Civil Engineering Reference
In-Depth Information
(a)
(b)
(c)
Failure slab
Bedding joint
Fault
(d)
(e)
(f)
(g)
(h)
Figure 15.6
Example 2—kinematically possible failure modes.
For highwall domains, the key failure modes
that controlled stability included toppling on bed-
ding (Figure 15.6(f)), stepped-path plane failure
involving sliding along cross-joints with release
on bedding joints (Figure 15.6(g)), and raveling
(i.e. rock falls involving individual detached rock
blocks) (Figure 15.6(h)).
orientation, bedding joint spacing, rock mass
competency, discontinuity shear strength and
ground water conditions. The analyses techniques
used for simple plane, wedge and toppling failure
were similar to those presented in Chapters 6, 7
and 9. More complex failure modes, such as bilin-
ear slab, ploughing and buckling failure, were
analyzed using limit equilibrium methods similar
to those described by Hawley
et al
. (1986).
Analyses results for footwall domains were
presented in the form of stability curves that
related the dip of bedding to slope or bench
height for a given factor of safety. As illustrated
schematically in Figure 15.7, multiple curves were
developed for each mode to assess sensitivity to
15.3.7 Stability analyses
Stability analyses were conducted for each of the
primary modes of failure in each domain using
limit equilibrium techniques. Failure models were
developed to assess the sensitivity of stability to
variations in the geometry of the slope, bedding
