model,which takes into account the interaction between the shotcrete lining and rock mass,the interaction between the rock bolts and rock mass.On the basis of analysis of the calculated results,this paper presents a criterion of limit state of tunnel instability.It is reasonable that the safety factor is calculated by the proposed limit state criterion.