(a)
(b)
(c)
(d)
Figure 13: Failure zone scope in the water-resistant strata obtained by the user-defined program on FLAC3D. (a) The water-resistant thickness of 3.5 m. (b) The water-resistant thickness of 4.0 m. (c) The water-resistant thickness of 4.5 m. (d) The water-resistant thickness of 5.0 m.