Sensitivity Analysis of Factors Affecting the Stability of Deep Buried Tunnel

The excavation of deep tunnels has significant spatial and temporal effects on the stress distribution of the surrounding rock. Accurately describing the distribution characteristics of the surrounding rock stress state is a key issue in analyzing the failure mechanism of the surrounding rock. Based on the numerical analysis, a study on the influencing factors of the surrounding rock stress state during the excavation of deep tunnels was conducted. The results show that (i) the surrounding rock was divided into stress mutation, disturbed, and stables zones using the quantitative index: the peak and stable value of the stress triaxiality, which can reflect the influence of the principal stress orientation; (ii) the evolution law of the stress path of the surrounding rocks in different areas was obtained, and the detailed loading method of laboratory test is proposed, which could consider the influence of the principal stress magnitude and orientation during tunnel excavation; and (iii) five variable indices were used to conduct sensitivity analysis on the influencing factors of the surrounding rock stress state. Specifically, the direction of in situ stress and lateral pressure coefficient considerably influences the disturbance range, and the depth the tunnel is buried affects the deformation and failure characteristics of the surrounding rock. This paper provides a modified and quantified test method for tunnel stability analysis.