Research Article

The Influence of Hydraulic Conditions on the Stability of Dual Circular Tunnels in Unsaturated Soils

Figure 9

Collapse mechanisms for  = 20°, H/D = 1, and S/D = 3: (a) /D = 1, (b) /D = 1.5, (c) /D = 2, (d) /D = 2.5, (e) /D = 3, and (f) /D = 4.
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(b)
(c)
(d)
(e)
(f)