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

<div>Superposition calculation of the secondary stress field of the surrounding rock. (a) Secondary stress field in the perimeter rock after excavation. (b) Initial stress field in the surrounding rock. (c) Disturbed stress field.</div>

Advances in Civil Engineering

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Figure 3

Figure 3: Study on Mechanical Effect and Plastic Zone Distribution of Tunnel Surrounding Rock in the Presence of Various Expansion Approaches 