Civil Engineering Reference
In-Depth Information
Slope
design
concept
Basic
slope
type
Bedding
orientation
failure
modes
F-I
Benched
footwall
slope; bedding
undercut.
Bedding dips
shallowly out
of the slope.
Stepped planar
failure on
bedding.
Domains where
bedding joints are
discontinuous or
bedding dip is
flatter than the
friction angle.
Excavate benched slope. Benches
designed to limit the size of
potential stepped failures and
provide catchment for small
failures and raveling debris.
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F-ll
Unbenched
footwall
slope; bedding
not undercut.
Bedding dips
shallowly to
moderately
out of the
slope.
Planar failure
on bedding.
Domains where
bedding joints are
continuous or
bedding dip is
steeper than the
friction angle, but
not steep enough
to initiate
buckling,
ploughing,
bilinear or other
slab-type failures.
Excavate slope parallel to bedding.
Do not undercut bedding.
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F-III
Benched
footwall
slope; bedding
not undercut.
Buckling,
ploughing,
bilinear or
other
slab-type
failures.
Domains where
bedding joints are
continuous and
bedding dip is
significantly
steeper than the
friction angle.
Excavate bench faces parallel to
bedding. Do not undercut
bedding. Bench height designed to
limit potential for development of
slab-type failures. Bench width
designed to provide catchment for
small failures and raveling debris.
Bedding dips
moderately to
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steeply out of
the slope.
F-IV
Unbenched,
supported
footwall
slope; bedding
not undercut.
Buckling,
ploughing,
bilinear or
other
slab-type
failures.
Domains where
bedding joints are
continuous and
bedding dip is
significantly
steeper than the
friction angle.
Excavate slope parallel to bedding.
Apply artificial support to prevent
development of major slab-type
failures.
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H-I
Benched,
unsupported
highwall
slope.
Toppling;
raveling.
Domains where
bedding joints are
continuous and
closely spaced.
Excavate slope using single
benches. Flat bench face angle
designed to limit potential for
toppling. Minimal bench width
designed to provide catchment for
raveling debris.
Bedding
dips
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steeply
into slope.
H-II
Excavate benched slope. Artificial
support designed to limit potential
for toppling, maximize bench
height and/or bench face angle
and/or increase available bench
width to contain small slab-type
failures and raveling debris.
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H-III
Benched,
supported
highwall
slope.
Toppling;
raveling.
Domains where
bedding joints are
continuous and
closely spaced.
Benched,
unsupported
highwall
slope.
Bedding dips
shallowly to
moderately
into slope.
Planer, stepped
planar,
wedges or
stepped
wedges on
cross-joints;
raveling.
Domains not
subject to other
kinematically
possible failure
modes.
Excavate benched slope. Benches
designed to limit the size of
potential planar, wedge and
stepped failures and provide
catchment for small failures and
raveling debris.
Source: Adapted after Hawley and Stewart (1986).
