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

Figure 19

The length and depth of crack for three load paths. (a) Left depth. (b) Right depth. (c) Left length. (d) Right length. (e) Average depth. (f) Average length.

(a)

(b)

(c)

(d)

(e)

(f)