Instability Process of Crack Propagation and Tunnel Failure Affected by Cross-Sectional Geometry of an Underground Tunnel

<div>Numerical simulation results of the minimum principal stress in the rock surrounding the deep tunnel. (a) The horseshoe tunnel. (b) The circular tunnel.</div>

Advances in Civil Engineering

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Figure 14

Figure 14: Instability Process of Crack Propagation and Tunnel Failure Affected by Cross-Sectional Geometry of an Underground Tunnel 