Stability Analysis on Surrounding Rockmass of Deep Tunnel Based on YAI and FD Concepts

摘要

This paper proposes two concepts in order to estimate the stability of surrounding rockmass of deep tunnel, one is YAI (yielding approach index) which is used to denote the stability difference among the zones in surrounding rockmass whose stress states are close to yielding, the other is FD (failure degree) which focuses on the estimation of failure degree of the zones in surrounding rockmass and can be calculated by the equivalent plastic strain when failure occurs. Finally, a numerical analysis on the excavating process of a deep tunnel is performed, and YAI and FD are used to estimate the stability states of rockmass. The accurate estimation on plastic field and the proper evaluation on stability state indicate that these two concepts are rational and of perfectly practical use.