Civil Engineering Reference
In-Depth Information
(c)
How much more undercutting of the fault
must occur before toppling failure takes
place?
(b)
From the dimensions given on Figure 9.13,
the following values are obtained to test
stability conditions:
(d)
What
stabilization
measures
would
be
appropriate for this slope?
x/y
=
0.3
Solution
tan 15
=
0.27
(a)
The
factor
of
safety
against
sliding
is
determined
by
the
methods
described
in
The block is stable against toppling because
0.3
>
0.27.
Chapter 6; the equation for a dry slope is
(c)
If weathering results in the width of the base
of the block being reduced by a further 0.2 m,
toppling is likely to occur because:
x/y
cA
+
W
cos
ψ
p
·
tan
φ
p
FS
=
W
sin
ψ
p
=
(
1.8
−
0.2
)/
6
≈
0.27.
=
((
25
×
1.8
)
+
(
254
×
cos 15
(d)
Stabilization measures which could be used
on this slope include the following:
×
×
tan 20
))/(
254
sin 15
)
≈
2.0
where
•
Prevention of ground water infiltration
to limit build-up of water pressure both
in the tension crack and on the fault at
the toe.
A
=
base area of block
1.8 m
2
/
m
=
•
Application of reinforced shotcrete to the
fault to prevent further weathering.
W
=
weight of block/m
•
Trim blasting to reduce the slope angle
and the dimension
y
, if this can be
achieved without destabilizing the block.
=
23.5
×
1.8
×
6
=
254 kN
/
m
