Study on Mechanical Effect and Plastic Zone Distribution of Tunnel Surrounding Rock in the Presence of Various Expansion Approaches

Figure 6

Distribution of the plastic zone in the surrounding rock of 1SEE. (a) Expansion of the excavation by 1.5 m. (b) Expansion of the excavation by 3.0 m. (c) Expansion of the excavation by 4.5 m. (d) Expansion of the excavation by 6.0 m.

(a)

(b)

(c)

(d)