Fig. 15

Reinforcement 3D model. [①No reinforcement; ② Full under-pit reinforcement; ③ Portal frame reinforcement; ④ Portal anti-uplift reinforcement; ⑤ Grouting reinforcement; ⑥ Portal frame reinforcement combined with counter-pressure].

Reinforcement 3D model. [①No reinforcement; ② Full under-pit reinforcement; ③ Portal frame reinforcement; ④ Portal anti-uplift reinforcement; ⑤ Grouting reinforcement; ⑥ Portal frame reinforcement combined with counter-pressure].