Stability Analysis of Surrounding Rock and Treatment Structures in Superlarge Karst Cave of Naqiu Tunnel

Figure 13

Vertical stress of tunnel surrounding rock under different excavation distances: (a) excavation of 3 m; (b) excavation of 12 m; (c) excavation of 21 m; (d) excavation of 30 m.

(a)

(b)

(c)

(d)