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

<div>Destruction the interior wall of tunnels with different cross-sectional shapes after excavation in the physical model test. (a) The horseshoe tunnel. (b) The circular tunnel.</div>

Advances in Civil Engineering

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Figure 15

Figure 15: Instability Process of Crack Propagation and Tunnel Failure Affected by Cross-Sectional Geometry of an Underground Tunnel 